Study On Water Conservation Function Of Typical Forest Vegetation Types In Rocky Desertification Area Of Western Hunan Province

This paper takes three typical forest types in the rocky desertification area of Xiangxi as the research object.Through field investigation and indoor analysis,using the methods of canonical correlation,linear regression,the soil physical and chemical factors under the three forest types were quantitatively analyzed with the water-holding capacity of the shrub layer,litter layer and soil layer,and their correlations were explored,and the water conservation capacity of the three forest types was compared,aiming to provide reference for the restoration and reconstruction of forest ecosystems in the rocky desertification areas of western Hunan.Research indicates:(1)Changes in soil physical and chemical properties under three types of forest types:soil bulk density in different depth soil layers are:fir forest>masson pine forest>cypress forest;The order of soil pores and soil moisture in different depth soil layers is as follows:cypress forest>masson pine forest>fir forest.Compared with the three types of stands,the soil structure and traits of the cypress forest are better,and the potential for water storage and regulation of rainfall runoff is stronger.The soils under the three forest types were all acidic soils,and the soil pH value was not significantly different among the three forest types.The organic matter,total N,total P,total K,effective P and effective K content in the soil layer all showed the regularity of decreasing with the deepening of the soil depth.The contents of soil organic matter,total N,total K,total P and effective P in three kinds of stands were as follows:cypress forest>fir forest>masson pine forest;The effective K content of soil showed:Pinus massoniana>Cunninghamia lanceolata>Cypress forest.Compared with the three types of stands,cypress forest showed the highest soil fertility.(2)Correlation between physical and chemical properties of soil under three forest types:Under the three forest stands,there was a positive correlation between the total P,all N,all K,and effective P indicators in soil chemical properties and soil porosity and soil moisture in soil physical properties,and negative with soil bulk density;Soil pH was positively correlated with soil bulk density,total porosity,saturated water holding capacity,and capillary water holding capacity,and negatively correlated with capillary porosity,non-capillary porosity,and field water holding capacity;There was a positive correlation between soil organic matter and soil porosity and soil moisture index,and a negative correlation with soil bulk density.Soil available K was negatively correlated w:ith non-capillary porosity and positively correlated with soil bulk density,soil moisture,total soil porosity and capillary porosity.(3)Water conservation characteristics of three forest types:The biomass,maximum water holding capacity and maximum water holding capacity of the three forest types were the best in the cypress forest.The order of maximum water holding capacity of the shrub layer was:cypress forest>masson pine forest>fir forest,the order of biomass and maximum water holding capacity of shrub layer was:cypress forest>fir forest>masson pine forest.The biomass,maximum water holding capacity,maximum water holding capacity,effective intercepting rate and effective storage capacity of the three types of litter types were:Chinese fir forest>Cypress forest>Masson pine forest.The order of maximum water holding capacity,capillary water holding capacity and effective water holding capacity of the three forest types was:cypress forest>masson pine forest>fir forest.By comparing the comprehensive water holding capacity of the three stands,it was concluded that the comprehensive water holding capacity of the cypress forest was the strongest,followed by the masson pine forest and the weakest fir.(4)The correlation between forest water conservation indicators and soil physical and chemical factors is as follows:There is a positive correlation between total water holding capacity of forest land and total porosity in soil physical and chemical properties,capillary porosity,non-capillary porosity,saturated water holding capacity,capillary water holding capacity,field water holding capacity,all N,all P,all K,effective P,Effective K and organic matter,a negative correlation between soil bulk density and pH performance.The research indicates that the cypress forest should be planted at the initial stage of the rocky desertification control in the study area.Compared with the Chinese fir forest and the masson pine forest,the comprehensive water conservation capacity of the cypress forest is stronger.The soil water holding capacity of the three forest types is more than 95%of the comprehensive water holding capacity of the forest,and the soil nutrient is closely related to the water holding capacity of the soil layer,therefore,in the restoration process of forestland vegetation-soil system,improving soil nutrient content can increase soil water holding capacity and promote forestland vegetation growth,thereby effectively improving the comprehensive water holding capacity of forest land.