Abstract: Based on ETM+ remote sensing images,spatial variation of the vegetation landscape of the Tangjiahe nature reserve was analyzed along the gradients from east to west,north to south,and northwest to southeast with the aid of a software,Fragstats.Results show that along the gradient from east to west,diversity of the landscape varies in a saddle pattern,"up-down-up",while its fragmentation degree and complexity decrease.Along the gradient from north to south,diversity,complexity and connectivity of the landscape all decrease,while the landscape becomes more fragmented and more complicated in shape.And along the gradient from northwest to southeast,diversity and complexity of the landscape showed an undulated fluctuation,"down-up-down-up".In the northwest and central parts,plaque neighboring degree is relatively high and varies quite significantly,while in the southeast part,it is low and relatively stable.The natural factors of the Tangjiahe nature reserve are the major causes and prerequisites of the gradient variations of its landscape.The distribution of vegetation communities was obviously governed by its hydrogeological conditions.

Key words: Tangjiahe nature reserve, vegetation landscape, heterogeneity, gradient analysis, landscape index