Analysis on Dynamic Characteristics of Landscape Patterns in Hailer and around Areas
This paper analyzed the spatial-temporal dynamic changes of landscape patterns in Hailer and around areas. Firstly, landscape patterns types of research area were divided into water, sand, farmland, city and grassland based on remote sensing images of 1986, 1991, 1996 and 2001 and field investigation. Then the grassland was classified into higher coverage grassland, high coverage grassland, medium coverage grassland and low coverage grassland by Normalized Difference Vegetation Index. Finally, the spatial-temporal dynamic changes of above-mentioned eight kinds of landscape patterns were analyzed using landscape ecology principle. The results indicated that human activities intensified significant from 1986 to 2001in research area. The area of grassland landscape decreased quickly, and the fragmentation extent intensified. The dominant landscape in research area changed from higher-high coverage grassland to medium-low coverage grassland. The expansion of sand landscape is obvious in periphery of road, city and farmland. The grassland vegetation degenerated seriously. Fragmentation of city landscape lightened, and city landscape patches tended to decrease and centralized. Economy development pattern of research area is in a stage that is transforming from extensive pattern to intensive urbanization pattern.
Degradation and diversity changes of meadow grassland in Keerqin Sandy Land
The dynamic characteristics of species composition and species diversity of meadow grassland in Keerqin Sandy Land in the last 20 years were studied.The results showed that the meadow vegetation in Keerqin Sandy Land has seriously degraded.Species diversity and evenness of community has decreased and ecological dominance increased.The quality and production of herbaceous plants in general has declined.The quantity and dominance of fine herbaceous species decreased while that of poor quality and of poisonous grass species increased.The reasons for this grassland degradation included: warming and drying of the local climate,habitat drying,soil salinization and over grazing.Over grazing was the main and direct reason for degradation of the meadow vegetation.The influence of over grazing on species composition,biomass,diversity and nutrient content in of the main communities were also analyzed.
[Analysis of formation causes of grassland degradation in Maduo County in the source region of Yellow River].
Natural and artificial factors of grassland degradation in Maduo County in source region of Yellow River were analyzed in this paper. The results showed that overgrazing was the major reason for grassland degradation. Compared with historical average, annual temperature and precipitation in Maduo had an obvious rise since the end of 1980s. Temperature rise concentrated in winter, and precipitation rise concentrated in spring and summer. Therefore, the change in water and heat condition was advantageous to grass growth there. Maduo was a county totally dependent on stock raising, and enlarging livestock population was the only choice for economic development. Together with the pressure of population growth and local Tibetan's traditional value, the number of livestock had been increased continuously, and finally reached summit in the end of 1970s. Since then, the grassland had been kept in the state of overgrazing and degradation, which also created favorable condition for the invasion of pikas, and thus sped up the process of degradation.