Bracken (Pteridium aquilinum (L.) Kuhn) infestation of rough grazing land in the catchment of the River Tyne,

The distribution of bracken (Pteridium aquilinum (L.) Kuhn)within the catchment of the River Tyne, Northern England, was surveyed in the field by stratifying sampling effort within land classes of a national environmental landscape classification developed by the Institute of Terrestrial Ecology (LT. E.). A total of 182 I-km squares were surveyed in 1991 (equivalent to 6.3 % of the catchment). The areas of bracken and rough grazing land differed significantly between land classes. Bracken was estimated to cover 0·7 % of the total land surface, and 1·9 % of rough grazing land, within the catchment. The results are compared with those of previous surveys of bracken, and it is concluded that a standard survey method is needed if such comparisons are to be statistically reliable. It is proposed that the LT.E. land classes offer a suitable framework for the organisation of future surveys