2002-2021年陕西省NPP变化趋势及空间分异特征研究

Analysis of the trend of NPP and its spatial discrepancy in Shaanxi Province from 2002 to 2021

生态系统净初级生产力(Net primary productivity,NPP)是生态系统生态产品供给的基础,同时亦是表征生态系统碳收支的重要指标。陕西省地跨南北,开展NPP时空动态研究可加深对NPP变化规律的认识。本研究采用MYD17A3数据产品,通过趋势分析、地理探测器模型以及多元回归等方法,系统分析陕西省NPP动态变化趋势,识别NPP变化的热点地区,探索气候因素与人为活动对NPP动态变化的作用。研究结果显示,2002-2021年间,陕西省年均NPP呈现南多北少的分布特征,但NPP年际变化趋势却呈现北多南少的分布格局;过去近二十年,陕西省NPP整体呈增加趋势,其中尤以黄土高原及宝鸡西北部地区增幅最大;各地级市中,延安、宝鸡、咸阳和榆林NPP年均增幅超过6.0 gC·m^(-2);NPP减小的地区主要位于关中平原城市周边地区;地理探测器模型分析显示,年均降水量和年均温对NPP变化趋势的空间分异有较大影响,其中年均降水量的影响更大;气候因素显著影响NPP的地区主要位于陕北长城沿线以及陕南秦岭山地东段,降水量年际变化的影响强于年均温;与气候因素相比,人为活动对陕西省NPP的影响更大,尤其是在黄土高原及关中平原西北部地区,研究期内人为活动显著增大上述两地的NPP。研究结果可为今后陕西省植被保护与生态建设提供科学借鉴。

The net primary productivity(NPP)is the basis for the supply of ecological products,and is also an important indicator to characterize the carbon budget of the terrestrial ecosystem.Shaanxi Province spans the north and the south,and the research on the spatio-temporal dynamics of NPP can deepen our understanding of the dynamics of NPP.In this study,the MYD17A3 data provided by NASA was used to analyze the dynamics of NPP in Shaanxi Province through the trend analysis,geographic detector model and multiple regression methods,to identify the hot spots of NPP change,and explore the effect of climate factors and human activities on the dynamic change of NPP.The results showed that from 2002 to 2021,the annual average NPP in Shaanxi Province gradually decreased from the south to the north.Contrary to this,the inter-annual trend of NPP gradually decreased from the north to the south.In the past two decades,NPP in Shaanxi Province has shown an overall increasing trend,especially in the Loess Plateau and northwestern of Baoji City.Among the cities,Yan'an,Baoji,Xianyang and Yulin have an average annual increase of NPP with more than 6.0 gC·m^(-2).The areas with reduced NPP are mainly located in the surrounding areas of the urbanized area in the Guanzhong Plain.The geographic detector model analysis showed that the annual mean precipitation and the annual mean temperature had great impact on the spatial differentiation of the NPP trend,especially the annual mean precipitation.The areas where climatic factors significantly affect NPP were mainly located along the Great Wall in northern of Shaanxi and the eastern section of the Qinling Mountains in southern of Shaanxi.Compared with climatic factors,anthropogenic activities have a greater impact on NPP in Shaanxi Province,especially in the Loess Plateau and the northwestern of Guanzhong Plain.During the study period,anthropogenic activities significantly increased the NPP in these two places.These results can provide scientific reference for vegetation protection and ecological construction in Shaanxi Province in the future.