Soil organic carbon storage in a tropical freshwater wetland: the influence of vegetation type

The impact of different vegetation communities on soil organic carbon (SOC) in a tropical freshwater wetland in Uganda was investigated. SOC content, density and storage potential were determined under three different dominant vegetation communities: Cyperus papyrus L., Typha latifolia L. and Phragmites mauritianus Kunth. SOC content (123.7 ± 2.6 SE g C kg−1 dry soil) in C. papyrus was significantly higher (p < 0.05) than in both T. latifolia and P. mauritianus, whereas SOC density (kg C m−2) insignificantly varied (p > 0.05) among the three vegetation communities (C. papyrus = 7.2 ± 0.1, T. latifolia = 6.7 ± 0.1 and P. mauritianus = 6.2 ± 0.1). Similarly, for the entire sampled soil depth (0–50 cm), SOC storage potential was significantly higher (p < 0.05) in C. papyrus (36 118.08 ± 552.52 t C km−2), and was in the order of decreasing magnitude: C. papyrus > T. latifolia > P. mauritianus. Plant biomass density, and soil physico-chemical characteristics, bulk density, salinity, pH and temperature were significantly correlated (p < 0.05) with SOC. In conclusion, where climate change mitigation is considered as a wetland ecosystem service, restoration priorities for degraded/lost tropical freshwater wetlands need to consider C. papyrus plants. In addition, comparing SOC storage by ecosystems, Uganda’s wetlands contain three times more SOC than is contained in the country’s forests.