Evaluation of the faster initial decomposition of tropical floating leaves ofNymphaea elegans Hook

Contributions of abiotic and biotic processes to the decomposition of floating leaves ofNymphaea elegans were separately evaluated by comparing the rate obtained from anin situ experiment of submerging dry leaf material in a lake, and that from a laboratory experiment of submerging dry leaf material in lake water with a bio-fixing reagent. It took 8 days to decompose 79.4% of the initial dry weight of the floating leaf ofN. elegans in a tropical lake. Of the dry weight loss, 32.9% and 67.1% were atributed to abiotic and biotic decomposition, respectively. The relationship between decomposition rate and the mesh size of the leaf litter bags was examined by the application of a mathematical model. A reasonable value of decomposition loss at an early stage could be obtained using a bag with a mesh opening of 9.9 mm². The decomposition rate of floating leaves is faster than that of other aquatic plants. Rapid decomposition ofN. elegans leaves may be attributed to the fact that the plant has a low carbon to nitrogen ratio.