盐池县荒漠草原人工植被重建对区域生态系统蒸散的影响

Effects of Artificial Vegetation Reconstruction on Regional Ecosystem Evapotranspiration in Desert Steppe of Yanchi County

[目的]研究荒漠草原人工植被重建对区域蒸散的潜在影响,旨在为区域生态恢复重建提供理论依据。[方法]基于2001-2018年MODIS ET和NDVI产品,利用趋势分析、相关分析和分区统计等方法,以宁夏回族自治区盐池县为例,研究了荒漠草原人工植被重建对区域生态系统蒸散的影响。[结果]①2001-2018年盐池县NDVI整体呈上升趋势,增长幅度为0.006 0/a,98.55%的区域显著上升。②2001-2018年均蒸散量(ET)为266.73 mm,空间上表现为西南高于西北的特征,近18 a盐池县蒸散量显著上升(p<0.01),增长幅度为6.27 mm/a,全县区域内ET均达到了显著上升趋势。③盐池县大面积人工植被重建后,ET显著升高,ET与NDVI呈显著正相关。ET与NDVI的变化趋势相关性为0.76(p<0.01)。④在盐池荒漠草原地区,人工植被重建造成的植被结构变化导致生态系统蒸散量更大,消耗更多的水分,同时也使ET增长速率加快。[结论]盐池荒漠草原人工植被重建提高了区域NDVI值,也增强了生态系统的ET,水分消耗的加剧将影响生态系统的稳定性。

[Objective] The potential impacts of artificial vegetation reconstruction of desert steppe on regional evapotranspiration were studied in order to provide a theoretical basis for regional ecological restoration and reconstruction. [Methods] Based on the MODIS ET and NDVI products from 2001 to 2018, trend analysis, correlation analysis, and zoning statistics were used to study the effects of artificial vegetation reconstruction on regional ecosystem evapotranspiration, with the desert steppe in Yanchi County of Ningxia Hui Autonomous Region being used as an example ecosystem. [Results] ① The NDVI value in Yanchi County showed an upward trend from 2001 to 2018, with the growth rate reaching 0.006 0/a, and the growth area of the desert steppe in Yanchi County reached 98.55%. ② In 2001-2018, the average evapotranspiration(ET) was 266.73 mm, which showed that the ET in the southwest was higher than that in the northwest. The evapotranspiration in Yanchi County increased significantly over the past 18 years(p<0.01), with a growth rate of 6.27 mm/a. The ET has a noticeable upward trend in all pixels of Yanchi County. ③ The ET increased notably after large-scale artificial vegetation reconstruction in Yanchi County, and the ET and NDVI showed a significant positive correlation. The correlation between the changes in the ET and NDVI was 0.76(p<0.01). ④ Vegetation structure change caused by vegetation reconstruction leads to greater evapotranspiration of the ecosystem, more water consumed in the desert steppe area of Yanchi County, and an accelerated growth rate of the ET. [Conclusion] The artificial vegetation reconstruction of the desert steppe has increased the NDVI value and enhanced the ET of the regional ecosystem in Yanchi County. The increased water consumption will affect the stability of the desert steppe ecosystem.