Nest Habitat Suitability Modeling for Red-Crown Crane (Grus Japonensis) Based on Ecological Niche Factor Analysis

摘要

Zhalong wetland natural reserve is one of the most important breeding areas for Red-crown crane around the world. With the assistance of GIS, the landscape map was generated by utilized two Landsat TM images (2006) that covering the study area. Besides, the elevation data was collected. Then, the nest habitat suitability of this rare and endangered species in this reserve was modeled and evaluated based on ecological niche factor analysis methodology. The results showed that Red-crown cranes prefer to choose the low elevation zones with relatively low slops to build nests. They tend to select areas with South and Southeast aspects as their nest habitat. Reed swamp is the most important habitat for them during the breeding season and it seems that they never build nests on other landscapes in this area. Human disturbances play important roles in affecting the quality of the nest habitats, making them more separated and fragmentized. Because artificial landscapes usually have intensive disturbances, Red-crown crane tend to avoid areas that within or close to artificial landscape. Among the eco-geographical variables that describe the degree of human disturbance, the frequencies of the dry land (M_f=-0.314) is the major factor that treating the nest habitat, while distance to man-made pool and reservoir (M_d=-0.107) plays the minimal role, mainly because they provide food sources during the breeding season. The total area of the suitable, less suitable nest habitats are calculated as 357.18km~2 and 160.3km~2 respectively, with 65.31% and 74.5% of which protected by the core area of the reserve. Suffering from the disturbances from human activities, 52.26% of the core area are not suitable to build nest. Besides, 27.51 % (98.27km~2) of suitable habitats located in the buffer zone, the other 7.18% (25.64km~2) in the experimental area and tourism area, where the protection measures are less powerful, making these habitats more vulnerable by human activities. For all the considerations above, comprehensive measures should be taken to alleviate the negative affects made by human, and the nest habitat quality for this endangered species should be maintained or improved.