Publications by year
In Press
Bebber DP, Richards VR (In Press). A meta-analysis of the effect of organic and mineral fertilizers on soil microbial diversity.
Abstract:
A meta-analysis of the effect of organic and mineral fertilizers on soil microbial diversity
ABSTRACTOrganic agriculture, employing manures or composts, has been proposed as a way of mitigating undesirable impacts of mineral fertilizer use. of particular interest is the effect of fertilizer regime on soil microbes, which are key to nutrient cycling, plant health and soil structure. However, the effect of fertilizers on soil microbial diversity remains poorly understood. Since biological diversity is an important determinant of ecosystem function and a fundamental metric in community ecology, the effects of fertilizer regimes on soil microbial diversity are of theoretical and applied interest. Here, we conduct a meta-analysis of 37 studies reporting microbial diversity metrics in mineral fertilized (NPK), organically fertilized (ORG) and unfertilized control (CON) soils. of these studies, 32 reported taxonomic diversity derived from sequencing, gradient gel electrophoresis, or RFLP. Functional diversity, derived from Biolog Ecoplate™ measures of carbon substrate metabolism, was reported in 8 studies, with 3 studies reporting both diversity metrics. Bacterial and archaeal diversity was reported in 28 taxonomic studies, and fungal diversity in 8 taxonomic studies. We found that functional diversity was 2.8 % greater in NPK compared with CON, 7.0 % greater in ORG vs CON, and 3.8 % greater in ORG vs NPK. Bacterial and archaeal taxonomic diversity was not significantly different between NPK and CON, but on average 2.9% greater in ORG vs CON, and 2.4 % greater in ORG vs. NPK. Fungal taxonomic diversity was not significantly different between any treatment pairs. There was very high residual heterogeneity in all meta-analyses of soil diversity, suggesting that a large amount of further research is required to fully understand the influence of fertilizer regimes on microbial diversity and ecosystem function.
Abstract.
Bebber DP, Gurr SJ (In Press). Biotic interactions and climate in species distribution modelling.
Abstract:
Biotic interactions and climate in species distribution modelling
SummarySpecies have preferred environmental niches 1 and their geographical distributions respond to global climate change 2. Predicting range shifts under climate change has profound implications for conservation of biodiversity 3, provision of ecosystem services, and in the management of invasive species 4. Species distribution modelling (SDM) has largely focussed on climate variations, but biotic interactions, such as predation and competition, can alter potential distributions 5,6 and affect migration rates 7. However, a lack of data on biotic interactions has restricted consideration of these factors for many species 1. Here, we compare the power of biotic and climatic factors as predictors of global distributions of hundreds of crop pests and pathogens (CPPs), for which host preferences are known. We show that host availability is a more important predictor of endobiotic pathogen distributions (fungi, oomycetes, bacteria, viruses and nematodes) than of epibiotic pest distributions (insect herbivores). Conversely, climatic variables are better predictors of epibiotic pest distributions. These results are robust to statistical controls for varying observational capacity among countries. Our findings demonstrate that life history affects global scale species distributions and that SDM should incorporate biotic interactions as well as climate.
Abstract.
Raza MM, Bebber DP (In Press). Climate change, biotic yield gaps and disease pressure in cereal crops.
Abstract:
Climate change, biotic yield gaps and disease pressure in cereal crops
AbstractPlant diseases are major causes of crop yield losses and exert a financial burden via expenditure on disease control. The magnitude of these burdens depends on biological, environmental and management factors, but this variation is poorly understood. Here we model the effects of weather on potential yield losses due to fungal plant pathogens (the biotic yield gap, Ygb) using experimental trials of fungicide-treated and untreated cereal crops in the UK, and project future Ygb under climate change. We find that Ygb varies between 10 and 20 % of fungicide-treated yields depending on crop, and increases under warmer winter and wetter spring conditions. Ygb will increase for winter wheat and winter barley under climate change, while declining for spring crops because drier summers offset the effects of warmer winters. Potential disease impacts are comparable in magnitude to the effects of suboptimal weather and crop varieties.
Abstract.
Reyes-Herrera PH, Torres-Bedoya E, Lopez-Alvarez D, Burbano-David D, Carmona SL, Bebber DP, Studholme DJ, Betancourt M, Soto-Suarez M (In Press). Genome sequence data reveal at least two distinct incursions of the tropical race 4 (TR4) variant of <i>Fusarium</i> wilt into South America.
Abstract:
Genome sequence data reveal at least two distinct incursions of the tropical race 4 (TR4) variant of Fusarium wilt into South America
AbstractThe global banana industry is threatened by one of the most devastating diseases: Fusarium wilt (FWB). FWB is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc), which almost annihilated the banana production in the late 1950s. A new strain of Foc, known as tropical race 4 (TR4), attacks a wide range of banana varieties including Cavendish clones which are the source of 99% of banana exports. In 2019, Foc TR4 was reported in Colombia, and more recently (2021) in Peru. In this study, we sequenced three fungal isolates identified as Foc TR4 from La Guajira (Colombia) and compared them against 19 whole-genome sequences of Foc TR4 publicly available, including four genome sequences recently released from Peru. To understand the genetic relatedness of the Colombian Foc TR4 isolates and those from Peru, we conducted a phylogenetic analysis based on a genome-wide set of single nucleotide polymorphisms (SNPs). Additionally, we compared the genomes of the 22 available Foc TR4 isolates looking for the presence-absence of gene polymorphisms and genomic regions. Our results reveal that (i) the Colombian and Peruvian isolates are genetically distant, which could be better explained by independent incursions of the pathogen to the continent, and (ii) there is a high correspondence between the genetic relatedness and geographic origin of Foc TR4. The profile of present/absent genes and the distribution of missing genomic regions showed a high correspondence to the clades recovered in the phylogenetic analysis, supporting the results obtained by SNP-based phylogeny.
Abstract.
Chaloner TM, Gurr SJ, Bebber DP (In Press). Geometry and evolution of the ecological niche in plant-associated microbes.
Abstract:
Geometry and evolution of the ecological niche in plant-associated microbes
AbstractThe ecological niche of a species can be conceptualized as a volume in multidimensional space, where each dimension describes an abiotic condition or biotic resource. The shape and size of this volume strongly determines interactions among species and influences their global distribution, but the geometry of the niche is poorly understood. Here, we analyse temperature response functions and host plant ranges for hundreds of fungi and oomycetes. We demonstrate that niche specialization is independent on abiotic and biotic axes, that host interactions restrict fundamental niche breadth to form the realized niche, and that both abiotic and biotic niches show limited phylogenetic constraint. Such niche adaptability makes plant pathogens a formidable threat to agriculture and forestry.
Abstract.
Bebber DP, Field E, Heng G, Mortimer P, Holmes T, Gurr S (In Press). Many unreported crop pests and pathogens are probably already present. Global Change Biology
Varma V, Thompson W, Duarte SB, Krütli P, Six J, Bebber DP (In Press). Mapping the impacts of hurricanes Maria and Irma on banana production area in the Dominican Republic.
Abstract:
Mapping the impacts of hurricanes Maria and Irma on banana production area in the Dominican Republic
AbstractExtreme weather events can have devastating impacts on agricultural systems, and the livelihoods that depend on them. Tools for rapid, comprehensive and cost-effective assessment of impacts, especially if carried out remotely, can be of great value in planning systematic recovery of production, as well as assessing risks from future events. Here, we use openly available remote sensing data to quantify the impacts of hurricanes Irma and Maria in 2017 on banana production area in the Dominican Republic — the world’s largest producer of organic bananas. Further, we assess the risk to current production area if a similar extreme event were to re-occur. Hurricane associated damage was mapped using a simple change detection algorithm applied to Synthetic Aperture Radar (SAR) data over the three main banana growing provinces of northern Dominican Republic, i.e. Monte Cristi, Valverde and Santiago. The map of hurricane affected area was overlaid with banana plantation distributions for 2017 and 2019 that were mapped (accuracy = 99.8%) using a random forest classifier, and a combination of SAR and multi-spectral satellite data. Our results show that 11.35% of banana plantation area was affected by hurricane damage in 2017. Between 2017 and 2019, there was a high turnover of plantation area, but with a net gain of 10.8%. However, over a quarter (26.9%) of new plantation area spatially overlapped with regions which had seen flooding or damage from hurricanes in 2017. Our results indicate that banana production systems in northern Dominican Republic saw extensive damage in the aftermath of hurricanes Irma and Maria. While production area has recovered since then, a substantial proportion of new plantations, and a greater fraction of production area in general, occur at locations at risk from future extreme events.
Abstract.
Wu Y, Gong Z, Bebber DP, Miao J, Zhao Z, Jiang Y, Xiao S, Zhang G, Yu D, Fang J, et al (In Press). Phenological matching drives wheat pest range shift under climate change.
Abstract:
Phenological matching drives wheat pest range shift under climate change
AbstractShifting geographical ranges of crop pests and pathogens in response to climate change pose a threat to food security (1, 2). The orange wheat blossom midge (Sitodiplosis mosellana Géhin) is responsible for significant yield losses in China (3), the world’s largest wheat producer. Here we report that rising temperatures in the North China Plain have resulted in a mean northward range shift of 3.3° (58.8 km per decade) from the 1950s to 2010s, which accelerated to 91.3 km per decade after 1985 when the highly toxic pesticide hexachlorocyclohexane (HCH) was banned (4). Phenological matching between wheat midge adult emergence and wheat heading in this new expanded range has resulted in greater damage to wheat production. Around $286.5 million worth of insecticides were applied to around 19 million hectares in an attempt to minimize wheat midge damage to crops between 1985 and 2016. Despite use of these pesticides, wheat midge caused losses of greater than 0.95 million metric tons of grain during this period. Our results demonstrate the potential for indirect negative impacts of climate change on crop production and food security, and constitute the first large scale example of plant pest range shift due to global warming.
Abstract.
Chaloner TM, Gurr SJ, Bebber DP (In Press). Plant pathogen infection risk tracks global crop yields under climate change.
Abstract:
Plant pathogen infection risk tracks global crop yields under climate change
AbstractGlobal food security is strongly determined by crop production. Climate change-induced losses to production can occur directly, or indirectly, including via the distributions and impacts of plant pathogens. However, the likely changes in pathogen pressure in relation to global crop production are poorly understood. Here we show that temperature-dependent infection risk, r(T), for 80 fungal and oomycete crop pathogens will track projected yield changes in 12 crops over the 21st Century. For most crops, both yields and r(T) are likely to increase at high latitudes. In contrast, while the tropics will see little or no productivity gains, r(T) is also likely to decline. In addition, the USA, Europe and China may experience major changes in pathogen assemblages. The benefits of yield gains may therefore be tempered by the increased burden of crop protection due to increased and unfamiliar pathogens.
Abstract.
Bebber DP (In Press). The Brazilian Amazon Protected Area Network was largely unaffected by recent satellite-detectable fires.
Abstract:
The Brazilian Amazon Protected Area Network was largely unaffected by recent satellite-detectable fires
AbstractAugust 2019 saw dramatic increases in wildfires in the Brazilian Amazon, leading to arguments between Brazil and G7 leaders and widespread concern among conservationists. Popular media reports suggested that ‘swathes of the Amazon rainforest in Brazil are on fire’. Here we investigate the spatial distribution of fires through August 2019, showing that fires were largely restricted to deforested regions and areas with low canopy cover, particularly in unprotected areas that comprise half the region. In contrast, Brazil’s protected areas had one third as many fires, and forest in protected areas with high canopy cover was almost entirely unaffected by fire. Protected areas reduce deforestation and carbon emissions, and have proved largely untouched by recent fires. However, fires in closed-canopy forest cannot readily be detected by satellite remote-sensing and so this analysis likely underestimates the burned area in intact forest, both in protected and unprotected areas.
Abstract.
2023
Reyes-Herrera PH, Torres-Bedoya E, Lopez-Alvarez D, Burbano-David D, Carmona SL, Bebber DP, Studholme DJ, Betancourt M, Soto-Suarez M (2023). Genome Sequence Data Reveal at Least Two Distinct Incursions of the Tropical Race 4 Variant of Fusarium Wilt into South America.
Phytopathology,
113(1), 90-97.
Abstract:
Genome Sequence Data Reveal at Least Two Distinct Incursions of the Tropical Race 4 Variant of Fusarium Wilt into South America.
The global banana industry is threatened by one of the most devastating diseases: Fusarium wilt of banana. Fusarium wilt of banana is caused by the soilborne fungus Fusarium oxysporum f. sp. cubense (Foc), which almost annihilated the banana production in the late 1950s. A new strain of Foc, known as tropical race 4 (TR4), attacks a wide range of banana varieties, including Cavendish clones, which are the source of 99% of banana exports. In 2019, Foc TR4 was reported in Colombia, and more recently (2021) in Peru. In this study, we sequenced three fungal isolates identified as Foc TR4 from La Guajira (Colombia) and compared them against 19 whole-genome sequences of Foc TR4 publicly available, including four genome sequences recently released from Peru. To understand the genetic relatedness of the Colombian Foc TR4 isolates and those from Peru, we conducted a phylogenetic analysis based on a genome-wide set of single nucleotide polymorphisms (SNPs). Additionally, we compared the genomes of the 22 available Foc TR4 isolates, looking for the presence-absence of gene polymorphisms and genomic regions. Our results reveal that (i) the Colombian and Peruvian isolates are genetically distant, which could be better explained by independent incursions of the pathogen to the continent, and (ii) there is a high correspondence between the genetic relatedness and geographic origin of Foc TR4. The profile of present/absent genes and the distribution of missing genomic regions showed a high correspondence to the clades recovered in the phylogenetic analysis, supporting the results obtained by SNP-based phylogeny.
