NEMATODES FROM AN ENGLISH CHALK GRASSLAND - SPECIES DISTRIBUTIONS

A total of 154 nematode species were identified from the chalk grasslands of Porton Down, a Site of Special Scientific Interest in southern England. Twelve soil samples were taken each january and June during 1990 and 1991 at two sites with differing vegetation and topographic position. The abundance of many species differed between the sites. There were also seasonal and probably drought-related changes in the abundance of many species. Some of the species distributions accord with previous records showing preferences by particular species for certain types of soil, others do not. Species are divided into generalist, intermediate and specialist species on the basis of spatial distribution. Seasonal, drought-tolerant, drought-susceptible and temporally stable species are recognized on the basis of temporal distribution. Patchy species are recognized on the basis of spatial land temporal distribution