2004—2014年太湖流域植被覆盖时空变化特征

Spatio-Temporal Variations of Vegetation Coverage in Taihu Lake Basin From 2004 to 2014

太湖流域历来是我国经济比较发达的地区之一。随着经济发展、人口聚集、城市化水平的提高,太湖流域森林生态系统遭到严重破坏,因此,研究该区域植被覆盖空间格局变化及其影响因素,为科学制定流域可持续发展方案提供依据。选取MODIS-NDVI数据,运用像元二分模型、变异系数、线性趋势分析及主成分分析等方法,分析了2004—2014年太湖流域植被覆盖时空变化特征、变化趋势特征及影响因素。结果表明:(1)近11 a太湖流域植被覆盖总体呈显著下降趋势,下降速率为2.6%·(10 a)-1。植被覆盖度均值由2004年的0.606 5下降到2014年的0.594 2,下降2.03%。(2)太湖流域植被覆盖空间分布呈现西南部高、东部低的分布特征,空间波动特征表现为东部地区变化最剧烈,北部和西部地区次之,西南部地区变化最稳定。(3)太湖流域植被覆盖严重退化区域面积占35.08%,明显改善区域面积占40.00%,且呈现西南部和东部植被覆盖明显增加、西北部明显减少的空间格局。(4)太湖流域植被覆盖减少主要是降水增加、人口增长和经济发展共同作用的结果,人类活动对植被覆盖变化有双重影响。因此,太湖流域应控制人口增长,提高土地利用效率,加快退耕还林还草等植被恢复工程,从而改善流域生态环境。

As is well known,the Taihu Lake Basin is always one of the regions relatively well-developed in economy in China. With the region developing rapidly in economy,growing in population and rising in urbanization level,the forest ecosystem therein has been deteriorating seriously. Therefore,it is very important for us to study changes in spatial pattern of its vegetation cover and their influencing factors,so as to lay down certain basis for formulating scientific sustainable development programs for the basin. Relevant MODSI-NDVI data available were analyzed using the dimidiate pixel model,variation coefficient,linear trend analysis,principal component analysis and some other analysis methods to characterize changes in spatio-temporal pattern of the vegetation cover of the basin,and trends and influential factors of the changes from 2004 to 2014. Results show:(1) In the past 11 years from 2004 to 2014,the vegetation cover,on the whole,was on a significant declining trend,with a rate being 2. 6%·(10 a)-1. Its mean dropped from 0. 606 5 in 2004 to 0. 594 2 in2014,or by 2. 03%;(2) The spatial distribution of the vegetation cover in the basin exhibited a downward trend from the southwest to the east,and varied the most drastically in the east,less in the north and west,and the least in the southwest;(3) The areas with vegetation cover seriously degraded accounted for 35. 08% of the total of the basin in area,whilethose with vegetation cover obviously improved accounted for 40. 00% and were mostly distributed in the southwest and east and rarely in northwest; and(4) The decrease in the vegetation cover of the basin was attributed mainly to the joint effect of the increases in precipitation,population and economic development. And human activities had dual effects on vegetation cover. It is,therefore,essential for the Taihu Lake Basin to control the population growth,optimize the employment structure,and accelerate the construction of ecological civilization and vegetation restoration,for the purpose of mitigating the detrimental effect of population and industrial development on the vegetation,enhancing citizens' environmental protection consciousness,and reducing destruction of the ecological environment.