基于时间序列遥感数据的嵯岗国家沙化土地封禁保护成效评估

Effect Evaluation of the Enclosure-Rehabilitation of Desertification Land in Cuogang Based on Time Series Remote Sensing Data

2013年中国启动实施了内蒙古自治区新巴尔虎左旗嵯岗国家沙化土地封禁保护区试点。本研究利用2001-2017年生长季NDVI数据分析了嵯岗封禁保护区及周边区域植被长势时空演变特征,分析了多年的生长季降水量和历年旱情,之后利用植被降水利用效率和NDVI残差趋势分析对保护成效进行了评估。结果表明:(1)封禁项目实施之前,封禁区内外植被长势变化趋势基本一致,而在项目实施后的2016、2017年,封禁区内NDVI距平明显高于封禁区外;(2)降水为影响该区域植被长势的主导气候因素,在封禁实施后的2015-2017年该区域连续3 a干旱,极大地限制了区域植被生长;(3)封禁区内植被降水利用效率和NDVI残差均呈现明显的增加趋势,而封禁区外变化不明显,说明封禁提升了植被的自我修复能力;(4)嵯岗封禁保护区由3个地块组成,其中嵯岗林场封禁效果比牧场八队和牧场十一队明显。国家沙化土地封禁保护措施有效促进了植被自我修复,提高了沙漠生态系统应对气候变化的能力。

The pilot project for enclosure-rehabilitation of desertification land in Cuogang started in 2013. In this study, we used the time series MODIS NDVI dataset in 2001-2017 to analyze the vegetation spatial-temporal trend. And the effects were evaluated by precipitation use efficiency and NDVI residual trend analysis. Before the enclosure(2001-2013), vegetation trends in and outside the reserve were similar. While after the enclosure(2013-2017), vegetation outside the reserve showed significant decreasing trend. In 2016 and 2017, the NDVI anomaly percentages inside the reserve was higher that the outside. Standardized precipitation index(SPI) analysis showed that Cuogang has experienced constant drought in 2015-2017, which had caused vegetation degradation. Results of precipitation use efficiency and NDVI residual trend analysis showed that the implementation of the project has significantly increased the vegetation efficiency of precipitation utilization, improved the capability of sandland vegetation in adapting to climate change, effectively protected the sandland vegetation by minimizing the drought impact on vegetation growth.