Soil GHGs Emission response to Landuse Change in Tropics, Southwest China

To explore the response of soil greenhouse gas emissions(GHGs) from tropical forest to landuse change in Yunnan, Southwest China, we have conducted a series of studies based on the GHGs monitoring platform established since 2003 in tropical rainforest (TRF) and rubber plantation(RP). The research results indicate that 1) TRF transplanted to RP did not change the annual soil CO2 emissions (TRF, 359 ±91 and RP 352 ±41 mg CO₂ m^-2 h ^-1) but decreased soil CH4 uptake significantly (TRF, -0.11 ± -0.18 mg CH4 m ^-2 h ^-1; RP, -0.020 ± -0.087 mg CH4 m^-2 h^-1). (2) The most important influence on soil CO2 and CH4 emissions in the RP was the leaf area index and soil water content, respectively, whereas the soil water content, soil temperature, and dead fine roots were the most important factors in the TRF. Variations in the soil CO2 and CH4 caused by landuse transition were individually explained by soil temperature and fine root growth and decomposition, respectively. (3)  The N2O emissions from the fertilized and unfertilized plots in RP were 4.0 and 2.5 kg N ha−1 yr−1, respectively; Annual N2O emissions from the control and no litter input treatments were 0.48 and 0.32 kg N2O–N ha-1 year in TRF, respectively.(4) When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest’s carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming. (5) And further, land use change alter the structure and sources of soil organic matter, which in turn feedback to the microbial processes involved in soil greenhouse gas production and alter the mechanisms of soil greenhouse gas emissions.(6) The 15N isotope tracing experiment used isotope tracing technology to distinguish the microbial process of N2O production in tropical rainforest soil, proving that the microbial process of N2O production in tropical rainforest soil during the dry season is a nitrification process; In the future, we will use 13C,14C and 15N isotope and qPCR to study the microbiological mechanisms of land use change on soil greenhouse gas production in the context of climate change, providing scientific basis for quantifying the underground processes of soil greenhouse gas production; Provide mechanism support for accurately estimating soil greenhouse gas emissions to achieve the dual carbon goals in the context of climate change.