Site Classification Of Hills And Evaluation For Pinus Tabulaeformis Afforestation In Xinghe,Inner Mongolia

In order to promote the development of ecological vegetation construction in semi-arid area,also to explore the rational forestry use of barren hills in this area,we selected hilly Pinus tabulaeformis forests in Xinghe County as the example.By using correlation analysis,regression analysis,single factor variance analysis,cluster analysis,we screened the main factors which affecting the height of young Pinus tabulaeformis and the aboveground biomass of herbaceous plants,Also hills afforestation was classified into different site types,and we evaluated the vegetation suitability of different site types and effects of afforestation preparation.The main conclusions are as follows:(1)Factors which affecting vegetation growth in semi-arid areas included soil moisture,soil physical properties and chemical properties,while the main factors affecting the fifth years of tree height of Pinus tabulaeformis were soil thickness and average soil moisture content.The main factors which influencing aboveground biomass of herbaceous plants were surface soil moisture,gravel content,total nitrogen and phosphorus content in surface soil.(2)Topography,landform,slope,soil texture,soil thickness and gravel content were selected as the site classification factors.According to the growth of vegetation and site classification factors,hills afforestation in study area was divided into 2 site type districts:A.Rock Mountains Site Type District and B.Loess Hill Site Type District.Four site types group and eight site types were classified as:a.Rock Mountains-Thick Soil Layer Site Type Group(I.Sandy Loam-Shady Slope Site Type and ?.Sandy Loam-Flat Site Type)and b.Rock Mountains-Thin Soil Layer Site Type Group(?.Gravel and Thin Soil-Sunny Slope Site Type and ?.Gravel Soil-Shady Slope Site Type and ? Gravelly Sandy Loam-Sunny Slope Site Type),c.Loess Hill-Sandy Loam Site Type Group(?.Sunny Slope Site Type and ?.Shady Slope Site Type)and d.Loess Hill-Clay Site Type Group(?I.Clay Site Type).(3)Results of the vegetation suitability evaluation showed that,the 1st suitability class included site type ?,site type ? and site type ?,sites in this class are also suitable for Pinus tabulaeformis saplings and herbaceous plant.The 2nd suitability class included site type ? and site type ?,sites in this class are suitable for Pinus tabulaeformis but not suitable for herbaceous plants.The 3rd suitability class included site type IV and site type V,sites in this class are suitable for herbaceous plants,although growth of Phus tabulaeformis is slightly worse.The 4th suitability class included site type ?,it is not suitable for Pinus tabulaeformis,but the herbaceous plants slightly better.(4)According to the analysis on afforestation preparation,parallel ditches could promote the growth of Pinus tabulaeformis by the way of increasing soil moisture,while fish-scale pits are a little different.The fish-scale pits could increase soil moisture and promote the growth in site type ?.Also them could improve the soil thickness and promote the growth of Pinus tabulaeformis in site type ?.In site type ?and V,fish-scale pits could hardly promote the growth of Pinus tabulaeformis,while them could prevent soils from erosion and being thinner.It is meaningful for the growth of Pinus tabulaeformis.