Strong temperature dependence and no moss photosynthesis in winter CO 2 flux for a Kobresia meadow on the Qinghai–Tibetan plateau

Abstract

We examined the CO 2 exchange of a Kobresia meadow ecosystem on the Qinghai–Tibetan plateau using a chamber system. CO 2 efflux from the ecosystem was strongly dependence on soil surface temperature. The CO 2 efflux–temperature relationship was identical under both light and dark conditions, indicating that no photosynthesis could be detected under light conditions during the measurement period. The temperature sensitivity ( Q 10) of the CO 2 efflux showed a marked transition around −1.0 °C; Q 10 was 2.14 at soil surface temperatures above and equal to −1.0 °C but was 15.3 at temperatures below −1.0 °C. Our findings suggest that soil surface temperature was the major factor controlling winter CO 2 flux for the alpine meadow ecosystem and that freeze–thaw cycles at the soil surface layer play an important role in the temperature dependence of winter CO 2 flux.