| China is one of countries with serious rocky desertification area in the world.Vegetation recovery is the primary approach to governance rocky desertification disasters,while it is a global environmental science problem to reconstruct the arbor-shrub-grass ecosystem.In this paper,the characteristics of large area bare rock in rocky desertification area,atmospheric precipitation and artificial rainfall can not be preserved,soil lack and lack of nutrient components.Making the best of the actual situation of rock fissure development in the rocky desertification area and the groundwater rich in fissure,following the idea to reconstruct ecosystem from “arbor to shrub to grass” and the principle “one tree in a baseplate”,the baseplate technique for tree planting is developed,it includes the research and the development of the baseplate of the field application,the composition of the nutrient soil was selected and the optimal mixture ratio was obtained through the experiment,on the basis of analysis of water performance of wet root.The main conclusions are summarized as follows:(1)The baseplate includes the parent body,the wet root,and the cover to prevent evaporation.Especially,there are filled in nutritional soil for the parent body and the root.In view of the actual conditions of fracture development of rock mass in rocky desertification area and rich fissure water,the wet root is set up at the bottom of the base plate creatively,the root provides a good channel for the deep growth of the rock mass of a single tree plant growing in the early stage of the baseplate.The roots of the tree can absorb ground water and nutrients from the fracture of the rock mass through this channel,and solve the problem of sustainable growth in the later period of the tree;Based on the actual situation of bare rock and lack of soil in rocky desertification areas,"the parent body" was developed.The self nourishment structure of the baseplate water holding and water absorption has solved the problem of lack of nutrients and water in the early growth of the plant;In view of the strong solar radiation,large amount of evaporation,drought and the difficulty of plant growth,the "anti-evaporation cover" is developed in the rocky desertification area.In order to reduce the evaporation of water,the baseplate can easily absorb the atmospheric precipitation and promote the growth of the trees in the baseplate.(2)The baseplate is the core of the tree planting technique.The nutrient soil in the baseplate is made up of mushroom residue,straw,vermiculite,cow dung,waterretention agent,perlite,fertilizer,adhesive and loam,the vegetative soil with the structure of self nutrition and water conservation provides the necessary conditions for the survival and growth of the arbor.Robinia pseudoacacia was selected as the plant seed in a pot experiment,a total of 26 groups of proportions,the first 13 groups analyzed the effect of three materials of mushroom residue,straw and cow dung on the water conservation of plant growth,especially the nutrient soil,the latter 13 groups discussed the effect of water retention agent,vermiculite,perlite and fertilizer on the water retention of nutrient soil.Soil moisture measurement was used every 5 days to determine the change of nutrient soil moisture,continuous observation and recording,no artificial normalization of water during the experiment.(3)A proper amount of mushroom residue,straw and vermiculite can improve the structure of nutrient soil and promote the growth of plants.The suitable content of the volume ratio of mushroom residue is 10%,a proper amount of straw can improve the physical and chemical properties of the nutrient soil,and the suitable content is 10%,and the excess pore will be increased.Vermiculite can improve the permeability and water content of soil,and the suitable content is 4%.Cow dung can improve soil fertility,and excessive content will impede plant growth,the suitable content is 10%.The water retention agent can significantly enhance the water conservation and water use efficiency of the soil,and the suitable content is 0.2%.Perlite provides a rich surface area for soil moisture and nutrient content with a suitable content of 8%.(4)In the growth matrix,cow dung,water retention agent and perlite are the main factors affecting the water conservation of the basalplate nutrient soil,and the mushroom residue,straw and vermiculite are the secondary factors.The water retention of No.7,No.11 and No.18 soil was better,and the water content of nutrient soil was respectively 38.4%,29.1% and 31.3% after 75 days,in addition,the optimum ratio of the three groups selected according to the plant growth was No.7,No.10 and No.17,the effects of the content change of the growth matrix on the water conservation and plant growth of the nutrient soil were analyzed,the final selection of the optimal ratio of No.7,according to the results of performance the test of wet root water drain.(5)The wet root is the key part of the tree planting technique.According to the results of the indoor pot experiment,the wet root was prepared by using the ratio of No.7,and the experiment was divided into two groups: D=2cm,L=25cm and D=1.5cm,L=25cm,each group made 5 the same wet roots.The moisture content of the upper,middle and lower segments of the wet root were measured by drying method every 3days,respectively,continue to record the related data of the wet root.On the fifteenth day,the water content in the upper,middle and lower segments of the first group of wet roots were respectively 0.06%,41.9% and 59.7%,and the moisture content in the upper,middle and lower parts of the second groups were respectively 6%,62.3% and 51.6%.On the fifteenth day,the dry and wet dividing length of the first group of the wet roots was 16.4cm,and the second groups was 12.5cm.The total water absorption volume of the first group of the wet roots is 80 ml,and the second groups of wet roots is 11 ml.Experiments show that the higher the temperature is,the bigger the diameter of the wet root,the wet root moisture transport faster,the root extract water height of the larger,more water volume,which the wet root water performance is better.(6)This experiment shows that:In the 26 groups,No.7: mushroom residue 10%,straw 10%,cow dung 10%,water retaining agent 0.2%,vermiculite 4%,perlite 8%,loam 57.2%,fertilizer 0.6%,adhesive 0.15%,water,fertilizer,gas,heat and other conditions are suitable for the sustainable growth of plants,especially suitable for the ecological environment of rocky desertification areas,it can be used as the best proportion of tree planting baseplate technology in rocky desertification areas.The wet root can be made with this ratio,and the water-retaining and absorption is good,in a certain degree,the higher the temperature and the diameter of the wet root,the greater the height of the water extraction and the more volume of water absorption,then the wet root performance is higher,it will be more conducive to transporte the moisture of the rock fissure to th ebottom of the baseplate,for the plant to continue to absorb and grow,and to promote the restoration of vegetation in the rocky desertification areas.(7)The optimal ratio of nutrient soil is obtained by indoor pot experiment,the test in field of the tree planting technique is carried out in the rocky desertification area of Nanshan,Chongqing.The field application method of baseplate technology is given in detail.The test in field results from October 2017 to April 2018 have proved that this technology can ensure the survival and sustainable growth of arbor trees in rocky desertification areas.If it can be applied in the rocky desertification area,will be take the lead in the reconstruction of trees in the ecological system of the arbor-herbaceous-shrub vegetation. |
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