1. How humans interact with nature affects the health of both people and ecosystems. Yet, long-term data on nature engagement are scarce because traditional survey methods are expensive, time consuming and require commitment over multiple years. Digital data sources (e.g. aggregated data from online searches) have major potential as a supplementary source of information and, in the absence of available data, as a proxy for more direct measurement of nature engagement.

2. Using Google Trends, we created a list of refined and relevant search terms relating to diverse outdoor spaces and activities. We then compared trends in Google search volumes in England across both a 1-year and 10-year period to those from Google Community Mobility Reports, and from nationally representative survey data (Natural England’s People and Nature Survey and the Monitor of Engagement with the Natural Environment).

3. Search, survey and mobility data all support a general increase in public engagement with nature since 2009, and a more substantial increase during, or following, the initial national ‘lockdown’ period of the COVID-19 pandemic in England. Search volumes increased for many urban and rural outdoor green spaces (e.g. woodlands), blue spaces (e.g. reservoirs), exercise activities (e.g. walking, running, and hiking), and explicitly nature-based activities (e.g. fishing, wild swimming, and encouraging wildlife).

4. Overall, volumes of Google searches were more closely related with longer-term (10-year) trends from survey data, than more subtle, shorter-term changes during the COVID-19 pandemic. There was a statistically significant relationship between search volumes, survey data (self-reported past behaviour) and mobility data (movement trends) for around half of comparisons. of these, an average of 13-44% of variation in the data was explained.

5. The findings show that Google Trends provides valuable information about public engagement with nature, which can help to supplement existing survey data by providing new insights about behavioural trends. The paper also provides a proof of concept for using Google Trends to understand changes in public engagement with nature, which could be applied to the many countries that lack long-term survey monitoring.

During the main COVID-19 global pandemic lockdown period of 2020 an impromptu set of pollination ecologists came together via social media and personal contacts to carry out standardised surveys of the flower visits and plants in gardens. The surveys involved 67 rural, suburban and urban gardens, of various sizes, ranging from 61.18° North in Norway to 37.96° South in Australia, resulting in a data set of 25,174 rows, with each row being a unique interaction record for that date/site/plant species, and comprising almost 47,000 visits to flowers, as well as records of flowers that were not visited by pollinators, for over 1,000 species and varieties belonging to more than 460 genera and 96 plant families. The more than 650 species of flower visitors belong to 12 orders of invertebrates and four of vertebrates. In this first publication from the project, we present a brief description of the data and make it freely available for any researchers to use in the future, the only restriction being that they cite this paper in the first instance. The data generated from these global surveys will provide scientific evidence to help us understand the role that private gardens (in urban, rural and suburban areas) can play in conserving insect pollinators and identify management actions to enhance their potential.

The study was carried out in Cornwall, United Kingdom in 2019 and 2020. First, we used roadside surveys to assess the spatial distribution of pollution, flowers and pollinators in road verges. Second, we used field experiments (away from roads) to simulate each form of pollution separately and measure the impacts on pollinator densities and foraging behaviour to explain the distribution of pollinators observed across road verges.

Roads form vast and pervasive networks across the earth, with diverse and often profound negative environmental impacts. However, these roads are bordered by a parallel network of habitats in the form of road verges. In this thesis, I propose that roads present a nearly ubiquitous environmental pressure, but that their verges offer an equally widespread opportunity to benefit nature, the environment and, as a result, people.

I begin by using spatial mapping and modelling to estimate the extent of road pollution, in various forms, across Great Britain. This reveals that half of land is less than 216 m from a road, and that roads have a zone of influence that extends across > 70% of the land area. Whilst high levels of road pollution are estimated to be relatively localised, low levels are pervasive.

Second, I synthesise the literature to determine the global potential of road verges for mitigating such pollution, for supporting nature and for providing further environmental and social benefits via ecosystem services. I estimate that road verges may currently cover 270,000 km2 globally, and that they provide a wide range of benefits, including biodiversity provision, regulating services (e.g. air and water filtration) and cultural services (e.g. health and aesthetic benefits by providing access to nature). However, verges also displace other habitats and provide ecosystem disservices (e.g. plant allergens and damage to infrastructure).

