Meta-analysis of relationships between environmental factors and aboveground biomass in the alpine grassland on the Tibetan Plateau

摘要

The Tibetan Plateau, known as the "world's third pole" for its extremelyharsh and fragile ecological environment, has attracted great attentionbecause of its sensitivity to global changes. Alpine grassland on the TibetanPlateau has an important function in the global carbon cycle. Many studieshave examined the effects of various environmental factors on biomassdistribution. In this study, the relationships between the habitat parametersand the aboveground biomass (AGB) abundance on the Tibetan Plateau wereexamined through a meta-analysis of 110 field sites across the widelydistributed alpine steppe and meadow. The obtained data were then analysedusing the classification and regression tree model and the generalizedadditive model. The results showed that the AGB abundance in alpine steppewas positively correlated with six environmental factors, namely, soilorganic carbon density of the top soil layer from 0 cm to 30 cm(SOC30 cm), longitude, mean annual precipitation (MAP), latitude, clay, andsoil moisture. For the alpine meadow, five main factors were detected,namely, altitude, soil moisture, nitrogen, MAP, and mean annual temperature.The increased AGB abundance in the alpine steppe was associated with theincreased SOC30 cm, MAP, and latitude, and the increased longitude resultedin decreased AGB abundance. For the alpine meadow, altitude and soil moistureshowed strongly negative effects on AGB abundance, and soil nitrogen contentwas positively related to the AGB distribution across all examined sites. Ourresults suggest the combined effects of meteorological, topographic, and soilfactors on the spatial patterns of AGB on the Tibetan Plateau.