Phosphorus Cycling in Tropical Forests Growing on Highly Weathered Soils

Phosphorus (P) is an essential element for living cells, and to some extent the abundance and activity of all organisms are regulated by P availability. However, the importance of P in terrestrial ecosystems may be most profound in tropical rain forests, where P supply is often very low. Thus, soil P availability could strongly limit various aspects of ecosystem function in tropical forests, as well as regulate tropical forest responses to anthropogenic perturbation. In this chapter, we describe P cycling in tropical forests growing on highly weathered soil (e.g., Ultisols and Oxisols). We focus on P inputs, transformations, and losses, and highlight aspects of the P cycle that are somewhat unique to this biome. In addition, we consider the implications of tropical P limitation at present and in the context of global change.