蒙古高原植被碳水利用效率时空变化特征及其影响因素

The spatiotemporal variation and influencing factors of vegetation carbon and water use efficiency in the Mongolian Plateau

作为反映生态系统碳水循环的重要参数,植被碳水利用效率动态变化及驱动要素分析对干旱、半干旱生态系统可持续发展意义重大。本研究基于MODIS的GPP、NPP、ET数据、ERA5的降水和温度数据以及生态分区数据,利用趋势分析、偏相关分析以及残差分析等方法分析2000—2019年蒙古高原植被碳利用效率(CUE)和水分利用效率(WUE)的时空变化特征,并探讨其与降水、温度以及人类活动的定量关系。结果表明:2000—2019年蒙古高原植被CUE呈显著增加趋势,增长速率为0.2%·a^(-1);而WUE呈不显著下降趋势;除落叶林、混交林和高山草甸外,各生态分区CUE均显著增加;而WUE仅在针叶林和荒漠草原区呈增加趋势;超过60%的区域植被CUE和WUE与降水呈正相关,与温度呈负相关;受人类活动影响,高原上62.9%区域的CUE残差显著增加,仅10.6%区域的WUE残差呈显著增加趋势。研究结果可为气候变化背景下蒙古高原地区碳水循环研究提供参考。

The carbon and water use efficiency of vegetation are the important variables reflecting ecosystem carbon-water cycle.Analyzing their dynamics and driving factors is of great significance for ecosystem sustainable development in the arid and semi-arid Mongolian Plateau.Using trend analysis,partial correlation analysis,and residual analysis,we analyzed the spatiotemporal variations of vegetation carbon use efficiency(CUE)and water use efficiency(WUE)of the Mongolian Plateau from 2000 to 2019,and examined their relationships with precipitation,temperature,and human activities.The CUE of vegetation in the Mongolian Plateau showed a significant increasing trend during 2000-2019,with a rate of 0.2%·a^(-1),while the WUE showed a non-significant decreasing trend.The CUE increased significantly in all ecological divisions except broad-leaved forests,mixed forests,and alpine meadows,while WUE showed an increasing trend only in coniferous forests and desert steppe.The CUE and WUE were positively correlated with precipitation and negatively correlated with temperature in most of the Mongolian Plateau(>60%).Affected by human activities,62.9%of the plateau area suffered a significantly increased CUE residual,while only 10.6%of the study area showed a significant increasing trend in WUE residual.Our results provide vital information for understanding the impacts of climate change and human activities on carbon-water cycling in the Mongolian Plateau.