VELOCITY OF LITTER DECOMPOSITION IN DIFFERENT MANGROVE SUBSTRATES DURING THE RAINY SEASON IN SAN ANDRÉS ISLAND, COLOMBIAN CARIBBEAN

Abstract

Litter degradation was studied in various substrates of three mangrove wetlands in San Andrés Island, Colombian Caribbean, during the rainy season. Decomposition rates of Rhizophora mangle L. (red mangrove), Laguncularia racemosa (L.) C.F. Gaertn. (white mangrove) and Avicennia germinans (L.) L. (black mangrove) were measured in mesh bags. Some bags were placed below ground, other submerged in water, and other on the ground. Two sites in the study were fringe wetlands and the other one was an inland wetland. Some physical-chemical factors inuencing the decomposition of vegetal organic matter were evaluated. The best regression model tted to the degradation trends was the single square root. The interactions of time with biotic and abiotic factors determined the loss of weight from leaves. The faster degradation rates were obtained in fringe wetlands; aquatic and moisten edaphic environments; on A. germinans; and at the sites with associated consumer macrofauna. The fastest velocities were presented In the early stages of decomposition. In general, the smaller average percentage of remaining biomass after 15 weeks of incubation was presented by A. germinans (10 %), respect to R. mangle (29 %) and L. racemosa (28 %). By means of the results obtained and those one related with the rates of litter production in the same wetlands in study, a basic conceptualquantitative model of litter production-decomposition dynamic in San Andrés Island is proposed.