Temperature and moisture sensitivities of CO2 efflux from lowland and alpine meadow soils

This study was conducted to (i) determine if soil CO2 efflux is more sensitive to temperature changes in alpine areas than in lowland grasslands, (ii) examine the effects of temperature and moisture on soil respiration, and (iii) evaluate the potential for change in soil carbon storage in response to global warming in different grasslands in East Asia. We collected soil samples from two different temperate grasslands, an alpine meadow on the Qinghai-Tibetan plateau, China, and a lowland grassland in Tsukuba, Japan. The CO2 emission rate was then measured for these soil samples after they were incubated at 25 degrees C and 60% of the water holding capacity for 7 days. (i) The soil respiration rate was more sensitive to temperature change in the alpine soil than in the lowland soil. The average Q(10) was 7.6 for the alpine meadow soil but only 5.9 for the lowland soil. The increased sensitivity appears to be due, at least in part, to the soil organic carbon content and/or soil carbon to nitrogen ratio, especially in the surface layer. (ii) The relationship between the CO2 emission rate and the soil moisture content revealed that the alpine meadow had a more clear response than the lowland soil. (iii) This study suggests that changes in soil moisture and soil temperature may have larger impacts on soil CO2 efflux in the alpine meadow than in the lowland grassland evaluated here.