西南地区植被生态系统GPP时空变化及其主导气候因子识别

Temporal and spatial variations of gross primary productivity(GPP)in vegetation ecosystems andits dominant climatic factors identification in Southwest China

关键词:  西南地区, 植被生态系统, 总初级生产力(GPP), 气候因子, 通径分析

Key words:  Southwest China, vegetation ecosystem, gross primary productivity(GPP), climatic factors, path analysis

摘要:

探究西南地区植被生态系统(农田、林地和草地)总初级生产力(GPP)时空变化及气候因子对其变化的影响,对全球气候变化背景下植被资源分类管理具有重要的意义。该研究基于2000—2022年植被GPP、气温和降水数据,以及2020年土地利用类型数据,基于Theil-Sen Median趋势分析和Mann-Kendall显著性检验,解析西南地区植被生态系统GPP时间变化特征和空间变迁格局,并通过通径分析揭示气温和降水对植被GPP的直接、间接和综合影响及其主导影响因子。结果表明:(1)2000—2022年西南地区各植被生态系统GPP呈显著上升趋势(P<0.05),其中农田生态系统GPP上升速率最高,草地生态系统GPP上升速率最低。(2)区域尺度上,西南地区气温对植被GPP的直接影响、间接影响和综合影响均为正向作用,而降水对植被GPP的影响均为负向作用。气温对草地生态系统GPP变化的直接影响最大,降水对农田生态系统GPP变化的直接影响最大。(3)像元尺度上,气温对西南地区和各生态系统GPP变化的影响强于降水。气温直接影响主导54.89%植被GPP变化。综上可知,西南地区植被生态系统植被GPP呈正向变化的面积占比较大,气温的直接影响主导各植被生态系统GPP的变化。在全球气候变化情境下,该研究结果为制定具有区域针对性的生态恢复与管理政策提供了有价值的参考依据。

Abstract:

Exploring the spatiotemporal variations of gross primary productivity(GPP)across vegetation ecosystems(cropland, forest, and grassland)in Southwest China, as well as the direct, indirect, and comprehensive impacts of climatic factors on these variations, holds significant importance for managing regional vegetation resources amidst climate change. Based on GPP, temperature, and precipitation data spanning from 2000 to 2022, coupled with land use type data from 2020, Theil-Sen Median trend analysis, Mann-Kendall significance test, and path analysis were study adopted to investigate the spatiotemporal patterns of GPP within Southwest China's vegetation ecosystems. It further dissected the direct, indirect, and overall effects of temperature and precipitation on vegetation GPP, revealing the dominant climatic factors and their modes of influence on GPP changes in the region. The results were as follows:(1)From 2000 to 2022, a significant upward trend(P<0.05)was observed in GPP across all vegetation ecosystems in Southwest China, with the cropland ecosystem experiencing the highest increase rate, and the grassland ecosystem, the lowest.(2)At the regional scale, temperature had a positive direct, indirect, and comprehensive impact on vegetation GPP, whereas precipitation exerted a negative influence. Temperature had the most significant direct impact on grassland ecosystem GPP, while precipitation's direct impact was the greatest on cropland ecosystem GPP.(3)At the pixel scale, temperature's influence on GPP changes in Southwest China and its individual ecosystems was stronger than that of precipitation. Temperature directly dominated 54.89% of the changes in vegetation GPP. In summary, a considerable proportion of vegetation ecosystems in Southwest China shows positive changes in GPP, with temperature's direct effect being the primary driver of GPP variations across these ecosystems. These findings provide valuable insights for formulating regionally adaptive ecological restoration and management policies amidst global climate change.