| With the rapid growth of social economy and the increasing population,a large number of wetlands have been overoccupied,transformed into fields,overexploited resources,forest vegetation has decreased,and unreasonable lifestyles have led to wetlands being polluted.The shortage of water resources,the serious destruction of forest land wetland environment,the disappearance of biological species and so on.Xiangjiang River,as the mother river of Hunan people,is the largest river in Hunan Province,and the wetland environment has also been seriously damaged.Therefore,it is very important to carry out the pilot project of returning farmland to forest and wetland in Xiangjiang River Basin.The research content of this paper is divided into three aspects.Firstly,the contents of returning farmland to forest and dampness at home and abroad are reviewed.Secondly,starting from the technology of returning farmland to forest and wet in Hunan Province,the basic theory of the technical model of returning farmland to forest and humidity in Hunan Province is summarized.Then,on the basis of this theory,following the principle of low cost,easy to implement and replicable,the design scheme and effect of the pilot project of returning farmland to forest and dampness in Daxinglong Village,a new town in Leiyang City,are studied.The main results of this paper are as follows:1.Theoretical study on pilot Construction of returning cropland to Forest and Wet in Hunan ProvinceThe theory of pilot project of returning farmland to forest and dampness in Hunan Province includes:(1)the basis of guiding ideology,principles,laws and regulations;(2)site selection requirements:between Hunan,Zhi,Yuan,Li four main streams,primary tributary waters and farmland,priority should be given to the intersection of tributaries and main streams,the coastal length is more than 1000 meters,and the width is 100?200m to return farmland to forest and wet.The goal is to control agricultural non-point source pollution.The pilot area must be more than 300 mu,in which the proportion of wetland area must reach more than 60%.(3)determine the scale of returning farmland to forest and wet:the effective area of returning farmland to forest should be calculated according to hydraulic load.Through the conversion of cropland to forest and humidity,the surface water quality III or effluent quality is improved by more than one grade compared with the influent water quality.(4)the model of returning farmland to forest:the main choice is that the terrain in the pilot area is relatively high,and the cultivated land with obvious seasonal water shortage can not be realized,and the wasteland and the slope bank zone on both sides of the operation road can be used as the conversion of cropland to forest area.Mainly planted Taxus chinensis,Photinia koraiensis,Willow,Luan Tree,Metasequoia glyptostroboides,camphor tree,Lagerstroemia and other landscape tree species;from the economic and sustainable considerations,the construction of water and moisture resistance afforestation seedling cultivation base or forest and fruit base,more in line with the actual needs of the local.There are three models:common forest return mode,landscape protection forest model and wetland nursery type forest return mode.(5)conversion of cropland to wet mode:stop planting in farmland or water area,culture,reduce human disturbance,through artificial measures,damaged wetland ecosystem will gradually restore or develop into a virtuous circle.There are three modes of ecological and economic measures of returning farmland to wet,ecological landscape of returning farmland to wet,and ecological purification of returning farmland to wet.(6)Wetland restoration model:wetland restoration is carried out according to the existing water surface(ponds and canals)in the pilot area.From shallow to deep,weeping willow,Taxus,Canna,Acorus calamus,cattail,submerged algae and aquatic plants such as Wuling,Water Lotus,Xianglian and other aquatic plants are planted from shallow to deep.(7)Wetland.Animal system construction:through wetland restoration,investigate the local wetland animal species composition,distribution location,population quantity,protected species,rare and endangered species,alien species and so on.Through wetland restoration to provide harmonious and unified living conditions for wetland animal system,to protect the survival and migration of fish and migratory birds.(8)maintenance and management in the later stage:including the formulation of monitoring scheme,timely monitoring after the completion of construction.The monitoring contents include:plant growth index,water quality change and so on;It is necessary to manage the conversion of cropland to forest for a long time,clean up,replant and harvest in time.(9)Evaluation and acceptance:according to the monitoring results,according to the construction objectives formulated by the implementation plan,the evaluation and acceptance is carried out.Second,the design scheme and effect of the experiment of returning farmland to wet forest in Daxing long Village,Leiyang New Town.1.Design research:including the pattern of returning farmland to forest,the model of returning farmland to wet,the model of wetland restoration,the data of water quality detection before and after construction,the drawing of plant configuration,the planting mode of plant,Quantity required for plants and complete construction design drawings.2.The effect research includes:after the pilot project of returning farmland to forest and wetting in Daxing long Village of Leiyang New Town was completed,the wetland area was restored to 305 mu.The detection of sampling points showed that both outlet 1 and outlet 2 met the national III water quality standard,and the water quality was improved obviously.Through the conversion of farmland to forests and wet construction,22 species of local trees,including 10 species of octopus,3 species of submerged plants,I species of floating-leaf plants and 5 species of trees,were purposefully introduced into the pilot area with a variety of local trees with water and moisture tolerance,including 10 species of octopus plants,3 species of submerged plants,1 species of floating-leaf plants and 5 species of trees.2 species of herbaceous plants,in addition,wetland restoration will form a good beach ecology.Forest landscape and small scale constructed wetland landscape can improve the living environment of the surrounding villagers and promote the development of local rural tourism. |
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