Abstract：
Vegetation is an essential component of terrestrial ecosystems, influenced by climate change and human activities. Quantifying the relative contributions of climate change and human activities to vegetation dynamics is crucial for addressing global climate change. Sichuan Province is one of the essential ecological functional areas in the upper reaches of the Yangtze River, and its vegetation change is of great significance to the environmental function and ecological security of the Yangtze River Basin and southwest China. In this paper, the modified Carnegie-Ames-Stanford Approach(CASA) model was used to estimate the monthly NPP (Net Primary Productivity) of vegetation in Sichuan Province from 2000 to 2018, and the univariate linear regression analysis was used to analyze the temporal and spatial variation of vegetation NPP in Sichuan Province from 2000 to 2018. In addition, taking vegetation NPP as an index, Pearson correlation analysis, partial correlation analysis, and second-order partial correlation analysis were carried out to quantitatively analyze the contribution of climate change and human activities to vegetation NPP. Finally, the Hurst index and nonparametric Man-Kendall significance test were used to predict the future change trend of vegetation NPP in Sichuan Province. The results show that (1) from 2000 to 2018, the NPP of vegetation in Sichuan Province has a significant increasing trend (Slope = 6.09gC·m-2·a-1), with a multi-year average of 438.72 gC·m-2·a-1, showing a trend of low in the east and high in the middle. The response of vegetation NPP to altitude is different at different elevations; (2) the contribution rates of climate change and human activities to vegetation NPP change are 4.12gC·m-2·a-1 and 1.97gC·m-2·a-1, respectively. In contrast, the impact of human activities on NPP is more significant than climate change. Human activities are the main factors affecting vegetation restoration and degradation in Sichuan Province. However, the positive contribution to NPP change is less than climate change; (3) the future vegetation NPP change trend in Sichuan Province is mainly rising, and the same direction change trend is much larger than the reverse change trend. The areas with an increasing trend in the future account for 89.187% of the total area. This research helps understand the impact of climate change and human activities on vegetation change in Sichuan Province. It offers scientific bases for vegetation restoration and ecosystem management in Sichuan and the surrounding areas.
摘要：
植被是陆地生态系统的重要组成部分,受气候变化和人类活动的影响。量化气候变化和人类活动对植被动态的相对贡献对于应对全球气候变化至关重要。四川省是长江上游重要的生态功能区之一,植被变化对长江流域和西南地区的环境功能和生态安全具有重要意义。在本文中,采用修正的Carnegie-Ames-Stanford方法(CASA)模型估算四川省2000-2018年植被月净初级生产力(NPP),采用单因素线性回归分析四川省2000-2018年植被NPP的时空变化.此外,以植被NPP为指标，皮尔逊相关分析，偏相关分析，和二阶偏相关分析定量分析了气候变化和人类活动对植被NPP的贡献。最后,采用Hurst指数和非参数Man-Kendall显著性检验对四川省植被NPP未来变化趋势进行预测。结果表明:(1)2000~2018年,四川省植被NPP呈显著增加趋势(Slope=6.09gC·m-2·a-1),多年平均值为438.72gC·m-2·a-1，呈现东部低，中部高的趋势。不同海拔地区植被NPP对海拔的响应不同；（2）气候变化和人类活动对植被NPP变化的贡献率分别为4.12gC·m-2·a-1和1.97gC·m-2·a-1。相比之下,人类活动对NPP的影响比气候变化更显著。人类活动是影响四川省植被恢复和退化的主要因素。然而,对NPP变化的正向贡献小于气候变化;(3)未来四川省植被NPP变化趋势以上升为主,同方向变化趋势远大于反向变化趋势。未来有增长趋势的面积占总面积的89.187%。这项研究有助于了解气候变化和人类活动对四川省植被变化的影响。它为四川及周边地区的植被恢复和生态系统管理提供了科学依据。
