四合木(Tetraena mongolica)分布区景观结构时空变化分析

Spatial-temporal Change of Landscape Structure in the Distribution Region of Tetraena mongolica

利用 3S技术、1 972年航空黑白像片、1 988年 TM CCT磁带数据以及 1 995年 1 :1 0万TM影像等信息源 ,以斑块为最小景观结构单元 ,对西鄂尔多斯特有种四合木 (Tetraena mon-golica)的分布及其分布区的景观结构进行了研究。结果表明 :(1 )四合木的分布区面积约为 2754km2 ;(2 )分布区面积及斑块平均面积都在减少。 1 988年实际占有 1 456km2 ,1 995年为1 2 68km2 ,平均每年减少 2 7km2 ,单个斑块平均面积 1 988年为 1 8.79km2 ,1 995年为 1 5.38km2 ,减少了 1 8.1 % ;(3)四合木分布面积的减少在不同时空尺度上并不相同 ,1 988～ 1 995年间的年变化率比 1 972～ 1 988年间的年变化率高 5倍 。

The distribution and the change of Tetraena mongolica,endemic to the western Ordos,are studied in the form of patch units based on the aerial image(1972),CCT of TM(1988) and the image of TM(1995)(Scale: 1∶100000 ).The results are as follows:(1) the distribution of Tetraena mongolica is determined and distribution area is 2754 km 2;(2) the distribution area and the average patch area of Tetraena mongolica are decreasing,from 1456 km 2 to 1268 km 2 in 1995.The average patch area of Tetraena mongolica is 18 79 km 2,and decreases to 15 38 km 2 in 1995,decreasing 18 1%;and (3)the decreasing of distribution area of Tetraena mongolica is varied in dif ferent spatial temporal scale,the annual rate of decreasing is 5 times higher in periods of 1988～1995 than in periods of 1972～1988,and the decreasing rate in the urban and industry area is higher than that in the grazing area.