The impact of selective logging and forest conversion for subsistence agriculture and pastures on terrestrial nutrient dynamics in the Amazon

ABSTRACT

The conversion of primary forests in the Amazon via selective logging, slash and burn agriculture, and pasture establishment, will continue because of the increasing demand for timber and agricultural land. Forest conversion has major impacts on the stocks and flows of essential plant nurtrients. For example, the burning of slashed vegetation results in most of the carbon and nutrients in the biomass being volatilized during burning. Nutrient stocks are further depleted by the nutrient exports in timber and crop harvests. Poor crop and pasture mamagement practices can result in rapid declines in soil fertility and reduced vegetation regrowth potential. These changes can influence the rate of secondary forest regrowth and carbon sequestration on abandoned crop and pasture lands. The dominant land use practives following forest conversion in the Amazon are identified and the data on the impact of selective logging, subsistence cropping, and extensive pastures, on nutrient stocks and budgets in terrestrial Amazonian ecosystems are reviewed.