Book

The Ecology of Hedgerows and Field Margins

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Abstract

Hedges and field margins are important wildlife habitats and deliver a range of ecosystem services, and their value is increasingly recognized by ecologists. This book reviews and assesses the current state of research on hedgerows and associated field margins.
... The definition of hedgerows varies between countries and assessment frameworks. Hedgerows are commonly considered boundary lines of trees or shrubs that are more than 20 m long and less than five meters wide at the base (DEFRA, 2007), or simply linear woody structures that are permanently vegetated with trees or shrubs (Dover, 2019). The European Nature Information System (EUNIS) defines hedgerows as woody vegetation (mainly shrub species) forming strips within a matrix of grassland or cultivated land (EEA, 2019). ...
... They also mitigate habitat fragmentation by connecting populations of mobile organisms (Gelling et al., 2007). Consequently, the loss of hedgerows in agricultural landscapes negatively affects biodiversity in agroecosystems (Baudry et al., 2000;Dover, 2019). Both Barr et al. (2000) and Graham et al. (2018) focused their work on how different management strategies and hedgerow maintenance approaches affect the biodiversity of different animal taxa. ...
... • The investigated structural landscape element meets the definition of hedgerows or windbreaks (Dover, 2019) as linear woody structures that are permanently vegetated with trees or shrubs. • More than five hedgerow structural parameters were addressed (see Appendix A: Table 1). ...
... In this regard, hedgerows are particularly interesting amongst semi-natural habitats. Hedgerows are perennial structures requiring little management (Staley et al. 2012), that are found in many agricultural environments across the world (Burel 1996;Baudry et al. 2000;Dover 2019), often occupying the narrow strips between fields that are sometimes difficult to cultivate. In industrial countries, most hedgerows have been destroyed in the past 70 years, because of the simplification of agricultural landscapes that came with the Green Revolution. ...
... But hedgerows are now experiencing renewed interest. They have been the subject of numerous studies, particularly recently in the context of the agroecological transition regarding the provision of regulation services (Holland et al. 2016;Albrecht et al. 2020) or biodiversity protection (Dover 2019). ...
... Other types of semi-natural habitats than hedgerows (such as grass field margins or flower strips) seem to have a more widespread or more regular effects on biotic regulation services. This difference may be due to the fact that hedgerows are rarely designed to provide such services (Albrecht et al. 2020); they rather correspond to pre-existing features in the landscape or are planted for other purposes (Dover 2019). Hedgerows have been shown to provide many other important ecosystem services (Dover 2019), not least of them, recreational, cultural, and educational resources. ...
Article
Central to the agroecological transition is biodiversity, which, once restored in agroecosystems, should provide multiple ecosystem services that result from the interactions between different organisms. However, the diversity of expected services raises questions about the capacity of agroecosystems to simultaneously provide many of them as well as the possible existence of synergies and antagonisms. In particular, the relationships between crop-associated biodiversity (i.e. biodiversity in action in crops) and spontaneous biodiversity (i.e. biodiversity not directly related to agriculture) remain unclear. In this article, we analyse the impact of hedgerows on the preservation of spontaneous biodiversity, on the promotion of biotic regulation services such as pollination and pest control in agriculture, and on the interactions between spontaneous and associated biodiversity. Our analysis of the scientific literature shows that hedgerows are unique assets for the preservation of spontaneous biodiversity, while they also provide biotic regulation services to adjacent crops but only under specific conditions, which need to be better understood. We propose a functional conceptual framework of the ecological effects of hedgerows on associated biodiversity and we highlight the possible synergistic and antagonistic effects related to hedgerow characteristics and the life-history traits of the organisms under consideration. Our analysis therefore seeks to overcome the cleavage between associated biodiversity and spontaneous biodiversity. This approach is in keeping with a more harmonious relationship between agriculture and biodiversity.
... Field boundaries provide key habitats and refuges for much of the remaining farmland biodiversity, being uncropped and receiving no direct inputs of agrochemicals (Dover, 2019; but see Gove et al., 2007 for diffuse effects). Hedgerows are the dominant field boundary feature across lowland farmed landscapes in Western Europe and parts of North America, and also occur in South America, Australia and China (Baudry et al., 2000). ...
