Studies on the biology of moorland Collembola

Abstract

Work on the biology of Collembola (Springtails) was carried out betweenn Ootober 1959 and October I962, on the Moor House National Nature Reserve, in Westmorland. This is an area of high Pennine moorland (l840ft. O.D.) which experiences a sub-Arctic olimate. Population studies wars made on Limestone grassland, Alluvial grassland and Heather moor, by means of a statistical sampling method. Juncus squarrosus grassland and the erosion and recolonisation of blanket bog were also studied from the points of view of population densities and species differences. In an attempt to explain the fluctuations in numbers rocorded, biological data was also obtained from laboratory cultures of selected species. Observations on reproductive behaviour, fecundity, egg development, frequency of moulting, sex ratios and age distributions were made. Breeding experiments on members of the Onychiurus arnatus species group were carried out, and these revealed what appears to be an unusual form of parthenogenesis; these experiments also showed that in some species, at least, the criteria for the division of the 0. aimatus species group, which have been questioned by some continental workers, are valid. Regular sampling of the selected vegetation types provided data on horizontal distribution (aggregations), vertical distribution and seasonal variations in the numbers and biomass of Collembola. Limestone grassland carried the highest mean anual population density (52.92 x 10(^3) per m(^2)) and Juncus squarrosus grassland the lowest (20.93 x 10(^3) per m(^2)). A flotation extractor, to remove Collembola from organic soils, was designed and built, and this may prove an important step forward in the technique of studying the moorland fauna. The work forms a contribution to the study of moorland ecology, but it is clear that to obtain a comprehensive picture of the ecological importance of Collembola on moorland, a great deal of work will be necessary in the future.