Carbon stocks and soil sequestration rates of tropical riverine wetlands

[摘要] Riverine wetlands are created and transformed by geomorphological processesthat determine their vegetation composition, primary production and soilaccretion, all of which are likely to influence C stocks. Here, we comparedecosystem C stocks (trees, soil and downed wood) and soil N stocks ofdifferent types of riverine wetlands (marsh, peat swamp forest andmangroves) whose distribution spans from an environment dominated by riverforces to an estuarine environment dominated by coastal processes. We alsoestimated soil C sequestration rates of mangroves on the basis of soil Caccumulation. We predicted that C stocks in mangroves and peat swamps wouldbe larger than marshes, and that C, N stocks and C sequestration rates wouldbe larger in the upper compared to the lower estuary. Mean C stocks inmangroves and peat swamps (784.5 ± 73.5 and 722.2 ± 63.6 MgC ha⁻¹, respectively) were higher than those of marshes(336.5 ± 38.3 MgC ha⁻¹). Soil C and N stocks of mangroves werehighest in the upper estuary and decreased towards the lower estuary. Cstock variability within mangroves was much lower in the upper estuary(range 744–912 MgC ha⁻¹) compared to the intermediate and lower estuary(range 537–1115 MgC ha⁻¹) probably as a result of a highly dynamiccoastline. Soil C sequestration values were 1.3 ± 0.2 MgC ha⁻¹ yr⁻¹ and were similar across sites. Estimations of C stockswithin large areas need to include spatial variability related to vegetationcomposition and geomorphological setting to accurately reflect variabilitywithin riverine wetlands.

[学科分类] 地球化学与岩石