Characterization of the soil biota and methodological approaches Key Functional Groups The taxonomic diversity of the soil biota is so high that inevitably some selection must be made. The taxonomic groups described below were selected on the basis of their diverse functional significance to soil fertility (hence the term "target taxa"); and their relative ease of sampling. 1) Earthworms , which influence both soil porosity and nutrient relations through channeling, and ingestion of mineral and/or organic matter. 2) Termites and ants , which influence a) soil porosity and texture through tunnelling, soil ingestion and transport, and gallery construction; b) nutrient cycles through transport, shredding and digestion or organic matter. 3) Other macrofauna such as woodlice, millipedes and some types of insect larvae which act as litter transformers, with an important shredding action on dead plant tissue, and their predators (centipedes, larger arachnids,...
