日尺度下水热因子变化对呼伦贝尔草甸草原生产力的影响特征OA

This study investigated the response mechanism of grassland ecosystem productivity to hydrothermal factors in the Hulun Buir meadow steppe.Using daily-scale air temperature and precipitation data and grassland productivity observation data from 1990 to 2023,the characteristics of water and heat fluctuations across different time scales were quantified through the application of a time-window approach.We utilized a partial least squares regression(PLSR)model and analyzed the response mechanisms of grassland aboveground net primary productivity(ANPP)to water and heat factors using stepwise regression.The results indicate that:1)Although the average annual air temperature and precipitation in the study area increased at rates of 0.03℃·yr-1 and 1.05 mm·yr-1,respectively,ANPP showed a significant decline(2.17 g·m-2·yr-1)during 1990-2023.Compared to air temperature,precipitation within the same temporal window has a stronger explanatory relationship with ANPP,indicating that the water-heat imbalance induced by warming and drying is the principal factor contributing to the decline in productivity.2)Critical periods were identified for both precipitation(July 10-29,R2=0.308;September 12-21,R2=0.206)and temperature(September 10-October 7,R2=0.273;June 30-July 19,R2=0.280;April 23-May 4,R2=0.202).The interaction between these hydrothermal factors accounted for 79.5%of the interannual variability in ANPP(P<0.001).3)Although winter warming has a weak effect on ANPP(standardized regression coefficients,β=0.0039-0.0057),summer precipitation plays a more decisive role in driving productivity dynamics.4)Short-term variations in water availability have a stronger influence on the study area than temperature fluctuations.While a synergistic response to hydrothermal factors is present during the overlapping period(such as July 10-19),no significant interaction between them was detected(variance inflation factor,VIF>10).This study quantitatively analyzes the dynamic responses of hydrothermal factors on a daily scale,providing a high-resolution management framework to support grassland restoration in semi-arid regions.