Biogeography Studies On Grasshopper In Shaanxi Based On GIS

Grasshopper is a kind of insect, which is abroad distributional and has many different species. There are more than 10000 species all over the world, above 900 species are recorded in china. Most of them live in northwest and southwest mountainous region of China, only a few species distribute in Middle East plain oppositely. Shaanxi province locates in Middle West of china, belongs to a transition region from middle plain to West Mountains. The landform of Shaanxi is long and narrow, south-north tendency. Its climates are transit the north semiarid climate of temperate zone to north humid semi-tropical climate. The unique geography position and special environment result in the rich species in Shaanxi, which is one of the grasshopper species rich provinces in China. There are 104 recorded grasshopper species in Shaanxi. Chinese scholars did more about the biogeography studies of grasshopper. There are many reports and articles, which is the base for the development of biogeography. However, for a long time, the biogeography study has been restricted by a bigger quantity data and unadvanced technique, especially encountering multiple factors spatial layer fold analysis, the traditional means behaved helpless. As an effective spatial analysis technique, GIS infuse new vigor into the development of biogeography. More and more scholars use GIS to Biogeography study. This paper used GIS technique to study the distributional rules, divisional characteristics and components of grasshopper in Shaanxi, which will give an evidence for zoogeography division study. Meanwhile this paper combined GIS techniques and mathematics model to predict the locusts' infestation in Shaanxi, in order to give an evidence for scientific management and prevention for locusts' infestation.There are three parts in this study:1) Through a lot of information, we have coordinated and build the database of the grasshopper distribution in Shaanxi, used GIS to analyze the species distribution data, studied the distribution rule and geography division of the grasshopper distribution in Shaanxi. The results shows: Taibai and Ankang are the richest species area of grasshopper in Shaanxi. The vegetation of the Ordos Plateau is rare, but the species of grasshopper is higher than Shaanbei Plateau. The cluster analysis as follows: the 593 distributional units are clustered into 9 groups with the proximity coefficients of 0.538. This result is similar to the Entironment Division of Shaanxi. There are somedifferences: Qinling Mountain are divided into two groups— the South Slope of Qinling and the North Slope of Qinling;Shangnan Hill is separated from Qinling Mountain;Ankang Area and Bashan Mountain are clustered into one group;Bashan Mountain and Micang Mountain are clustered into two paratactic groups. The geography distribution of grasshopper in Shaanxi follows the rule of advanced division in zoogeography, but it has its own characteristic. The diversity climates are the main reason of the grasshopper diversity in Shaanxi. The species in Guanzhong plain and Hanzhong basin are different from other regions. Human's activity has important effect on grasshopper species distribution.2) With clustering analyzing method, we study the geography distribution of Shaanxi grasshopper both inside and outside of Shaanxi Province, and analyze the distribution pattern and geography relativity. Using 593 longitude and latitude grid cells (0.2° XO.20) , we count the distribution data of grasshopper, and according to the range of distributions, we know that grasshoppers in Shaanxi can be divided into three groups. First, all-area-distributed species (distributed in all the 593 grid cells), second, more-area-distributed species (distributed in more than 9 grid cells), third, one-area-distributed species (distributed in less than 9 grid cells). The more-area-distributed species were clustered based on distributions, and it could be divided into 12 groups with the proximity coefficients of 0.153. Then we used the spatial layers analysis of GIS to judge the distribution pattern of each group. The results show: (1) The obstruct function of Qinling mountain to grasshopper is distinct. The species in south of Qinling is predominated by Palaeoarctic realm species, while north of Qinling is predominated by Oriental realm species. (2) The geographical distribution pattern of grasshopper in Shaanxi is almost consistent with the pattern all over China. (3) The regions of Taibai Mountain have higher biology diversity. It is a hot spot for the study of biology diversity.3) Via multiple factors analysis, we predict the locusts' potential outbreaks areas in Wennan of Shaanxi province. Using GIS technique and Mahalanobis Distance, we model the locusts potential outbreaks in Weinan area, then obtain the most suitable habitat of locusts in Weinan. According to this, we can judge where is the mainly infestation area, where is the potentially infestation area and where likely infestation area for locust in Weinan Area. We also analyze the correlation between locust outbreak and the different factors (landform, climate, soil and vegetation), this result can offer adirection for locust prevention and control. The result show, the most danger area of locusts' outbreak along the coast of Yellow River and Wei River, especially concentrate on Dali and Huaxian bank and the influx area of Yellow River, Wei River and Luo River. These areas should be regarded as the main prevention and cure area for locusts' outbreak.