Changes in the abundance of farmland birds in relation to the timing of agricultural intensification in England and Wales

摘要: 1. Over the past three decades changes in agricultural management have resulted increased crop and grass production. This intensification has been accompanied by population declines among farmland bird species a decline biodiversity. We analysed trends order to quantify degree of intensification, considered how they match change community. 2. Changes agriculture through time (1962–95) were examined quantitatively for 31 variables representing areas, livestock numbers, fertilizer application, production pesticide use. The majority highly intercorrelated because factors facilitating simultaneously affected many activities. 3. Change was measured using detrended correspondence analysis (DCA). period 1970–88 saw most characterized increases area oilseed rape, autumn-sown cereals, use pesticides inorganic fertilizers. Spring-sown bare fallow root crops declined. 4. Indices relative between 1962 1996 determined 29 data from Common Birds Census (CBC) plots on England Wales. Principal components (PCA) described gradient that had declined those increased. 5. The ordinations broadly matching but with lag response birds. accurately 1974–91 matched birds more closely. 6. We conclude large shifts are plausible explanation populations. propose threshold model relating critical amounts high-quality habitat or food resources may be relevant explaining birds, it should taken into account predicting effects future agri-environment schemes. Identifying individual responsible is not possible without detailed experimental work interdependent. responding suite interacting rather aspects farm management. Holistic conservation strategy encourages general extensification farming practices will likely benefit communities.