Yulin area is situated in the transitional zone between the typical wind-sand-grassland area and the knoll-gully area

where both water erosion and wind erosion are extremely serious.The regional ecological environment is more and more brittle and changeable.For the judgment to the Yulin ecological environmental quality and the change

research was conducted to establish ecological environmental appraisal index systems of the transitional zone.The research was based on RS and GIS software and three issues of Landsat TM4

3

2 wave bands synthesized satellite data.Information source of Yulin area in 1980

1995

and 2000 were used and information extraction was carried on under the man-machine interactive work way.Combined with various influence factors of ecological environment quality

the ecological environment quality appraisal model for the area was established.By the study of 20 year land utilization and land cover change

as well as the appraisal analysis of various types of ecological environment quality

it is found that the Yulin ecological environment has been improved remarkably.However

on the whole

its ecological environment quality level is not high and the deteriorated tendency has not been under control.