嘉陵江流域植被景观异质性的空间梯度变化

在遥感图像基础上,利用ArcView GIS和景观统计软件FRAGSTATS从东西、南北以及西北至东南3个方向对嘉陵江流域的植被景观异质性进行了空间梯度分析。结果表明:(1)"栽培植被"面积占总流域面积的51.81%,为整个流域植被景观的基质,聚合性最强,联结度最高;"针叶林"和"灌丛"的斑块数较多,但面积较小,破碎化程度较高,而"裸地/城镇"破碎化最低;"灌丛"斑块间距最大,聚合性最弱;"高山植被"分布零星,联结度最低;(2)沿东西方向,植被景观异质性逐步下降,在流域中部降至最低,但随着进一步向西推移又明显升高,表现出"先降后升"的总趋势;(3)从北至南植被景观异质性向上波动3次后逐步下降,在接近流域南端时降至最低后又略有升高,表现出"先升高再逐渐波动下降"的总趋势;(4)沿西北至东南方向植被景观异质性上下波动1次后在近东南端降至最低,随后略有小幅波动,但波动次数和幅度远低于北南方向,表现出"先降低再波动下降"的总趋势。

Spatial Gradient Variations of Vegetation Landscape Heterogeneity in Jialing River Basin

Based on remote sensing images,spatial gradient variations of vegetation landscape heterogeneity was analyzed from east to west,north to south,and northwest to southeast in Jialing River basin by using software ArcView GIS and FRAGSTATS.The results showed that:(1)"cultivated vegetation" was dominating vegetation landscape component with the highest values of aggregation and proximity in the basin."needleleaf forests" and "shrub" had higher degree of fragmentation due to more patch number and smaller area than others,while "bare ground/city" was linked with lowest value of fragmentation."shrub" had the weakest aggregation ability than other components because of its long space length between patches.Meanwhile,"alpine vegetation" had the lowest value of proximity for its sparse distribution.(2)With space change from east to west,the heterogeneity of vegetation landscape decreased gradually,and then reached to the lowest values in the middle of the basin.But it increased gradually with space further change to west.So there was a significant variation tendency for heterogeneity that changed from "decreasing at first" to "increasing at last" in the basin.(3)With space change from north to south,the heterogeneity of vegetation landscape increased at first and then decreased gradually after several fluctuations,and reached to the lowest values in the adjacent areas of south region in the basin,then it increased a little with space change to south at last.There was a significant variation tendency for heterogeneity that changed from "increasing at first" to "decreasing gradually at last after several fluctuations" in the basin.(4)With space change from northwest to southeast,the heterogeneity of vegetation landscape decreased gradually after one fluctuation,and reached to the lowest values in the adjacent areas of southeast region,then it fluctuated slightly again.But the number and amplitude of curves were lower than that of change form north to south.There was a significant variation tendency for heterogeneity that change from "decreasing at first" to "decreasing gradually at last after fluctuation" in the basin.