Evaluation of ecological conservation importance via GIS approach in the middle reaches of Nujiang watershed

The importance of ecological conservation at regional level is reflected in the sustainability and protection of valuable/ fragile ecosystems. Several factors (e.g., soil erosion, eco-hydrological environment, stone desertification and geological disaster) influence ecological conservation. This paper used Geographic Information System (GIS) technology to build a combined multi- factor approach to evaluate ecological conservation. The approach combined one fold factor overlay method with logical reasoning method to formulate a comprehensive systems approach. The concept of ecological sensitivity was extended to ecological conservation importance, which is a critical factor of ecological conservation. The paper discussed the concept of importance of ecological conservation and evaluated the ecological conservation importance of the middle reaches of Nujiang watershed from soil erosion sensitivity and biodiversity. The results showed that the ecological conservation extremely important zone lied in the river valley region. This region was situated at an altitude over 1 300 m and covered 11.43% of the total studied area. The ecological conservation highly important zone covered about 48.02% of the studied area, and was at an altitude of 1 800~3 100 m. The ecological conservation moderately important zone was 35.22% of the studied area, located at an altitude of 3 100 m. The ecological conservation slightly important zone was small, accounting for 5.29% of the studied area, and with patched distribution. The ecological conservation unimportant zone was the smallest zone, covering only 0.04% of the total area and mainly distributed in residential areas. This evaluation work provided the basis for prioritizing ecological conservation efforts, with the main focus on ecological protection, recovery and construction.