Nitrogen Pools in Tropical Plantations of N2-Fixing and Non-N2-Fixing Legume Trees under Different Tree Stand Densities

We investigated the nitrogen pools in monocultures of legume species widely used reforestation Brazil that have contrasting growth and acquisition strategies. The plantations were established with slow-growing N2-fixing tree Anadenanthera peregrina var. peregrina, fast-growing non-fixing Schizolobium parahyba amazonicum. measurements N biomass soil followed standard methods carried out on 54 experimental plots. N2 fixation evaluated by abundance natural 15N accretion methods. content was similar magnitude between stand densities. showed amounts biomass, but divergent patterns accumulation, as well signature leaves. S. accumulated most stem, while A. roots However, accumulation less constrained environment than stands. percentage derived from stands decreased increase density. biological estimates depended method response to environment.