科尔沁沙地农牧交错区景观持续性研究

科尔沁沙地农牧交错区景观持续性的分析表明,在不同时间尺度上,景观多样性的持续性增加1.038(±0.033),而景观优势度持续性下降0.873(±0.112),说明在1958年固定沙丘地占主导地位的景观逐渐演化成流动沙丘、半固定沙丘、固定沙丘和农田相间分布、平分秋色的景观。在农牧业生产活动的影响下,景观格局的持续性在空间形状的变化上趋向复杂(景观分维数持续性为1.008),而其相邻性下降(景观修改分维数0.953)。斑块尺度上,不同时间尺度的分析显示,流动沙丘和半固定沙丘斑块面积持续性增加,而固定沙丘和农田斑块面积持续减少;从斑块格局的持续性来看,半固定沙丘地空间格局的持续性呈增加的趋势最明显,为1.038(±0.087),固定沙丘地空间格局的持续性呈减少的趋势最明显,为0.806(±0.032);40年来科尔沁沙地的农牧交错活动对斑块修改分维数的持续性影响是一致的,呈下降的趋势,说明该过程减少了景观中斑块间的相邻性。

A study on landscape sustainability for agri-pastural ecotone in Horqin Sandy Land

Aimed at measuring the change trend and characters of landscape pattern in the past forty years,this paper analyzed the landscape sustainability of agri-pastural ectone in Horqin Sandy Land by using Landsat TM images data.The results showed that the sustainability index of landscape diversity increases some 1.038(±0.033)and the sustainability index of landscape dominance decrease about 0.873(±0.112)on different temporal scales.The data suggested that the fixed sand-dune landscape as the main part in1958have changed into the mosaic landscape pattern consisting of shift sand-dunes,semi-fixed sand-dunes,fixed sand-dunes and cropland in1998.Because of the influence of agricultural and the grazing activities on the landscape,the sustainability of landscape patterns in spatial scale became more complicated and the sustain-ability of fractal dimensions was1.008,meanwhile the juxtaposition decreased and the modified fractal dimension was0.953.The analysis of different time scales indicated that the sustainabili-ty of patch areas of mobile sand-dunes and semi-fixed sand-dunes increased and that of fixed sand-dunes and cropland decreased.In terms of patch pattern,the sustainability of semi-fixed sand-dunes increased more obviously and its index reached1.038(±0.087)while the sustainabili-ty of fixed sand-dunes decreased most obviously and its index was0.806(±0.032).The impacts of agricultural and grazing activities on sustainability of modified fractal dimensions appeared to decline,which suggested a decrease of the patches juxtaposition in the past years in Horqin re-gion.