基于改进CASA模型的陕西省植被NPP遥感估算

Remote Sensing Estimation of Vegetation NPP in Shaanxi Province Based on Improved CASA Model

[目的]探究陕西省陆地生态系统植被群落生产状况,分析陕西省植被NPP时空格局变化及影响因素,为准确评估陕西省陆地生态系统碳源/汇,实现区域生态可持续发展,达成碳中和目标提供参考依据。[方法]基于温度—植被干旱指数(Temperature Vegetation Dryness Index, TVDI)对CASA(Carnegie-Ames-Stanford Approach)模型水分胁迫因子进行改进,从而估算陕西省2010—2020年植被NPP,并利用热点分析法、趋势分析法以及地理探测器对陕西省植被NPP进行空间分布格局、年际变化趋势和驱动因子研究。[结果](1)陕西省NPP空间分布呈现南高北低、冷热点区域差异明显的特征;(2)陕西省2010—2020年NPP平均值介于331.02~416.34 gC/(m^(2)·a),NPP均值在100~600 gC/(m^(2)·a)占比最大,最低值和最高值区间占比不足20%;(3)全省2010—2020年83.3%的面积植被NPP值无显著变化,4.2%的面积呈增加状态,12.5%的面积NPP值呈下降趋势;(4)降水是陕西省植被NPP变化的单因子主导驱动力,太阳辐射量及土地利用类型交互作用下对NPP变化解释力更强。[结论]基于TVDI改进的CASA模型能够有效量化区域植被NPP,且陕西省植被NPP南北分布差异明显,降水、土地利用类型及太阳辐射量是其主要影响因子。

[Objective]The aims of this study are to investigate the production status of vegetation communities in Shaanxi Province terrestrial ecosystems,to analyze the changes in spatial and temporal patterns of vegetation NPP and the factors affecting them,and to provide a reference basis for accurately assessing the carbon sources/sinks of the terrestrial ecosystems in Shaanxi Province,realizing the sustainable development of the region′s ecology,and reaching the goal of carbon neutrality.[Methods]Based on the CASA(Carnegie-Ames-Stanford Approach)model water stress factor improved by the Temperature Vegetation Dryness Index(TVDI),the improved CASA model was used to estimate the vegetation NPP in Shaanxi Province from^(2)010 to 2020,and then the spatial distribution pattern,inter-annual change trend and driving factors were analyzed by hotspot analysis,trend analysis,and GeoDetector.[Results](1)The spatial distribution of NPP in Shaanxi Province showed the characteristics of high level in the south and low level in the north,with obvious differences in cold and hot spot areas.(2)The average value of NPP in Shaanxi Province from^(2)010 to 2020 ranged from^(3)31.02 to 416.34 gC/(m^(2)·a),with the largest proportion of average NPP values between 100 and 600 gC/(m^(2)·a),and less than 20 percent of the lowest and highest value intervals.(3)83.3 percent of the province′s area had no significant change in vegetation NPP values from^(2)010 to 2020,4.2 percent showed an increase,and 12.5 percent showed a decreasing trend in NPP values.(4)Precipitation was the single factor dominant driver of vegetation NPP change in Shaanxi Province,with solar radiation and land use type interacting to explain NPP change more strongly.[Conclusion]The CASA model improved by TVDI can effectively quantify the regional vegetation NPP,and there are obvious differences in the distribution of vegetation NPP between north and south in Shaanxi Province,with precipitation,land use type and solar radiation as the main influencing factors.