Leaf litter decomposition of tree species in three successional phases of tropical dry secondary forest in Campeche, Mexico

Leaf litter decomposition rate and nitrogen, carbon and phosphorous (NCP) concentration of three species: Croton lundellii Standl., Metopium brownei (Jacq.) Urban and Manilkara zapota (L.) van Royen were evaluated in different phases of development (3, 13 and >50 years old) of secondary dry forest in Campeche, Mexico, to test two hypotheses: (1) leaf decomposition rate is higher in older successional stages of secondary dry forest; (2) decomposition rate is more rapid in pioneer species than late successional species, because of differences in substrate quality. The litterbag method was employed to evaluate decomposition. Results indicated that decomposition was related to forest development phase but the strongest influence was due to leaf chemical composition. Decomposition was fastest in C. lundellii, intermediate in M. brownei and slowest in M. zapota. The C/N, C/P ratios and total N and P concentrations were good indicators of decomposition rates across species in all successional stages. In comparing leaf litter collected locally and decomposed in situ, the earlier successional phase showed higher decomposition rates than later stages of succession. Neither N concentration or C/N ratio explained this difference, but it was correlated with higher P concentration. (C) 2002 Elsevier Science B.V. All rights reserved.