Abstract.
Author URL.
Thompson WJ, Varma V, Joerin J, Bonilla-Duarte S, Bebber DP, Blaser-Hart W, Kopainsky B, Späth L, Curcio B, Six J, et al (2023). Smallholder Farmer Resilience to Extreme Weather Events in Global Food Value Chains.
2022
Bebber DP, Richards VR (2022). A meta-analysis of the effect of organic and mineral fertilizers on soil microbial diversity. Applied Soil Ecology, 175, 104450-104450.
Bebber DP (2022). CLIMATE CHANGE Global warming and China's crop pests.
NATURE FOOD,
3(1), 6-7.
Author URL.
Garrett KA, Bebber DP, Etherton BA, Gold KM, Plex Sulá AI, Selvaraj MG (2022). Climate Change Effects on Pathogen Emergence: Artificial Intelligence to Translate Big Data for Mitigation.
Annu Rev Phytopathol,
60, 357-378.
Abstract:
Climate Change Effects on Pathogen Emergence: Artificial Intelligence to Translate Big Data for Mitigation.
Plant pathology has developed a wide range of concepts and tools for improving plant disease management, including models for understanding and responding to new risks from climate change. Most of these tools can be improved using new advances in artificial intelligence (AI), such as machine learning to integrate massive data sets in predictive models. There is the potential to develop automated analyses of risk that alert decision-makers, from farm managers to national plant protection organizations, to the likely need for action and provide decision support for targeting responses. We review machine-learning applications in plant pathology and synthesize ideas for the next steps to make the most of these tools in digital agriculture. Global projects, such as the proposed global surveillance system for plant disease, will be strengthened by the integration of the wide range of new data, including data from tools like remote sensors, that are used to evaluate the risk ofplant disease. There is exciting potential for the use of AI to strengthen global capacity building as well, from image analysis for disease diagnostics and associated management recommendations on farmers' phones to future training methodologies for plant pathologists that are customized in real-time for management needs in response to the current risks. International cooperation in integrating data and models will help develop the most effective responses to new challenges from climate change.
Abstract.
Author URL.
Raza MM, Bebber DP (2022). Climate change and plant pathogens.
Curr Opin Microbiol,
70Abstract:
Climate change and plant pathogens.
Global food security is threatened by climate change, both directly through responses of crop physiology and productivity, and indirectly through responses of plant-associated microbiota, including plant pathogens. While the interactions between host plants, pathogens and environmental drivers can be complex, recent research is beginning to indicate certain overall patterns in how plant diseases will affect crop production in future. Here, we review the results of three methodological approaches: large-scale observational studies, process-based disease models and experimental comparisons of pathosystems under current and future conditions. We find that observational studies have tended to identify rising temperatures as the primary driver of disease impact. Process-based models suggest that rising temperatures will lead to latitudinal shifts in disease pressure, but drying conditions could mitigate disease risk. Experimental studies suggest that rising atmospheric CO2 will exacerbate disease impacts. Plant diseases may therefore counteract any crop yield increases due to climate change.
Abstract.
Author URL.
Johns LE, Bebber DP, Gurr SJ, Brown NA (2022). Emerging health threat and cost of Fusarium mycotoxins in European wheat.
Nature Food,
3(12), 1014-1019.
Abstract:
Emerging health threat and cost of Fusarium mycotoxins in European wheat
AbstractMycotoxins harm human and livestock health, while damaging economies. Here we reveal the changing threat of Fusarium head blight (FHB) mycotoxins in European wheat, using data from the European Food Safety Agency and agribusiness (BIOMIN, World Mycotoxin Survey) for ten years (2010–2019). We show persistent, high, single- and multi-mycotoxin contamination alongside changing temporal-geographical distributions, indicative of altering FHB disease pressure and pathogen populations, highlighting the potential synergistic negative health consequences and economic cost.
Abstract.
Zurek M, Ingram J, Sanderson Bellamy A, Goold C, Lyon C, Alexander P, Barnes A, Bebber DP, Breeze TD, Bruce A, et al (2022). Food System Resilience: Concepts, Issues, and Challenges. Annual Review of Environment and Resources, 47(1), 511-534.
Chaloner T (2022). Plant Pathogen Temperature Ecology.
Abstract:
Plant Pathogen Temperature Ecology
Plant pathogenic fungi and oomycetes (hereafter ‘plant pathogens’) pose serious risks to crop production and natural landscapes, thereby threatening global food security and ecosystem health. Temperature directly affects plant pathogen physiology and is a key determinant of pathogen distributions and resultant crop risk, both in space and time. Global mean surface temperature is increasing and extreme weather events, such as heat waves, are becoming more common. To protect the warming biosphere we need to better understand how plant pathogens respond to temperature. In this thesis I interrogate previously published data on temperature responses for hundreds of plant pathogens, as well as utilise the fungal wheat pathogen, Zymoseptoria tritici, as a model pathogen system for studying plant pathogen temperature ecology. In Chapter 1, I summarize existing literature on plant pathogen temperature ecology and present the major aims of research detailed in this thesis. Materials and Methods that are used in more than one data Chapter are described in Chapter 2. In Chapter 3, I investigate the geometry and evolution of two ecological niche axes, temperature response and host range, for hundreds of potentially destructive plant pathogens. I find evidence for Hutchinson’s distinction between the fundamental and realized niche. I also find that abiotic and biotic niches can evolve independently in these microbial species. Chapter 4 explores how climate change will directly shift global infection risk, for a suite of plant pathogens. I find that infection risk will likely spread polewards during the 21st century. This Chapter also highlights the importance of considering plant pathogen infection risk, when quantifying changes in agricultural productivity under climate change. A mechanistic, weather-dependent model of Septoria tritici blotch (STB) disease risk is developed in Chapter 5. The model was unable to accurately predict annual STB disease risk across the UK. This Chapter nevertheless presents a new approach to mechanistically modelling STB and could provide a useful resource for future model development. In Chapter 6, I investigate Z. tritici responses to short-term elevated temperatures. I report the first preliminary evidence of within-species variation in survival at elevated temperature in Z. tritici, the first evidence for thermal priming in Z. tritici, as well as the first description of morphological changes of Z. tritici in response to fluctuating temperatures. In Chapter 7, I discuss the findings of this thesis and detail outstanding questions that require future investigation. Previously published (but poorly accessible) plant pathogen temperature response data collated and used in this thesis are deposited in an open-access repository, representing the most comprehensive dataset of its kind currently available for plant pathogens.
Abstract.
Bebber DP, Chaloner TM (2022). Specialists, generalists and the shape of the ecological niche in fungi. New Phytologist, 234(2), 345-349.
Bebber DP (2022). The long road to a sustainable banana trade. PLANTS, PEOPLE, PLANET
Bebber DP (2022). Weather does influence fungal and oomycete crop disease outbreaks, but ProMED‐mail reports don’t prove it. New Phytologist, 234(5), 1557-1558.
Falloon P, Bebber DP, Dalin C, Ingram J, Mitchell D, Hartley TN, Johnes PJ, Newbold T, Challinor AJ, Finch J, et al (2022). What do changing weather and climate shocks and stresses mean for the UK food system?. Environmental Research Letters, 17(5), 051001-051001.
2021
Tibpromma S, Dong Y, Ranjitkar S, Schaefer DA, Karunarathna SC, Hyde KD, Jayawardena RS, Manawasinghe IS, Bebber DP, Promputtha I, et al (2021). Climate-Fungal Pathogen Modeling Predicts Loss of up to One-Third of Tea Growing Areas.
Frontiers in Cellular and Infection Microbiology,
11Abstract:
Climate-Fungal Pathogen Modeling Predicts Loss of up to One-Third of Tea Growing Areas
Climate change will affect numerous crops in the future; however, perennial crops, such as tea, are particularly vulnerable. Climate change will also strongly influence fungal pathogens. Here, we predict how future climatic conditions will impact tea and its associated pathogens. We collected data on the three most important fungal pathogens of tea (Colletotrichum acutatum, Co. camelliae, and Exobasidium vexans) and then modeled distributions of tea and these fungal pathogens using current and projected climates. The models show that baseline tea-growing areas will become unsuitable for Camellia sinensis var. sinensis (15 to 32% loss) and C. sinensis var. assamica (32 to 34% loss) by 2050. Although new areas will become more suitable for tea cultivation, existing and potentially new fungal pathogens will present challenges in these areas, and they are already under other land-use regimes. In addition, future climatic scenarios suitable range of fungal species and tea suitable cultivation (respectively in CSS and CSA) growing areas are Co. acutatum (44.30%; 31.05%), Co. camelliae (13.10%; 10.70%), and E. vexans (10.20%; 11.90%). Protecting global tea cultivation requires innovative approaches that consider fungal genomics as part and parcel of plant pathology.
Abstract.
Rhiney K, Guido Z, Knudson C, Avelino J, Bacon CM, Leclerc G, Aime MC, Bebber DP (2021). Epidemics and the future of coffee production.
Proceedings of the National Academy of Sciences of the United States of America,
118(27).
Abstract:
Epidemics and the future of coffee production
In this perspective, we draw on recent scientific research on the coffee leaf rust (CLR) epidemic that severely impacted several countries across Latin America and the Caribbean over the last decade, to explore how the socioeconomic impacts from COVID-19 could lead to the reemergence of another rust epidemic. We describe how past CLR outbreaks have been linked to reduced crop care and investment in coffee farms, as evidenced in the years following the 2008 global financial crisis. We discuss relationships between CLR incidence, farmer-scale agricultural practices, and economic signals transferred through global and local effects. We contextualize how current COVID-19 impacts on labor, unemployment, stay-at-home orders, and international border policies could affect farmer investments in coffee plants and in turn create conditions favorable for future shocks. We conclude by arguing that COVID-19's socioeconomic disruptions are likely to drive the coffee industry into another severe production crisis. While this argument illustrates the vulnerabilities that come from a globalized coffee system, it also highlights the necessity of ensuring the well-being of all. By increasing investments in coffee institutions and paying smallholders more, we can create a fairer and healthier system that is more resilient to future social-ecological shocks.
Abstract.
Chaloner TM, Gurr SJ, Bebber DP (2021). Plant pathogen infection risk tracks global crop yields under climate change. Nature Climate Change, 11(8), 710-715.
Torres Bedoya E, Bebber DP, Studholme DJ (2021). Taxonomic Revision of the Banana Fusarium Wilt TR4 Pathogen is Premature.
Phytopathology,
111(12), 2141-2145.
Abstract:
Taxonomic Revision of the Banana Fusarium Wilt TR4 Pathogen is Premature.
Taxonomic revisions for pathogens of crops should be based on robust underpinning evidence. Recently, a substantial revision was proposed for the taxonomy of the causative agent of Fusarium wilt on banana. We reanalyzed the data on which this revision was based and discovered that the data do not robustly support the proposals. Several apparent discrepancies and errors in the published phylogenies cast further doubt on the conclusions drawn from them. Although we do not assert that the authors' conclusions are incorrect, we posit that the taxonomic changes are premature, given the data currently in the public domain.[Formula: see text] Copyright © 2021 the Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Author URL.
Bebber DP (2021). The gap between atmospheric nitrogen deposition experiments and reality. Science of the Total Environment, 801, 149774-149774.
Ristaino JB, Anderson PK, Bebber DP, Brauman KA, Cunniffe NJ, Fedoroff NV, Finegold C, Garrett KA, Gilligan CA, Jones CM, et al (2021). The persistent threat of emerging plant disease pandemics to global food security (vol 118, e2022239118, 2021).
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA,
118(40).
Author URL.
Ristaino JB, Anderson PK, Bebber DP, Brauman KA, Cunniffe NJ, Fedoroff NV, Finegold C, Garrett KA, Gilligan CA, Jones CM, et al (2021). The persistent threat of emerging plant disease pandemics to global food security.
Proc Natl Acad Sci U S A,
118(23).
Abstract:
The persistent threat of emerging plant disease pandemics to global food security.
Plant disease outbreaks are increasing and threaten food security for the vulnerable in many areas of the world. Now a global human pandemic is threatening the health of millions on our planet. A stable, nutritious food supply will be needed to lift people out of poverty and improve health outcomes. Plant diseases, both endemic and recently emerging, are spreading and exacerbated by climate change, transmission with global food trade networks, pathogen spillover, and evolution of new pathogen lineages. In order to tackle these grand challenges, a new set of tools that include disease surveillance and improved detection technologies including pathogen sensors and predictive modeling and data analytics are needed to prevent future outbreaks. Herein, we describe an integrated research agenda that could help mitigate future plant disease pandemics.
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Author URL.
2020
Fones HN, Bebber DP, Chaloner TM, Kay WT, Steinberg G, Gurr SJ (2020). Author Correction: Threats to global food security from emerging fungal and oomycete crop pathogens. Nature Food, 1(7), 455-456.
Chaloner TM, Gurr SJ, Bebber DP (2020). Geometry and evolution of the ecological niche in plant-associated microbes.
Nature Communications,
11(1).
Abstract:
Geometry and evolution of the ecological niche in plant-associated microbes
AbstractThe ecological niche can be thought of as a volume in multidimensional space, where each dimension describes an abiotic condition or biotic resource required by a species. The shape, size, and evolution of this volume strongly determine interactions among species and influence their current and potential geographical distributions, but the geometry of niches is poorly understood. Here, we analyse temperature response functions and host plant ranges for hundreds of potentially destructive plant-associated fungi and oomycetes. We demonstrate that niche specialization is uncorrelated on abiotic (i.e. temperature response) and biotic (i.e. host range) axes, that host interactions restrict fundamental niche breadth to form the realized niche, and that both abiotic and biotic niches show limited phylogenetic constraint. The ecological terms ‘generalist’ and ‘specialist’ therefore do not apply to these microbes, as specialization evolves independently on different niche axes. This adaptability makes plant pathogens a formidable threat to agriculture and forestry.
