TEMPORAL CHANGE OF CRESTED IBIS HABITAT IN SHAANXI PROVINCE, CHINA

摘要

Although the crested ibis lived over the East Asia, the population decreased drastically by overhunting or urban development by the beginning of the 20th century. In Japan, crested ibis was extinct in 2003, and now, the re-introduction project of the crested ibis has been carried out. When formulating the conservation measure, it is important to examine why crested ibis decreased. It was reported the change of the feeding area has contributed greatly to reduction of crested ibis. Therefore, it is important to detect the change of the feeding area quantitatively. In this study, multi-temporal land-cover maps were compared, and it aimed at clarifying change of the feeding environment in a crested ibis habitat. The study area was Shaanxi province of China that is main habitat for crested ibis. We used multi-temporal Landsat series data that represent the 1970s, the 1980s and the 2000s land-cover condition. In the 2000s land-cover classification, object-oriented image classification was applied. In the 1970s and 1980s land-cover classification, we combined object-oriented image classification and the change detection using principal component analysis. The kappa coefficient of three land-cover maps were 0.85 (2002), 0.77 (1988) and 0.74 (1978). Urban development and/or the crop diversification from paddy field to wheat was extracted in the change of land-cover from past to present. The study area is enacted as a nature preserve and the large-scale deforestation or land development are not progressed. Also in such area, it is suggested that management of feeding environment for crested ibis is not enough. Therefore, we suggest that the land-cover changes such as urban development or the crop diversification affect crested ibis behavior.