海河流域植被覆盖度变化的图谱特征及其地形梯度差异分析

Spectrum characteristics of vegetation coverage change and analysis of the difference of topographic gradient in Haihe River Basin

为了从整体上了解1999—2013年间海河流域植被覆盖的变化情况及其与地形因子的关系,基于1999、2004、2009和2013年的SPOT/NDVI数据,结合图谱分析法,对海河流域植被覆盖度变化图谱的特征进行分析,并探讨了其在海拔、坡向、坡度和地形起伏度4种地形因子梯度上的差异.结果显示:(1)以高→高→高→高为主的稳定型是主要的图谱类型,海河流域1999—2013年期间植被覆盖度以高等为主,且较稳定.(2)海河流域不同地形梯度上均以高→高→高→高为主的稳定型图谱分布最广泛;植被覆盖度呈明显变化的图谱类型主要集中在<200 m的低海拔与1 000~2 000 m的中高海拔、中低地形起伏度(0~200 m)、0~6°的平坡与缓坡、阴坡与半阴坡.变化特征以中、高等植被覆盖度相互转换为主,且具有明显的时间阶段性.研究结果可以较好地反映该流域植被覆盖度变化在不同地形因子下的状况,为海河流域生态环境保护和未来合理开发提供科学指导.

In order to understand the changes of vegetation coverage in the Haihe River Basin from 1999 to 2013 and the relation between them and topographic factors, based on the SPOT/NDVI data of 1999, 2004, 2009 and 2013, spectrum characteristics about vegetation coverage change and the difference of 4 kinds of terrain factors, such as elevation, slope, aspect and topographic relief in Haihe River Basin were analyzed combining with the spectrum analysis. The results indicate that： （1）stable type is the main conversion type, and the vegetation coverage is high and stable in recent years in Haihe River Basin in 1999--2013. （2）The vegetation coverage change spectrum pattern of stable is the main type of distribution in different terrain gradient. The vegetation coverage change spectrum pattern of the middle and high vegetation cover conversion mainly concentrate in the elevation of 〈200 m and 1 000-2 000 m, slope less than 6°, landform relief less than 200 m, shady slope and semi shady slope. The results show that the vegetation cover change is more obvious in some topographic gradient range of Haihe River Basin, and has obvious time phase. These findings may help to reflect the variety of vegetation coverage in different terrain factors in time, and provide scientific guidance for the ecological environment protection and sustainable development of Haihe River Basin.