... Whether originating as remnants of forest clearance, by deliberate planting or natural growth, linear woody features are recognised as highly valuable biodiverse habitats and landscape features, often protected by environmental legislation (Pollard et al., 1974;Dover, 2019). However, the original function of hedgerows as boundaries and a means of enclosing livestock became less important in the 20th Century, due to the availability of inexpensive wire fencing and a desire to increase field sizes to maximise the efficiency of mechanised farming. ...
... However, the original function of hedgerows as boundaries and a means of enclosing livestock became less important in the 20th Century, due to the availability of inexpensive wire fencing and a desire to increase field sizes to maximise the efficiency of mechanised farming. As such, hedgerow conservation has increasingly relied on agri-environment schemes to subsidise regular maintenance to prevent their deterioration (Pollard et al., 1974;Dover, 2019). In landscapes such as the UK and western France, networks of hedgerows and other linear woody features have existed for centuries, with modern hedgerow densities of up to 17 km/km 2 (Fuller et al., 2001;Michel and Burel Butet, 2006). ...
Article
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Farmland birds have declined throughout Europe over recent decades. Many farmland songbirds are associated with linear woody features on field boundaries, such as hedgerows and tree lines. Previous studies have assessed songbird associations with specific hedgerow and tree characteristics, and their landscape context, but large-scale assessments have been limited by difficulties in mapping linear woody networks over large extents, particularly their height structure. We used a high-resolution lidar model of the complete network of linear woody features in southwest England (9424 km 2), summarising linear feature lengths by height class. Associations were tested between heights of linear woody features and the abundance of 22 farmland birds, using bird survey data summarised for 1446 near-contiguous tetrads, and a weighted version of the phi coefficient of association. Land cover mapping defined tetrads as grassland, mixed or arable farmland. Results showed that the linear woody network was dominated by features corresponding to managed hedgerows (1.5-2.9 m tall, 42− 47% of the network by land cover type), followed by tree lines (≥ 6.0 m, 28-35 %). All songbird species had statistically significant, but weak, associations with combinations of land cover and height class of linear woody features, although land cover appeared to be the dominant factor. Many species showed more positive associations with linear woody features on arable farmland than on grassland, particularly for taller hedgerows and tree lines. The results suggest that land-use diversification may benefit some farmland songbirds, such as introducing pockets of arable farming in landscapes dominated by intensively managed grassland. Diverse heights in the linear woody network, incorporating tall hedgerows and trees, would also likely benefit a range of songbird species. The study demonstrates the significant potential of lidar in characterising the structure of linear woody features at the landscape scale, facilitating detailed analyses of wildlife habitat associations and landscape ecology.
... Non-target habitats, such as field margins, are often in close proximity to arable fields and are widespread in agricultural landscapes. These habitats may have an important function for beneficial insects within the agroecosystem, e.g. by providing overwintering sites, food resources due to presence of alternate prey or flower resources, reproduction sites, or dispersal corridors (Marshall and Moonen, 2002;Pywell et al., 2015;Dover, 2019;Li et al., 2020). Drift or overspray of insecticides impacts plant community structure and plant diversity (Schmitz, Hahn and Brühl, 2014), and affects non-target insects in field margins through (i) close contact to polluted areas, (ii) eating of contaminated food, and (iii) uptake through mouth and nose airways (Marshall and Moonen, 2002;Botías et al., 2019). ...
... McHugh et al. (2020) found that herbaceous habitat was positively associated with predation of aphids, while woody linear habitat was negatively associated with predation of aphids. There are also studies reporting positive associations between biocontrol rates and woody elements in the landscape (Bianchi et al., 2005;Bianchi, Goedhart and Baveco, 2008;Dainese et al., 2017;Dover, 2019). Thus, these effects vary across studies and appear contextual (Karp et al., 2018). ...
... Once a common feature of northwestern European landscapes, many hedgerows have been extensively removed since the 1950 ′ s, and in many cases, they have been replaced with more engineered solutions such as barbed wire or electric fences. Yet, hedgerows are still pervasive in many European landscapes (Dover, 2019;Müller, 2013) though they can also be found in North America, Kenya, India, and other countries that were colonised by European countries (Fritz and Merriam, 1993;Iversen, 1981;Moxham, 2001;Mwangi et al., 2012). Where extant, hedgerows are often still providing those solutions for which they were created (enclosure, delineation, animal shelter, etc.) and, as this paper will argue, over time they have attained unforeseen co-benefits. ...
