四川小河沟自然保护区植被类型在地形上的分异研究

Topographic Variation of Vegetation Types in Xiaohegou Nature Reserve of Sichuan Province

以四川小河沟自然保护区为研究对象，在遥感影像和DEM数据的基础上，对植被类型在地形上的分布差异进行研究。结果表明：（1）随着海拔高度的逐渐上升，各种植被类型依次出现和消失，呈顺序分布，并且每种植被类型在相应的海拔段上拥有优势地位。（2）植被类型的分布与坡向之间存在相关性，大面积的常绿落叶阔叶林和次生落叶阔叶林常常在西南坡向上出现，高山灌丛和高山草甸在南坡上的分布面积最大，而在平地、北坡和西北坡上则少有亚高山草甸分布。（3）随着坡度由缓变陡，各植被类型的面积比例在不同的坡度段内发生相应变化，但各坡度段上的植被类型均以次生落叶阔叶林和亚高山针叶林为主，除亚高山草甸外，其余植被类型均主要分布在坡度20°～50°的区域内。

The variation of vegetation types in Xiaohegou Nature Reserve of Sichuan Province was studied based on its remote sensing images and digital elevation model （DEM） data. The results showed that ① as the elevation gradually increases,various vegetations appear and disappear in turn presenting a sequential distribution ,and each of the vegetation types dominates at its corresponding elevation. The distribution of the vegetation types appears to correlate with the slope aspects. ② Large areas of evergreen deciduous broadleaf forests and secondary deciduous broadleaf forests frequently occur on southwest-facing slopes and alpine shrubs and alpine meadows occupy the largest areas on southern-facing slope, whereas subalpine meadows rarely occur on flat land,north-facing slope and northwest slope.③ As the slope becomes sharp,the area proportions of various vegetation types differ with different slope-gradient ranges but the vegetation types are mainly secondary broadleaf deciduous forests and sub-alpine needle-leaf forest within various slope-gradient ranges and all the other vegetation types but sub-alpine meadows mainly distribute within the slope-gradient range of 20°-50°.