Species composition and structure of Bornean rain forests greatly vary across landscapes. I and co-workers have been studying the mechanisms of the diversification of rain forests in relation to the availability of soil N and P. Soil N availability is often decoupled from P availability in a landscape context due to several biogeochemical asymmetries between these elements. Just to mention a few: The ultimate source of N is the atmosphere, while that of P is the Earth’s crust. N availability is primarily dependent on the mineralization of organic N, while P availability is determined as the sum of solubilization of inorganic P and the mineralization of organic P. Microbial enzymes are involved in the former, while both microbial/plant enzymes are involved in the latter. Therefore, factors affecting the availability differ between N vs. P across landscapes. N availability is reduced in acidic Spodosols where heath forests occur, while P availability is relatively reduced in highly weathered soils (Ultisols/Oxisols) where lowland mixed dipterocarp forests occur. These two forest types form two end members of a continuum of forest ecosystems, along which tree species shift reflecting differences in their strategy for the efficient use/acquisition of N vs. P.