... With the modernization of agriculture in the 1950s, and the associated decline in biodiversity, much research has been carried out on the values of semi-natural areas in differing landscapes (for example: Ali et al., 2014;Rawes and Hobbs, 1979;Sullivan et al., 2011;Uematsu et al., 2010), and hedgerows have come to the fore with extremely high biodiversity and ecosystem service values, especially as wildlife reserves and corridors (Puth and Wilson, 2001;Roy and de Blois, 2008;Wehling and Diekmann, 2009), and may be considered the earliest recognised green infrastructure (sensu Benedict and McMahon, 2006). They have become extremely valued ecologically as linear refuges and genetic reserves for an appreciative and increasing collection of terrestrial flora and fauna species in European agri-environmental landscapes (see: Barr and Petit, 2001;Dover, 2019), especially in light of increasing agricultural intensification, biodiversity loss, and increased hedgerow removal / destruction / over-management (Bates and Harris, 2009;Byrne and delBarco-Trillo, 2019;Chamberlain et al., 1999;Evens, 1993;Froidevaux et al., 2019;Sotherton et al., 1981;Sparks and Martin, 1999;Staley et al., 2015Staley et al., , 2013. There is also a wider body of research on the diverse and newer values of hedgerows in the rural landscape with respect to their potential for intercepting excess diffuse nutrient runoff (Borin et al., 2010;Ghazavi et al., 2008;Grimaldi et al., 2012;Marshall and Moonen, 2002;Thomas and Abbott, 2018;Viaud et al., 2004) as well as pesticide and herbicide drift (Andresen et al., 2012;Froidevaux et al., 2019;Marshall and Moonen, 2002;Ricci et al., 2011;Tiwary et al., 2006). ...
Article
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The arrival of the phrase nature-based solutions into the lexicon of academics, planners, managers and policy makers in recent years has sparked a heated debate as to the effectiveness of using nature as a viable solution for mitigating the impacts of anthropogenic environmental change. One of the difficulties of evaluating the potential efficacy and impact of nature-based solutions is that it is believed that there is little evidence by way of a precedent or long-term successful examples. Much literature exists on the subject of designing with nature to provide multi-functional green infrastructure, connectivity in the landscape, and ecosystem service provision. Indeed, in the opinion of many, the nature-based solution approach appears to synergise research into green infrastructure, ecological connectivity and ecosystem service provision for building climate-related resilience. However, when a nature-based solution has been specifically selected over, say, an engineered solution the literature is rather less clear. So, decision-makers may find it necessary to rely on less reliable sources of impact evidence. This paper argues that field boundary hedgerows may be considered to be exemplars of a nature-based solution, one that was planned, designed, perfected and mainstreamed at a landscape scale, that was specifically selected over a non-nature-based solution, and one that is still in providing solutions and co-benefits today. Therefore, hedgerows may provide some perspective into the potential or emergent co-benefits that the current nature-based solution approach seeks to provide.
... Non-target habitats, such as field margins, are often in close proximity to arable fields and are widespread in agricultural landscapes. These habitats may have an important function for beneficial insects within the agroecosystem, e.g. by providing overwintering sites, food resources due to presence of alternate prey or flower resources, reproduction sites, or dispersal corridors (Dover, 2019;Li et al., 2020;Marshall and Moonen, 2002;Pywell et al., 2015). Drift or overspray of insecticides impacts plant community structure and plant diversity (Schmitz et al., 2014), and affects non-target insects in field margins through (i) close contact to polluted areas, (ii) eating of contaminated food, and (iii) uptake through mouth and nose airways Marshall and Moonen, 2002). ...
... McHugh et al. (2020) found that herbaceous habitat was positively associated with predation of aphids, while woody linear habitat was negatively associated with predation of aphids. There are also studies reporting positive associations between biocontrol rates and woody elements in the landscape (Bianchi et al., 2008(Bianchi et al., , 2005Dainese et al., 2017;Dover, 2019). Thus, these effects vary across studies and appear contextual (Karp et al., 2018). ...
