2000-2020年陕西省植被覆盖时空变化多尺度分析

[目的]退耕还林还草工程实施以来，陕西省植被覆盖度明显提高。然而，省级尺度上植被覆盖度的增加一定程度上掩盖了部分市、县级区域植被覆盖度下降的实事，当前迫切需要加强对不同空间尺度植被覆盖变化及其驱动因素的研究。[方法]基于MODIS NDVI数据计算了陕西省植被覆盖度，分析了2000—2020年陕西省、地区、市和县四级尺度植被覆盖度时空变化趋势。[结果]2000—2020年陕西省植被平均覆盖度为64.3%±2.1%,增长率为0.24%/a;陕北植被覆盖度平均为37.6%±4.4%,增长率为0.63%/a;陕南植被覆盖度平均为89.6%±1.2%,增长率为0.13%/a;关中植被覆盖度平均为70.6%±3.5%,下降率为-0.18%/a。延安市、榆林市、铜川市、宝鸡市、安康市、商洛市的植被覆盖度呈持续增加趋势，而西安市、渭南市、咸阳市和汉中市的植被覆盖度呈先增加后下降趋势；全省有72.3%的区县植被覆盖度呈增加趋势，有22.3%的区县植被覆盖度变化方向与所在市相反。在不同空间尺度上，陕西省植被覆盖度增速均表现为2000—2010年高于2010—2020年，这与两个时期的造林面积差异有关。[...

Multi-Scale Analysis of Spatiotemporal Change of Vegetation Cover in Shaanxi Province from 2000 to 2020

[Objective]Since the Grain for Green Project was implemented, the vegetation coverage in Shaanxi Province has been improved significantly. However, the increase of vegetation cover at the provincial scale conceals the fact that the vegetation cover decreases in some cities and counties. Thus, there is an urgent need to strengthen the study of vegetation cover change and its driving factors in different spatial scales. [Methods] The vegetation coverage of Shaanxi Province from 2000 to 2020 was calculated based on the MODIS NDVI data, and the spatiotemporal change trend of vegetation coverage in different spatial scales was analyzed. [Results] The average vegetation coverage of Shaanxi Province was 64.3%±2.1% and the annual growth rate was 0.24%, the average vegetation coverage of northern Shaanxi was 37.6%±4.4% with the annual growth rate of 0.63%, and the average vegetation coverage of southern Shaanxi was 89.6%±1.2% with the annual growth rate of 0.13%, the average vegetation coverage in middle Shaanxi was 70.6%±3.5% with the annual decline rate of -0.18% from 2000 to 2020. The vegetation coverage of Yan'an, Yulin, Tongchuan, Baoji, Ankang and Shangluo continued to increase, while the vegetation coverage of Xi'an, Weinan, Xianyang and Hanzhong increased first and then decreased from 2000 to 2020. In the whole province, vegetation coverage in 72.3% of the districts and counties showed an increasing trend, and changes of vegetation coverage in 22.3% of the districts and counties showed the opposite direction. The growth rate of vegetation coverage in Shaanxi Province was higher in 2000—2010 than that in 2010—2020 at different spatial scales, which could be attributed to the difference of afforestation area in the two periods. [Conclusion] The change of vegetation cover in Shaanxi Province is dependent on spatial scale. The accurate understanding of the change of vegetation cover at different scales is helpful to scientifically evaluate the effectiveness of regional ecological construction.