Abstract: Precipitation is one of the most important factors impacting variation of vegetation productivity in the agro-pastoral ecotone in North China. However,the increase in canopy temperature due to rising air temperature has been impacting vegetation productivity under climate warming background. Therefore,the impacts of changes in canopy temperature and precipitation on vegetation productivity need to be further investigated. Here,this study examined the spatio-temporal changes in gross primary productivity (GPP) across agro-pastoral ecotones in Inner Mongolia during 2005-2015. Moreover,we further assessed the impacts of canopy temperature (Tc) and precipitation (Prec) on GPP using a robust ensemble of satellite remotely sensed data. As results,we observed an upward GPP trend over 94.2% of vegetated grid cells (27.7% with a significant increase,Mann-Kendall test:P < 0.05). Our results indicated that Tc and Prec could explain 75.7% of inter-annual variations in GPP. Specifically,Tc showed a strong negative impact on GPP,however,Prec had a weak positive impact on GPP. Overall,our findings highlight the important role of Tc on vegetation productivity in agro-pastoral ecotones. In addition,further studies are still needed to fully reveal the impacts of climate change on the agro-pastoral ecotone ecosystems to provide management options and mitigation measures for sustainable agro-pastoral production to adapt to future climate change.

Key words: Canopy temperature, Gross primary productivity, Climate change, Remote sensing

摘要： 降水是影响北方农牧交错带植被生产力变化的最重要因子之一。然而，随着气候变暖，较高的冠层温度会对植被生产力产生不利影响。因此，需要进一步加深关于冠层温度和降水变化对植被生产力变化的理解。本研究使用卫星遥感数据集探讨了2005—2015年内蒙古农牧交错带生长季植被总初级生产力（Gross primary productivity，GPP）的时空变化特征，进而分析了冠层温度（Canopy temperature，Tc）以及降水（Precipitation，Prec）对植被GPP的影响。结果表明：研究区内94.2%的区域GPP呈现上升趋势，其中约27.7%具有显著性（P < 0.05）；Tc和Prec能够解释约75.7%的该地区平均GPP年际变化；GPP与Tc具有较强的负相关关系，而与Prec呈较弱的正相关关系。研究结果强调了冠层温度变化对农牧交错带植被生产力的重要影响。未来仍需要开展研究以全面揭示气候变化对农牧交错带生态系统的影响，以便为可持续农牧生产提供适应气候变化的管理方案和减灾措施。

关键词: 冠层温度, 总初级生产力, 气候变化, 遥感