Effects of Plant Community Type on Soil Methane Flux in Semiarid Loess Hilly Region, Central Gansu Province, China

Methane (CH₄) is an important greenhouse gas second only to CO₂ in terms of its greenhouse effect. Vegetation plays an important role in controlling soil CH₄ fluxes, but the spatial variability of soil CH₄ fluxes during vegetation restoration in Loess Hilly Region (LHR) is not fully understood. The effects of different plant community types Medicago sativa grassland (MS); Xanthoceras sorbifolium forestland (XS); Caragana korshinskii bushland (CK); Hippophae rhamnoides shrubland (HR); and Stipa bungeana grassland (SB) on soil CH₄ flux in LHR were studied via the static chamber technique. The results showed that the five plant community types were sinks of soil CH₄ in LHR, the plant community type significantly affected the soil CH₄ flux, and the average CH₄ uptake from high to low was in SB, HR, CK, MS, and XS. During the whole study period, the soil CH₄ flux showed similar interannual variation. The maximum absorption of soil CH₄ appeared in the growing season, while the minimum appeared in winter. Soil CH₄ uptake was positively correlated with soil temperature and soil moisture. Soil temperature and moisture are important controlling factors for the temporal variability of soil CH₄ flux. In LHR, the Stipa bungeana grassland is the more suitable plant community type for reducing soil CH₄ emissions. In the process of vegetation restoration in LHR, the soil CH₄ absorption potential of different plant community types should be considered, ecological benefits should be taken into account, and vegetation more suitable for mitigating the greenhouse effect should be selected.