唐家河保护区主要植被类型景观格局的梯度分析

在遥感图像基础上，利用GIS技术从景观指数方面定量分析了唐家河自然保护区主要植被类型在东西、南北和西北至东南3个方向上的梯度变化。结果表明：次生落叶阔叶林、常绿落叶阔叶混交林、针阔叶混交林与针叶林的梯度变化明显，并且在各方向上具有不同的变化特征。其中，常绿落叶阔叶混交林从西北至东南方向的梯度变化最为复杂， 斑块数量与面积分别呈“升—降—升—降”与“升—降—升”的波动变化趋势，而边界密度与平均最近距离呈先升后降的变化趋势，两端破碎度高但连接性好，中部相反。针叶林从北至南的梯度变化最为简单，斑块面积减少，破碎度与复杂度降低，南北两端分布较多，中部较少。唐家河自然保护区植被景观格局在不同方向上的梯度变化研究为地震后该地区的植被保护与管理提供重要指导意义。

GRADIENT ANALYSIS OF THE REPRESENTATIVE VEGETATION CLASSES IN TANGJIAHE NATURE RESERVE

Based on remote sensing images，spatial gradient variations of the representative vegetation classes in Tangjiahe Nature Reserve was quantitatively analyzed from east to west，south to north，and northwest to southeast by using GIS technology.The results showed that：Secondary deciduous broad leaved forest，evergreen broad leaved and deciduous broad leaved mixed forest，coniferous and broad leaved mixed forest and coniferous forest classes showed distinctive peaks and different gradient variations in different direction.Among them，with space change from northwest to southeast，gradient variations of evergreen broad leaved and deciduous broad leaved mixed forest are the most complex.There are fluctuant variation tendency for the number of patch and class area that change from “increasing at first” then “decreasing”then “increasing” to “decreasing at last” and change from “increasing at first” then “decreasing” to “decreasing at last” in the reserve.But the edge density and mean nearest neighbor distance have same variation tendency that change from “increasing at first” to “decreasing gradually at last” in the reserve.The two terminals of this direction have bigger degree of fragmentation with the higher values of proximity in the reserve，and in the middle it was opposite.With space change from north to south，gradient variations of coniferous forest is the simplest one due to decreasing class area，fragmentation and complexity.While the number of it be distributed relatively more on the two terminal of this direction and less in the middle.The research of spatial gradient variations which happened to the vegetation landscape in different direction will also provide important guiding significance for the useful protection and management of vegetation in Tangjiahe nature reserve after the serious earthquake.