2000—2019年吕梁市植被NDVI时空动态及其影响因素分析

为了详细分析吕梁市植被生长变化与气候变化和人类活动的关系,基于吕梁市的2000—2019年逐年归一化植被指数(NDVI)数据和13个县(市、区)气象观测站年气温和降水观测数据,采用空间插值方法、空间相关性分析法和残差分析法,对吕梁市多年植被NDVI的时空变化特征进行分析,并探讨了气候变化和人类活动对吕梁市植被覆盖变化的影响。结果显示:2000—2019年吕梁市96.32%的区域NDVI呈现增加趋势,但各区域间存在明显空间性差异,中部吕梁山山区NDVI较高,东部平川地带和西部沿黄区域NDVI较小。总体而言,2000—2019年吕梁市的NDVI呈波动增加趋势,2018年达最大值。2000—2019年吕梁市NDVI与降水量和气温在年尺度上均呈正相关关系,且植被生长发育受降水的影响强于气温,全市38%的区域植被NDVI与气温-降水的复相关性通过0.05显著水平检验; 人类活动对吕梁市95%以上地区的植被生长有积极影响,表明退耕还林还草等生态修复工程对吕梁市植被覆盖增加有积极作用,生态提升效应逐渐凸显。

Analysis of Spatiotemporal Dynamics and Influencing Factors of Vegetation NDVI in Lüliang City from 2000 to 2019

Based on the method of spatial interpolation, spatial correlation analysis and residual analysis, the annual normalized difference vegetation index(NDVI), annual temperature and precipitation meteorological observation data at 13 meteorological observation stations from 2000 to 2019 were selected to analyze the spatiotemporal variation characteristics of vegetation NDVI and the impact of climate change and human activities. NDVI showed a fluctuating increase trend from 2000 to 2019 in 96.32% of Lüliang City. However, there were obvious spatial differences in Lüliang City. NDVI was higher in the Lüliang Mountain, and lower in the eastern plain area and along the western Yellow River area. As a whole, NDVI in Lüliang City showed a fluctuating increase trend, with the maximum in 2018. Spatial correlation analysis showed that NDVI was positively correlated with both annual precipitation and temperature in the whole of regions, which was significantly correlated(p<0.05)in 38% of Lüliang City. As for precipitation, the influence was stronger than temperature. Residual analysis shows that human activities influenced positively the vegetation coverage change in more than 95% of Lüliang City. Therefore, returning farmland to forestland and grassland projects have boosted increase of vegetation coverage in Lüliang City.