Primary production and decomposition of Loudetia phragmitoides (A. Peter) in the littoral wetland of a small satellite lake (L. Nabugabo, Uganda).

Loudetia phragmitoides (A. Peter) C.E. Hubbard is one of the dominant grass species occupying the Lake Nabugabo littoral wetlands, another prominent species being Miscanthedium violaceum (K. Schum) Robyns. Lake Nabugabo is a satellite lake, about 5 km to the west of Lake Victoria. It is a unique ecosystem, which is nutrient poor due to the highly leached ancient soils in the catchment. To determine the significance of wetland functions on the open lake ecosystem, the primary production and biomass decomposition process in the wetland of the dominant grass species, Loudetia phragmitoides were assessed. A biomass yield of 1638 gm⁻² and an average primary production rate of 941 gm⁻² year⁻¹ were obtained for the Nabugabo wetland. Litter decomposed faster in the open lake compared with the littoral wetland with half of the litter weight lost in 110 and 321 days, respectively. Phosphorus leached more rapidly from decomposing litter compared with nitrogen. The study found that wetland dominant grass species can be an important nutrient reservoir and that the decomposition process in the wetland is influenced by the flooding regime, which exports significant nutrients (nitrogen and phosphorus) to the open lake. The importance of the littoral wetland to the overall ecology of the Nabugabo ecosystem is discussed. [ABSTRACT FROM AUTHOR]