Changes in weed species in Scotland at the new millennium

摘要

The Countryside Survey is a UK-wide assessment of land cover repeated at intervals of six to eight years. Changes recorded on agricultural land in Scotland between 1990 and 1998 were consistent with arable expansion, improvement of grassland for grazing or forage cropping, and rotational use. Increases in the total length of fences implied the further enclosure of land, and there was also a reduction in the length of walls in the marginal uplands. Species presence and cover were recorded in permanently marked field plots paired with linear plots on adjacent boundaries. The greatest average number of plant species was recorded on plots that were improved grassland in both 1990 and 1998. Boundary plots were more species rich than field plots except inimproved grassland in the marginal uplands. An increase in the frequency of competitive species indicative of high soil nutrient status implied intensification of land management. Although the number of species recorded was similar in 1990 and 1998, changes in vegetation type, and the continuing loss of semi-natural habitats to improved grassland, suggest that the aims of Habitat Action Plans to improve and restore the biodiversity of agricultural land by 2010 may not be achievable in Scotland in thattime-scale.