This practical handbook describes sampling and laboratory assessment methods for the biodiversity of a number of key functional groups of soil organisms, including insects, earthworms, nematodes, fungi and bacteria. The methods have been assembled and the protocols drafted by a number of scientists associated with the UNEP-GEF funded Conservation and Sustainable Management of Below-Ground Biodiversity project, executed by the Tropical Soil Biodiversity and Fertility (TSBF) institute of the International Center for Tropical Agriculture (CIAT). The methods provide a standardized basis for characterizing soil biodiversity occurring in terrestrial natural and agro-ecosystems in the tropics and current land uses in forest and forest margin areas. The aim is to assess soil biodiversity against current and historic land use practices both at plot and landscape scales and further to identify opportunities for improved sustainable land management through the introduction and/or management of...