中国南方双季稻田转菜地对CO_2和CH_4通量的影响

Effects of land-use conversion from double rice cropping to vegetables on CO_2 and CH_4 fluxes in southern China

采用静态箱-气相色谱法观测了我国南方亚热带水稻田转为旱作蔬菜地后第1年的CO2和CH4通量变化,旨在探索稻田转菜地初期对CO2和CH4通量的影响.结果表明：CO2通量因蔬菜种类、生长状况及生长季节的不同而不同.种植豇豆菜地CO2通量显著高于稻田,种植辣椒菜地CO2通量则显著低于稻田.稻田转菜地CH4通量从6.96 mg C·m^-2·h^-1显著下降到-0.004 mg C·m^-2·h^-1（P〈0.001）.转菜地后CO2和CH4的净累积碳吸收为543kg C·hm^-2,显著低于稻田的3641 kg C·hm^-2,但由净CO2和CH4排放造成的增温效应无显著差异.转成菜地1年后的土壤有机碳含量有所升高,且10-20 cm土层显著高于对照水稻田.

CO2 flux from the vegetable field was greater than that from the paddy rice field when cowpea was planted, but was lower when pepper was planted. The CH4 flux significantly decreased from 6.96 mg C ·m^-2·h^-1 to -0.004 mg C·m^-2·h^-1 with the land use conversion from rice to vegetables. The net carbon absorption （CO2＋ CH4 ） of the vegetable fields was 543 kg C·hm^-2, significantly lower than that （3641 kg C ·hm^-2） of the rice paddies. However, no significant difference was found in their global warming impact. In addition, soil carbon content increased in vegetable fields compared to the paddy rice fields after a year of conversion, especially in the 10-20 cm soil layer.