Abstract.
Bütikofer L, Anderson K, Bebber DP, Bennie JJ, Early RI, Maclean IMD (2020). The problem of scale in predicting biological responses to climate. Global Change Biology, 26(12), 6657-6666.
Fones HN, Bebber DP, Chaloner TM, Kay WT, Steinberg G, Gurr SJ (2020). Threats to global food security from emerging fungal and oomycete crop pathogens. Nature Food, 1(6), 332-342.
2019
Chaloner TM, Fones HN, Varma V, Bebber DP, Gurr SJ (2019). A new mechanistic model of weather-dependent Septoria tritici blotch disease risk.
Philos Trans R Soc Lond B Biol Sci,
374(1775).
Abstract:
A new mechanistic model of weather-dependent Septoria tritici blotch disease risk.
We present a new mechanistic model for predicting Septoria tritici blotch (STB) disease, parameterized with experimentally derived data for temperature- and wetness-dependent germination, growth and death of the causal agent, Zymoseptoria tritici. The output of this model (A) was compared with observed disease data for UK wheat over the period 2002-2016. In addition, we compared the output of a second model (B), in which experimentally derived parameters were replaced by a modified version of a published Z. tritici thermal performance equation, with the same observed disease data. Neither model predicted observed annual disease, but model a was able to differentiate UK regions with differing average disease risks over the entire period. The greatest limitations of both models are: broad spatial resolution of the climate data, and lack of host parameters. Model B is further limited by its lack of explicitly defined pathogen death, leading to a cumulative overestimation of disease over the course of the growing season. Comparison of models a and B demonstrates the importance of accounting for the temperature-dependency of pathogen processes important in the initiation and progression of disease. However, effective modelling of STB will probably require similar experimentally derived parameters for host and environmental factors, completing the disease triangle. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'. This issue is linked with the subsequent theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'.
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Author URL.
Bebber DP (2019). Climate change effects on Black Sigatoka disease of banana.
Philos Trans R Soc Lond B Biol Sci,
374(1775).
Abstract:
Climate change effects on Black Sigatoka disease of banana.
Climate change has significantly altered species distributions in the wild and has the potential to affect the interactions between pests and diseases and their human, animal and plant hosts. While several studies have projected changes in disease distributions in the future, responses to historical climate change are poorly understood. Such analyses are required to dissect the relative contributions of climate change, host availability and dispersal to the emergence of pests and diseases. Here, we model the influence of climate change on the most damaging disease of a major tropical food plant, Black Sigatoka disease of banana. Black Sigatoka emerged from Asia in the late twentieth Century and has recently completed its invasion of Latin American and Caribbean banana-growing areas. We parametrize an infection model with published experimental data and drive the model with hourly microclimate data from a global climate reanalysis dataset. We define infection risk as the sum of the number of modelled hourly spore cohorts that infect a leaf over a time interval. The model shows that infection risk has increased by a median of 44.2% across banana-growing areas of Latin America and the Caribbean since the 1960s, due to increasing canopy wetness and improving temperature conditions for the pathogen. Thus, while increasing banana production and global trade have probably facilitated Black Sigatoka establishment and spread, climate change has made the region increasingly conducive for plant infection. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'. This issue is linked with the subsequent theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'.
Abstract.
Author URL.
Varma V, Bebber DP (2019). Climate change impacts on banana yields around the world. Nature Climate Change, 9(10), 752-757.
Warmington RJ, Kay W, Jeffries A, O'Neill P, Farbos A, Moore K, Bebber DP, Studholme DJ (2019). High-Quality Draft Genome Sequence of the Causal Agent of the Current Panama Disease Epidemic.
Microbiol Resour Announc,
8(36).
Abstract:
High-Quality Draft Genome Sequence of the Causal Agent of the Current Panama Disease Epidemic.
We present a high-quality draft genome assembly for Fusarium oxysporum f. sp. cubense tropical race 4 (Fusarium odoratissimum), assembled from PacBio reads and consisting of 15 contigs with a total assembly size of 48.59 Mb. This strain appears to belong to vegetative compatibility group complex 01213/16.
Abstract.
Author URL.
Bebber DP, Field E, Heng G, Mortimer P, Holmes T, Gurr SJ (2019). Many unreported crop pests and pathogens are probably already present.
2018
Bebber DP, Butt N (2018). Author Correction: Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.
Sci Rep,
8(1).
Abstract:
Author Correction: Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Abstract.
Author URL.
Lewis CM, Persoons A, Bebber DP, Kigathi RN, Maintz J, Findlay K, Bueno-Sancho V, Corredor-Moreno P, Harrington SA, Kangara N, et al (2018). Potential for re-emergence of wheat stem rust in the United Kingdom.
Commun Biol,
1Abstract:
Potential for re-emergence of wheat stem rust in the United Kingdom.
Wheat stem rust, a devastating disease of wheat and barley caused by the fungal pathogen Puccinia graminis f. sp. tritici, was largely eradicated in Western Europe during the mid-to-late twentieth century. However, isolated outbreaks have occurred in recent years. Here we investigate whether a lack of resistance in modern European varieties, increased presence of its alternate host barberry and changes in climatic conditions could be facilitating its resurgence. We report the first wheat stem rust occurrence in the United Kingdom in nearly 60 years, with only 20% of UK wheat varieties resistant to this strain. Climate changes over the past 25 years also suggest increasingly conducive conditions for infection. Furthermore, we document the first occurrence in decades of P. graminis on barberry in the UK. Our data illustrate that wheat stem rust does occur in the UK and, when climatic conditions are conducive, could severely harm wheat and barley production.
Abstract.
Author URL.
Warren-Thomas EM, Edwards DP, Bebber DP, Chhang P, Diment AN, Evans TD, Lambrick FH, Maxwell JF, Nut M, O'Kelly HJ, et al (2018). Protecting tropical forests from the rapid expansion of rubber using carbon payments.
Nat Commun,
9(1).
Abstract:
Protecting tropical forests from the rapid expansion of rubber using carbon payments.
Expansion of Hevea brasiliensis rubber plantations is a resurgent driver of deforestation, carbon emissions, and biodiversity loss in Southeast Asia. Southeast Asian rubber extent is massive, equivalent to 67% of oil palm, with rapid further expansion predicted. Results-based carbon finance could dis-incentivise forest conversion to rubber, but efficacy will be limited unless payments match, or at least approach, the costs of avoided deforestation. These include opportunity costs (timber and rubber profits), plus carbon finance scheme setup (transaction) and implementation costs. Using comprehensive Cambodian forest data, exploring scenarios of selective logging and conversion, and assuming land-use choice is based on net present value, we find that carbon prices of $30-$51 per tCO2 are needed to break even against costs, higher than those currently paid on carbon markets or through carbon funds. To defend forests from rubber, either carbon prices must be increased, or other strategies are needed, such as corporate zero-deforestation pledges, and governmental regulation and enforcement of forest protection.
Abstract.
Author URL.
2017
Boukili VKS, Bebber DP, Mortimer T, Venicx G, Lefcourt D, Chandler M, Eisenberg C (2017). Assessing the performance of urban forest carbon sequestration models using direct measurements of tree growth.
Urban Forestry and Urban Greening,
24, 212-221.
Abstract:
Assessing the performance of urban forest carbon sequestration models using direct measurements of tree growth
Across cities worldwide, people are recognizing the value of greenspace in ameliorating the health and well-being of those living there, and are investing significant resources to improve their greenspace. Although models have been developed to allow the quantification of ecosystem services provided by urban trees, refinement and calibration of these models with more accurate site- and species-specific data can increase confidence in their outcomes. We used data from two street tree surveys in Cambridge, MA, to estimate annual tree mortality for 592 trees and diameter growth rates for 498 trees. Overall tree turnover between 2012 and 2015 was relatively low (annualized 3.6% y−1), and mortality rate varied by species. Tree growth rates also varied by species and size. We used stem diameter (DBH) and species identity to estimate CO2 sequestration rates for each of 463 trees using three different model variations: (1) i-Tree Streets, (2) Urban Tree Database (UTD) species-specific biomass allometries and growth rates, and (3) empirically measured growth rates combined with UTD biomass allometries (Empirical + UTD). For most species, the rate of CO2 sequestration varied significantly with the model used. CO2 sequestration estimates calculated using i-Tree Streets were often higher than estimates calculated with the UTD equations. CO2 sequestration estimates were often the lowest when calculated using empirical tree growth estimates and the UTD equations (Empirical + UTD). The differences among CO2 sequestration estimates were highest for large trees. When scaled up to the entire city, CO2 sequestration estimates for the Empirical + UTD model were 49.2% and 56.5% of the i-Tree Streets and UTD estimates, respectively. We suggest future derivations of ecosystem service provision models allow localities to input their own species-specific growth values. By adding capacity to easy-to-use tools, such as i-Tree Streets, we can increase confidence in the model output.
Abstract.
Bebber DP, Butt N (2017). Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.
Sci Rep,
7(1).
Abstract:
Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.
Tropical deforestation is responsible for around one tenth of total anthropogenic carbon emissions, and tropical protected areas (PAs) that reduce deforestation can therefore play an important role in mitigating climate change and protecting biodiversity and ecosystem services. While the effectiveness of PAs in reducing deforestation has been estimated, the impact on global carbon emissions remains unquantified. Here we show that tropical PAs overall reduced deforestation carbon emissions by 4.88 Pg, or around 29%, between 2000 and 2012, when compared to expected rates of deforestation controlling for spatial variation in deforestation pressure. The largest contribution was from the tropical Americas (368.8 GgC y-1), followed by Asia (25.0 GgC y-1) and Africa (12.7 GgC y-1). Variation in PA effectiveness is largely driven by local factors affecting individual PAs, rather than designations assigned by governments.
Abstract.
Author URL.
Bebber DP, Butt N (2017). Tropical protected areas reduced deforestation carbon emissions by one third from 2000–2012. Scientific Reports, 7
2016
Bebber DP, Castillo ÁD, Gurr SJ (2016). Modelling coffee leaf rust risk in Colombia with climate reanalysis data.
Philosophical Transactions of the Royal Society B: Biological Sciences,
371(1709).
Abstract:
Modelling coffee leaf rust risk in Colombia with climate reanalysis data
Many fungal plant diseases are strongly controlled by weather, and global climate change is thus likely to have affected fungal pathogen distributions and impacts. Modelling the response of plant diseases to climate change is hampered by the difficulty of estimating pathogen-relevant microclimatic variables from standard meteorological data. The availability of increasingly sophisticated high-resolution climate reanalyses may help overcome this challenge. We illustrate the use of climate reanalyses by testing the hypothesis that climate change increased the likelihood of the 2008–2011 outbreak of Coffee Leaf Rust (CLR, Hemileia vastatrix) in Colombia. We develop a model of germination and infection risk, and drive this model using estimates of leaf wetness duration and canopy temperature from the Japanese 55-Year Reanalysis (JRA-55).We model germination and infection as Weibull functions with different temperature optima, based upon existing experimental data. We find no evidence for an overall trend in disease risk in coffee-growing regions of Colombia from 1990 to 2015, therefore, we reject the climate change hypothesis. There was a significant elevation in predicted CLR infection risk from 2008 to 2011 compared with other years. JRA-55 data suggest a decrease in canopy surface water after 2008, which may have helped terminate the outbreak. The spatial resolution and accuracy of climate reanalyses are continually improving, increasing their utility for biological modelling. Confronting disease models with data requires not only accurate climate data, but also disease observations at high spatio-temporal resolution. Investment in monitoring, storage and accessibility of plant disease observation data are needed to match the quality of the climate data now available.
Abstract.
Mi X, Swenson NG, Jia Q, Rao M, Feng G, Ren H, Bebber DP, Ma K (2016). Stochastic assembly in a subtropical forest chronosequence: evidence from contrasting changes of species, phylogenetic and functional dissimilarity over succession.
Sci Rep,
6Abstract:
Stochastic assembly in a subtropical forest chronosequence: evidence from contrasting changes of species, phylogenetic and functional dissimilarity over succession.
Deterministic and stochastic processes jointly determine the community dynamics of forest succession. However, it has been widely held in previous studies that deterministic processes dominate forest succession. Furthermore, inference of mechanisms for community assembly may be misleading if based on a single axis of diversity alone. In this study, we evaluated the relative roles of deterministic and stochastic processes along a disturbance gradient by integrating species, functional, and phylogenetic beta diversity in a subtropical forest chronosequence in Southeastern China. We found a general pattern of increasing species turnover, but little-to-no change in phylogenetic and functional turnover over succession at two spatial scales. Meanwhile, the phylogenetic and functional beta diversity were not significantly different from random expectation. This result suggested a dominance of stochastic assembly, contrary to the general expectation that deterministic processes dominate forest succession. On the other hand, we found significant interactions of environment and disturbance and limited evidence for significant deviations of phylogenetic or functional turnover from random expectations for different size classes. This result provided weak evidence of deterministic processes over succession. Stochastic assembly of forest succession suggests that post-disturbance restoration may be largely unpredictable and difficult to control in subtropical forests.
Abstract.
Author URL.
Murthy IK, Bhat S, Sathyanarayan V, Patgar S, Beerappa M, Bhat PR, Bhat DM, Ravindranath NH, Khalid MA, Prashant M, et al (2016). Vegetation structure and composition of tropical evergreen and deciduous forests in Uttara Kannada district, Western Ghats under different disturbance regimes.
