INFESTATION OF IMPROVED GRASSLANDS BY JUNCUS-EFFUSUS L IN THE CATCHMENT OF THE RIVER TYNE, NORTHERN ENGLAND - A FIELD SURVEY

Soft rush, Juncus efffusus L., is a widespread weed of managed grassla nds. In 1991, a sample-based field survey of the weed's distribution i n improved grasslands was conducted within the catchment of the River Tyne in Northern England. The land classes of the Institute of Terrest rial Ecology (ITE) environmental landscape classification system were used as sampling strata. In total, 182 1-km grid squares were surveyed . Areas of improved grassland and levels of J. effusus infestation dif fered significantly between land classes, but there was also wide vari ation between grid squares within land classes. Most squares within a land class had no J. effusus, while a proportion had large areas. Extr a-polation from the sample data suggested that an area equivalent to 2 4.0% of the 3000km(2) land surface of the catchment supported improved grassland, of which 3.5% was infested with the rush. Infestation of i mproved grassland was estimated to be lowest in the lowlands (20% of i mproved grassland), intermediate in the marginal uplands (30% of impro ved grassland) and greatest in the uplands (10.8% of improved grasslan d). Data from the Farm Business Survey, on broad patterns of utilizati on of improved grassland for hay, silage and livestock in lowland, mar ginal upland, and upland landscapes in the catchment, do not readily e xplain the observed variation in infestation levels, which may reflect local factors and the availability of propagules from adjacent rough grazing land.