Evalauation On The Eco-Environmental Vulnerability In The Mining Area And Character Analysis Of The Soil And Vegetation

Liudaogou watershed is the representative basin in the loess plateau farming-pastoralareas. The climate condition and social economic conditions are representative. As thearea’s long-term overgrazing, reclamation and mining, the problem is prominent and theecological environment is fragile.According to the connotation of vulnerability andanalysising the cause of vulnerability,selected the comprehensive index and bulit a set ofenvironmental vulnerability evaluation index system for Liudaogou watershed.Based on theinvestigation and research,with index method,the preliminary evaluation on theeco-environmental vulnerability in Liudaogou watershed is carried out and further analysisthe the soil nutrient content and vegetation characteristics.The main conclusions are asfollows:(1)Firstly,The comprehensive vulnerability in Liudaogou watershed is should beevaluated.In order to build Liudaogou watershed ecological environment vulnerabilityevaluation index system,we select18indexes from the six aspects,such as climatecondition,vegetation,topography,soil quality,hydrologic condition,population pressure andsocial economic indicators.Using the analytic hierarchy process (AHP) to attache the weightvalue for each indicators corresponding and then adopting index method to calculateLiudaogou watershed′s ecological environment fragile degrees values.The calculated valueis0.454.According to the vulnerability hierarchies table that in the study area the ecologicalenvironment vulnerability is belong to moderate fragile.The next is to analysis Liudaogouwatershed vegetation characteristics and soil quality situation.(2)According to the field investigation,the research area have13species trees,belonging to11genera7families,The main specie is Populus simonii,There are10speciesShrubs,belonging to10genera8families,the main species are Caragana korshinskii、Artemisia desertorum、Salix psammophila.There are62species Herb,belonging to23families51genera,the main species are Stipa bungeana、Lespedeza davurica、Medicagosativa.In general,the shrub vegetation and trees are less,herb species are more than shrubs and trees relatively,but the herb species distributed uneven in the basin.Different kinds ofvegetations appeared in different height of watershed,the number of species are increasedwith altitude increases.In addition to the Simpson index,Shannon-Wiener index,Margalefindex,Pielou index generally are present Increase trend with the altitudeincreases.Vegetation diversity index varies with the season changes,Rainy season′s(September) vegetation diversity index generally greater than the common water period(June).According to correlation analysis of vegetation diversity index,the correlation ofvegetation diversity index is better.In order to accurately understand the conditions of the vegetation coverage inLiudaogou watershed,vegetation coverage will be divided into5levels.The vegetationcoverage calculated by analysising:the level of3and4accounted for the proportion of78.4%of the whole basin,it shows that the vegetation coverage in basin is in low level;Fromspace distribution, the coverage coverage is roughly along the main trench line decreasingto around and the vegetation coverage on the east slope is better than the west.（3）The soil nutrient and moisture content directly affect local vegetation and cropgrowth.The study area soil organic matter and nitrogen content represent the decline trendfrom farmland,forest,grass,shrub.The arboreal lands′s Total potassium content is the highest（19.33g/kg）,the grass′s is least（17.35g/kg）.The farmland rapidly-available potassiumcontent is the biggest,arboreal lands′s is least.The farmland′s Total phosphorus,rapidly-available phosphorus content were higher than other vegetation types.The soil pH ofvegetation types are>8.7.The soil moisture content were less than10%and declind fromfarmland,grassland,shrub land,arboreal lands.After evaluating the soil fertility quality of the study area.The results showed that thesoil fertility of farmland, in which IFI is the highest（0.68）, is the best. The grassland andwoodland are inferior to the farmland, and the IFI them are0.53and0.40respectively. Thesoil fertility of shrublands, in which IFI is the lowest（0.35）, is the worst, judging from thetype of land use. On the spatial distribution pattern, IFI of Liudaogou basin is decreasingfrom the main trench line as center to around. Overall, the quality of soil fertility inLiudaogou watershed is in low level, which can be classified into five grade levels. Thethird grade occupied the largest area, which accounts for46.9%of the total area. The firstand second grade only occupied23.8%, while the rest grades account for76.2%, which ismore than3times the size of the former.