Tropical Ecology,
57(1), 77-88.
Abstract:
Vegetation structure and composition of tropical evergreen and deciduous forests in Uttara Kannada district, Western Ghats under different disturbance regimes
In the present paper, we present the structure and composition of tropical evergreen and deciduous forests in the Western Ghats monitored under a long-term programme involving Indian Institute of Science, Earth watch and volunteer investigators from HSBC. Currently, there is limited evidence on the status and dynamics of tropical forests in the context of human disturbance and climate change. Observations made in this study show that the ‘more disturbed’ evergreen and one of the deciduous plots have low species diversity compared to the less-disturbed forests. There are also variations in the size class structure in the more and ‘less disturbed’ forests of all the locations. The variation is particularly noticeable in the DBH size class 10 -15 cm category. When biomass stock estimates are considered, there was no significant difference between evergreen and deciduous forests. The difference in biomass stocks between ‘less disturbed’ and ‘more disturbed’ forests within a forest type is also low. Thus, the biomass and carbon stock has not been impacted despite the dependence of communities on the forests. Periodic and long-term monitoring of the status and dynamics of the forests is necessary in the context of potential increased human pressure and climate change. There is, therefore, a need to inform the communities of the impact of extraction and its effect on regeneration so as to motivate them to adopt what may be termed as “adaptive resource management”, so as to sustain the flow of forest products.
Abstract.
2015
Bebber DP, Gurr SJ (2015). Crop-destroying fungal and oomycete pathogens challenge food security.
Fungal Genet Biol,
74, 62-64.
Abstract:
Crop-destroying fungal and oomycete pathogens challenge food security.
Of the various crop pests and pathogens which blight our harvests, it is the fungi and oomycetes which are the most widely-dispersed groups and which lead the global invasion of agriculture. Here, we highlight the rapid growth in fungal and oomycete disease incidence and spread across the globe. We draw attention to the need for improved disease surveillance and for more sustainable agricultural intensification and consider the economic and humanitarian costs of fungal and oomycete diseases.
Abstract.
Author URL.
Crockatt ME, Bebber DP (2015). Edge effects on moisture reduce wood decomposition rate in a temperate forest.
Global Change Biology,
21(2), 698-707.
Abstract:
Edge effects on moisture reduce wood decomposition rate in a temperate forest
Forests around the world are increasingly fragmented, and edge effects on forest microclimates have the potential to affect ecosystem functions such as carbon and nutrient cycling. Edges tend to be drier and warmer due to the effects of insolation, wind, and evapotranspiration and these gradients can penetrate hundreds of metres into the forest. Litter decomposition is a key component of the carbon cycle, which is largely controlled by saprotrophic fungi that respond to variation in temperature and moisture. However, the impact of forest fragmentation on litter decay is poorly understood. Here, we investigate edge effects on the decay of wood in a temperate forest using an experimental approach, whereby mass loss in wood blocks placed along 100 m transects from the forest edge to core was monitored over 2 years. Decomposition rate increased with distance from the edge, and was correlated with increasing humidity and moisture content of the decaying wood, such that the decay constant at 100 m was nearly twice that at the edge. Mean air temperature decreased slightly with distance from the edge. The variation in decay constant due to edge effects was larger than that expected from any reasonable estimates of climatic variation, based on a published regional model. We modelled the influence of edge effects on the decay constant at the landscape scale using functions for forest area within different distances from edge across the UK. We found that taking edge effects into account would decrease the decay rate by nearly one quarter, compared with estimates that assumed no edge effect.
Abstract.
McMahon SM, Bebber DP, Butt N, Crockatt M, Kirby K, Parker GG, Riutta T, Slade EM (2015). Ground based LiDAR demonstrates the legacy of management history to canopy structure and composition across a fragmented temperate woodland.
Forest Ecology and Management,
335, 255-260.
Abstract:
Ground based LiDAR demonstrates the legacy of management history to canopy structure and composition across a fragmented temperate woodland
The structure of forest canopies correlates with stand maturity and biomass, and develops consistently over time. Remote-sensing technologies such as Light Detection and Ranging (LiDAR) have become prominent tools for measuring structural characteristics of forests.We walked a portable canopy LiDAR (PCL), an up-facing rangefinder that detects vegetation through the canopy at two kilohertz, along multiple transects at ten different forest stands in the area of Wytham Woods, Oxfordshire, UK. The stands had different species composition, were situated at forest edges and in forest core, were in fragments of different sizes and had different land-use histories. With these data we tested structural differences in vegetation across these stand types.Although none of the stands have been managed in the last 70. years, they have not converged structurally. Vertical canopy structure differed between stands that regrew naturally from open field and those with a history of coppice management. Forest stands that have developed following major fellings or through spread on to former grazing land showed some structural similarities to classic natural succession from large disturbances. Stands that were actively managed as coppice over preceding centuries, showed a similar structural pattern to mature forest, but without the tall overstorey that can develop into old growth communities.This structural divergence indicates two distinct pathways for secondary forests: with implications for the future biomass, stand structure, and species composition. The legacy of management practices can determine canopy structure decades after the forest is removed from active management, but can also be difficult to discern with remote sensing data. We recommend that "ground-truthing" remote sensing data go beyond traditional checks of height and topography, as the history and composition of secondary forests can have an important influence on the pace and compositional structure of recovery from management.
Abstract.
Bebber DP (2015). Range-expanding pests and pathogens in a warming world.
Annu Rev Phytopathol,
53, 335-356.
Abstract:
Range-expanding pests and pathogens in a warming world.
Crop pests and pathogens (CPPs) present a growing threat to food security and ecosystem management. The interactions between plants and their natural enemies are influenced by environmental conditions and thus global warming and climate change could affect CPP ranges and impact. Observations of changing CPP distributions over the twentieth century suggest that growing agricultural production and trade have been most important in disseminating CPPs, but there is some evidence for a latitudinal bias in range shifts that indicates a global warming signal. Species distribution models using climatic variables as drivers suggest that ranges will shift latitudinally in the future. The rapid spread of the Colorado potato beetle across Eurasia illustrates the importance of evolutionary adaptation, host distribution, and migration patterns in affecting the predictions of climate-based species distribution models. Understanding species range shifts in the framework of ecological niche theory may help to direct future research needs.
Abstract.
Author URL.
O Sullivan OS, Hopkinson L, Crockatt ME, Laird P, Bebber DP (2015). Stable forest carbon stocks support current assumption of biogenic carbon neutrality in the case of European-manufactured beverage cartons.
International Journal of Life Cycle AssessmentAbstract:
Stable forest carbon stocks support current assumption of biogenic carbon neutrality in the case of European-manufactured beverage cartons
Purpose: Life cycle assessments (LCAs) of forest-based products, such as beverage cartons, generally demonstrate lower greenhouse gas emissions than fossil fuel-based alternatives and often contain the implicit assumption that removal of carbon dioxide (CO2) by a growing forest and emission of CO2 at the end of a product’s life cancel each other out such that the net emission is zero. This study aims to test the validity of this assumption of biogenic CO2 neutrality in relation to beverage cartons by examining whether carbon stocks of the source forests are stable. The fact that over 95 % of the cartonboard used in their manufacture is sourced from the boreal forests of Sweden and Finland provides a scenario with a straightforward relationship between forest and product thus avoiding issues surrounding the complexities of global supply chains. Methods: the reviewed LCAs conclude that beverage cartons have lower greenhouse gas emissions than alternatives, although non-forest-derived components such as plastic caps and aluminium laminate often contribute disproportionately to those emissions. We discuss issues surrounding the assumption of biogenic CO2 neutrality and explore the factors that influence carbon stocks in boreal forests that supply much of the raw material for beverage cartons. Results and discussion: an analysis of published rates of carbon sequestration in the managed forests of Finland and Sweden reveals that forest carbon is stable under current harvest rates. This lends support to the assumption of biogenic CO2 neutrality in the case of beverage cartons produced from these forests. We conclude that greenhouse gas emissions would not change if an LCA included forest carbon. However, future forest dynamics and thus carbon stocks are predicted to alter in response to climate change, for example, which will have knock on effects for greenhouse gas emissions from packaging derived from forests. Conclusions: This review combines current thinking on inclusion of forest carbon in LCAs with an analysis of issues that will influence carbon stocks in managed forests. Although current assumptions of biogenic CO2 neutrality are valid in the case of European-manufactured beverage cartons, we argue that this assumption needs to be explicitly addressed in LCAs. While there is no accepted methodology for integrating biogenic forest carbon uptake into LCA, our assessment of current trends in forest carbon stocks allows for assumptions of biogenic CO2 neutrality to be tested, although our approach may not be practical for more complex supply chains.
Abstract.
Falloon P, Bebber DP, Bryant J, Challinor A, Dessai S, Gurr S (2015). Using climate information to support crop breeding decisions and adaptation in agriculture.
World Agriculture,
5(1), 25-42.
Abstract:
Using climate information to support crop breeding decisions and adaptation in agriculture
Population growth in the next few decades will increase the need for food production, while the yields of major food crops could be impacted by the changing climate and changing threats from pests and pathogens. Crop breeding, both through conventional techniques, and GM assisted breeding could help meet these challenges, if adequately supported by appropriate information on the future climate. We highlight some of the major challenges for crop breeders and growers in the coming decades, and describe the main characteristics of crop breeding techniques and other adaptation options for agriculture. We review recent uses of climate information to support crop breeding decisions and make recommendations for how this might be improved. We conclude that there is significant potential for breeders to work more closely with climate scientists and crop modellers in order to address the challenges of climate change. It is not yet clear how climate information can best be used. Fruitful areas of investigation include: provision of climate information to identify key target breeding traits and develop improved success criteria (e.g. for heat/drought stress); identification of those conditions under which multiple stress factors (for example, heat stress, mid-season drought stress, flowering drought stress, terminal drought stress) are important in breeding programmes; use of climate information to inform selection of trial sites; identification of the range of environments and locations under which crop trials should be performed (likely to be a wider range of environments than done at present); identification of appropriate duration of trials (likely to be longer than current trials, due to the importance of capturing extreme events); and definition of appropriate methods for incorporating climate information into crop breeding programmes, depending on the specific needs of the breeding programme and the strengths and weaknesses of available approaches. Better knowledge is needed on climate-related thresholds important to crop breeders, for example on the frequency and severity of extreme climate events relevant to the product profile, or to help provide tailored climate analyses (particularly for extreme events). The uncertainties inherent in climate and impact projections provide a particular challenge for translating climate science into actionable outcomes for agriculture. Further work is needed to explore relevant social and economic assumptions such as the level and distribution of real incomes, changing consumption patterns, health impacts, impacts on markets and trade, and the impact of legislation relating to conservation, the environment and climate change.
Abstract.
2014
Feng G, Svenning J-C, Mi X, Jia Q, Rao M, Ren H, Bebber DP, Ma K (2014). Anthropogenic disturbance shapes phylogenetic and functional tree community structure in a subtropical forest.
Forest Ecology and Management,
313, 188-198.
Abstract:
Anthropogenic disturbance shapes phylogenetic and functional tree community structure in a subtropical forest
Forests across the world are increasingly affected by human activities, with unmanaged forests often in early- and mid-successional phases after anthropogenic disturbances. In consequence, it is important to obtain a better understanding of these successional dynamics and their implications for the functioning of forest ecosystems. Here, we investigate this issue for a highly diverse subtropical forest in China, as it is particularly relevant here. China naturally harbors large forested areas and much forest biodiversity, but its forests are also subject to strong anthropogenic pressures, with only 2% of its forest remaining undisturbed. We assess how anthropogenic disturbance shapes two important aspects of forest biodiversity, namely phylogenetic and functional community structure. Comparing plots that have not been disturbed within the last 100 years, plots clear-cut ∼50 years ago, and plots clear-cut ∼50 years ago and then selectively cut ∼20 years ago, we find that the abundant gymnosperm species which are important pioneer species in southern China strongly affect phylogenetic structure, causing over-dispersion among large stems in disturbed stands. A tendency for decreasingly clumped phylogenetic structure over succession when considering only angiosperms may reflect an initial filtering by disturbance whose legacy decreases during succession. Multi-trait functional structure, which was not significantly affected by gymnosperms, has similar patterns to the phylogenetic structure without gymnosperms. Phylogenetic and functional structure differs among stem size classes, but with partially divergent trends. Functional structure is more strongly linked to a disturbance indicator, the proportion of light-demanding species, than phylogenetic structure. Our results illustrate that past tree harvesting has left strong legacies in the phylogenetic and functional structure of tree stands in a highly diverse southern Chinese forest and thus may also shape their functioning.
Abstract.
Feng G, Svenning JC, Mi X, Jia Q, Rao M, Ren H, Bebber DP, Ma K (2014). Anthropogenic disturbance shapes phylogenetic and functional tree community structure in a subtropical forest.
Forest Ecology and Management,
313, 188-198.
