Function And Value Evaluation Of Water Conservation,Soil Reinforcement And Fertility Maintenance Of Different Forests In The Hilly Area Of Southern Jiangxi Province

Because the red soil in the hilly area of Southern Jiangxi is easily eroded,and the rainfall is large and the spatial and temporal distribution is uneven,the hilly area of Southern Jiangxi has always been one of the areas where the phenomenon of soil erosion occurs frequently in China.In recent years,with the rapid development of fruit forestry in the hilly area of Southern Jiangxi,it has brought great economic benefits to the local residents,and a large area of artificial economic fruit forest planting has caused a lot of losses However,the destruction of forest reduces the regional ecosystem services and intensifies the risk of regional soil erosion.In this paper,two main natural forests(coniferous and broadleaf mixed forest and Phyllostachys heterocycla forest)and two typical artificial economic fruit forests(Citrus sinensis forest and Camellia sinensis forest)in Chongyi County of Southern Jiangxi hilly region were selected as the research objects.The water holding capacity and soil physical and chemical properties of different forest litter layers and soil layers were measured by field fixed-point sampling and indoor experimental analysis.The main component analysis method was used to evaluate the soil and water conservation capacity of different forest stands,and the difference of soil and water conservation capacity of different forest stands was further clarified.At the same time,the alternative engineering method and market value method were used to evaluate the water conservation and soil and fertilizer conservation value of different forest stands.The research results can provide reference for the soil and water conservation function of hilly area in southern Jiangxi Province And provide a theoretical basis for the restoration of ecosystem services.The main results are as follows:(1)The litter volume of the four stands ranged from 9.19 t·hm^-2 to 16.70 t·hm^-2,and the coniferous and broad-leaved mixed forest was the largest,while the Camellia sinensis forest was the smallest.The maximum litter holding capacity of the four stands ranged from 14.43 t·hm^-2 to 31.02 t·hm^-2.The water holding capacity of Citrus sinensis and Camellia sinensis forests was significantly lower than that of coniferous and broad-leaved mixed forests and Phyllostachys heterocycla forests.Soil bulk density increased with soil depth,and the average value of soil bulk density in Citrus sinensis forest was1.22g·cm^-3,and that in Phyllostachys heterocycla forest was 1.03 g·cm^-3.The soil water holding capacity and infiltration capacity of Citrus sinensis forest and Camellia sinensis forest were significantly lower than those of coniferous and broad-leaved mixed forest and Phyllostachys heterocycla forest.In general,the order of the overall water conservation capacity of the stand was as follows:coniferous and broadleaf mixed forest>Phyllostachys heterocycla forest>Camellia sinensis>Citrus sinensis forest.Soil steady infiltration rate was the main factor affecting the overall water conservation capacity of the stand.(2)By using the universal soil loss equation to analyze four kinds of forest soil fixation function,it is concluded that four types of woodland soil loss range of 3.387?20.175 t·hm^-2·a^-1,with largest Camellia sinensis forest,mixed needle leaf and the smallest,soil conservation quantity to make mixed needle leaf and maximum 48.543t·hm^-2·a^-1,followed by Phyllostachys heterocycla forest,the forest of Citrus sinensis and Phyllostachys heterocycla forest compared with mixed needle was reduced by33.78%and 34.58%respectively.The soil organic matter,total nitrogen,total phosphorus and total potassium of each forest were measured,and the soil fertility conservation of four forest types were obtained:conifer and broadleaf mixed forest(1.881 t·hm^-2·a^-1)>Camellia sinensis forest(1.483 t·hm^-2·a^-1)>Phyllostachys heterocycla(1.045 t·hm^-2·a^-1)>Citrus sinensis forest(1.023 t·hm^-2·a^-1).(3)Principal component analysis was used to evaluate the soil and water conservation capacity of four kinds of forest land.The order of soil and water conservation capacity of each forest land was coniferous and broadleaf mixed forest>Phyllostachys heterocycla forest>Camellia sinensis forest>Citrus sinensis forest.Based on the comprehensive analysis of the factors affecting the soil and water conservation capacity of each stand,it is concluded that the stable infiltration rate of soil,the content of soil organic matter and the maximum water holding capacity of litter are the main factors affecting the soil and water conservation capacity of the stand,which can better reflect the overall soil and water conservation capacity of the stand.The order of water conservation value of each stand was:Coniferous and broad-leaved mixed forest(2.599 billion yuan·a^-1)>Phyllostachys heterocycla forest(1.283 billion yuan·a^-1)>Camellia sinensis forest(146 million yuan·a^-1)>Camellia sinensis forest(63 million yuan·a^-1),indicating that the water conservation benefits of coniferous and broad-leaved mixed forest and Phyllostachys heterocycla forest were significantly better than those of two economic fruit forests(Citrus sinensis forest and Camellia sinensis forest).The order of soil and fertilizer conservation value of each stand was coniferous and broad-leaved mixed forest(2.599 billion yuan·a^-1)>Phyllostachys heterocycla forest(1.283 billion yuan·a^-1)>Camellia sinensis forest(146 million yuan·a^-1)>Citrus sinensis forest(63 million yuan·a^-1),indicating that coniferous and broad-leaved mixed forest and Phyllostachys heterocycla forest had obvious advantages in soil and fertilizer conservation compared with Citrus sinensis forest and Camellia sinensis forest.