High fragility of the soil organic C pools in mangrove forests

Mangrove forests play an important role in biogeochemical cycle of C, storing large amounts of organic carbon. However, these functions can be controlled by the high spatial heterogeneity of these intertidal environments. In this study were performed an intensive sampling characterizing mangrove soils under different type of vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. The soils were anoxic, with a pH similar to 7; however other soil parameters varied widely (e.g., clay, organic carbon). Dead mangrove area showed a significant lower amounts of total organic carbon (TOC) (6.8 +/- 2.2%), in comparison to the well-preserved mangrove of Avicennia or Rhizophora (TOC = 17-20%). Our results indicate that 56% of the TOC was lost within a period of 10 years and we estimate that 11,219 kg m(-2) of CO2 was emitted as a result of the mangrove death. These results represent an average emission rate of 11.2 +/- 19.17 tCO(2) ha(-1) y(-1).