Article
Full-text available
Insecticides are used widely to manage pests, but they may cause mortality in natural enemy populations and non-target prey. On the other hand, resources provided by the landscape – often associated with semi-natural habitat – may enhance natural enemy communities. While there is substantial information on how insecticide use and semi-natural habitats influence biocontrol in crop fields, little is known about how local insecticide use interacts with landscape variables to govern natural biocontrol in field margins. In this 2-year study we assessed predation and parasitism rates of eggs of the cabbage moth (Mamestra brassicae) on potted cabbage plants in field margins adjacent to 20 organically managed fields and 18 conventionally managed fields We analysed egg predation and parasitism rates in field margins using three predictors for insecticide use: (i) farming system (organic or conventional), (ii) frequency of insecticide use in the adjacent focal fields, and (iii) estimated insecticide use quantity within a radius of 1 km from the sampling sites. Insecticide use included foliar or soil-applied applications, including mineral oils. Landscape variables were used as covariables to account for landscape effects. Mean predation and parasitism rates were 14 % and 6%, respectively. There were no significant associations between predation and parasitism rates in field margins with insecticide use in the adjacent field or the wider landscape. Our findings suggest that field margins can be valuable habitats for natural enemies in agricultural landscapes, irrespective of the insecticide use intensity at the local and landscape scale.
... This could be due to road design or abundance of prey. Also, the edges on roads and shrubbery have significant capacity as bird territory (Dover, 2019). Barn owls are drawn to grassy fields because of larger quantities of prey (Arnold et al., 2019;Barn Owl Trust, 2015). ...
... Meticulous design of roadside flora assemblages is therefore crucial to decrease negative impacts in order for birds and wildlife to benefit (Dover, 2019). To decrease owl road mortality, perhaps a realistic choice of mitigation would be to further implement strategies and management to enhance the quality of farmlands in such a manner that alternative land would be able to support larger numbers of prey (rodents) (Arnold et al., 2019;De Jong, van den Burg, & Liosi, 2018). ...
Preprint
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Roads are an important way to transport people and goods, but they sometimes have negative impacts on wildlife. One of the leading causes of mortality for several species is identified as road strikes, and the most significant remains bird-vehicle collisions. This study aimed to investigate what species of birds are most affected, and what other factors impact in their susceptibility in road collisions, such as age, sex, season, and type of transports. A total of N=5413 records, and 140 bird species were documented by BTO ringers. For analysis four Bayesian Hierarchical Models were used, with random effects results showing that Barn owls were most affected by collisions. Road mortality presents the highest cause of mortality among species when contrasted with rail mortality. Age and sexual bias was detected across all species, however juveniles and males did appear to be prominent in relation to other age classes. Winter and early spring were the months with most reported casualties and 2016 had lower abundance of mortality across the 10-year period. 75% of birds were found within a week, which may indicate some bias interference from scavenging animals, as true figures could be up to 16 times more. This study discusses some mitigation measures found in current research, that could dramatically reduce numbers of birds affected each year by road mortality.
... Ucar and Hall 2001;Kristoffersen et al. 2008;Lazzaro et al. 2008;van de Zande et al. 2008;Nuyttens et al. 2011)and may play a major role in mitigating REAP (Faure et al. 2018a). Moreover, vegetation barriers, such as wooded hedgerows, are the easiest LULC elements to manage through planning processes in order to provide multiple and significant benefits (Moreno et al. 2018;Dover 2019). Planting hedgerows in agricultural areas ('bocagement' in French) or using more grassland to mitigate the influence of pesticide drift agrees with objectives of the International Union for Conservation of Nature, which promotes nature-based solutions to provide benefits to nature, the climate and human well-being (Cohen-Shacham et al. 2016). ...
... Hedgerow and 'bocage' landscapes are already present in many rural areas around the world, especially in Europe (e.g. many parts of France, the Alps, England, Belgium) and Canada, the Andes and New Zealand (Forman and Baudry 1984;van der Zanden et al. 2016;Dover 2019). Developing epidemiological studies to define generic environmental sampling protocols to assess the precise role of LULC in protecting or worsening REAP are relevant for current research, societal and planning issues. ...
Article
Exposure of the general population to pesticides, especially in agricultural areas, is a major public health concern. This review analyses the role of Land Use and Land Cover (LULC) in Residential Exposure to Agricultural Pesticides (REAP) and how it is measured and modelled. Some epidemiological studies have shown that basic LULC variables, such as distance to a crop and field size, are relevant for explaining REAP. However, the potential of LULC mitigation elements, such as vegetation barriers, grassy strips and buffer zones, to mitigate REAP has been poorly studied. The availability of recent low-cost and high-quality geospatial data enables REAP models to include alternative and more precise LULC variables. This review also highlights the need for (i) generic environmental sampling protocols, (ii) exposure and spraying datasets and (iii) assessment of the mitigation capacity of LULC to improve REAP modelling significantly.
