Abstract:

Using technology of remote sensing and geographical information system, the paper analyzed four remote sensing images of Tetraena mongolica distribution area in different periods (1977, 1990, 2000, 2005) to study the dynamic changes of landscape composition in the study area. Through some substitutive indexes of climate fluctuation and human activities, the paper analyzed the variation characteristic of driving factors on landscape dynamics at time scale. On this basis, the method of Principal Component was applied to analyze the influence and the contribution rate of different factors to landscape dynamics of T. mongolica's habitats. The results showed that the landscape composition of T. mongolica's habitat has been changed largely and the population inhabited area of T. mongolica has been decreasing while farmland, urban and industrial land, desertified land and else vegetations increased largely. The temperature, the mean wind velocity and the gale days had a process of rising continuously while the precipitation in the distribution region of T. mongolica had a process of reducing from the 1980s. The disadvantageous change of climate had a disadvantageous impact on T. mongolica's growth and reproduction. Meanwhile, with population growth, industrial development and rapid urbanization, the survival entironment of T. mongolica becomes more serious. There were consanguineous relationship between the dynamic changes of landscape composition and the trend of drought and human activities. From the contribution of the information of Principal Components, the contribution rate of human activities was 55.66% , and that of natural factors was 44.34% . Therefore, human activities were the main reasons for the decrease of T. mongolica population area and the changes of landscape structure in its habitat.

Key words: driving factors, habitat, landscape dynamics, principle component analysis, Tetraena mongolica