Third, I use satellite and ground-level imagery to estimate the extent of road verges across Great Britain and to explore their potential to benefit nature, the environment and people. I estimate that there are 2579 km2 (2149-3010 km2) of road verges in Great Britain, equivalent to 1.2% of land area, of which 707 km2 (27.5%) is short, frequently-mown grassland, 1062 km2 (40.9%) is regular grassland, 480 km2 (18.7%) is woodland, and 272 km2 (10.7%) is scrub. Only 27% of frequently-mown grassland verges contain trees, indicating potential for planting trees and shrubs to provide environmental and social benefits.

Fourth, I take insect pollinators as a case study and, using a combination of roadside surveys, field experiments, a literature review, and meta-analyses, determine the suitability of road verges for pollinator conservation, and how they could be enhanced for this purpose. The findings demonstrate that road verges can be hotspots of flowers and pollinators in human-dominated landscapes, but that traffic and road pollution can cause mortality and other negative impacts on pollinators. Surveys in Cornwall, UK, show that pollinator densities are lower closer to the road edge – particularly within the first 2 m (55% lower than at 7-9 m) – where pollution is greatest. Field experiments reveal that these trends can be explained by pollinators being deterred by turbulence, and avoiding concentrations of metals that are more frequently found in flowers within 2 m of roads. Overall, evidence suggests that the benefits of road verges for pollinators outweigh the negative impacts of road pollution and pollinator-vehicle collisions.

The research shows clearly that road verges already provide many environmental and social benefits, but that these could be enhanced considerably through strategic design and management. Several reoccurring management recommendations are reducing mowing frequencies to no more than twice per year, leaving some areas uncut on rotation, and planting trees in urban verges and in low quality verge habitats. I finish by reflecting on the project and its outcomes, and on the remaining barriers to managing road verges for nature, the environment and people. This reveals the most important directions for future research, namely, the importance of overcoming social barriers to change that inhibit uptake of environmental management recommendations.

The importance of wild bees for crop pollination is well established, but less is known about which species contribute to service delivery to inform agricultural management, monitoring and conservation. Using sites in Great Britain as a case study, we use a novel qualitative approach combining ecological information and field survey data to establish a national list of crop pollinating bees for four economically important crops (apple, field bean, oilseed rape and strawberry). A traits data base was used to establish potential pollinators, and combined with field data to identify both dominant crop flower visiting bee species and other species that could be important crop pollinators, but which are not presently sampled in large numbers on crops flowers. Whilst we found evidence that a small number of common, generalist species make a disproportionate contribution to flower visits, many more species were identified as potential pollinators, including rare and specialist species. Furthermore, we found evidence of substantial variation in the bee communities of different crops. Establishing a national list of crop pollinators is important for practitioners and policy makers, allowing targeted management approaches for improved ecosystem services, conservation and species monitoring. Data can be used to make recommendations about how pollinator diversity could be promoted in agricultural landscapes. Our results suggest agri-environment schemes need to support a higher diversity of species than at present, notably of solitary bees. Management would also benefit from targeting specific species to enhance crop pollination services to particular crops. Whilst our study is focused upon Great Britain, our methodology can easily be applied to other countries, crops and groups of pollinating insects.

