Landscape Dynamic And Endangered Reason Of Helianthemum Ordosicum

Helianthemum ordosicum is a endemic species of the desert in middle Asia, which has important scientific value in studying the origin of desert flora in middle Asia and particularly in China and the links with the Mediterranean flora. Taking the H. ordosicum as the object of study in the article by remote sensing (RS), geographic information system (GIS) and the global positioning system (GPS) technology, the H. ordosicum distribution area has been limited for the first time, and the landscape dynamic change of the distribution area in the past 18 years has been carried on the analysis. Furthermore, the vegetation types in the distribution area, present surviving situation of H. ordosicum, the reason to be in imminent danger and the protective measures have been studied throughout the article. Its conclusion is as follows:(1)The distribution area of H. ordosicum is 1123.771km~2, and the species was born in the elevation 1100~1600m scope. Its geographical coordinate is in 106°36 ' - 107°25 ' E, 39°10 ' - 40°10 ' N scope. Its present distribution is primarily limited in Erdos etuokeqi qipanjing, around the Wuhai qianligou, the Gandger mountain and the Zhuozi wuhushan, with graval foothills as the major habitats in the rocky hill crown, the denudation mountains dry sunny slope and so on landform spots, assumes the island shape distribution.(2) During 1990~2008 years, the H. ordosicum distribution area has reduces and the patch tends fragmented. During the 18 years, H. ordosicum dispersal area reduced 102.756km~2, the community area reduced 45.918km~2.(3) Since 1990, the research area landscape pattern has had the very big change. In the entire landscape, the fragmentation index, patch quantity, the patch density, the diversity and the evenness index increase unceasingly, but the patch area and the patches average area reduce year by year, which indicated that the research area the landscape component tends the complication, stave and the multiplication.(4) The primary factor which causes the H. ordosicum to be in imminent danger is the human activity. The industry and mining land during1990~2008 years increase from 61.878 km~2 to 130.828 km~2, the transportation land during1990~2008 years increases from 4.01 km~2 to 11.269km~2. increasing artificial landscape area like the insustry and mining land and overgrazing and so on causes the H. ordosicum population area to reduce. And causes the H. ordosicum habitat between the humanity environment causes the competition.(5) Establishes the system in the GIS database, and the community type chart to be advantageous for the management on the spot with the picture connection, can respond the H. ordosicum tendency promptly, so that the policy-maker can take the prompt effective protective measures.