THE EFFECTS OF BIOENERGY CROPS ON FARMLAND BIRDS IN THE UNITED KINGDOM: A REVIEW OF CURRENT KNOWLEDGE AND FUTURE PREDICTIONS

摘要

Large areas of bioenergy crops planted on farmland in the United Kingdom could have a potentially major impact on the population of farmland birds and all other components of farmland biodiversity. This paper summarises current knowledge on the impacts of bioenergy crops on farmland bird populations and make predictions where data are lacking. Woody and perennial grass bioenergy crops represent a large ecological shift from conventional farmland habitats. Both may support a range of flora and fauna and there is evidence from short rotation willow coppice that overall bird species diversity may be higher than on conventional farmland. However, vegetation structure is likely to make these crops an unsuitable breeding habitat for several open-field species of high conservation concern. It is unlikely that these crops will provide significant annual food resources for seed-eating birds, which are a group of particular conservation concern. The scale, spatial arrangement and geographic location of bioenergy crops are likely to have a significant influence on bird populations using the crops. Where bioenergy crops represent an increase in land use heterogeneity - for example, by introducing an arable system into a grassland-dominated area - biodiversitybenefits are likely. Conversely, if energy crops are concentrated in large blocks of monoculture, biodiversity at the landscape level is likely to be reduced. Measures to increase habitat heterogeneity within areas of bioenergy crops and to maintain land use diversity should be encouraged to maximise the benefits to farmland birds and other wildlife. Replacement of land use with high wildlife value, such as set-aside, by bioenergy crops is likely to impact negatively on farmland bird populations. Suchchanges should be prevented or adequately mitigated against to prevent further declines of farmland bird species already suffering heavily from the effects of agricultural intensification.