阴山北麓地区植被覆盖动态时空分析

Spatial and Temporal Analysis on Vegetation Cover Dynamics in North Piedmont of Yinshan Mountain

阴山北麓地区是我国典型的生态脆弱带及北方重要的生态屏障,监测其植被覆盖变化是研究该地区以及农牧交错带对全球变化响应问题的基础与切入点.本文基于1998年～2003年该地区SPOT-4/VEGETATION的S10数据集,通过分析年均NDVI、年最大NDVI、NDVI变化值、NDVI变化率等指标,得出:①全区年最大NDVI与全区年均NDVI具有可替代性;②1999年～2001年的全区年最大NDVI连续减少,而后两年连续增加,2003年情况与1998年基本持平;③林地、草地和耕地的年最大NDVI和年内变化幅度都是耕地＞林地＞草地,而6年间年最大NDVI变化幅度是林地＞耕地＞草地.2003年林地和耕地的年最大NDVI较1998年分别有微弱和较显著增加,而草地仍有较显著减少;④2001年较1998年的年最大NDVI除达茂旗中部、多伦县东部和商都县东南部少数地区有所改善外,其他大部地区呈现严重退化和显著减少;2003年较2001年除达茂旗西北部、多伦县东部零星地区呈现退化和减少外,其他所有地区都有中高度的改善和显著增加;2003年较1998年西北部有中度退化和显著减少,其他地区退化与改善并存.

North piedmont of Yinshan Mountain is a typical ecological fragile zone and an important eco-shelter in north China. It is therefore important to study impact of global change in this area in order to monitor and analyze dynamics of vegetation cover. Based on annual SPOT4/VEGETATION images of the area from 1998 to 2003, we did time series analysis on dynamics of annual maximum NDVI and annual mean NDVI, and drew the following conclusions: 1)Annual maximum NDVI of the whole area is related to annual mean NDVI, which indicates that the former could represent the best vegetation condition in a year, and the average condition as well; 2)The annual maximum NDVI of the area decreased continuously from year 1999 to 2001, while increased continuously in the next two years, and remained equivalent in 2003 and 1998; 3)Ranking of annual maximum NDVI in a year is cropland>woodland>grassland, while the ranking of change during 1998～2003 is: woodland>grassland>cropland. In addition, annual maximum NDVI of cropland and woodland in 2003 has been improved in comparison with those of 1998, while grassland has degenerated; 4)Compared with the year of 1998, annual maximum NDVI of the whole area in year 2001 has been degraded seriously, except for the areas in middle Damao Banner,east Duolun County and southeast Shangdu County, while it has been improved in 2003 in comparison with that of the year 2001, except for northwest Damao Banner and sporadic spots in east Duolun County. In general, annual maximum NDVI in 2003 has been degraded in the northwest part of the area, compared with that of the year 1998, and degeneration and improvement coexisted in other places.