Greenhouse gas fluxes in mangrove forest soil in an Amazon estuary

[摘要] Tropical mangrove forests are important carbon sinks, the soilbeing the main carbon reservoir. Understanding the variability and the keyfactors that control fluxes is critical to accounting for greenhouse gas(GHG) emissions, particularly in the current scenario of global climatechange. This study is the first to quantify carbon dioxide (CO 2 ) andmethane (CH 4 ) emissions using a dynamic chamber in natural mangrovesoil of the Amazon. The plots for the trace gases study were allocated atcontrasting topographic heights. The results showed that the mangrove soilof the Amazon estuary is a source of CO 2 (6.66 g CO 2  m −2  d −1 ) and CH 4 (0.13 g CH 4  m −2  d −1 ) to theatmosphere. The CO 2 flux was higher in the high topography (7.86 g CO 2  m −2  d −1 ) than in the low topography (4.73 g CO 2  m −2  d −1 ) in the rainy season, and CH 4 was higher in the lowtopography (0.13 g CH 4  m −2  d −1 ) than in the high topography(0.01 g CH 4  m −2  d −1 ) in the dry season. However, in the dryperiod, the low topography soil produced more CH 4 . Soil organic matter,carbon and nitrogen ratio ( C / N ), and redox potential influenced the annualand seasonal variation of CO 2 emissions; however, they did not affectCH 4 fluxes. The mangrove soil of the Amazon estuary produced 35.40 Mg CO 2 eq.  ha −1  yr −1 . A total of 2.16 kg CO 2  m −2  yr −1 needs to be sequestered by the mangrove ecosystem to counterbalanceCH 4 emissions.

[学科分类] 大气科学