... In addition to local farming systems and practices, landscape-scale measures generally consist in preserving or increasing landscape compositional or configurational heterogeneity, to increase species pools in the landscape and promote the dispersal of beneficial organisms into crop fields (Priyadarshana et al., 2024). In agricultural landscapes, seminatural habitats such as hedgerows are more stable than cropped habitats, provide perennial refuges and trophic resources for a wide range of taxa, and ensure habitat connectivity (Dover, 2019). Hedgerows are part of the European Union Biodiversity Strategy for 2030 (European Commission, 2021), given their potential to improve below-ground and above-ground functioning, and delivering supporting, regulating, and provisioning services in agricultural landscapes (Montgomery et al., 2020;Staley et al., 2023). ...
Article
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Finding more sustainable ways to produce food is a major challenge for humanity in the face of biodiversity extinction and climate change. Consequently, research on the ability of agroecosystems to provide multiple functions is growing. In this regard, the relative importance of organic farming and landscape‐scale measures for improving multifunctionality has recently been debated. We investigated the effects of farming system (conventional vs. organic) at field scale, total length of hedgerows in the landscape and their interaction on the multifunctionality of 40 winter cereal fields in Brittany (France). Our multifunctionality assessment integrated 21 indicators of five agroecosystem goods: biodiversity conservation, nutrient cycling and soil structure, pest and disease regulation, food production and socio‐economic performance. Many indicators of biodiversity conservation, pest and disease regulation, and socio‐economic performance were higher in organic than in conventional systems. However, indicators of nutrient cycling and soil structure did not improve and food production was much lower in organic systems. Total hedgerow length in the landscape had less influence than organic farming on indicators, although we observed positive interactions. Granivorous carabid abundance and semi‐net margin were highest in organic fields located in well‐preserved hedgerow landscapes. Synthesis and applications. Our study suggests that field‐scale organic farming is necessary to promote biodiversity conservation and associated ecological functioning in crop fields, whereas landscape‐scale preservation of semi‐natural habitats alone is likely insufficient. Preservation of hedgerows in the landscape brings additional ecological and socio‐economic benefits for organic systems without compromising agricultural production. More broadly, our results call for more ambitious research into the myriad possible combinations of farming practices and agri‐environmental measures at both field and landscape scales, to improve both below‐ground and above‐ground functioning.
... These habitats are very important for biodiversity conservation and ecosystem service provision in agricultural landscapes, as they are generally more stable and less affected by agricultural disturbances than cropland [1,2]. As a result, field margins allow the survival, establishment and dispersal of many plant and animal species that would otherwise disappear from intensive production areas [3]. Beyond its intrinsic value, the preservation of plant diversity in field margins is a prerequisite for maintaining a variety of ecosystem services in space and time [4]. ...
Article
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Field margins are major habitats for biodiversity conservation and ecosystem functioning in agricultural landscapes, but biotic homogenization of plant communities threatens their ecological and agronomic functions. Our objective is to determine the drivers of plant diversity in field margins for conservation and restoration purposes. To do so, we assessed the effects of field margin structure and long-term management over 20 years (1995-2015) on the taxonomic and functional α-and β-diversity, and the functional composition of herbaceous plant communities. In 2015, we surveyed 302 field margins in bocage landscapes of Brittany, northwestern France. Results were very similar between taxonomic and functional diversity but revealed important discrepancies between the drivers of α-and β-diversity. Deep ditches, mowing and grazing increased α-diversity but did not affect β-diversity. Denser hedgerows had lower α-diversity than other field margins but strongly contributed to β-diversity by harbouring more unique sets of species or life strategies. Long-term herbicide spraying in field margins and cropping intensity in adjacent habitats did not affect α-diversity, but had more complex effects on β-diversity and selected for common weeds. All in all, preservation of dense hedgerows, abandonment of herbi-cide spraying, and protection against agrochemical drifts are key measures to prevent the establishment of common weeds and biotic homogenization of herbaceous plant communities in field margins. Above all, our study shows how important it is to go beyond α-diversity to make robust conservation and restoration decisions.
