The Mechanism Of Habitat Regulation In Different Governance Models In Severely Red Soil Eroded Degradation Land

Hydraulic erosion is the most common form of soil degradation.It is a frontier scientific issue in the field of degraded restoration.The study on the habitat regulation mechanism of soil degradation caused by hydraulic erosion in the red soil region of southern China,which is important for understanding the restoration from degraded ecosystem to natural ecosystem at home and abroad.This paper selects ASG,CC,FSG,GGH,IFT of five modes of governance and severely degraded land(HDL),native forest(NV)as the control plots in Hetian Town,Changting County in Fujian Province.The vegetation community structure,soil physiochemical properties,soil microbial community structure and biomass,plant roots,runoff and sediment yield were systematic studied by the method of field investigation,field artificial rainfall and laboratory experiments,The mechanism of habitat control and the suitability of different governance models,as well as the determination of the best governance model,in order to provide scientific basis and practical guidance for the restoration and control of degraded land caused by soil and water loss in the forest in the red soil region of southern China.The main results showed as follows:(1)Plant diversity index,diversity index,evenness index and dominance index of different governance models,severely eroded degraded land and native forest were significantly different.Plant diversity index and evenness index of the ASG in the five governance models were maximum and dominance index are the smallest,and the soil physical indicators are the best.The soil physical indicators of the ASG treatment model are second only to the native forest,and the indicators of severe degraded land are the worst.(2)Different treatment models increased the pH value of 0?60 cm soil layer,and increased the carbon,nitrogen,phosphorus,potassium content and sequestration of each soil layer.The overall performance was as the soil depth increased,soil pH and soil nutrients.The clay content in the soil particle composition determines the soil nutrient content.Among the five treatment models,the pH value and soil nutrient content and soil retention of different soil layers are the highest,but they do not reach the native forest.The level of severe degraded land is the smallest indicator.(3)Different treatment models increased the total root length,root surface area,root volume,root quality and root diameter of the 0?60 cm soil layer.The root indexes of native forest reached the maximum value,the root index of severely degraded land was the minimum,and the pattern of ASG root indicators are second only to native forests.Soil nutrient,soil permeability and root index were positively correlated in different treatment models,and soil hardness,soil bulk density,sand and siltcontent and root index were negatively correlated.(4)Different treatment models increased gram negative bacteria,fungi,actinomycetes,arbuscular mycorrhizal fungi,microbial carbon and nitrogen contents in 0?5cm soil layer,reduced gram positive bacteria content,soil microbial community structure and microbial carbon in severely degraded soils.The nitrogen content is the lowest,and the microbial content of the ASG treatment model approaches the native forest.The main environmental factors affecting soil microbes are soil organic carbon,total nitrogen,available potassium,soil hardness,soil water content,and sand content.(5)The overall characteristics of different governance models,the runoff and sediment yield are the largest in the severely degraded land,while the native forest is the least.The ability of the ASG mode reduce the runoff and sediment yield is close to that of native forest.The main factors affecting runoff and sediment yield are soil organic carbon,total root length,average permeability,soil hardness,soil microbial carbon,arbuscular mycorrhizal fungi and gram positive bacteria.The critical values of soil microbial carbon biomass,arbuscular mycorrhizal fungi,average permeability,gram-positive bacteria content,and soil hardness were 80 mg/kg,3.5 Mol%,100mmmin^-1,45 Mol%,and 5 kg/m²,respectively.(6)This study suggests that the different governance models are to improve the soil nutrient content and sequestration of red soil erosion and degraded land by reducing the soil nutrient-rich cohesive loss in the soil surface,and to regulate the habitat nutrient cycle of red soil degraded land;the second is with the combined action of vegetation diversity,root system,soil organic carbon,arbuscular mycorrhizal fungi and clay content,which promotes soil aggregate stability and enhances soil permeability,achieves soil and water conservation functions,enhances red soil self-regulation ability,and effectively promotes red soil erosion and degradation habitats to benign succession.At the same time,it is most suitable and effective to control the serious soil erosion degradation of red soil.At the same time,ASG is the most suitable to control the serious soil erosion degradation of red soil among different management modes.