Researches On Eco-Environment Features And Vegetation Restoration Technologies In Dry-Hot Valley Of Jinshajiang River

According to the existing situation and key problems of vegetation restoration technologies for development and construction projects in dry-hot valley of Jinshajiang River,and based on the theories of soil science and restoration ecology and so on,the studies on the integrated evaluation of soil quality,the classification of vegetation site type,the field survey of vegetation resources,the evaluation of vegetation drought tolerance,and the simulated experiments on the mechanism of reducing soil water evaporation of sandy pebble covering and water-absorbent polymer application were conducted in the paper,by using the integrated method of field survey and experimental analysis.As a result,a vegetation restoration pattern suitable for Qiaojia dry-hot valley of Jinshajiang River and its several guarantee measures were proposed,which could provide some references for vegetation restoration of development and construction projects in dry-hot valley of Jinshajiang River.The main obtained results in the paper are as follows:Firstly,the soil quality and nine native vegetation species in the Qiaojia dry-hot valley of Jinshajiang River were evaluated by using membership function evaluation method.The results indicated that the soil quality of different land uses in the Qiaojia dry-hot valley of Jinshajiang River in term of descending order was as follows:woodland＞bared land＞economic crop land＞cultivated land,and the vegetation drought tolerance ability of different native vegetation species in term of descending order was as follow:Opuntia monacantha Haw＞Pistacia weinmannifolia Franch＞Cycas panzhihuaensis＞Populus yunnanensis Dode＞Eucalyptus camaldulensis Dehnh＞Morusspp＞Leucaena leucocephala＞Zanthoxylum bungeanum Maxm＞Pueraria.Secondly,the vegetation site environment features in the Qiaojia dry-hot valley of Jinshajiang River were studied preliminarily,and the restrictive factors of vegetation restoration in the Qiaojia dry-hot valley of Jinshajiang River,mainly including soil moisture and soil nutrition, were revealed.In addition,based on the main factors of the classification of vegetation site types including elevation,slope aspect and so on,the vegetation site type plot in the Qiaojia dry-hot valley of Jinshajiang River was divided into two site type groups and eight site types.Thirdly,the plant life forms of 68 native vegetation species in the Qiaojia dry-hot valley of Jinshajiang River were partitioned in the paper,from which 22 native vegetation species were screened out and considered as the dominant species to be used for the vegetation restoration in the Qiaojia dry-hot valley of Jinshajiang River.And the suitable allocation between vegetation site type and dominant species in the Qiaojia dry-hot valley of Jinshajiang River were conducted preliminarily,and four vegetation restoration,pattern suitable for Qiaojia dry-hot valley of Jinshajiang River and its several guarantee measures were proposed in the paper.Fourthly,sandy pebble covering and water-absorbent polymer application could reduce soil water evaporation.The simulated soil water evaporation reduction experiments indicated that both of the diameters of sandy pebble and the covering depth had a significant effect on reducing soil water evaporation.In other word,if the diameter of sandy pebble was smaller or the covering depth was bigger,the effect of reducing soil water evaporation by sandy pebble covering was better,and the application of water-absorbent polymer to soil could reduce effectively soil water evaporation and retain soil moisture.The best concentration is one percent.Finally,the application of water-absorbent polymer to soil could improve the nutrition-retaining abilities of soil and the germination rates of different plants in pot.The experimental studies in the paper indicated that the application of water-absorbent polymer to soil could improve the nitrogen-fixing,nitrogen-absorption,and nitrogen-disporting abilities of soil and the germination rates of different plants in pot.When the applicate concentration of water-absorbent polymer is one percent of soil.The nutrition-retaining and germination rates of different plants are all good.