... Regardless of the past changes from medieval and early modern land-uses to the later enclosure movement, areas of 18th-and 19th-century Fieldscape clearly harbour important biodiversity in the present (seeDover, 2019;Jefferson, 2005). There is undoubtedly diversity underlying this dominance of 18th-and 19th-century Fieldscape, which may be in part or in whole responsible for important diversity and thus often protected by the Study Region's PAs. ...
Article
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Establishing and expanding protected areas (PAs) has become a key conservation tool in efforts to halt global declines in biodiversity. Given the ubiquity of past and present human influence, PAs inevitably include landscapes and seascapes with varying levels of human modification. We briefly review the geographical biases in England's terrestrial PA network, noting that landscape‐scale PAs (National Parks and Areas of Outstanding Natural Beauty) across England disproportionately occupy rugged upland terrain of low agricultural value as a result of the specific history of PA creation, but that this also biases which historic landscapes compose PAs. We explore these biases using Historic Landscape Characterisation (HLC). Analysis of HLC revealed that PAs in our focal region in northern England are defined by land‐use changes and landscape reorganisation processes of the 18th and 19th centuries, primarily that of enclosure. The impact this landscape transformation had on biodiversity should now form a priority for further research. This historic landscape influence on PA designation has resulted in PAs being typically owned by large estates with consequences for their biodiversity, management and wider social impact (e.g. greater wealth inequalities). The results highlight that historic landscape perspectives are useful to address conservation priorities and practices related to the protection of biodiversity and could be especially helpful in understanding the interaction between biodiversity protection and historic land‐uses, ownership, management, access and other social impacts. Read the free Plain Language Summary for this article on the Journal blog.
... Lineaere strukturer som f.eks. grønne korridorer i et ellers intensivt drevet jordbrukslandskap kan fungere som funksjonelle biologiske korridorer som tillater spredning av pollen via pollinatorenes bevegelsesmønstre (Dover, 2019;Senapathi et al., 2017). Li et al. (2020) dokumenterte at viktigheten av slike korridorer øker med økende intensitet i produksjonen i jordbrukslandskapet. ...
Technical Report
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Pollinating insects are in decline over large parts of the world. This global decline is expected to have adverse consequences for biodiversity, ecosystem services and food production in the future. Norway has prepared a pollinator strategy where the goal is, among other things, to ensure viable populations of pollinating insects in order to maintain pollination in food production. This report provides a broad overview of research-based knowledge of factors that affect pollinators and pollination services in different landscapes, as well as an overview of different models for predicting the occurrence of pollinators.
... Even in the example cited by Boinot et al., the majority of farmers stated to plant hedges for conservation and cultural purposes [2,6]. Hedges offer habitat to different taxonomic groups and we would welcome a formal meta-analysis on the effect of hedges in different landscapes, in addition to existing reviews [7][8][9]. For our meta-analysis, we have chosen the ...
Article
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In our article ‘European agroforestry has no unequivocal effect on biodiversity: a time-cumulative meta-analysis’ (BMC Ecology and Evolution, 2021) we synthesize the effect of agroforestry on biodiversity. Boinot et al. (BMC Ecology and Evolution, 2022) criticise our approach arguing that our definitions of agroforestry and biodiversity are too narrow; that we use inappropriate control sites for primary studies lacking distance to the treatment sites; that there are too few studies for a meta-analysis in silvoarable systems; and that local practice should be emphasized. We agree on the importance of local practices and that more studies would improve the robustness of our meta-analytical results. However, our conclusions are robust to removing studies criticised for inappropriate controls. We also recognize the problem of different definitions of agroforestry and using species richness as sole proxy for biodiversity. We appreciate being given the opportunity to clarify our results and to trigger future discussions about definitions and the interpretation of results from meta-analysis.
... While this does not support the hypothesis that plantings increase ES provision or delivery, it also shows that plantings do not decrease it. This is important because there is a concern among some farmers that plantings may draw pollinators away from the crop field resulting in lower crop pollination (Dover, 2019;Lundin et al., 2017). If this were the case, we would expect to see a significant negative impact of plantings on pollinators in the crop, an observation that was not supported by our analyses. ...
