Re-structuring hedges: rejuvenation management can improve the long term quality of hedgerow habitats for wildlife in the UK

Hedgerows provide key wildlife habitat in intensive agricultural landscapes, but are declining in length and structural condition due to a lack of rejuvenation management, neglect and over-frequent trimming with mechanised flails. Here, we test cheaper, alternative methods to traditional hedge laying methods using a multi-site manipulative field experiment. In the first quantitative test of new approaches to hedge rejuvenation management, hedge regrowth, structure, berry provision for over-wintering wildlife and cost of rejuvenation were assessed in response to five methods, for three years following rejuvenation. Three ‘laying’ methods and coppicing were effective at improving hedgerow condition by stimulating basal regrowth, thus increasing the density of woody material at the base and reducing gap size. The pros and cons of coppicing are discussed in relation to its impact on different wildlife groups, and it is recommended in limited circumstances. Differences between the three ‘laying’ methods reduced over time, so a cheaper conservation hedging method is recommended as an alternative to traditional hedge laying. This new approach to hedge management offers the potential to restore twice the length of hedgerow currently rejuvenated under agri-environment schemes

Little and late: how reduced hedgerow cutting can benefit Lepidoptera

Hedgerows are a key semi-natural habitat for biodiversity in intensive agricultural landscapes across northern Europe and support a large invertebrate fauna. Management can have large effects on the value of hedgerows as a wildlife habitat, thus sensitive management is incentivised through agri-environment schemes (AES). We tested how current and potential future AES hedge management regimes affected the diversity and abundance of Lepidoptera species that utilise the hedge as a breeding resource, using a long term, multi-site, manipulative field experiment. Hedgerow management in some current AES options (reduced trimming frequency and cutting in winter) increased Lepidoptera abundance and the diversity of components of the Lepidoptera community linked with specific lifecycle traits. However, the most frequently applied hedgerow AES option currently applied in the UK (cutting once every 2 years in autumn) did not benefit Lepidoptera compared to standard hedgerow management outside AES (annual trimming in autumn). Decreasing the intensity of hedgerow trimming improves the diversity of the whole Lepidoptera assemblage, and should be considered as part of biodiversity conservation in farmed landscapes

Does agri-environmental management enhance biodiversity and multiple ecosystem services?: A farm-scale experiment

Agri-environmental management has been promoted as an approach to enhance delivery of multiple ecosystem services. Most agri-environment agreements include several actions that the farmer agrees to put in place. But, most studies have only considered how individual agri-environmental actions affect particular ecosystem services. Thus, there is little understanding of how the range of agri-environmental actions available to a farmer might be deployed on any individual farm to enhance multiple services. To address this knowledge gap, we carried out an experimental study in which we deployed a set of agri-environmental actions on a commercial farm in southern England. Agri-environmental actions comprised wildflower margins and fallow areas in arable fields, creating and enhancing grassland with wildflowers, and digging ponds. Alongside biodiversity responses, we measured effects on a number of ecosystem services: pollination, pest control, crop and forage yield, water quality, climate regulation and cultural services. Wildflower margins enhanced invertebrates, pest control and crop yield, and aesthetic appeal. A greater number of pollinators was linked to enhanced oilseed rape yield. But these margins and the fallows did not prevent run-off of nutrients and sediment into waterways, and showed limited carbon sequestration or reduction of greenhouse gas emissions. Newly-dug ponds captured large amounts of sediment and provided aesthetic appeal. Grasslands had higher soil carbon content and microbial biomass, lower N20 emissions, and net sequestration of carbon compared to arable land. Enhancement of grassland plant diversity increased forage quality and aesthetic appeal. Visitors and residents valued a range of agri-environmental features and biodiversity across the farm. Our findings suggest one cannot necessarily expect any particular agri-environmental action will enhance all of a hoped-for set of ecosystem services in any particular setting. A bet-hedging strategy would be for farmers to apply a suite of options to deliver a range of ecosystem service benefits, rather than assuming that one or two options will work as catch-all solutions

The status of the world's land and marine mammals: diversity, threat, and knowledge

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action

The status of the world's land and marine mammals: Diversity, threat, and knowledge

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action