Ecological Effects Of Different Revegetation Patterns In Windy And Sandy Area Of North Shanxi

The ecological environment of windy and sandy region of north Shanxi is extremely fragile.In the past decades,a large amount of artificial forest has been planted.The artificial forest has played an important role in the improvement of the ecological environment.However,there are also problems such as improper selection of tree species and excessive proportion of pure forest,which has affected the effect of recovery.Therefore,the evaluation of ecological effects of different revegetation patterns is of great significance to the restoration of vegetation and the construction of ecological environment in windy and sandy region.This study took Jiajiayao catchment of Youyu County in windy and sandy region of north Shanxi as the test area,the characteristics of soil moisture,soil physical properties,soil nutrient,soil microbial biomass,soil enzyme activity and soil erosion of different revegetation patterns?grass land,Pinus tabulaeformis and Caragana korshinskii,Pinus tabulaeformis,Caragana korshinskii,Populus simonii Carr and Pinus sylvestris var.mongolica?was analyzed by using the method of field tests as well as laboratory analysis in July 2016.The ecological effect of different revegetation patterns was evaluated by using principal component analysis?PCA?.The main findings were as follows:?1?Mean soil moisture content of six revegetation patterns in 0²00 cm soil profile showed following sequence:Pinus sylvestris var.mongolica?Populus simonii Carr?Caragana korshinskii?grass land?Pinus tabulaeformis and Caragana korshinskii?Pinus tabulaeformis.Mean soil moisture content in the topsoil?0²0 cm?among six revegetation patterns was relatively low.The variation tendency of soil moisture of different revegetation patterns was not consistent with increasing of depth,which was affected by plant transpiration,depth and density of root distribution and other factors.The grain size characteristic of all six revegetation patterns was similar that silt and very fine sand content was the highest in 0²0 cm soil profile.For the average grain size,the order was:Pinus sylvestris var.mongolica?grass land?Populus simonii Carr?Pinus tabulaeformis and Caragana korshinskii?Caragana korshinskii?Pinus tabulaeformis.The soil physical properties of different revegetation patterns were different in 0¹00 cm soil profile.The bulk density and total porosity were low at Pinus sylvestris var.mongolica,it hadpoor improvement in soil physical structure.?2?The content of soil organic matter and soil available P in the top soil?0²0 cm?among six revegetation patterns was relatively low.The analysis of variance showed that the differences of soil available K,soil total N and soil NO₃-N among six revegetation patterns were significant and the differences of soil organic matter,soil available P and soil NH₄-N among six revegetation patterns were not significant.The soil available K was high at Pinus tabulaeformis and Pinus tabulaeformis and Caragana korshinskii.The soil total N was high at Pinus tabulaeformis and Caragana korshinskii,Pinus tabulaeformis and grass land.The soil NO₃-N and soil NH₄-N were the highest at Caragana korshinskii.The soil organic matter,available P,available K and total N at Pinus sylvestris var.mongolica were low,it had poor nutrient conditions.?3?The differences of soil microbial biomass C and soil microbial biomass N in the top soil?0²0 cm?among six revegetation patterns were significant.The soil microbial biomass N at Caragana korshinskii was much better than the other revegetation patterns.The soil microbial biomass C at Pinus tabulaeformis and Caragana korshinskii was better than Pinus tabulaeformis or Caragana korshinskii,it showed that the soil microbial biomass C was improved by mixed planting.The diffenence of soil urease,soil hydrogen peroxidas,soil polyphenol oxidase and alkaline phosphatase among six revegetation patterns were significant,and the differences of soil invertase was not significant?4?The differences of soil erosion properties at Pinus tabulaeformis,Caragana korshinskii,Pinus tabulaeformis and Caragana korshinskii and grass land were significant.The volume of runoff and sediment yield at Pinus tabulaeformis or Caragana korshinskii was the lowest among four revegetation patterns,the effect of water erosion was reduced by it.The volume of runoff and sediment yield at grass land and Pinus tabulaeformis or Caragana korshinskii was high.?5?The results of ecological effects evaluation of revegetation patterns showed that the difference of restoration effect among six revegetation patterns were significant.Pinus tabulaeformis and Caragana korshinskii had the greatest restoration effect,the improvement for soil quality at mixed forest was better than pure forest and grass land,the restoration effect of Caragana korshinskii was also good,so these two models should be given priority in the process of vegetation restoration in windy and sandy region.