Landscape-moderated biodiversity effects of agri-environmental management: a meta-analysis

Abstract

Agri-environmental management (AEM) is heralded as being key to biodiversity conservation on farmland, yet results of these schemes have been mixed, making their general utility questionable. We test with meta-analysis whether the benefits of AEM for species richness and abundance of plants and animals are determined by the surrounding landscape context. Across all studies (109 observations for species richness and 114 observations for abundance), AEM significantly increased species richness and their abundance. More specifically, we test the hypothesis that AEM benefits species richness and abundance (i.e. increases the difference between fields with and without AEM) more in simple than in complex landscapes. In croplands, species richness but not abundance was significantly enhanced in simple but not in complex landscapes. In grasslands, AEM effectively enhanced species richness and abundance regardless of landscape context. Pollinators were significantly enhanced by AEM in simple but not in complex landscapes in both croplands and grasslands. Our results highlight that the onesize-fits-all approach of many agri-environmental programmes is not an efficient way of spending the limited funds available for biodiversity conservation on farmland. Therefore, we conclude that AEM should be adapted to landscape structure and the species groups at which they are targeted.

Learning from agri-environment schemes in Australia. Investing in biodiversity and other ecosystem services on farms

“…The greatest positive biodiversity response has been observed in landscapes with an intermediate level of 'complexity' -the degree of variation within landscape (Concepción et al 2012). Despite this, other studies have found inconsistent results for different taxonomic groups for both simple and complex landscapes, and that the effect of complexity depends on the type of surrounding vegetation (Batáry et al 2011). Landscapes with a greater proportion of area covered by management demonstrate stronger positive biodiversity response (Baker et al 2012;Dallimer et al 2010), although whether this is in response to direct agri-environment scheme investment or greater inclusion of suitable landscapes remains unclear.…”

“…Recent studies have found that the biodiversity response to agri-environment scheme investment is influenced by the context of the surrounding landscape (Carvell et al 2011;Concepción et al 2012), although this response is inconsistent and poorly resolved (Batáry et al 2011). The greatest positive biodiversity response has been observed in landscapes with an intermediate level of 'complexity' -the degree of variation within landscape (Concepción et al 2012).…”

“…While some schemes have been successful in addressing the social and policy elements of farmland conservation (Zammit 2013), very few have been able to demonstrate effective biodiversity outcomes across the scale of program implementation (Whittingham et al 2007). One of the key reasons for this is that, in order to work across large spatial scales, programs have tended to employ rigid management actions, or a one-size-fits-all approach (Batáry et al 2011;. However, recent studies have demonstrated that the effectiveness of agri-environment schemes is influenced by a number of scale-dependant factors, including the amount invested in agri-environment schemes (Dallimer et al 2010;Hiron et al 2013), surrounding landscape context (Batáry et al 2011;Concepción et al 2012;, and the underlying delivery mechanisms used in scheme design Siriwardena 2010).…”

“…One of the key reasons for this is that, in order to work across large spatial scales, programs have tended to employ rigid management actions, or a one-size-fits-all approach (Batáry et al 2011;. However, recent studies have demonstrated that the effectiveness of agri-environment schemes is influenced by a number of scale-dependant factors, including the amount invested in agri-environment schemes (Dallimer et al 2010;Hiron et al 2013), surrounding landscape context (Batáry et al 2011;Concepción et al 2012;, and the underlying delivery mechanisms used in scheme design Siriwardena 2010). Designing better agri-environment schemes requires a greater understanding and incorporation of these scale-effects.…”

“…Agri-environment schemes, where farmers are paid through agri-environment subsidies to manage land primarily for wildlife, have been implemented in an attempt to conserve and prevent further declines in biodiversity on farmland. However, the effectiveness of these schemes, in terms of biodiversity conservation, has been questioned (Kleijn et al 2011). They may also lead to reductions in crop yield (Kaphengst et al 2010).…”