XVI International Botanical Congess

Forest recovery in the Amazon can ben influenced by the effect of previous land use practices on soil fertility. Pasture creation can trigger soil transformations of relatively stable pools of nutrients such as P, into pools that can be more susceptible to losses if land use is intensified. We documented changes to nutrient pools using chronosequences of forest and pastures of 3 to 41 years old in southwestern Brazilian Amazon state of Rondônia. Organic P increased from 21% of total soil P in the forest to 35% in older pastures at the expense of occluded P and was consistent with increasing stocks of organic matter. We develop a series of hypothesis for potential changes to stocks and availability of nutrients that can occur under projected scenarios of future land uses, including tilling for agriculture and suggest how future trends toward land use intensification in the Amazon might influence nutrient availability and hence possible trajectories of secondary succession during forest recovery.