CH4 CH4 emissions CO2 CO2 effluxes CO2 emission CO2 emissions CO2 production and diffusion Camellia oleifera DCD IPCC Larix principis-rupprechtii Mayr N addition N2O N2O emissions South Korea anthropogenic effect assisted natural regeneration autotrophic respiration bacterial community biochar calcareous soil calcareous soils carbon source–sink carbon stock changes clear-cutting climate change mitigation coastal wetlands decomposition fitting parameters forest