Abstract:
Dynamics of leaf litter in Trat mangrove forest was studied in a 50x120 sq.m. plot, which was separated by dominant tree species into 3 zones from the river fringe to inland as Avicennia, Rhizophora, and Xylocarpus, during November 2008 to October 2009, and emphasized on 5 process categories; leaf-litter fall, import-exporting leaf-litter, leaf-litter standing stock, leaf-litter decomposition and consumed leaf-litter. The results showed that averages of leaf-litter fall entrapped in 1x1 sq.m. litter traps from Avicennia and Rhizophora zones were 2.27 and 2.51 g/sq.m./d, respectively. These were significantly higher than that from Xylocarpus zone (1.37 g/sq.m./d). In addition, importing leaf-litter collected from forest floor under the traps, and leaf-litter standing stocks on the floor nearby were significantly different between mangrove community zones. Rhizophora zone has the highest amount of leaf-litter accumulated on the forest floors, followed by Avicennia and Xylocarpus zones, respectively. This might be a consequence of dense Rhizophora stilt root system that was able to trap most leaf-litter within the zone. Leaf-litter decomposition rates studied by litter-bag method were not clearly different among zones but the process tended to slow down from the fringe to inland. Leaf-litter consumers found in the studied plots were Perisesarma eumolpe and Episesarma versicolor. The crabs were found in Xylocarpus zone more than those found in Rhizophora zone, resulting in significant higher consumed leaf-litter; 83.55% and 22.85% of all fallen leaves. This study draws the diverse patterns of leaf-litter dynamics in 3 different mangrove species zones. Even though average amount of leaf-litter input from falling leaves in these 3 zones were similar (72.9-100%), exporting leaf-litter processes from those systems were quite different i.e. most leaf-litter was removed from Avicennia and Rhizophora zones by tide, but in Xylocarpus zone great amount of leaf-litter was consumed by crabs. Therefore biological and physical factors, including species root systems, topography, inundation period, soil texture and temperature affect the dynamics of leaf-litter in mangrove forest.