中国北方地区植被春季光合物候对气候因素的响应.

[Objective] The aims of this study are to understand the spatiotemporal trends in vegetation photosynthetic phenology (SOS) in spring, to reveal the contribution of climate factors, and to provide a scientific basis for increasing carbon sequestration capacity of vegetation. [Methods] Northern China was taken as a case study. The changing characteristics of SOS from 2001 to 2020 in this region were analyzed based on the gross primary productivity data from solar-induced chlorophyll fluorescence (GOSIF-GPP) and meteorological data. Furthermore, the responses of different climate factors (e. g., minimum air temperature, maximum air temperature, precipitation, and solar radiation) on SOS were assessed. [Results] The mean value of SOS in northern China mainly occurred from the 105th day to the 150th day in a year, and the later SOS was mainly distributed in Qinghai and east-central Inner Mongolia. The regional mean SOS from 2001 to 2020 showed a significant advancing trend (p＜0.05) with a magnitude of-0.31 d/a, and the SOS of all vegetation types showed a significant advancing trend (p＜0.05). The SOS was negatively sensitive to four climate factors, especially the maximum and minimum air temperatures were important climate factors influencing the SOS changes, reflecting that warmer temperature was favorable to the advancing SOS in the most region of northern China. [Conclusion] The SOS changes in the northern China are heterogeneous, and air temperature is the main factor affecting SOS changes. [ABSTRACT FROM AUTHOR]