宁夏回族自治区NDVI的时空变化特征研究

Spatiotemporal Variations of NDVI in Ningxia Hui Autonomous Region

利用1999年以来的SPOT-VGT NDVI及气象数据,在合成月、年最大值NDVI及标准化植被异常指数等指标的基础上,运用回归分析、相关分析和变异系数等NDVI时空分析方法,对宁夏回族自治区近11a来的植被活动特征进行了研究。结果表明,在空间分布上,NDVI存在南北好,中部差的特征,这与宁夏植被分布格局和地理气候特点相吻合;在年际变化上,NDVI值受降雨影响较大,特别是中部干旱带的NDVI对干旱胁迫响应明显;在变化趋势上,该区大部分地区的NDVI值处于逐渐增加的态势,只有5个地级市所在的少部分地区,其NDVI处于降低趋势。NDVI的时空变化特征表明,该区近年来的生态环境在逐步改善,且NDVI变化对区域生态系统变动响应明显。近年来,该区实施的许多重大生态治理工程是导致区域NDVI增强的主要因素。

Based on SPOT-VGT NDVI and meteorological data from 1999 to 2009,the paper synthesized monthly and yearly maximum NDVI,and standardized anomaly NDVI.Using some spatiotemporal analysis methods,such as regression analysis,correlation analysis and variation coefficient,the paper studied the dynamic characteristics of vegetation in Ningxia Hui Autonomous Region over recent 11 years.The spatial distribution analysis results show that the NDVI values were higher in the north and the south part,but lower in middle.This characteristic agreed with the geographical division and vegetation distribution pattern of Ningxia.The NDVI values changed greatly over time and responded closely to yearly precipitation,especially in the drought zone located in the middle of the region.The NDVI in most places within the region increased during the period and in only five areas decreases of NDVI were found,which indicated the whole vegetation cover the region became better over the period.The spatiotemporal variations of NDVI show that the ecosystem has been gradually improved in recent years as the NDVI variations responded clearly to the ecosystem changes.There had some ecological restorations projects applied recently,which might be the major factor that resulted in the increase of NDVI in the region.