Abstract:
Anthropogenic disturbance shapes phylogenetic and functional tree community structure in a subtropical forest
Forests across the world are increasingly affected by human activities, with unmanaged forests often in early- and mid-successional phases after anthropogenic disturbances. In consequence, it is important to obtain a better understanding of these successional dynamics and their implications for the functioning of forest ecosystems. Here, we investigate this issue for a highly diverse subtropical forest in China, as it is particularly relevant here. China naturally harbors large forested areas and much forest biodiversity, but its forests are also subject to strong anthropogenic pressures, with only 2% of its forest remaining undisturbed. We assess how anthropogenic disturbance shapes two important aspects of forest biodiversity, namely phylogenetic and functional community structure. Comparing plots that have not been disturbed within the last 100. years, plots clear-cut ~50. years ago, and plots clear-cut ~50. years ago and then selectively cut ~20. years ago, we find that the abundant gymnosperm species which are important pioneer species in southern China strongly affect phylogenetic structure, causing over-dispersion among large stems in disturbed stands. A tendency for decreasingly clumped phylogenetic structure over succession when considering only angiosperms may reflect an initial filtering by disturbance whose legacy decreases during succession. Multi-trait functional structure, which was not significantly affected by gymnosperms, has similar patterns to the phylogenetic structure without gymnosperms. Phylogenetic and functional structure differs among stem size classes, but with partially divergent trends. Functional structure is more strongly linked to a disturbance indicator, the proportion of light-demanding species, than phylogenetic structure. Our results illustrate that past tree harvesting has left strong legacies in the phylogenetic and functional structure of tree stands in a highly diverse southern Chinese forest and thus may also shape their functioning. © 2013 Elsevier B.V.
Abstract.
Bebber DP, Wood JRI, Barker C, Scotland RW (2014). Author inflation masks global capacity for species discovery in flowering plants.
New Phytologist,
201(2), 700-706.
Abstract:
Author inflation masks global capacity for species discovery in flowering plants
Species discovery is a fundamental first step for all of biodiversity science. Recent research has claimed that the increasing number of authors associated with the description of new species represents an expanding workforce discovering the remaining new species from an ever-diminishing pool. Here, we present a comprehensive dataset from the International Plant Names Index (IPNI) of new species of flowering plant published between 1970 and 2011. We show that, on average, 1855 new species have been described annually since 1970. We show that compared to other scientific disciplines the increased number of authors on taxonomic papers is relatively small and may reflect changes in scientific practice rather than an increase in taxonomic capacity. These data, alongside published results demonstrating a lag period of 35 yr between a specimen being collected and published as a new species, strongly suggest that the global taxonomic capacity to describe new species of flowering plant is stagnant at a time of unprecedented concern for conservation and extinction. © 2013 the Authors. New Phytologist © 2013 New Phytologist Trust.
Abstract.
Bebber DP, Holmes T, Smith D, Gurr SJ (2014). Economic and physical determinants of the global distributions of crop pests and pathogens.
New Phytologist,
202(3), 901-910.
Abstract:
Economic and physical determinants of the global distributions of crop pests and pathogens
Crop pests and pathogens pose a significant and growing threat to food security, but their geographical distributions are poorly understood. We present a global analysis of pest and pathogen distributions, to determine the roles of socioeconomic and biophysical factors in determining pest diversity, controlling for variation in observational capacity among countries. Known distributions of 1901 pests and pathogens were obtained from CABI. Linear models were used to partition the variation in pest species per country amongst predictors. Reported pest numbers increased with per capita gross domestic product (GDP), research expenditure and research capacity, and the influence of economics was greater in micro-organisms than in arthropods. Total crop production and crop diversity were the strongest physical predictors of pest numbers per country, but trade and tourism were insignificant once other factors were controlled. Islands reported more pests than mainland countries, but no latitudinal gradient in species richness was evident. Country wealth is likely to be a strong indicator of observational capacity, not just trade flow, as has been interpreted in invasive species studies. If every country had US levels of per capita GDP, then 205 ± 9 additional pests per country would be reported, suggesting that enhanced investment in pest observations will reveal the hidden threat of crop pests and pathogens. © 2014 New Phytologist Trust.
Abstract.
Lambrick FH, Brown ND, Lawrence A, Bebber DP (2014). Effectiveness of Community Forestry in Prey Long
Forest, Cambodia. Conservation Biology
Lambrick FH, Brown ND, Lawrence A, Bebber DP (2014). Effectiveness of community forestry in prey long forest, Cambodia.
Conservation Biology,
28(2), 372-381.
Abstract:
Effectiveness of community forestry in prey long forest, Cambodia
Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005-2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context-specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18-20 randomly placed variable-radius plots and fixed-area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income. © 2014 Society for Conservation Biology.
Abstract.
Riutta T, Slade EM, Morecroft MD, Bebber DP, Malhi Y (2014). Living on the edge: Quantifying the structure of a fragmented forest landscape in England.
Landscape Ecology,
29(6), 949-961.
Abstract:
Living on the edge: Quantifying the structure of a fragmented forest landscape in England
Forest ecosystems have been widely fragmented by human land use, inducing significant microclimatic and biological changes at the forest edge. If we are to rigorously assess the ecological impacts of habitat fragmentation, there is a need to effectively quantify the amount of edge habitat within a landscape, and to allow this to be modelled for individual species and processes. Edge effect may extend only a few metres or as far as several kilometres, depending on the species or process in question. Therefore, rather than attempting to quantify the amount of edge habitat by using a fixed, case-specific distance to distinguish between edge and core, the area of habitat within continuously-varying distances from the forest edge is of greater utility. We quantified the degree of fragmentation of forests in England, where forests cover 10 % of the land area. We calculated the distance from within the forest patches to the nearest edge (forest vs. non-forest) and other landscape indices, such as mean patch size, edge density and distance to the nearest neighbour. of the total forest area, 37 % was within 30 m and 74 % within 100 m of the nearest edge. This highlights that, in fragmented landscapes, the habitats close to the edge form a considerable proportion of the total habitat area. We then show how these edge estimates can be combined with ecological response functions, to allow us to generate biologically meaningful estimates of the impacts of fragmentation at a landscape scale. © 2014 Springer Science+Business Media Dordrecht.
Abstract.
Riutta T, Slade EM, Morecroft MD, Bebber DP, Malhi Y (2014). Living on the edge: quantifying the structure of a fragmented forest landscape in England. Landscape Ecology
Butt N, Bebber DP, Riutta T, Crockatt M, Morecroft MD, Malhi Y (2014). Relationships between tree growth and weather extremes: Spatial and interspecific comparisons in a temperate broadleaf forest.
Forest Ecology and Management,
334, 209-216.
Abstract:
Relationships between tree growth and weather extremes: Spatial and interspecific comparisons in a temperate broadleaf forest
Three years of monthly growth increment data identified large interannual differences in growth rate across six contrasting species in a broadleaved, temperate forest with minimum management intervention (Wytham Woods, UK). Growth rates varied by species and canopy position, and were higher in canopy species. Growth rate in 2010 was up to 40% lower than in 2011 and 2012. This can best be explained as an effect of low temperature, which delayed the start of spring and the growing season. This had a greater impact on the growth of sub-canopy trees than that of canopy species. In temperate systems, late spring and summer is an important component of the whole growing season carbon balance because of long day length. In 2010 there were also periods of lower-than-average rainfall, which may additionally have constrained growth during the growing season. Fluctuations and seasonal changes in both temperature and rainfall are projected to continue, so we may expect to see increasing differences in growth and growth rates. A small effect of location relative to the nearest edge was also detected, with higher growth rates only found >50. m from the forest edge. The findings have implications for forest structure and productivity under climate change, and may thus inform current and future forest management.
Abstract.
Butt N, Bebber DP, Riutta T, Crockatt M, Morecroft MD, Malhi Y (2014). Relationships between tree growth and weather extremes: Spatial and interspecific comparisons in a temperate broadleaf forest.
Forest Ecology and Management,
334, 209-216.
Abstract:
Relationships between tree growth and weather extremes: Spatial and interspecific comparisons in a temperate broadleaf forest
Three years of monthly growth increment data identified large interannual differences in growth rate across six contrasting species in a broadleaved, temperate forest with minimum management intervention (Wytham Woods, UK). Growth rates varied by species and canopy position, and were higher in canopy species. Growth rate in 2010 was up to 40% lower than in 2011 and 2012. This can best be explained as an effect of low temperature, which delayed the start of spring and the growing season. This had a greater impact on the growth of sub-canopy trees than that of canopy species. In temperate systems, late spring and summer is an important component of the whole growing season carbon balance because of long day length. In 2010 there were also periods of lower-than-average rainfall, which may additionally have constrained growth during the growing season. Fluctuations and seasonal changes in both temperature and rainfall are projected to continue, so we may expect to see increasing differences in growth and growth rates. A small effect of location relative to the nearest edge was also detected, with higher growth rates only found >50. m from the forest edge. The findings have implications for forest structure and productivity under climate change, and may thus inform current and future forest management.
Abstract.
Bebber DP, Polaszek A, Wood JRI, Barker C, Scotland RW (2014). Taxonomic capacity and author inflation.
New Phytol,
202(3), 741-742.
Author URL.
Bebber DP, Holmes T, Gurr SJ (2014). The global spread of crop pests and pathogens.
Global Ecology and BiogeographyAbstract:
The global spread of crop pests and pathogens
Aim: to describe the patterns and trends in the spread of crop pests and pathogens around the world, and determine the socioeconomic, environmental and biological factors underlying the rate and degree of redistribution of crop-destroying organisms. Location: Global. Methods: Current country- and state-level distributions of 1901 pests and pathogens and historical observation dates for 424 species were compared with potential distributions based upon distributions of host crops. The degree of 'saturation', i.e. the fraction of the potential distribution occupied, was related to pest type, host range, crop production, climate and socioeconomic variables using linear models. Results: More than one-tenth of all pests have reached more than half the countries that grow their hosts. If current trends continue, many important crop-producing countries will be fully saturated with pests by the middle of the century. While dispersal increases with host range overall, fungi have the narrowest host range but are the most widely dispersed group. The global dispersal of some pests has been rapid, but pest assemblages remain strongly regionalized and follow the distributions of their hosts. Pest assemblages are significantly correlated with socioeconomics, climate and latitude. Tropical staple crops, with restricted latitudinal ranges, tend to be more saturated with pests and pathogens than temperate staples with broad latitudinal ranges. We list the pests likely to be the most invasive in coming years. Main conclusions: Despite ongoing dispersal of crop pests and pathogens, the degree of biotic homogenization of the globe remains moderate and regionally constrained, but is growing. Fungal pathogens lead the global invasion of agriculture, despite their more restricted host range. Climate change is likely to influence future distributions. Improved surveillance would reveal greater levels of invasion, particularly in developing countries. © 2014 John Wiley. &. Sons Ltd.
Abstract.
2013
Bebber DP, Wood JRI, Barker C, Scotland RW (2013). Author inflation masks global capacity for species discovery in flowering plants. New Phytologist
Bebber DP, Wood JRI, Barker C, Scotland RW (2013). Author inflation masks global capacity for species discovery in flowering plants. New Phytologist
Bebber DP, Ramotowski MAT, Gurr SJ (2013). Crop pests and pathogens move poleward in a warming world.
Nature Climate Change,
3, 985-988.
Abstract:
Crop pests and pathogens move poleward in a warming world
Global food security is threatened by the emergence and spread of crop pests and pathogens. Spread is facilitated primarily by human transportation, but there is increasing concern that climate change allows establishment in hitherto unsuitable regions. However, interactions between climate change, crops and pests are complex, and the extent to which crop pests and pathogens have altered their latitudinal ranges in response to global warming is largely unknown. Here, we demonstrate an average poleward shift of 2.7±0.8 km yr−1 since 1960, in observations of hundreds of pests and pathogens, but with significant variation in trends among taxonomic groups. Observational bias, where developed countries at high latitudes detect pests earlier than developing countries at low latitudes, would result in an apparent shift towards the Equator. The observed positive latitudinal trends in many taxa support the hypothesis of global warming-driven pest movement.
Abstract.
Slade EM, Mercx T, Riutta T, Bebber DP, Readhead D, Riordan P, Macdonald DW (2013). Life-history traits and landscape characteristics predict macro-moth responses to forest fragmentation.
Ecology,
94(7), 1519-1530.
Abstract:
Life-history traits and landscape characteristics predict macro-moth responses to forest fragmentation
How best to manage forest patches, mitigate the consequences of forest
fragmentation, and enable landscape permeability are key questions facing conservation
scientists and managers. Many temperate forests have become increasingly fragmented,
resulting in reduced interior forest habitat, increased edge habitats, and reduced connectivity.
Using a citizen science landscape-scale mark–release–recapture study on 87 macro-moth
species, we investigated how both life-history traits and landscape characteristics predicted
macro-moth responses to forest fragmentation. Wingspan, wing shape, adult feeding, and
larval feeding guild predicted macro-moth mobility, although the predictive power of
wingspan and wing shape depended on the species’ affinity to the forest. Solitary trees and
small fragments functioned as ‘‘stepping stones,’’ especially when their landscape connectivity
was increased, by being positioned within hedgerows or within a favorable matrix. Mobile
forest specialists were most affected by forest fragmentation: despite their high intrinsic
dispersal capability, these species were confined mostly to the largest of the forest patches due
to their strong affinity for the forest habitat, and were also heavily dependent on forest
connectivity in order to cross the agricultural matrix. Forest fragments need to be larger than
five hectares and to have interior forest more than 100 m from the edge in order to sustain
populations of forest specialists. Our study provides new insights into the movement patterns
of a functionally important insect group, with implications for the landscape-scale
management of forest patches within agricultural landscapes.
Abstract.
Chisholm RA, Muller-Landau HC, Abdul Rahman K, Bebber DP, Bin Y, Bohlman SA, Bourg NA, Brinks J, Bunyavejchewin S, Butt N, et al (2013). Scale-dependent relationships between tree species richness and ecosystem function in forests.
Journal of Ecology,
101(5), 1214-1224.