Article
Planting flowers along crop field edges is an increasingly common management strategy for addressing pollinator declines and improving crop pollination. However, few reviews have been published summarizing the efficacy of this specific management practice and how it impacts ecosystem service delivery to crops. We conducted a systematic review (54 studies) and meta-analysis (4–29 studies, depending on the response) to determine whether such plantings 1) increase pollinator abundance or richness within field edges, 2) increase the abundance or richness of pollinators visiting crop flowers, or 3) improve crop yields. Our review and meta-analysis suggest that field-edge flower plantings are highly effective at increasing pollinator richness and abundance in field edges and that plantings become more effective as they mature. However, the influence of field-edge plantings on crop pollination and yield is inconsistent. Planting size and richness did not change these results. While this analysis shows that field-edge flower plantings consistently increase pollinator abundance and richness, there remain critical gaps in our knowledge of when and how plantings can improve ecosystem service provision and delivery. Determining if field-edge plantings affect pollinator population growth may clarify how plantings improve crop pollination, while further research on landscape context and crop type may define when this happens.
... The importance of hedgerows as refuges and corridors in the landscape is well established (e.g. Barr & Petit, 2001;Baudry et al., 2000;Burel & Baudry, 1990;Corbit et al., 1999;Dover, 2019;Marshall & Moonen, 2002;Petit et al., 2003;Roy & de Blois, 2008;Wehling & Diekmann, 2009). The manifest lack of systematic research into field boundary stone wall ecology is unfortunate, not only from a scholarly standpoint, but also due to the possibility that dry stone walls may be of ecological significance, especially considering their age and longevity in many landscapes. ...
Article
Despite the fact that field boundary (dry) stone walls are globally common in rural landscapes, very little research has been carried out regarding them. Dry stone walls may act as refuges for a range of plants and animals, especially in areas where conditions do not favour a high biodiversity or areas of high exposure. They may also provide connectivity via habitat corridors and may even serve as a habitat in their own right. This paper reports on a case study survey of the forb assemblages of field boundary dry stone walls in terms of species richness, biodiversity, and composition in comparison to the surrounding landscape, and aims to provide some insight into the floral ecology characteristics of dry stone walls. To accomplish this, the forbs growing in and immediately adjacent to 18 segments of dry stone wall in the Burren region of western Ireland, were surveyed. The forb assemblages growing within the walls were compared with those growing in the 0.5 m closest to the walls and those growing the areas 0.5-1.0 m on either side of the walls. The wall assemblages were shown to have lower species richness and each category of assemblage was shown to have significantly different species composition. This research indicates that the dry stone walls of the Burren may be associated with a distinct floral ecology, and therefore may act as habitat corridors in an otherwise exposed landscape.
... Butterflies are useful indicators of environmental quality (Erhardt and Thomas, 1989) as populations respond rapidly to environmental change (Thomas, 2005), thus they represent useful model organisms for understanding the wider benefits of agri-environment schemes for terrestrial insects. Butterflies gain multiple benefits from field margins (Dover, 2019) and florally enhanced margins provide nectar resources for the adults which have important consequences for individual fecundity, longevity, dispersal (Geister et al., 2008;Lebeau et al., 2016a, Lebeau et al., 2016bWatt et al., 1974), and species richness and abundance (Curtis et al., 2015;Luppi et al., 2018). Therefore, predicting the responses of butterflies to agri-environment schemes has direct application in conservation management. ...
Article
The intensification of agricultural practices throughout the twentieth century has had large detrimental effects on biodiversity and these are likely to increase as the human population rises, with consequent pressure on land. To offset these negative impacts, agri-environment schemes have been widely implemented, offering financial incentives for land-owners to create or maintain favourable habitats that enhance or maintain biodiversity. While some evidence is available on the resulting species richness and abundance for groups such as natural predators, pollinating insects including butterflies and moths, this is costly to obtain and it is difficult to predict the effects of specific habitat designs. To alleviate this problem we here develop an individual-based model (IBM), modelling the detailed movement behaviour, foraging, and energy budget of a grassland butterfly Maniola jurtina Linn. in patches of varying dimensions and quality. The IBM is successfully validated against data on M. jurtina densities, movement behaviour, resource use, fecundity and lifespan in habitats of varying quality. We use the IBM to quantify the benefits for life-history outcomes of M. jurtina of increasing the quantity and the quality of field margins within agricultural landscapes. We find that increasing the quantity of field margin habitat from 1 to 3 ha per 100 ha, as recommended in agri-environment schemes, increases the average number of eggs laid across a two-week period by 60% and adds an extra day to the average lifespan. Similar effects are reported for variation in the quality of field margins. We discuss the implications of the result for modelling butterfly responses to management scenarios.
