Forest Soil as an Ecological Community With Special Reference to the Fauna

Abstract

A basis is presented for the study of soil organisms associated with decomposition of plant litter in forest soils. These can be studied as a community in which the first trophic level is plant litter. In lieu of a "food web" the organisms found in forest soils are grouped broadly on the basis of feeding habits into four categories: plant litter feeders, fungal feeders, bacterial and algal feeders, and micro- and macro predators. The feeding relationships are so complex that no simple relationship between protozoans and bacteria can be drawn. The role of large predators of soil organisms is less well known. Diversity of species characteristic of soil fauna is attributed (a) to diversity of the different sorts of spaces in the soil, (b) to heterogeneity of the soil''s solid constituents and (c) to the diurnal and seasonal changes in temperature and soil moisture. A procedure is suggested for the study of the role of different organisms in soil on the basis of the amount of energy that flows through them during a year. Tables are given of numbers of organisms in different soils and the energy utilization of such of these which have been studied.