Density, biomass, and guild structure of arboreal arthropods as related to their inhabited tree size in aCryptomeria japonica plantation

Research paper by Naoki Hijii

Indexed on: 01 Aug '86Published on: 01 Aug '86Published in: Ecological Research


Arboreal arthropods in a 15-year-old plantation ofCryptomeria japonica were surveyed using the smoking method under open conditions and also in the enclosed condition in which the whole above-ground part of a tree was covered by a cloth bag. Per tree, the number of individuals collected was 8200–14000, with a biomass of 340–1700 mg d.wt. Collembola and Acarina were major components in number, while Diplopoda, Collembola, and Araneae occupied the larger part of the biomass. About 60–70% of total numbers of individuals dropped within two hours after the open fumigation. Clear power-form regressions between total numbers of individuals and biomasses of all animals and their host tree size (stem diameter at clear length,DB) showed they were approximately proportional toDB2. The guilds of scavengers and tourists demonstrated the most significant correlations between their numbers and biomasses and the tree size. Numbers and biomasses of Collembola, Diptera, and Araneae revealed remarkable dependence on the tree size. From these regressions, numbers of individuals and biomasses per unit ground area were estimated for all arthropods to be 3755/m2 and 165.87 mg d.wt./m2, respectively. Power-form regressions were observed between numbers and biomasses of prey and predators. The number-and biomass ratios of all predators to all prey tended to decrease with increasing tree size. A similar trend was observed in the corresponding ratios of parasitic Hymenoptera to lepidopteran larvae, while those of Araneae to Collembola were almost constant, irrespective of tree size.