The effectiveness of integrated farm management, organic farming and agri-environment schemes as interventions for conserving biodiversity in temperate Europe. (systematic map)
Background
Agriculture is the dominant land use throughout much of Europe. Changes to farming practices have led to concerns about negative impacts on biodiversity, and current agricultural policy has an emphasis towards conservation. The objective of this study was to investigate and describe the nature and coverage of research pertaining to the effectiveness of integrated farm management, organic farming and agri-environment schemes as interventions for conserving biodiversity in temperate Europe.
Systematic mapping methodology was adapted from social sciences, and used to create a searchable database of relevant research.
Methods
Searches were made of 10 electronic databases containing peer reviewed journals, PhD theses, conference proceedings and organisational reports. Web searches for relevant research were also made. The title and abstracts of results were examined for relevance. Studies were included when published in English, when an intervention was applied to increase biodiversity or species diversity on farmland, and where there was a measured effect on study organism(s). Correlative and manipulative studies from temperate Europe were included. The research was incorporated into a searchable database (systematic map) and key wording used to describe, categorise and code studies.
Results
The searches identified 83,590 records. Following removal of duplicates and the application of inclusion criteria, 743 references were coded for the final systematic map database. Most of the studies reported were from Western Europe, particularly from the UK. Invertebrates were the most commonly studied organism followed by plants and birds, and field margins were the most commonly studied biotope.
Conclusions
The systematic map describes the scope of research on the topic. It can be used to inform future primary research, or research synthesis and evaluation methods such as systematic review. Areas for which there appear to be evidence gaps, and so may have potential for further primary research, are highlighted. They include the effectiveness of agri-environment options under different farming systems and in providing for amphibians and reptiles. Implications for the development of future systematic maps are discussed, including the question of how to incorporate study quality appraisal. The development of a Collaboration for Environmental Evidence systematic mapping methods group will address some of these issues.
Keywords
Farmland biodiversity, Conservation, Systematic map, Systematic review, Agri-environment, Organic farming, Integrated farm management, Evidence-based policy
Background
Agriculture is the dominant land use throughout much of Western Europe, and since the 1940s, farming has increasingly become more intensive. This has resulted in widespread declines in many groups of organisms associated with farmland (Robinson & Sutherland, 2002). Farmland birds in particular are well documented (Fuller et al., 1995, but losses of other organisms are also much recorded. Bumblebee declines are especially marked (Carvell et al., 2004), and butterflies declined by 22.5% between 1994 and 2003 (Butterfly Conservation, 2006)
Following a green paper in 1985 which addressed the environmental impact of agriculture (CEC 1985), agri-environment schemes (AES) have been available to European Union member states under the Common Agricultural Policy (CAP) (Kleijn & Sutherland, 2003). However, schemes are subject to change due to ongoing reforms, and also vary between different countries.
In Britain, there are a number of schemes available that provide financial incentives to farmers to adopt environmentally friendly land management. In 2005 the Environmental Stewardship Scheme (ESS) was introduced to replace a number of previous schemes. ESS has three different entry levels, Entry Level Stewardship (ELS), available to all farmers, Organic Level Stewardship (OLS) available to organic farmers and Higher Level Stewardship (HLS) for targeted environmental management.
A number of studies have examined whether AES can be effective in conserving or increasing biodiversity (Kleijn & Sutherland, 2003; Kleijn et al., 2006 for example), but results appear to be variable (Whittingham, 2007). Marshall et al. (2005) suggested that landscape structure affects the success of farmland biodiversity initiatives. This may need to be addressed in future agri-environment schemes (Wittingham, 2007).
Similar questions are raised as to the effectiveness of organic farming on biodiversity. For example Hole et al. (2005) compared data from Europe, New Zealand, the US and Canada and suggested that organic farming increased biodiversity at every level of the food chain, yet a meta-analysis by Bengstsson et al. (2005) found that results varied between studies, and between organism groups and landscapes. Fuller et al. (20052) suggested that the magnitude of biodiversity variation between taxa is because the scale of organic farms may be too low to affect species with large spatial needs.
Integrated farming has also been shown to increase biodiversity when compared with conventional farming (Berry et al., 2005) although results again vary between studies and species.
The question of how different farming systems compare in their effects on biodiversity and other environmental impacts was recently identified by policy makers and scientists as one of the top 100 priority policy-relevant ecological questions in the UK. The need to learn from AES to optimize future biodiversity gain and ecological benefits was also prioritised. (Sutherland et al., 2006).
Using systematic review methodology, terrestrial biodiversity of farmland under different management interventions will be critically appraised. The review will consider the best available evidence of the effectiveness of different management regimes in different situations (Table 1). Publication bias will be limited through the use of comprehensive literature searching (published and unpublished), specific inclusion criteria, and formal assessment of the quality and reliability of the studies retrieved. Subsequent data synthesis (qualitative and/or quantitative) will summarise evidence to provide guidance to land managers and highlight any gaps in the research evidence.