| Soil desertification,known as “earth cancer”,is one of the main causes of ecological degradation and productivity decline,and has affected and restricted human production and life.The main stream of the Liaohe River Basin is the main economic and political center of Liaoning Province.In recent years,the problem of land desertification has become increasingly serious,and it has become the main source of sand in Liaoning Province,and it is urgent to carry out ecological restoration.Based on the status of desertification in the main stream of Liaohe River Basin,this paper investigates the sandification restoration models of severe and extremely severe desertification areas according to different types of desertification distribution areas,and determines the typical plots of different restoration models to investigate the soil and vegetation growth status.Based on the NDVI index analysis and soil characteristics analysis of remote sensing images,the sandification repair effects of different restoration modes were determined.Based on the vegetation and soil as the key factors,the evaluation index system of sandification restoration effect of different restoration modes was established.The comprehensive evaluation method and entropy weight method were used to evaluate the sandification restoration effects of different restoration modes,and the optimal desertification land restoration model was selected.The main findings are as follows:(1)Comprehensive comparison of the NDVI index of the Liaohe River Basin in 2014 and 2018.The minimum NDVI index increased by 0.008 in 2018,indicating that the four-year ecological restoration and restoration promoted the restoration of regional vegetation.The NDVI index of the distribution pattern of the mixed cultivation model was increased by 0.06.The NDVI index of the closed forest area was increased by 0.02,the artificial forest model increased by 0.03,the natural restoration of grassland increased by 0.07,the enclosed grassland increased by 0.1,the agroforestry model decreased by 0.01,and the farmland increased by 0.02.Vegetation coverage in the Liaohe River basin has increased.The vegetation coverage of the arbor irrigation mixed planting pattern increased by 6.6%.The vegetation coverage of the closed forest area was increased by 2.4%;the vegetation cover of the plantation forest pattern increased by 0.07%,the vegetation cover of the natural restoration grassland increased by 7.5%,the vegetation coverage of the enclosed grassland increased by 10.1%,and the coverage of the agroforestry composite vegetation decreased by 2.1.%,farmland vegetation cover increased by 2.3%.Vegetation cover change: Qiao irrigation mixed planting > enclosed grassland > natural restoration grassland > closed forest land > farmland > agroforestry complex.In the annual ecological restoration measures,the basic indicators of forest arbor increased.In 2018 compared with 2014,within 1×1 sample,the herbaceous plant,the mixed pattern of arbor irrigation increased by 64 g in 4 years;the enclosed forest land increased by 4g in 4 years;artificial The forest model increased by 13 g in 4 years;the natural restoration of grassland increased by 35 g in 4 years;the agroforestry model decreased by 1g in five years.Comparing the 2018 with the 2014 Biodiversity Index,the hybrid irrigation model increased by 0.09.The enclosed forest land increased by 0.11,the enclosed grassland increased by 0.03,the plantation increased by 0.07,the natural grass increased by 0.01,and the agroforestry model increased by 0.02..(2)Experimental analysis of soil physical and chemical properties under different remediation measures.The order of soil bulk density from high to low is: agroforestry complex(1.62g/cm3)> enclosed grassland(1.53g/cm3)> farmland(1.42g/cm3)> bare land(1.41g/cm3)> enclosed forestland(1.41)g/cm3)>plantation(1.40g/cm3)>naturally restored grassland(1.38g/cm3)>choline irrigation(1.31g/cm3).The order of soil moisture content from high to low is: arbor(19%)> enclosed forest land(20%)> farmland(14%)> plantation(11%)> natural restoration grassland(8%)> bare land(6%)> enclosed grassland(5%)> agroforestry complex(4%).In the dry sieve soil aggregates,the proportion of large agglomerates is high;the aggregates of >0.25 mm are all above 60%.