Context: Maximising insect pollination of mass-flowering crops is a widely-discussed approach to sustainable agriculture. Management actions can target landscape-scale semi-natural habitat, cropping patterns or field-scale features, but little is known about their relative effectiveness. Objective: to test how landscape composition (area of mass-flowering crops and semi-natural habitat) and field-scale habitat (margins and hedges) affect pollinator species richness, abundance, and pollen deposition within crop fields. Methods: We surveyed all flower visitors (Diptera, Coleoptera and Hymenoptera) in oilseed rape fields and related them to landscape composition and field features. Flower visitors were classified as bees, non-bee pollinators and brassica specialists. Total pollen deposition by individual taxa was estimated using single visit pollen deposition on stigmas combined with insect abundance. Results: the area of mass-flowering crop had a negative effect on the species richness and abundance of bees in fields, but not other flower visitors. The area of semi-natural habitat in the surrounding landscape had a positive effect on bees, but was not as important as the area of mass-flowering crop. Taxonomic richness and abundance varied significantly between years for non-bee pollinators. Greater cover of mass-flowering crops surrounding fields had a negative effect on pollen deposition, but only when non-bee pollinator numbers were reduced. Conclusions: Management choices that result in landscape homogenisation, such as large areas of mass-flowering crops, may reduce pollination services by reducing the numbers of bees visiting fields. Non-bee insect pollinators may buffer these landscape effects on pollen deposition, and management to support their populations should be considered.

Flower and pollinator communities were surveyed in 2018, using transect counts and pan traps, to explore the role of road verges and their associated hedges in supporting pollinators in an agricultural landscape in southwest England, and the impacts of traffic and verge cutting. At 19 sites, the road verge (verge edge and verge centre), the verge hedge (both sides), a field hedge, and the field interior were surveyed.

Supporting pollinators in agricultural landscapes is important for reversing their global decline. Road verges and hedges are used by pollinators for feeding and reproduction, but few studies consider entire pollinator communities, and it remains unclear how they are distributed across adjacent verges, hedges and fields, or how they are affected by traffic and verge cutting. We surveyed flowers and pollinators, using transect counts and pan traps, to explore the role of road verges and their associated hedges in supporting pollinators in an agricultural landscape in southwest England, and the impacts of traffic and verge cutting. At 19 sites, we surveyed the road verge (verge edge and verge centre), the verge hedge (both sides), a field hedge and the field interior. Road verges and hedges had a much greater flower abundance, flower species richness and pollinator abundance than field interiors. Verge hedges had far less woody cover than field hedges, but greater flower species richness. There were fewer pollinators along verge edges (next to roads) than along verge centres (2–11 m from roads) and fewer pollinators in road verges next to busier roads. Road verges were generally cut once (in summer), and cuttings were never removed. There were substantially fewer flowers and pollinators in road verges that had been cut, even though surveys often took place many weeks after cutting. Synthesis and applications. Road verges and their associated hedges can provide hotspots of resources for pollinators in agricultural landscapes, but their capacity to do so is reduced by heavy traffic and summer verge cutting. We recommend that beneficial management for pollinators should prioritize wider road verges (at least 2 m wide), roads with less traffic, and areas away from the immediate vicinity of the road. Where possible, verge cutting should not be carried out during peak flowering times.

This thesis explores (i) how pollinator community characteristics relate to pollination service, and (ii) how pollinator communities will be affected by climate change-induced drought.
Chapter 1 gives an overview of the evidence for a relationship between biodiversity and ecosystem services (BES), with particular reference to pollination services. The major threats to pollinators are discussed, including how these affect the characteristics of pollinator communities and ultimately, pollination services.
Chapter 2 explores how pollinator community characteristics affect the pollination service to winter-sown oilseed rape, an economically important crop. A modelling approach was used to estimate the pollination service that is provided by different flower visitors and to explore the mechanisms that are driving the pollination service in this system. Overall, the contribution of bees and non-bees to pollination service was estimated to be similar. Functional group richness had a positive effect on estimated pollen deposition, providing evidence for a BES relationship due to community structuring. However, the abundance of common species was the primary driver of pollination service.
Chapter 3 explores how pollinators are likely to be affected by drought events, which are predicted to increase in frequency and intensity due to climate change. In a field experiment in calcareous grassland, rooves were placed over plant communities to simulate a single period of drought. Subsequent effects on floral resources and flower visitor activity were measured. Flowers in the drought treatment were less likely to contain nectar and racemes had fewer flowers overall. At the community scale, there were substantially fewer flowers in the drought treatment, suggesting that drought events will cause periods of floral resource scarcity.
In both case studies, changes to pollinator communities, by loss of biodiversity or due to effects of drought, have the potential to reduce pollination of both crop and wild plants.