Abstract:
Scale-dependent relationships between tree species richness and ecosystem function in forests
Summary: the relationship between species richness and ecosystem function, as measured by productivity or biomass, is of long-standing theoretical and practical interest in ecology. This is especially true for forests, which represent a majority of global biomass, productivity and biodiversity. Here, we conduct an analysis of relationships between tree species richness, biomass and productivity in 25 forest plots of area 8-50 ha from across the world. The data were collected using standardized protocols, obviating the need to correct for methodological differences that plague many studies on this topic. We found that at very small spatial grains (0.04 ha) species richness was generally positively related to productivity and biomass within plots, with a doubling of species richness corresponding to an average 48% increase in productivity and 53% increase in biomass. At larger spatial grains (0.25 ha, 1 ha), results were mixed, with negative relationships becoming more common. The results were qualitatively similar but much weaker when we controlled for stem density: at the 0.04 ha spatial grain, a doubling of species richness corresponded to a 5% increase in productivity and 7% increase in biomass. Productivity and biomass were themselves almost always positively related at all spatial grains. Synthesis. This is the first cross-site study of the effect of tree species richness on forest biomass and productivity that systematically varies spatial grain within a controlled methodology. The scale-dependent results are consistent with theoretical models in which sampling effects and niche complementarity dominate at small scales, while environmental gradients drive patterns at large scales. Our study shows that the relationship of tree species richness with biomass and productivity changes qualitatively when moving from scales typical of forest surveys (0.04 ha) to slightly larger scales (0.25 and 1 ha). This needs to be recognized in forest conservation policy and management. Our analysis of 25 forests across the world shows that the relationship of tree species richness to biomass (AGB) and productivity (CWP) changes qualitatively from positive at small spatial grains typical of forest surveys (0.04 ha) to mixed at slightly larger spatial grains (0.25 and 1 ha). This needs to be recognised in forest conservation policy and management. © 2013 British Ecological Society.
Abstract.
2012
Bebber DP, Carine MA, Davidse G, Harris DJ, Haston EM, Penn MG, Cafferty S, Wood JRI, Scotland RW (2012). Big hitting collectors make massive and disproportionate contribution to the discovery of plant species.
Proceedings of the Royal Society B: Biological Sciences,
279(1736), 2269-2274.
Abstract:
Big hitting collectors make massive and disproportionate contribution to the discovery of plant species
Discovering biological diversity is a fundamental goal-made urgent by the alarmingly high rate of extinction. We have compiled information from more than 100 000 type specimens to quantify the role of collectors in the discovery of plant diversity. Our results show that more than half of all type specimens were collected by less than 2 per cent of collectors. This highly skewed pattern has persisted through time. We demonstrate that a number of attributes are associated with prolific plant collectors: a long career with increasing productivity and experience in several countries and plant families. These results imply that funding a small number of expert plant collectors in the right geographical locations should be an important element in any effective strategy to find undiscovered plant species and complete the inventory of the world flora. © 2012 the Royal Society.
Abstract.
Riutta T, Slade EM, Bebber DP, Taylor ME, Malhi Y, Riordan P, Macdonald DW, Morecroft MD (2012). Experimental evidence for the interacting effects of forest edge, moisture and soil macrofauna on leaf litter decomposition.
Soil Biology and Biochemistry,
49, 124-131.
Abstract:
Experimental evidence for the interacting effects of forest edge, moisture and soil macrofauna on leaf litter decomposition
Forest ecosystems have been widely fragmented by human land use. Fragmentation induces significant microclimatic and biological differences at the forest edge relative to the forest interior. Increased exposure to solar radiation and wind at forest edges reduces soil moisture, which in turn affects leaf litter decomposition. We investigate the effect of forest fragmentation, soil moisture, soil macrofauna and litter quality on leaf litter decomposition to test the hypothesis that decomposition will be slower at a forest edge relative to the interior and that this effect is driven by lower soil moisture at the forest edge. Experimental plots were established at Wytham Woods, UK, and an experimental watering treatment was applied in plots at the forest edge and interior. Decomposition rate was measured using litter bags of two different mesh sizes, to include or exclude invertebrate macrofauna, and containing leaf litter of two tree species: easily decomposing ash (. Fraxinus excelsior L.) and recalcitrant oak (. Quercus robur L.). The decomposition rate was moisture-limited at both sites. However, the soil was moister and decomposition for both species was faster in the forest interior than at the edge. The presence of macrofauna accelerated the decomposition rate regardless of moisture conditions, and was particularly important in the decomposition of the recalcitrant oak. However, there was no effect of the watering treatment on macrofauna species richness and abundance. This study demonstrates the effect of forest fragmentation on an important ecosystem process, providing new insights into the interacting effects of moisture conditions, litter quality, forest edge and soil macrofauna. © 2012 Elsevier Ltd.
Abstract.
Chandler M, Bebber DP, Castro S, Lowman MD, Muoria P, Oguge N, Rubenstein DI (2012). International citizen science: Making the local global.
Frontiers in Ecology and the Environment,
10(6), 328-331.
Abstract:
International citizen science: Making the local global
The Earthwatch Institute is an international non-profit organization that works with scientists and scientific institutions to develop citizen-science-based research and environmental monitoring programs. Each year, Earthwatch supports close to 80 different projects in more than 30 countries and recruits over 3000 volunteers to aid scientists in collecting data. Participants recruited by Earthwatch seek to tap into their passion for learning about science by volunteering to act as assistants for authentic research projects. © the Ecological Society of America.
Abstract.
2011
Bebber DP, Watkinson SC, Boddy L, Darrah PR (2011). Simulated nitrogen deposition affects wood decomposition by cord-forming fungi.
Oecologia,
167(4), 1177-1184.
Abstract:
Simulated nitrogen deposition affects wood decomposition by cord-forming fungi
Anthropogenic nitrogen (N) deposition affects many natural processes, including forest litter decomposition. Saprotrophic fungi are the only organisms capable of completely decomposing lignocellulosic (woody) litter in temperate ecosystems, and therefore the responses of fungi to N deposition are critical in understanding the effects of global change on the forest carbon cycle. Plant litter decomposition under elevated N has been intensively studied, with varying results. The complexity of forest floor biota and variability in litter quality have obscured N-elevation effects on decomposers. Field experiments often utilize standardized substrates and N-levels, but few studies have controlled the decay organisms. Decomposition of beech (Fagus sylvatica) blocks inoculated with two cord-forming basidiomycete fungi, Hypholoma fasciculare and Phanerochaete velutina, was compared experimentally under realistic levels of simulated N deposition at Wytham Wood, Oxfordshire, UK. Mass loss was greater with P. velutina than with H. fasciculare, and with N treatment than in the control. Decomposition was accompanied by growth of the fungal mycelium and increasing N concentration in the remaining wood. We attribute the N effect on wood decay to the response of cord-forming wood decay fungi to N availability. Previous studies demonstrated the capacity of these fungi to scavenge and import N to decaying wood via a translocating network of mycelium. This study shows that small increases in N availability can increase wood decomposition by these organisms. Dead wood is an important carbon store and habitat. The responses of wood decomposers to anthropogenic N deposition should be considered in models of forest carbon dynamics. © 2011 Springer-Verlag.
Abstract.
Lander TA, Bebber DP, Choy CTL, Harris SA, Boshier DH (2011). The circe principle explains how resource-rich land can waylay pollinators in fragmented landscapes.
Current Biology,
21(15), 1302-1307.
Abstract:
The circe principle explains how resource-rich land can waylay pollinators in fragmented landscapes
Global declines in pollinators, associated with land-use change [1-6] and fragmentation [7-10], constitute a serious threat to crop production and biodiversity [11]. Models investigating impacts of habitat fragmentation on pollen flow have categorized landscapes simply in terms of habitat and nonhabitat. We show that pollen flow depends strongly on types of land use between habitat fragments. We used paternity analysis of seeds and a combination of circuit and general linear models to analyze pollen flow for the endangered tree Gomortega keule (Gomortegaceae) [12] in the fragmented Central Chile Biodiversity Hotspot [13]. Pollination probability was highest over pine plantation, moderate over low-intensity agriculture and native forest, and lowest over clearfells. Changing the proportions of the land uses over one kilometer altered pollination probability up to 7-fold. We explain our results by the novel "Circe principle." in contrast to models where land uses similar to native habitat promote pollinator movement, pollinators may actually be waylaid in resource-rich areas between habitat patches. Moreover, pollinators may move with higher probability between habitat patches separated by some resource-poor land uses. Pollination research in fragmented landscapes requires explicit recognition of the nature of the nonhabitat matrix, rather than applying simple binary landscape models. © 2011 Elsevier Ltd all rights reserved.
Abstract.
2010
Bebber DP, Carine MA, Wood JRI, Wortley AH, Harris DJ, Prance GT, Davidse G, Paige J, Pennington TD, Robson NKB, et al (2010). Herbaria are a major frontier for species discovery.
Proceedings of the National Academy of Sciences of the United States of America,
107(51), 22169-22171.
Abstract:
Herbaria are a major frontier for species discovery
Despite the importance of species discovery, the processes including collecting, recognizing, and describing new species are poorly understood. Data are presented for flowering plants, measuring quantitatively the lag between the date a specimen of a new species was collected for the first time and when it was subsequently described and published. The data from our sample of new species published between 1970 and 2010 show that only 16% were described within five years of being collected for the first time. The description of the remaining 84% involved much older specimens, with nearly one-quarter of new species descriptions involving specimens >50 y old. Extrapolation of these results suggest that, of the estimated 70, 000 species still to be described, more than half already have been collected and are stored in herbaria. Effort, funding, and research focus should, therefore, be directed as much to examining extant herbarium material as collecting new material in the field.
Abstract.
Tero A, Takagi S, Saigusa T, Ito K, Bebber DP, Fricker MD, Yumiki K, Kobayashi R, Nakagaki T (2010). Rules for biologically inspired adaptive network design.
Science,
327(5964), 439-442.
Abstract:
Rules for biologically inspired adaptive network design
Transport networks are ubiquitous in both social and biological systems. Robust network performance involves a complex trade-off involving cost, transport efficiency, and fault tolerance. Biological networks have been honed by many cycles of evolutionary selection pressure and are likely to yield reasonable solutions to such combinatorial optimization problems. Furthermore, they develop without centralized control and may represent a readily scalable solution for growing networks in general. We show that the slime mold Physarum polycephalum forms networks with comparable efficiency, fault tolerance, and cost to those of real-world infrastructure networks - in this case, the Tokyo rail system. The core mechanisms needed for adaptive network formation can be captured in a biologically inspired mathematical model that may be useful to guide network construction in other domains.
Abstract.
2009
Fricker MD, Boddy L, Nakagaki T, Bebber DP (2009). Adaptive Biological Networks. In Gross T, Hiroki S (Eds.) Adaptive Networks: Theory, Models and Applications, Dordrecht: Springer, 51-69.
Fricker MD, Boddy L, Nakagaki T, Bebber DP (2009). Adaptive biological networks.
Understanding Complex Systems,
2009, 51-70.
Abstract:
Adaptive biological networks
Mycelial fungi and acellular slime molds grow as self-organized networks that explore new territory to search for resources, whilst maintaining an effective internal transport system in the face of continuous attack or random damage. These networks adapt during development by selective reinforcement of major transport routes and recycling of the intervening redundant material to support further extension. In the case of fungi, the predicted transport efficiency of the weighted network is better than evenly weighted networks with the same topology, or standard reference networks. Experimentally, nutrient movement can be mapped using radio-tracers and scintillation imaging, and shows more complex transport dynamics, with synchronized oscillations and switching between different pre-existing routes. The significance of such dynamics to the interplay between transport control and topology is not yet known. In a similar manner, the resilience of the network can be tested in silico and experimentally using grazing invertebrates. Both approaches suggest that the same structures that confer good transport efficiency also show good resilience, with the persistence of a centrally connected core. The acellular slime mold, Physarum polycephalum also forms efficient networks between food sources, with a good balance between total cost, transit distance and fault tolerance. In this case, network formation can be captured by a mathematical model driven by non-linear positive reinforcement of tubes with high flux, and decay of tubes with low flux. We argue that organization of these simple planar networks has been honed by evolution, and they may exemplify potential solutions to real-world compromises between search strategy, transport efficiency, resilience and cost in other domains. © 2009 Springer-Verlag Berlin Heidelberg.
Abstract.
Boddy L, Hynes J, Bebber DP, Fricker MD (2009). Saprotrophic cord systems: Dispersal mechanisms in space and time.
Mycoscience,
50(1), 9-19.
Abstract:
Saprotrophic cord systems: Dispersal mechanisms in space and time
In natural terrestrial environments, nutrients are often patchily and sparsely distributed, and the microclimate is constantly changing both temporally and spatially. To survive, fungi must be able to transfer to a new resource before the nutrient supplies in their current food base are exhausted. While the majority of fungi propagate as spores, some basidiomycetes can grow out of a resource as mycelium in search of new resources. The mycelium of these fungi typically aggregates to form linear organs, termed cords or rhizomorphs, that ramify at the soil-litter interface in forests, interconnecting disparate litter components to form extensive (many square meters or even hectares), long-lived (many years) systems. These mycelial systems form effective dispersal mechanisms in space and time. This article reviews the two main, but not mutually exclusive, mycelial dispersal (resource capture) strategies: (1) a "sit and wait" strategy, whereby a large mycelial network waits for resources to land on it and then actively colonises those resources; and (2) growing and searching actively for new resources. The way in which mycelia balance exploration and nutrient transport, and robustness to damage, against "cost" of production and speed with which an area can be colonised, is explored using techniques borrowed from graph theory and statistical mechanics. © 2009 the Mycological Society of Japan and Springer.
Abstract.
Boddy L, Hynes J, Bebber DP, Fricker MD (2009). Saprotrophic cord systems: dispersal mechanisms in space and time. Mycoscience, 50(1), 9-19.