>0.5mm is around 40%;>5-2mm is between 20%-30%;0.5-0.25 mm is no more than 8%.After the wet sieving process,the >5mm agglomerates decreased;the 5-2mm agglomerate content decreased in the range of 5%-10%;the 2-1mm,1-0.5mm agglomerates did not change much.The content of 0.5-0.25 mm agglomerates increased,the mixed planting of arbor irrigation increased by 99.7%,the natural grassland increased by 276%,and the plantation increased by 170%.Agroforestry and enclosed forest land increased by 7%,enclosed grassland increased by 23%,and farmland increased by 65%.After wet sieving,>0.25 mm agglomerate content: 31% reduction in agroforestry,32% reduction in enclosed forest land,45% reduction in enclosed grassland,47% reduction in enclosed grassland,49% reduction in mixed irrigation,and reduction of natural grassland 35 %,plantation decreased by 48%,and farmland decreased by 51%.Among the destruction rate of aggregates,the agroforestry compound was 40.98%;the enclosed forest land was 38.44%;the enclosed grassland was 50.38%;the arbor irrigation was 41.20%;the natural grassland was 54.18%;the artificial forest was 41.30%;and the farmland was 52.27%.Aggregate destruction rate from high to low: natural grassland > farmland > enclosed grassland > plantation > arbor irrigation > agriculture and forestry complex > closed forest land.The contents of soil organic matter were: Qiao irrigation mixed planting(40.4g/kg)> plantation forest(26.6g/kg)> natural grassland(22.3g/kg)> farmland(16.5g/kg)> enclosed grassland(15.4g/ Kg)> enclosed forest land(13.8g/kg)> bare land(13.1g/kg)> agroforestry complex(8.5g/kg).The available phosphorus content in soil was: farmland(40.0mg/kg)> enclosed forest land(27.7mg/kg)> plantation forest(24.1mg/kg)> enclosed grassland(19.7mg/kg)> natural grassland(19.4g/ Kg)>Qiao irrigation mixed plant(17.3mg/kg)>Agroforestry complex(15.8mg/kg)> bare land(14.8mg/kg).The order of soil total nitrogen content from high to low is: farmland(0.80g/kg)> arbor irrigation(0.70g/kg)> plantation(0.65g/kg)> natural grassland(0.63g/kg)> Grassland(0.61g/kg)> enclosed forest land(0.53g/kg)> agroforestry complex(0.50g/kg)> bare land(0.42g/kg).Some indicators related to soil corrosion resistance were selected,and the soil erosion resistance index was determined by principal component analysis method.With the increase of soil erosion resistance index,soil corrosion resistance also increased.The comprehensive index of soil surface erosion resistance is: 58.7 for arbor irrigation,24.3 for enclosed forest,23.2 for grassland,48.27 for artificial forest,34.63 for natural restoration,and 21.26 for agroforestry.The order of resistance to erosion is: arbor irrigation > plantation > natural restoration of grassland > enclosed forest land > closed grassland > agriculture and forestry complex.(3)Calculated by entropy weight method,the weights of each index are: vegetation coverage 0.114,biodiversity index 0.102,biomass 0.101,soil bulk density 0.119,soil water content 0.038,maximum water holding capacity 0.048,soil organic matter content 0.192,soil The aggregate content was 0.047,the soil total nitrogen content was 0.127,and the soil available phosphorus content was 0.112.The vegetation index weight is 0.317;the soil index weight is 0.682.The comprehensive index of the mixed irrigation and restoration model was 26.96,the comprehensive index of enclosed forestland was 15.65,the comprehensive index of plantation restoration was 21.51,the comprehensive index of enclosed grassland was 14.20,the comprehensive index of natural grassland was 17.83,and the comprehensive index of agroforestry was 9.33.The comprehensive index of cultivated farmland is 20.72.The restoration effects were followed by arbor irrigation > plantation > farmland > natural restoration of grassland > enclosed forestland > enclosed grassland > agroforestry combination,indicating that the sapling irrigation and restoration model had the best effect on the restoration of desertified land,suitable for suitable conditions.Regional application promotion... |
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