祁连山祁连圆柏凋落物产量分布特征及其对气候因子的响应OA

To investigate the spatial-temporal distribution characteristics of litterfall production of Juniperus przewalskii,an endemic tree species in the Qilian Mountains,and its response to climatic factors and altitude gradients,sample plots were established along an elevation gradient of 2 600-3 400 m in the Tianlaochi Basin of the Qilian Mountains from 2022 to 2023.Monthly litterfall data were collected and analyzed based on 1 km resolution monthly precipitation and mean temperature data(2022-2023)obtained from the National Tibetan Plateau/Third Pole Environment Data Center using ANOVA,correlation analysis,and multiple regression.The results showed that the annual average litterfall production of J.przewalskii was 1.96 t/hm2,with a unimodal monthly dynamic pattern peaking in July,and the seasonal production ranked as summer＞autumn＞spring＞winter.The annual litterfall production showed interannual variation with altitude:in 2023,significant increases were observed at low(2 600 m)and high(3 400 m)altitudes,while mid-altitudes generally decreased.Monthly litterfall production was significantly positively correlated with both monthly mean temperature and monthly rainfall(P＜0.01),with precipitation being the dominant driving factor.A 17.93％decrease in precipitation in 2023 reduced the explanatory power(R2)of climatic factors from 67.5％to 34.6％,indicating that water availability is the key limiting factor for litterfall production.Extreme drought significantly alters litterfall dynamics by weakening the driving effects of climate and triggering altitude-specific responses.