Life cycle, numbers, biomass and respiratory metabolism of Trichoniscus pusillus (Crustacea, Isopoda) in a beech woodland - Wytham Woods, Oxford.

T. pusillus produced two distinct generations per year (May-June and July-August), members of the early generation reproduced at ca. 12 and 15 months of age while those of the later generation did so at ca. 12 and 22 months. Mortality in summer was higher than in winter. The presence of overlapping generations is believed to aid population stability between years. Mean density and biomass were found to be 480-500 individuals m-2 and 256-268 mg live wt. m-2. Annual respiratory metabolism at 0.399 l O2 m-2 comprises 0.15% of the total soil metabolism. The production/biomass (P/B) ratio was estimated to be 3.5 and the net production efficiency (P=100/P+R) 42%.