Effects of different vegetation types on ecosystem respiration in semiarid Loess Hilly Region, Central Gansu Province, China

The principal channel of carbon export from ecosystems to the atmosphere, and an important connection in carbon exchange between land and atmosphere, is ecosystem respiration (ER). It has a significant impact on the global carbon cycle and the rate of CO2 increase in the atmosphere. The effects of different vegetation types [Medicago sativa grassland (MS); Xanthoceras sorbifolium forestland (XS); Caragana korshinskii bushland (CK); Hippophae rhamnoides shrubland (HR); and Stipa bungeana grassland (SB)] on ecosystem respiration fluxes in Loess Hilly Region (LHR) were studied via the static chamber technique. The results showed that different vegetation types had significant effects on ER fluxes, and the decreasing order of the cumulative fluxes was HR > MS > SB > CK > XS. Throughout the study period, the largest value of ER occurred in the summer and the lowest value occurred in the winter. Temperature (air temperature, soil temperature) and soil moisture were both significantly and positively linked with ER. For the temporal change of ER, the joint effect of soil temperature and moisture was a key regulating factor. The temperature sensitivity of ecosystem respiration varies greatly between vegetation types and seasons. In the process of LHR vegetation restoration, the ER, carbon sequestration capacity and ecological benefits of different plant types should be considered in order to select the vegetation type that is most conducive to reducing the greenhouse effect.