2005 年 10 巻 1 号 p. 11-23
In Central Asia, large-scale expansion of agriculture in Aral Sea basin caused by heavy exploitation of irrigation water from international rivers in the early 1960's. This resulted in the rapid shrinking of the natural wetlands and significant change in the ecosystems. The decrease in river water and the resultant shrinking of the water area have led to destruction of the natural environment. To evaluate such landscape changes satellite remote sensing is most useful. Thus, we started monitoring the ecosystem through investigation and using satellite remote sensing. The study site is the lower Syr-Darya region where is considered as the most unstable in the catchment environment. Ground-truth data of land surface was collected through expeditions from 1999 to 2003. Based on floristic composition and soil investigation, vegetation was classified by using multivariate and cluster analyses. Based on the classification, spectral reflectance, biomass, LAI and plant coverage were measured on each type of vegetation in summer, 2002 and 2003. We found that LAI is a good estimate of biomass, and LAI can be estimated from either NDVI or TSAVI depending on vegetation type in this region. Using these data and methods, we analyzed succession of vegetation on the dried bottom of Aral Sea and relationship between wetland and river flow changes, relationships between the occurrence of Pelican's colony and environmental factors of each lake. From the results, we found that artificial water control of upper irrigational canal is most important to rehabilitate declined ecosystem in this region. It is concluded that maintenance of water consumption will affect wetlands maintenance and preservation of water fowl.