四合木(Tetraena mongolica)分布区景观结构时空变化分析

利用3S技术，1972年航空黑白像片，1988年TM CCT磁带数据以及1995年1：10万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 mongolica)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2 754km2;(2)分布区面积及斑块平均面积都在减少，1988年实际占有1456km2，1995年为15．38km2，减少了18．1％；（3）四合木分布面积的减少在不同时空尺度上并不相同，1988－1995年间的年变化率比1972－1988年间的年变化率高5倍，空间尺度上城市工业区的年变化率比放牧分布区高。

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

The distribution and the change of T etraena mongolica,endemic to the western Ordos,are studied in the form o f patch units based on the aerial image(1972)，CCT of TM(1988) and the image of TM(1995)(Scale:1∶100　000).The results are as follows:(1 ) the distribution of Tetraena mongolica is determined and d istribution area is 2　754 km2；(2) the distribution area and the average patch area of Tetraena mongolica are decreasing,fro m 1　456 km2 to 1　268 km2 in 1995.The average patch area of Tetraena mongolica is 18.79 km2,and decreases to 15.38 km2 in 1995，decreasing 18.1%;and (3)the decreasing of distribu tion area of Tetraena mongolica is varied in dif-ferent spa tial-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.