The effect of wheat stubble treatment on the activities of microorganisms in the rhizosphere of summer maize(Zea mays L.) Early nitrogen deposition effects on CO2 efflux from a cold-temperate coniferous forest soil CO2 flux in the upland field with corn-rapeseed rotation in the karst area of southwest China Impact of Cutting Intensity on Soil Carbon Flux in Low-Quality Forest Stands of Lesser Khingan Range The controlling factors and coupling of soil CO2, CH4 and N2O fluxes in a temperate needle-broadleaved mixed forest