基于MODIS EVI的陇南山地植被覆盖时空变化

Spatial and Temporal Variation of Vegetation Coverage in Mountain Area of Longnan:Based on MODIS EVI

为了分析2000以来的退耕还林还草工程对高植被覆盖区甘肃省陇南市的影响,本研究基于2000—2010年MODIS EVI数据,通过均值分析、植被覆盖度分析和一元线性回归分析,对陇南山地连续11年以来的植被覆盖时空变化特征进行了研究。结果表明:2000—2010年陇南山地植被覆盖变化总体以0.2%/10 a的增速缓慢上升,低于同期甘肃河东地区、甘肃全省、秦巴山区以及西北地区的植被增长率。受气温、降水等地带性要素分布的影响,植被覆盖度存在明显的区域差异性,植被覆盖大体上存在由东南向西北递减的趋势。整个山区植被类型以覆盖度在45%以上的中覆盖、中高覆盖及高覆盖植被为主体,林地所占比例较大。尽管研究时段内植被改善区域显著增加,但高植被覆盖区却存在退化趋势,考虑到陇南市相对脆弱的生态环境,加强植被保护仍将是今后生态建设中不容忽视的内容。

The paper aims to analyze the influence of the project of returning farmland to forest and grassland since 2000 on Longnan of Gansu with a high vegetation coverage.Based on the MODIS EVI data from 2000 to 2010,the authors analyzed the spatial and temporal variation of vegetation coverage in the mountain area of Longnan by using the EVI average analysis,vegetation coverage analysis and monadic linear regression trend analysis.The results showed that：the growth rate of vegetation coverage in the mountain area of Longnan increased slowly with 0.2% /10 a,which was lower than that of Hedong region of Gansu,the whole province of Gansu,Qinba mountain area and northwest China;there was an obvious regional difference in vegetation coverage,which had a trend of decreasing from southeast to northwest,influenced by the distribution of regional elements such as temperature and precipitation;the vegetation types in the whole mountain area with vegetation coverage above 45% accounted for the majority part,which were the type of middle and high coverage,and high coverage,the proportion of forest land was larger than others;although the area of vegetation improvement was larger than that of the degraded area,there was a trend of degradation in high vegetation coverage area.Considering the relatively fragile ecological environment,strengthening vegetation protection should still be an essential part in future ecological construction.