There can be few people who do not appreciate and benefit from the diversity of landscapes in the UK and the wide range of flora and fauna they contain. This biodiversity has been under threat for many years from intensive agricultural land management.
There has been a widespread decline in the populations of many groups of organisms, resulting largely from habitat loss and sub-division, and a reduction in quality of the remaining habitats, which is often collectively termed habitat fragmentation.
However, farming is not all bad news for biodiversity, and less intensive farming practices of the past have created some of our most valuable habitats. Agri-environment schemes help to recreate this situation and aim to counteract the negative effects of more intensive modern agriculture. Many of the options in the latest agri-environment scheme, Environmental Stewardship (ES), reduce farming intensity and conserve and expand sites of high biodiversity.
ES was established in 2005 and designed to provide funding to farmers and other land managers in England who deliver effective environmental management on their land. It builds on the recognised success of the earlier Environmental Sensitive Areas scheme and the Countryside Stewardship Scheme. One of its five primary objectives is to “conserve wildlife (biodiversity)”.
The scheme is available in some form to all managers of land on the Rural Land Register and comes in the form of Entry Level (ELS) and Higher Level Stewardship (HLS). ELS, which has a suite of management options to select from, is generally described as broad and shallow, and aims to have very wide coverage throughout England. In contrast, HLS is described as narrow and deep and is largely targeted, at the present time, to the protection and improvement of Sites of Special Scientific Interest (SSSIs).
Climate change is a new and increasing threat to our biodiversity and is likely to have profound effects on individual species and habitats, and the landscape as a whole. The current agri-environment schemes are considered by many to be effective at achieving most of the objectives for which they were set up. However, there is concern about their contribution to the delivery of long-term outcomes for biodiversity, since the impact of climate change is not taken into account at present.
Defra has recently started an ES review of progress to look at all aspects of the scheme, and a key element of this is to develop climate change mitigation and adaptation measures for ES in the future. At Warwick HRI, we are contributing to this by assessing the impact of climate change on the delivery of biodiversity through agri-environment schemes (Defra project AC0304).
During the 20th century, there was considerable emphasis on the protection and conservation of key species and wildlife habitats, often within SSSIs. The importance of continuing to protect this existing biodiversity cannot be overemphasised, because future biodiversity will adapt and evolve from this resource. However, it is an increasingly common view that biodiversity should not be “preserved in aspic”, and that some of the features (species and habitats) that we currently value may disappear, whilst others may arrive and develop.
Detailed predictions of climate change have been made by the UK Climate Impacts Programme (UKCIP) and, using this information, scientists have made further predictions of the impact that climate change will have on individual species and habitats. These predictions are complex and varied, and the details are beyond the scope of this article, but the description that follows gives a flavour of the potential impact of climate change.
All species have a unique climate space in which they can live. For example, plants may require a particular physical habitat and have a species-specific range of temperatures and moisture levels within which they can survive. This combination of requirements often limits where they exist geographically. As the climate changes, the precise geographical location of the climate space of any particular plant species will change - the species will have to move to survive. However, even if the desired range of temperatures and moisture levels still exists elsewhere, the physical habitat that they need may be limited in the new location. Moreover, species do not exist in isolation, but interact and rely upon other species around them, e.g. for food, shelter and pollination. This further complicates the situation, because species have different tolerances and rates of adaptation, and so interacting species may lose synchrony with each other as the climate changes. For example, insect life cycles may change in relation to those of the plants and birds that depend on them, so they may no longer be sufficiently numerous at the correct time to pollinate the plants, or as food for newly hatched chicks.
The relative competitiveness of species may also change with the climate. For example, warmer winter temperatures will increase vegetative survival of some plant species, whilst the seeds of other species may not receive sufficient low temperature exposure to break dormancy and induce germination. As a result, the competitive balance between species with different survival strategies will be disturbed. These changes to life cycles, such as the early flowering of plants in the spring, are already being reported in the news. Combinations of these effects across species could have a profound effect on the functioning of the whole eco-system within the farmed landscape.
So how are these changes likely to affect ES? Most stakeholders that we contacted in our project thought that the range of options available within ELS was adequate, and that they will continue to be robust and effective in the face of climate change. However, it is anticipated that further options may be required, and management protocols within options selected by the farmer will need to be adapted as climate change occurs. Examples include:
• The timing of operations such as mowing and scarification of field margins, and hedgerow management will need to change in line with changes in the timing of target species life cycles
• Choices available for vegetation management in many of the ELS options may be compromised because of limitations imposed by weather conditions on mechanical operations, and on the efficacy and control windows of many herbicides
• The times of sowing and the content of species mixes used in some options may need to change (in particular to include species tolerant to drought in areas that are likely to be affected)
• Wetter winters and a greater frequency of extreme rainfall events, as well as hotter and drier summers, will impact on options concerned with soil erosion.
HLS agreements are much less prescriptive, so it is most likely that climate change will need to be considered separately in each plan, with the management tailored to take account of regional specific predictions of the future climate, and how it will impact on the site and species to be protected.
With the predicted impacts of climate, it is pertinent to ask whether ES can continue to be useful and effective at protecting and promoting biodiversity in the future. The answer seems to be definitely ‘yes’, if it is deployed effectively. As 70 per cent of the land area of England is used for agriculture, ES will be critical not just for conservation, but also for the protection of biodiversity in the face of climate change, because they have wide geographical coverage and the potential to:
• Conserve protected areas and high quality habitats as a gene pool for the migration and re-establishment of habitats and species
• Reduce sources of harm that are not linked to climate, by buffering existing bio-diverse sites from the intensive management systems that surround them and by generally reducing that intensity
• Increase landscape heterogeneity (i.e. more variable landscapes containing a greater variety of habitats at a range of scales), as this is generally agreed to increase the resilience of biodiversity to change
• Increase connectivity between wildlife habitats and hence allow animals and plants to move, if necessary, in response to climate change (i.e. create corridors, stepping stones and other means to develop landscapes that are permeable to wildlife movement).
To achieve this, the approach to agri-environment schemes is changing, from the conservation of natural habitats treated in isolation, to a more co-ordinated approach on a larger scale. At the same time, there will be less emphasis on individual species and habitats and an increasing concern about the functioning of whole eco-systems, with the aim of developing landscapes where biodiversity can be more resilient to climate change. In practice, it will remain important to encourage widespread uptake of ES by individual farmers and land managers through individual agreements, but increasingly these should form part of a larger co-ordinated plan, to have most impact in protecting and promoting biodiversity within our countryside.
Details of this Warwwick HRI project and a range of other climate change-related projects at can be found at www.go.warwick.ac.uk/climatechange/
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