Foliar nitrogen and phosphorus resorption and decomposition in the nitrogen-fixing tree Lysiloma microphyllum in primary and secondary seasonally tropical dry forests in Mexico

The tree Lytsiloma microphyllum (Fabaceae) dominates in the seasonally tropical dry forests of central Mexico. In this study foliar N and P concentrations (oil leaf mass basis), foliar N and 11 resorption efficiency and proficiency, as well as the decomposition of senescent leaves of L microphyllum were studied in primary and in regenerating, secondary seasonally tropical dry forests. Our study included all area of early successional forest (10 N, old), with phosphorus-poor soils and comparatively abundant nitrogen, all area of late-successional forest (similar to 60 y old), in which soil P and N were comparatively abundant, and all area of primary forest, in which soil P was comparatively abundant and N was less abundant than in the secondary counterparts. N and P concentrations in mature leaves varied across forests. reflecting soil nutrient availability. Nitrogen concentration in senescent leaves did not change among sites, which led to very different patterns of N resorption. In contrast, P concentration in senescent leaves was lower ill the early than in late-successional and primary forests. which resulted in similar patterns of resorption. Leaf decomposition increased from 70%, mass loss in the first year in the early Successional to similar to 80% in the same period in late-successional and primary forests. The element loss during decomposition change across forests in the following order: for N, early successional = late-successional > primary forest, and for P, primary forest > late-successional > early Successional forest. Overall, the pattern of variation ill leaf chemistry and nutrient release oil the forest floor among sites is consistent with soil nutrient availability along this sequence, while decomposition rate May be related with the P concentration in senescent leaves.