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The relative contributions of agricultural intensity and semi‐natural habitats to the multifunctionality and sustainability of ecosystems at different spatial scales remain largely under‐investigated. In this study, we assessed the multifunctionality of 40 winter cereal fields and 40 hedgerows based on ecological, agronomic and socio‐economic performance using data from field surveys and interviews with farmers. We specifically focused on the effects of local farming systems (organic vs. conventional) and management (cereals intercropped with legumes vs. monocrops), the effects of landscape heterogeneity related to hedgerow density, and the spatial extent of semi‐natural habitat and organic farming. Multifunctionality indices associated with increased values of proxies for biodiversity conservation and pest control functions were higher for hedgerows than crop fields. Agroecosystem multifunctionality was similar between organic and conventional farming as a consequence of antagonistic responses of individual function proxies. While organic farming promoted the ecological performance of crops, conventional farming resulted in higher agronomic performance (i.e. yield). Interestingly, lower yields of organic crops were not systematically associated with reductions in socio‐economic performance in terms of farmer income and labour. At the landscape scale, hedgerow density and the extent of semi‐natural habitats and organic farming had little influence on agroecosystem multifunctionality or individual function proxies. Synthesis and applications. Our results confirm the high value of hedgerows and organic farming at the local scale for the ecological performance of ecosystems. Our study suggests that, among existing agri‐environment schemes in Europe, hedgerow planting and organic farming are appropriate tools to optimise the ecological performance of ecosystems at the local scale even if antagonistic effects with agronomic performance should not be neglected.
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Linear features are important landscape elements, providing a range of ecosystem services including pollination to adjacent crops and wild plants. Whilst many aspects of linear features have been shown to impact on resource use by wild pollinators, our principal aim was to explore the impact of topographical variation on the abundance and richness of bumblebee (Bombus) species. Disused railway lines, repurposed as recreational tracks, were used to explore the impact of topography using standardised bee transects through Cuttings (track bed below the surrounding landscape), Flats (track bed at the same level as the surrounding landscape), and Embankments (track bed above the surrounding landscape) (15 each) in the East Midlands of the UK during August 2012. We also recorded general site characteristics including Ordnance Survey grid references, track orientation, and width of vegetation alongside the track. We carried out quadrat surveys of ground flora and estimated flower abundance and canopy cover. Over 1500 individual bumblebees were recorded from 11 species. Bumblebee abundance was × 6.4 higher in Flats and × 8.6 higher in Embankments compared with Cuttings. Dunn multiple comparisons with Bonferroni correction following Kruskal–Wallis Anova showed significantly (P < 0.05) more bumblebees in total, for Bombus pascuorum, and for B. lapidarius in Embankments compared with Cuttings, but no significant differences (P > 0.05) in abundance between Embankments and Flats. Significantly more bumblebees were found in Flats compared with Cuttings for total bumblebees and B. pascuorum, but not for B. lapidarius. Cuttings had the lowest total number of species (4) compared with Flats (11) and Embankments (8). Median bumblebee species richness was significantly greater in Embankments and Flats compared with Cuttings, but no significant difference was evident between Embankments and Flats. Following model simplification, averaged negative binomial and Poisson glm models were created of bumblebee abundance and richness (respectively). Modelling indicated that the total abundance of bumblebees was significantly affected by track morphology, and also by the abundance of Thistle/Knapweed (Cirsium/Carduus/Centaurea spp.) flowers. Canopy cover by trees/tall shrubs negatively impacted on bumblebee abundance. Modelling of the dominant species (Bombus pascuorum) confirmed the importance of Thistle/Knapweed flowers and Morphology, but also identified an interaction effect of track Orientation for Embankments. Canopy cover was the only significant influence (negative) on bumblebee richness identified by modelling. The results are discussed in relation to the resources available to bumblebees in disused railway lines, the impact of topography on resources, the timing of the surveys and management implications. Implications for insect conservation Our results show that disused railway lines can provide nectar resources for bumblebees. Further, the abundance and richness of Bombus species was modified by topographically-mediated impacts on vegetation (including shading and provision of nectar sources). Disused railway lines have the potential to provide a range of resources for insects in the wider countryside.
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