Spatial Structure Optimization Of Snail Control And Schistosomiasis Prevention Forest In Shishou City

Since the 1980 s,the construction of forestry ecological program of snail control and schistosomiasis prevention had achieved good effect at the epidemic area in China.However,some unreasonable phenomenon in some areas still exist,for example,the imperfections of spatial structure of forestry ecological program of snail control and schistosomiasis prevention,and the disequilibrium of ecological benefits,economic benefits and social benefits.This paper took the typical epidemic area Shishou city in Hubei province as the research object,according to the environmental characteristic of the reproduction of snails who was the only host of schistosoma,evaluated the risk level of snail reproduction in Shishou city by using the AHP.Using multi-source remote sensing data and forest resources inventory data,combined with the risk level of snail reproduction,the distribution of suitable land for forest and the updating place of the existing snail control and schistosomiasis prevention forest,determined the spatial structure optimization area of snail control and schistosomiasis prevention forest.Seting different patterns of snail control and schistosomiasis prevention forest according to different area,taking the area of each model as constraint conditions,aiming at ecological,social and economic benefits,applicating the multi-objective linear programming model,optimizated the spatial structure and structure configuration of snail control and schistosomiasis prevention forest in Shishou city,and put forward the spatial structure and structure configuration prioritization scheme of snail control and schistosomiasis prevention forest in Shishou city.Hoping to provide the basis of snail control and schistosomiasis prevention forest at epidemic area for further enhance efficiency.The main results were as follows:1.The high risk area of oncomelania reproduction in Shishou are mainly distributed in rivers,canals along the Yangtze river and its tributaries,irrigation canals and ditches and the formation of the large area of tidal flats after the Yangtze river diversion,accounting for 8.74% of the total area of the study area.Human activity is less,the region less agricultural land distribution,is the reproduction area of a large number of snails,the area should be given to priority at the process of optimization of snail control and schistosomiasis prevention forest.The medium risk area of snail reproduction is mainly distributed inside embankment of the Yangtze river,accounting for 23.77% of the total area of the study area.The region distribution of farmland cultivated land and the population density is small but human activities is much,so the area is in the key area of schistosomiasis infection.The low risk area of sanil reproduction are mainly distributed around urban area,the permanent water like large lakes and the Yangtze river,accounting for 67.49% of the total area of the study area.The area population density is high,less arable land,human disturbance is strong,hard mineralization degree is high,poor ecological environment.2.The total area of snail control and schistosomiasis prevention forest in Shishou city is 320.98 km~2,accounting for 22.84% of the study area,forest age structure is given priority to young aged forests and middle aged forests,covers an area of 258.30 km~2,accounting for 80.47% of total area of snail control and schistosomiasis prevention forest in Shishou city,it showed that in recent years,the construction speed of snail control and schistosomiasis prevention forest expedite.The area of mature forest and overripe forest is 37.60 km~2 and 7.52 km~2,the total accounted for 14.05% of total area of snail control and schistosomiasis prevention forest in Shishou city,the stand need to be updated.According to the site conditions,the requirement of tree species selection and structural configuration of snail control and schistosomiasis prevention forest,the area of suitable land for forest is 28.23 km~2,is the key areas of the construction of snail control and schistosomiasis prevention forest in the next few years.Therefore,the updated area of existing snail control and schistosomiasis prevention forest and suitable land for forest overlay,the optimization area is acquired,the total area is 45.125 km~2.After spatial arrangement optimization of snail control and schistosomiasis prevention forest in Shishou city,the forest coverage rate will increase to 24.85%.3.According to different site conditions at the risk area of snail reproduction and the configuration characteristics and development trends of snail control and schistosomiasis prevention in Shishou city,seting six kinds of structure configuration of snail control and schistosomiasis prevention forest according to different area.The comprehensive benefit evaluation of each model showed that prevention different structural configuration mode differences between social benefit and economic benefit,ecological benefit difference is minimal.The order of six kinds of structure configuration model of comprehensive benefits is as follow: high density pure forest> low density pure forest> low density wide and narrow row greenstuff-forestry> high density wide and narrow row greenstuff-forestry> low density wide and narrow row agro-forestry> high density wide and narrow row agro-forestry.The ecological benefits of high density pure forest is highest,it is 3183.45yuan·a-1·hm-2,the economic benefits of low density wide and narrow row greenstuff-forestry is highest,it is 67608.15yuan·a-1·hm-2,the social benefit of low density pure forest is highest,it is 126864.75yuan·a-1·hm-2.4.Multi-objective linear programming forecasts when the ecological benefits,economic benefits and social benefits of snail control and schistosomiasis prevention forest optimization area in Shishou city all are the best,the spatial structure is: Low density pure forest model of high-risk area,high density wide and narrow row agro-forestry model of medium risk area,high density wide and narrow row greenstuff-forestry model of the low risk area.After optimizating structure configuration of snail control and schistosomiasis prevention forest in Shishou city,the planting area of low density pure forest model is 3875.2 hm~2,about 52.83% of the whole optimization area,the planting area of high density wide and narrow row agro-forestry model is 1757.01 hm~2,accounted for 23.95% of the whole optimization area,the planting area of high density wide and narrow row greenstuff-forestry mode is 1703.63 hm~2,accounted for 23.22% of the total area.