2008
Fricker MD, Bebber D, Boddy L (2008). Chapter 1 Mycelial networks: Structure and dynamics.
British Mycological Society Symposia Series,
28(C), 3-18.
Abstract:
Chapter 1 Mycelial networks: Structure and dynamics
To survive saprotrophic fungi must be able to capture organic resources discontinuously dispersed in space and time. Some basidiomycetes can only achieve this by production of sexual and asexual spores or sclerotia - categorized as 'resource-unit-restricted', whereas 'non-resource-unit-restricted' basidiomycetes can also spread between organic resources as mycelium. Mycelial distribution and foraging within organic resources and among relatively homogeneously and heterogeneously distributed resources is reviewed. 'Non-resource-unit-restricted' Basidiomycota have evolved different patterns of mycelial spread appropriate to discovery of resources of different sizes and distributions. They show remarkable patterns of reallocation of biomass and mineral nutrients on discovery and colonization of new resources. Network architecture is a significant factor in the acquisition and distribution of nutrients, and in survival when parts of the network are destroyed. The costs and benefits of different architectures to large mycelial networks are considered. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Tlalka M, Bebber D, Darrah PR, Watkinson SC (2008). Chapter 3 Mycelial networks: Nutrient uptake, translocation and role in ecosystems.
British Mycological Society Symposia Series,
28(C), 43-62.
Abstract:
Chapter 3 Mycelial networks: Nutrient uptake, translocation and role in ecosystems
Sequestration and release of carbon in the decomposer subsystem of the forest floor are key ecosystem functions of saprotrophic basidiomycetes. Both are the result of fungal metabolic processes commonly regulated by nitrogen availability. Saprotrophic basidiomycetes are the primary wood decomposer organisms in N-limited boreal and temperate forests. To predict the ecosystem effects of atmospheric nitrogen deposition in forests, we need better understanding of the fungal adaptive responses that link carbon conversions to nitrogen dynamics. Some Basidiomycota clades have evolved the capacity to develop mass flow nutrient channels-cords-in response to nutrient context. Rapid bidirectional nutrient transport in cords enables these fungi to operate extensive and persistent resource supply networks, and to exploit the spatiotemporally uncoupled carbon and nitrogen resources of the upper soil horizons of the forest floor. Both the initiation of cord development and the velocity, direction and magnitude of amino acid flows within the corded network are regulated in response to the amounts and geometry of its carbon and nitrogen supply. Predictive models of fungal metabolic, physiological and developmental responses to environmental nitrogen, at cell and organism scale, can be realistically parameterized with data from experimentally manipulated saprotrophic mycelia in microcosms and ecosystems. In future, the whole-genome sequence of the basidiomycete cord-forming wood decay fungus Serpula lacrymans will provide a model for -omics technologies to dissect the extracellular and intracellular nutrient responses that underlie the functions of basidiomycete networks in ecosystems. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Fricker MD, Tlalka M, Bebber D, Takagi S, Watkinson SC, Darrah PR (2008). Corrigendum to "Fourier-based spatial mapping of oscillatory phenomena in fungi" [Fungal Genet. Biol. 44 (2007) 1077-1084] (DOI:10.1016/j.fgb.2007.02.012). Fungal Genetics and Biology, 45(4).
Fricker MD, Lee JA, Bebber DP, Tlalka M, Hynes J, Darrah PR, Watkinson SC, Boddy L (2008). Imaging complex nutrient dynamics in mycelial networks.
Journal of Microscopy,
231(2), 317-331.
Abstract:
Imaging complex nutrient dynamics in mycelial networks
Transport networks are vital components of multi-cellular organisms, distributing nutrients and removing waste products. Animal cardiovascular and respiratory systems, and plant vasculature, are branching trees whose architecture is thought to determine universal scaling laws in these organisms. In contrast, the transport systems of many multi-cellular fungi do not fit into this conceptual framework, as they have evolved to explore a patchy environment in search of new resources, rather than ramify through a three-dimensional organism. These fungi grow as a foraging mycelium, formed by the branching and fusion of threadlike hyphae, that gives rise to a complex network. To function efficiently, the mycelial network must both transport nutrients between spatially separated source and sink regions and also maintain its integrity in the face of continuous attack by mycophagous insects or random damage. Here we review the development of novel imaging approaches and software tools that we have used to characterise nutrient transport and network formation in foraging mycelia over a range of spatial scales. On a millimetre scale, we have used a combination of time-lapse confocal imaging and fluorescence recovery after photobleaching to quantify the rate of diffusive transport through the unique vacuole system in individual hyphae. These data then form the basis of a simulation model to predict the impact of such diffusion-based movement on a scale of several millimetres. On a centimetre scale, we have used novel photon-counting scintillation imaging techniques to visualize radiolabel movement in small microcosms. This approach has revealed novel N-transport phenomena, including rapid, preferential N-resource allocation to C-rich sinks, induction of simultaneous bi-directional transport, abrupt switching between different pre-existing transport routes, and a strong pulsatile component to transport in some species. Analysis of the pulsatile transport component using Fourier techniques shows that as the colony forms, it self-organizes into well demarcated domains that are identifiable by differences in the phase relationship of the pulses. On the centimetre to metre scale, we have begun to use techniques borrowed from graph theory to characterize the development and dynamics of the network, and used these abstracted network models to predict the transport characteristics, resilience, and cost of the network. © 2008 the Authors.
Abstract.
Tlalka M, Bebber DP, Darrah PR, Watkinson SC, Fricker MD (2008). Quantifying dynamic resource allocation illuminates foraging strategy in Phanerochaete velutina.
Fungal Genetics and Biology,
45(7), 1111-1121.
Abstract:
Quantifying dynamic resource allocation illuminates foraging strategy in Phanerochaete velutina
Saprotrophic woodland fungi forage for mineral nutrients and woody resources by extension of a mycelial network across the forest floor. Different species explore at different rates and establish networks with qualitatively differing architecture. However, detailed understanding of fungal foraging behaviour has been hampered by the absence of tools to quantify resource allocation and growth accurately and non-invasively. To solve this problem, we have used photon-counting scintillation imaging (PCSI) to map and quantify nutrient allocation and localised growth simultaneously in heterogeneous resource environments. We show that colonies spontaneously shift to an asymmetric growth pattern, even in the absence of added resources, often with a distinct transition between the two growth phases. However, the extent of polarisation was much more pronounced and focussed in the presence of an additional cellulose resource. In this case, there was highly localised growth, often at the expense of growth elsewhere in the colony, and marked accumulation of 14C-AIB in the sector of the colony with the added resource. The magnitude of the response was greatest when resource was added around the time of the endogenous developmental transition. The focussed response required a metabolisable resource, as only limited changes were seen with glass fibre discs used to mimic the osmotic and thigmotropic stimuli upon resource addition. Overall the behaviour is consistent with an adaptive foraging strategy, both to exploit new resources and also to redirect subsequent foraging effort to this region, presumably with an expectation that the probability of finding additional resources is increased. © 2008 Elsevier Inc. All rights reserved.
Abstract.
Higuchi P, Oliveira-Filho AT, Bebber DP, Brown ND, Silva AC, Machado ELM (2008). Spatio-temporal patterns of tree community dynamics in a tropical forest fragment in South-east Brazil.
Plant Ecology,
199(1), 125-135.
Abstract:
Spatio-temporal patterns of tree community dynamics in a tropical forest fragment in South-east Brazil
The tree community (dbh > 5 cm) of a fragment of tropical montane semi-deciduous forest in South-east Brazil was repeatedly surveyed over a 19-year period in order to assess spatial and temporal patterns of dynamics. The surveys took place in 1987, 1992, 1996, 2001, and 2006 in a grid of 126 20 × 20 m permanent plots covering almost the entire fragment (5.8 ha). Overall patterns indicated that a self-thinning process has taken place in the fragment since 1992. Community dynamics varied in space and time, with most dynamics highly spatially clustered. With exception of mortality rates, there were no changes in the spatial patterns of community dynamics through time. No relation between edges and dynamics variables was found. Most species with increasing density and basal area were shade-bearers, while most decreasing species were canopy light demanders and pioneers. © 2008 Springer Science+Business Media B.V.
Abstract.
Fricker MD, Lee JA, Boddy L, Bebber DP (2008). The Interplay between Structure and Function in Fungal Networks. Topologica, 1(1).
2007
Bebber DP, Hynes J, Darrah PR, Boddy L, Fricker MD (2007). Biological solutions to transport network design.
Proceedings of the Royal Society B: Biological Sciences,
274(1623), 2307-2315.
Abstract:
Biological solutions to transport network design
Transport networks are vital components of multicellular organisms, distributing nutrients and removing waste products. Animal and plant transport systems are branching trees whose architecture is linked to universal scaling laws in these organisms. In contrast, many fungi form reticulated mycelia via the branching and fusion of thread-like hyphae that continuously adapt to the environment. Fungal networks have evolved to explore and exploit a patchy environment, rather than ramify through a three-dimensional organism. However, there has been no explicit analysis of the network structures formed, their dynamic behaviour nor how either impact on their ecological function. Using the woodland saprotroph Phanerochaete velutina, we show that fungal networks can display both high transport capacity and robustness to damage. These properties are enhanced as the network grows, while the relative cost of building the network decreases. Thus, mycelia achieve the seemingly competing goals of efficient transport and robustness, with decreasing relative investment, by selective reinforcement and recycling of transport pathways. Fungal networks demonstrate that indeterminate, decentralized systems can yield highly adaptive networks. Understanding how these relatively simple organisms have found effective transport networks through a process of natural selection may inform the design of man-made networks. © 2007 the Royal Society.
Abstract.
Tlalka M, Bebber DP, Darrah PR, Watkinson SC, Fricker MD (2007). Emergence of self-organised oscillatory domains in fungal mycelia.
Fungal Genetics and Biology,
44(11), 1085-1095.
Abstract:
Emergence of self-organised oscillatory domains in fungal mycelia
Fungi play a central role in the nutrient cycles of boreal and temperate forests. In these biomes, the saprotrophic wood-decay fungi are the only organisms that can completely decompose woody plant litter. In particular, cord-forming basidiomycete fungi form extensive mycelial networks that scavenge scarce mineral nutrients and translocate them over long distances to exploit new food resources. Despite the importance of resource allocation, there is limited information on nutrient dynamics in these networks, particularly for nitrogen, as there is no suitable radioisotope available. We have mapped N-translocation using photon-counting scintillation imaging of the non-metabolised amino acid analogue, 14C-aminoisobutyrate. We describe a number of novel phenomena, including rapid, preferential N-resource allocation to C-rich sinks, induction of simultaneous bi-directional N-transport, abrupt switching between different pre-existing transport routes, and emergence of locally synchronised, oscillatory phase domains. It is possible that such self-organised oscillatory behaviour is a mechanism to achieve global co-ordination in the mycelium. © 2007 Elsevier Inc. All rights reserved.
Abstract.
Bebber DP, Harris SA, Gaston KJ, Scotland RW (2007). Ethnobotany and the first printed records of British flowering plants.
Global Ecology and Biogeography,
16(1), 103-108.
Abstract:
Ethnobotany and the first printed records of British flowering plants
Aim: to determine the relative influence of medicinal use, height and geographical range on the chronological sequence of the first verifiable printed records of 1239 native species of flowering plants in the UK. Location: UK. Methods: We used Cox proportional hazards models to provide a direct estimate of the influence through time of explanatory variables on the hazard function. Results: in the period from 1538 to 1550, medicinal plants were 5-15 (95% confidence interval) times more likely to be discovered than non-medicinal plants. By 1600, 75% of medicinal plants had been discovered, and subsequently medicinal use had no significant influence on the probability of discovery. From 1538 to 1983, a 100-hectad increase in area resulted in a 4-6% increase in the probability of discovery. There was a small but significant decrease in the influence of area on the probability of discovery over the entire time period. In the same time period, a 10-fold increase in height resulted in a 3-35% increased probability of discovery. Main conclusions: Our results demonstrate that the first written records (1538-1600) of UK flowering plants were very strongly influenced by the perceived medicinal properties of the plants. © 2006 the Authors Journal compilation © 2006 Blackwell Publishing Ltd.
Abstract.
Fricker MD, Tlalka M, Bebber D, Takagi S, Watkinson SC, Darrah PR (2007). Fourier-based spatial mapping of oscillatory phenomena in fungi.
Fungal Genet Biol,
44(11), 1077-1084.
Abstract:
Fourier-based spatial mapping of oscillatory phenomena in fungi.
Microorganisms display a range of oscillatory phenomena that operate over different temporal scales. Fourier analysis provides a compact description of such oscillations in terms of their frequency, magnitude and phase. However, in the majority of studies there is no explicit consideration of the spatial organisation of the oscillation. Here we describe procedures and a software package to map oscillatory phenomena in microorganisms in both the time and frequency domains. Key parameters of interest, such as frequency, phase or magnitude of the oscillations, are presented as pseudo-colour coded maps. This maintains the spatial information in the image and greatly facilitates understanding of potentially complex propagating waves or development of oscillatory domains with distinct behaviour. We illustrate the utility of this system with reference to spatial analysis of the pulsatile component to amino acid transport in mycelial systems of Phanerochaete velutina and Coniophora puteana, and actin-myosin based contractions in Physarum polycephalum.
Abstract.
Author URL.
Bebber DP, Tlalka M, Hynes J, Darrah PR, Ashford A, Watkinson SC, Boddy L, Fricker MD (2007). Imaging complex nutrient dynamics in mycelial networks. In Gadd G, Watkinson SC, Dyer PS (Eds.) Fungi in the Environment, 3-21.
