Abstract: A laboratory incubation test was conducted to study the organic C mineralization in gray forest soils after land use conversion and the temperature sensitivity of the mineralization. It was shown that after the conversion from wildwood land to farmland, the organic C and total N contents in 0〖KG-*2〗-〖KG-*7〗10 cm and 10〖KG-*2〗-〖KG-*7〗20 cm soil layers decreased by 685% and 768%, and 405% and 444%, and the average mineralization rate and cumulative mineralization of soil organic C in farmland were 244%〖KG-*2〗-〖KG-*7〗432% and 920%〖KG-*2〗-〖KG-*7〗137% of those in wildwood land, respectively. At lower temperature (<25 ℃), there was no significant difference in the temperature sensitivity of soil organic C mineralization between the two land use types; while at higher temperature (>25 ℃), this temperature sensitivity in farmland soil was higher in 0〖KG-*2〗-〖KG-*7〗10 cm layer but significantly lower in 10〖KG-*2〗-〖KG-*7〗20 cm layer, compared with that in wildwood land soil.

Key words: rice-wheat rotation, denitrification-decomposition (DNDC) model, CH_4, N₂O, global warming potential (GWP).