中国干旱半干旱区植被降水利用效率时空变化特征及影响因素分析

Spatio⁃temporal variation of vegetation precipitation use efficiency and influencing factors in arid and semi⁃arid areas of China

植被的降水利用效率(Precipitation use efficiency,PUE)是表征植被生产力对降水量时空动态变化响应特征的重要指示器,对了解干旱环境下植被生产力的变化尤为关键。基于中国干旱半干旱区2000—2020年的植被净初级生产力、降水量、气温、土地利用类型和地形等数据,分析了中国干旱半干旱区植被降水利用效率的时空特征及其变化趋势,探究了植被PUE与气候因子的关联以及气候变化下土地利用和地形对植被PUE的影响。研究结果表明:(1)2000—2020年中国干旱半干旱区植被平均PUE为0.41 g C m^(-2)mm^(-1),不同土地利用类型下植被PUE的大小顺序为:草地<湿地<灌木<耕地<林地。(2)植被PUE年际变化整体呈现波动上升趋势,上升速率为0.004 g C m^(-2)mm^(-1),其中呈现显著改善趋势的面积占总面积的12.24%。(3)气温升高在不同程度上对大多数植被PUE起到促进作用,而降水增多则会抑制绝大多数区域的植被PUE。植被较少的区域,植被降水利用效率与气温、降水两气候因子基本无关。(4)随着海拔的升高,植被PUE呈现出先减后增再减的趋势。随着海拔的变化,气温依然与植被PUE呈正相关,降水依然与植被PUE呈负相关。研究结果可为中国干旱半干旱区生态系统保护、恢复以及可持续利用提供科学参考。

Precipitation is a main factor that controlling the dynamic change of ecosystem structure and affecting the ecosystem biodiversity.In the arid and semi⁃arid areas of China,precipitation plays a particularly important role in the growth of vegetation.Vegetation is one of the most important indicators of ecological environment change,and it is also the most active and important components of the ecosystem in arid and semi⁃arid areas.Precipitation use efficiency(PUE)of vegetation is an index that represents the response characteristics of vegetation productivity to precipitation changes and the ability of vegetation to convert precipitation into biomass.More and more researches have been conducted on the PUE of vegetation precipitation.Nowadays,based on remote sensing data and model estimation,there are still few studies on the impact analysis of the PUE in arid and semi⁃arid areas of China which need to be further improved.Based on the data of average annual precipitation,air temperature,land use type,topographic,and net primary productivity of vegetation in arid and semi⁃arid areas of China from 2000 to 2020,this study analyzed spatial and temporal characteristics of vegetation precipitation use efficiency in arid and semi⁃arid areas.The results showed that:(1)The average PUE of all vegetation in arid and semi⁃arid areas of China from 2000 to 2020 was 0.41 g C m^(-2)mm^(-1),and the order of PUE of different vegetation was grassland<wetlands<bush<arable land<forest land.(2)The inter annual variation of vegetation PUE showed an overall fluctuating upward trend,with an increasing rate of 0.004 g C m^(-2)mm^(-1).For trend analysis,the area of significant improvement trend accounted for 12.24%of the total area.(3)Increasing temperature promoted the PUE of most vegetation to varying degrees while increasing precipitation inhibited the PUE increase of vegetation in most regions.In the area with less vegetation,the two climatic factors of temperature and precipitation almost did not affect the use efficiency of vegetation precipitation.(4)With the increasing of altitude,the PUE of vegetation showed a trend of first decrease,then increase,and then decrease.The maximum of the PUE of vegetation occured when the elevation gradient was 3001—4000 m,and the minimum vegetation PUE occured when the elevation gradient was 5001—6928 m.With the change of altitude,air temperature was still positively correlated with vegetation PUE,while precipitation was still negatively correlated with vegetation PUE.The results can provide scientific reference for the protection,restoration and sustainable utilization of ecosystems in arid and semi⁃arid areas in China.