Invertebrate-mediated transport processes in soils

Abstract

Invertebrates can directly or indirectly affect the transport of organic and inorganic materials within and between soil systems so that the environment for decomposition, and the location of nutrient release, is spatially and temporally different for relocated material and for the parent material. The direct effects involve the active carriage of soil and litter between habitats, but the processing and/or relocation of these materials can indirectly influence their transport by water, wind or gravity. The feeding and burrowing activities of macrofauna, notably termites and earthworms, also modify the physical properties of soil and litter habitats with important consequences for water balances of soils, water infiltration rates, overland flow and sediment transport. Hence these soil-fauna groups can indirectly affect pathways of energy and mass transfers in soils which are orders of magnitude higher than direct faunal contributions to energy and nutrient fluxes. The significance of these effects is frequently not apparent until natural systems are disrupted, but then the fauna may act as driving variables determining the rate of change and the new equilibrium state of soil processes.