An approach to estimating system carbon stocks in tropical forests and associated land uses

Estimates of carbon stocks within different land management systems are important elements in the design of land use systems that protect or sequester carbon. A method for the rapid estimation of total system carbon stocks in tropical forests and land uses derived from them was developed for field activities in Brazil, Cameroon, Indonesia and Peru. Careful selection of sites and land uses is necessary to ensure representativeness and assist in the later extrapolation of results. Carbon stocks in trees are estimated through allometric equations based on diameter at breast height. Carbon in understorey vegetation, litter, roots and soil is measured by destructive sampling. Modifications to sampling procedures are necessary within managed forests, incompletely cleared fields, recently felled and burned forests, tree plantations and thickly-vegetated bushland. The data collected are compiled into a spreadsheet data base containing 16 variables, four of which are used to sort cases and 12 are data for analytical comparison. Carbon stocks within land uses may be substituted for land use categories and overlay procedures of geographic information systems applied for spatial extrapolation. Ecosystems models, such as CENTURY (ver. 4.0) may be initialised with these data and long-term carbon dynamics compared in simulations of alternative land management practices.