Breakdown of leaf litter under different environmental conditions in a tropical mangrove

This study evaluated the decomposition process of leaf litter of Avicennia schaueriana Stapf & Leechm.ex Moldenke, Laguncularia racemosa (L.) C.F. Gaertn and Rhizophora mangle L. in the mangrove forest of the Mamanguape River estuary, Brazil.Senescent leaves were placed in litterbags and submitted to three experimental conditions: supratidal, not subjected to tidal inundation (SUP), intertidal 1, on the forest floor and subjected to inundation (INT1) and intertidal 2, on the bottom of a tidal creek (INT2).The leaf material showed rapid loss of mass in the first 30 days, followed by slower decay until the end of the experiment.The treatment effect was greater than the differences among species.Leaf litter subjected to flooding exhibited higher decomposition rates and lower half-life (t50%) and 95% lifespan (t95%) values compared to leaves exposed to air.In the SUP treatment, t50% and t95% values indicated that mass loss was significantly slower in R. mangle, intermediate in L. racemosa, and more accelerated in A. schaueuriana.Under conditions of higher tidal inundation frequency (INT2), decomposition rates were faster for R. mangle leaves, intermediate for A. schaueriana, and slower for L. racemosa.The results found in the present study suggest that environmental factors may have more influence on decomposition rates than species characteristics.