Ecological security pattern analysis of Jiuquan oasis using remote sensing and GIS

Ecological degradation has taken place in many arid regions, north-west China, especially in oases. The heterogeneous oasis is the soul and the most sensitivity pail of the arid regions, so it is important to M, attention to the ecological security of oasis. The aim of this stud's is to analyze the ecological security pattern from the aspect of spatial neighboring characteristics between the sand land/the salinized land and the various oasis patch types, taking the Jiuquan oasis as an example. Remote sensing and GIS were used to analyze ecological security pattern. Main data included Landsat 5 TM image in 1986, Landsat 7 ETM+ image in 2000 and topographic maps. Landscape maps of Jiuquan oasis were compiled based on the above data, then sand land and salinized land threats against oasis patch types were calculated The results showed that: 1) in 1986, the order of the sand land threat was C-farm land > C-grass land > C-woodland > C-water area > C-residential area; in 2000, except the threat against residential area, the threat against the other oasis patch types increased, and the value of C-grass land became the biggest, followed by C-woodland > C-farm land > C-water area > C-residential area: 2) in 1986, the order of the salinized land threat was C-grass land > C-woodland > C-farm land > C-water area > C-residential area and there was a decline in the salinized land threat against all oasis patch types in 2000, the order became C-grass land > C-farm land > C-water area > C-woodland > C-residential area; 3) as to the total oasis, there was an increasing of 73.9% in sandy desertification threat, while there was a decreasing of 39% in salinization threat from 1986 to 2000.