Tlalka M, Bebber DP, Darrah PR, Watkinson SC (2007). Mycelial networks: nutrient uptake, transport and role in ecosystems. In Boddy L, Frankland J, West PV (Eds.) Ecology of Saprotrophic Basidiomycetes, Academic Press, 43-62.
Fricker MD, Bebber DP, Boddy L (2007). Mycelial networks: structure and dynamics. In Boddy L, Frankland J, West PV (Eds.) Ecology of Saprotrophic Basidiomycetes, Academic Press, 3-18.
Fricker M, Boddy L, Bebber D (2007). Network Organisation of Mycelial Fungi. In (Ed) Biology of the Fungal Cell, 309-330.
Bebber DP, Marriott FHC, Gaston KJ, Harris SA, Scotland RW (2007). Predicting unknown species numbers using discovery curves.
Proceedings of the Royal Society B: Biological Sciences,
274(1618), 1651-1658.
Abstract:
Predicting unknown species numbers using discovery curves
A common approach to estimating the total number of extant species in a taxonomic group is to extrapolate from the temporal pattern of known species descriptions. A formal statistical approach to this problem is provided. The approach is applied to a number of global datasets for birds, ants, mosses, lycophytes, monilophytes (ferns and horsetails), gymnosperms and also to New World grasses and UK flowering plants. Overall, our results suggest that unless the inventory of a group is nearly complete, estimating the total number of species is associated with very large margins of error. The strong influence of unpredictable variations in the discovery process on species accumulation curves makes these data unreliable in estimating total species numbers. © 2007 the Royal Society.
Abstract.
2006
Bebber DP, Harris SA, Gaston KJ, Scotland RW (2006). Ethnobotany and the first printed records of British flowering plants. Global Ecology and Biogeography, 0(0), 061120101210020-???.
Boddy L, Tordoff GM, Wood J, Hynes J, Bebber D, Jones TH, Fricker MD (2006). Mycelial foraging strategies of saprotrophic cord-forming basidiomycetes.
Author URL.
Mountford EP, Savill PS, Bebber DP (2006). Patterns of regeneration and ground vegetation associated with canopy gaps in a managed beechwood in southern England.
Forestry,
79(4), 389-408.
Abstract:
Patterns of regeneration and ground vegetation associated with canopy gaps in a managed beechwood in southern England
In autumn 2001, 15 canopy gaps were selected for study in Rumerhedge Wood, a semi-natural, mesotrophic beechwood in southern England. The gaps were located in mature, beech-dominated stands, and had originated from openings created during a thinning in the early 1980s and wind damage in 1987/1990 and/or the consequent salvage operations. The extent of each gap and surrounding trees were mapped. Tree/shrub regeneration, ground vegetation, bare earth, leaf litter and canopy openness (using a canopy-scope) were measured within and around the gaps using a 5 × 5-m grid and placing a 1 × 1-m quadrat at each grid intersection (total number of quadrats = 400). Most of the gaps were
Abstract.
Watkinson S, Bebber DP, Darrah PR, Fricker MD, Tlalka M, Boddy L (2006). The role of wood decay fungi in the carbon and nitrogen dynamics of the forest floor. In Gadd GM (Ed) Fungi in Biogeochemical Cycles, 151-181.
2005
Bebber DP, Cole WG, Thomas SC, Balsillie D, Duinker P (2005). Effects of retention harvests on structure of old-growth Pinus strobus L. stands in Ontario.
Forest Ecology and Management,
205(1-3), 91-103.
Abstract:
Effects of retention harvests on structure of old-growth Pinus strobus L. stands in Ontario
Retention of structural elements, or legacies, of old-growth stands at harvest has been proposed as a means of maintaining wildlife habitat and ecosystem function in managed forests. However, little is known of the effects and consequences of such practices on the residual stand. A "structural retention harvest" of old-growth eastern white pine Pinus strobus L. was carried out in 1992 in the Algoma Forest of Central Ontario, Canada. In contrast to then-current guidelines, declining- and cavity-trees, snags and coarse woody debris (cwd) were retained at harvest. Cut and uncut stands were surveyed in 2001 to determine the effects of this harvest on forest structure. Basal area prism sweeps for trees and snags were taken at 100 m spacing in 12 logged and six unlogged stands in August 2001. Ground cover, regeneration, and cwd were recorded. White pine basal area before harvest varied among stands from 4.5 to 25.7 m 2 ha -1, or 21-68% of stand total. No white pine trees below 18 cm dbh were found. Around half of white pine basal area was removed at harvest. Logging damage was found on 7% of residual white pines. Harvested stands had similar numbers of cavity trees, standing snags, and volume of natural-origin cwd, to unharvested stands. Inputs of logged white pines left in situ increased the total volume of cwd in harvested stands compared with unharvested stands. Harvested stands also contained more recently dead pines and tip-over trees than unharvested stands. White pine regeneration was scarce, though marginally greater in cut stands. Regeneration was correlated with increased canopy openness in cut stands. Herbaceous cover and sapling density was greater in harvested stands. The study shows that structural retention harvesting can maintain or exceed levels of habitat provision such as cavity trees and cwd, found in old stands, though increased tree mortality and wind-throw can result. © 2004 Elsevier B.V. All rights reserved.
Abstract.
2004
Bebber DP, Thomas SC, Cole WG, Balsillie D (2004). Diameter increment in mature eastern white pine Pinus strobus L. following partial harvest of old-growth stands in Ontario, Canada.
Trees - Structure and Function,
18(1), 29-34.
Abstract:
Diameter increment in mature eastern white pine Pinus strobus L. following partial harvest of old-growth stands in Ontario, Canada
Little is known about the responses of large, old trees to release from competition, though such trees are of great interest in forest ecology, conservation and silviculture. Increment cores were taken from mature eastern white pines (Pinus strobus L.) in 144 sample points in 12 partially harvested and 6 unharvested control stands in Ontario, Canada, to determine how these trees responded to a 'structural retention harvest' that had occurred 9 years previously. Prior to harvest, increment growth was slightly lower in control stands, but not significantly so. Strong correlation in diameter increments among stands indicates external climatic forcing or internal synchronicity, e.g. reproductive allocation. Three years after harvest, growth in harvested stands overtook that in control stands, and increased to 63±8% SE above expected levels by 8 years after harvest. The study demonstrates the ability of old trees to respond markedly to reduced competition, questioning the concept of an age-related decline in forest productivity. In addition to increased timber production, growth responses of old trees have important implications for stand regeneration, wind firmness, and maintenance of wildlife habitat elements following partial stand harvests. Comparison of disturbed stands with undisturbed stands allows better estimation of tree responses than methods in which disturbance is inferred from diameter increment variation within individual trees.
Abstract.
Bebber DP, Brown ND, Speight MR (2004). Dipterocarp seedling population dynamics in Bornean primary lowland forest during the 1997-8 El Niño-Southern Oscillation.
Journal of Tropical Ecology,
20(1), 11-19.
Abstract:
Dipterocarp seedling population dynamics in Bornean primary lowland forest during the 1997-8 El Niño-Southern Oscillation
Dipterocarp seedling populations arising from a 1996 mast fruiting in closed-canopy primary lowland rain forest in Sabah, Malaysia, were monitored through the 1997-8 El Niño event to investigate the effects of drought and other factors on dipterocarp regeneration. of particular interest was the influence of herbivory and its relation to drought, since water stress is known to influence herbivore performance. For seedlings with less than 10% leaf damage, mortality during a 6-mo period spanning the driest part of the drought was three times higher than mortality in the previous and subsequent 6-mo periods (∼10% vs. ∼30%). Leaf production was also higher during this period. Survival was positively related to leaf number and negatively related to leaf damage. Dryohalanops lanceolata was the tallest and leafiest species, and had low levels of leaf damage. Depending on sample period, abscission of leaves with more than 50% damage was between two and three times more likely than those with less than 10% damage. Mortality of seedlings defoliated by more than 50% was around twice that of seedlings defoliated by less than 10%. However, fewer than 10% of seedlings were defoliated by more than 50% at any time. The effect of defoliation did not seem to be altered by drought. Defoliation levels increased after the drought, perhaps due to a resurgence of insect populations. Drought may become a more important influence on dipterocarp regeneration in future, since El Niño events are thought to be increasing in frequency.
Abstract.
2003
Bebber DP, Thomas SC (2003). Prism sweeps for coarse woody debris.
Canadian Journal of Forest Research,
33(9), 1737-1743.
Abstract:
Prism sweeps for coarse woody debris
A new method for sampling coarse woody debris (CWD) is presented, based on relascope sampling of CWD midpoint diameter. In this method, CWD is included in a sample if the angle subtended by the midpoint diameter viewed from plot center is greater than the critical relascope angle. The method is therefore referred to as diameter relascope sampling (DRS). Other methods for sampling CWD are reviewed and compared with DRS using sampling simulations and statistical power calculations. These are fixed area sampling, line intercept sampling, and point relascope sampling. DRS is shown to be have greater statistical power per unit sampling effort than other methods when CWD diameter and length are linearly or allometrically related, but results can vary with the diameter-length relationship employed. The relative benefits of different methods for sampling CWD are discussed.
Abstract.
2002
Bebber DP (2002). Dipterocarp susceptibility to drought: a role for wood structure?. Journal of Tropical Forest Science, 14(3).
Bebber D, Brown N, Speight M (2002). Drought and root herbivory in understorey Parashorea Kurz (Dipterocarpaceae) seedlings in Borneo.
Journal of Tropical Ecology,
18(5), 795-804.
Abstract:
Drought and root herbivory in understorey Parashorea Kurz (Dipterocarpaceae) seedlings in Borneo
The influence of herbivory on dipterocarp seedling growth and survival in Bornean primary lowland forest understorey during and after the 1997-8 El Niño-Southern Oscillation was investigated. During the drought, a coleopteran (Scolytidae) root borer attacked dipterocarp seedlings, primarily of the genus Parashorea. Infestation was spatially heterogeneous on a large (c. 100 m) scale. Attack rate decreased with plant vigour within infested areas. Experiments showed that root damage was fatal under drought conditions, but not after rain. Defoliation and apical meristem removal did not increase mortality. The spatio-temporal heterogeneity of herbivore outbreaks and difficulties involved in experimenting with root herbivores limit the power of such short-term investigations. However, the study shows that herbivores can cause differential mortality between species, and can therefore influence dipterocarp regeneration dynamics. The effect of herbivory depends on the plant organ attacked and interactions with other stresses such as drought. El Niño-related droughts are increasing in frequency in South-East Asian rain forests, which may lead to increased numbers of herbivore outbreaks and greater seedling mortality due to these factors.
Abstract.
Bebber D, Brown N, Speight M, Moura-Costa P, Wai YS (2002). Spatial structure of light and dipterocarp seedling growth in a tropical secondary forest.
Forest Ecology and Management,
157(1-3), 65-75.
Abstract:
Spatial structure of light and dipterocarp seedling growth in a tropical secondary forest
Variation in forest canopy openness influences the growth and survival of seedlings below, and is therefore of practical importance when wishing to restock a forest with valuable timber species after logging. In this study, growth and light environment of dipterocarp seedlings in an enrichment planting project in secondary lowland forest in Borneo were analysed using geostatistics, in order to determine the spatial relationships between canopy openness and seedling performance. Seedling growth was correlated with canopy openness measures up to 50 m away along planting lines but was uncorrelated across planting lines, because the dense understorey between planting lines blocked lateral light. It is recommended that planting be conducted in patches rather than along lines, so that understorey clearance can allow light from canopy gaps in all directions to reach seedlings. © 2002 Elsevier Science B.V. All rights reserved.
Abstract.
2000
Brown N, Press M, Bebber D (2000). Growth and survivorship of dipterocarp seedlings: differences in shade persistence create a special case of dispersal limitation. In (Ed) Changes and Disturbance in Tropical Rainforest in South-East Asia, 123-131.
1999
Brown N, Press M, Bebber D (1999). Growth and survivorship of dipterocarp seedlings: differences in shade persistence create a special case of dispersal limitation.
Philos Trans R Soc Lond B Biol Sci,
354(1391), 1847-1855.
Abstract:
Growth and survivorship of dipterocarp seedlings: differences in shade persistence create a special case of dispersal limitation.
A series of growth experiments and observations on natural populations have been carried out on dipterocarp species of contrasting ecology growing in artificial gaps and the forest understorey. These studies have demonstrated that although differences exist between species in photosynthetic and growth responses to the high-light environment, competition for light in canopy gaps is highly asymmetrical and tends to reinforce any pre-existing dominance hierarchy. We propose that differences in seedling persistence in forest canopy shade are highly influenced by species-specific biotic and abiotic interactions. Our experiments suggest that as seedlings, dipterocarp species trade off traits which enhance persistence and growth in shade against those that enhance their ability to exploit gaps. Less competitive species survive for progressively longer periods of time after a gregarious fruiting event. This leads to significant shifts with time in the number of species present in the seedling bank and hence in the importance of interspecific competition in determining which species dominates regrowth in gaps. We propose that this special case of dispersal limitation is more likely to account for coexistence of dipterocarp species than differences in growth responses to gaps of different size, with stochastic and environmental variables interacting to determine species distribution and abundance.
Abstract.
Author URL.
Bebber D (1999). Sex is best. New Scientist, 161(2169), 51-52.
Bebber D, Koenig W (1999). Spatial autocorrelations [1] (multiple letters). Trends in Ecology and Evolution, 14(5).
Bebber D (1999). Spatial autocorrelations.
Trends Ecol Evol,
14(5).
Author URL.
