Study On Water Balance Of Main Tree Species Of Shelter Forest In Ulan Buh Desert Section Of The Yellow River

The Ulan Buh Desert section of the Yellow River has harsh natural conditions and sparse vegetation.There are strong winds and sandstorms throughout the year.At present,the coastal shelterbelt has a single species and is severely aging and dead,and its preservation rate is low.It has basically lost its protection function.A large amount of wind and sand enters the Yellow River from here every year,causing huge losses to the downstream.The reconstruction of this section of the protection forest is imminent,but the desert precipitation is scarce in the area,and moisture is the main factor restricting plant growth.The water balance method can quantitatively analyze the sources and expenditures of plants water.In order to strengthen the ecological management of the Ulan Buh Desert section of the Yellow River and improve the current situation of wind and sand entering the Yellow River,it is very necessary to use the water balance method to systematically study the selection of shelter forest tree species.Therefore,using Pinus sylvestris var.mongolica Litv,Populus alba var.pyramidalis Bge,Populus gansuensis,Elaeagnus angustifolia Linn.and Tamarix chinensis Lour.as research objects,the water consumption and water consumption laws of the main sand-fixing tree species are analyzed,in order to provide a theoretical basis for the restoration and reconstruction of the Ulan Buh Desert along the Yellow Section of the Shelter Forest.The main research conclusions are as follows:(1)The sap flow of Pinus sylvestris var.mongolica Litv is a single-peak curve under sunny conditions.During the observation period(June to September),the average daily water consumption of the three samples are: 4.57 kg/d,2.91 kg/d and 1.07 kg/d.d;the sap flow curve of Populus gansuensis is multi-peak or single-peak curve.During the observation period(May to October),the total water consumption of a single plant of poplar is 321.42 kg,and the average daily water consumption is 1.75 kg/day;the flow curve of Elaeagnus angustifolia L.is singlepeak or multi-peak curve,and there is night sap flow.The average daily water consumption of the three sample beads during the growing season is 1.79 kg/d,2.24 kg/d,and 1.83 kg/d,respectively.At the end of the growing season,the Elaeagnus angustifolia L.will have a relatively high sap flow.(2)Soil moisture provides a source of water for plant transpiration.In this experiment,the plant sap flow after the soil moisture is replenished is generally greater than the sap flow before the supplement.At the same time,after the water is replenished,it will also aggravate the evaporation of soil moisture.Experiments on soil moisture evaporation under the soil show that the treatments of sand and plastic mulching can effectively reduce the evaporation of soil moisture.The order of soil evaporation under the five different treatments is mulching(1620g)<sand(1660 g).)<Crusting(3100 g)<Straw-covering(3110 g)<Control(3350 g).(3)The tree species for afforestation consumes a lot of water,and the trees in the experiment are all in different degrees of water deficit.Relying on atmospheric precipitation is far from meeting the needs of tree growth.Irrigation must be used to ensure the healthy growth of trees,and continue to exert wind and resistance,sand and sand fixation.Shrub afforestation tree species consume less water,but they only rely on atmospheric precipitation to basically meet their water consumption needs,and they also need to use irrigation to ensure their normal growth.Experimental observations show that although the water consumption of Pinus sylvestris,Populus alba L.,Populus gansuensis,Elaeagnus angustifolia L.and Tamarix chinensis Lour are different,they are all excellent tree species that can be used in oasis protection forests and Yellow River protection forests.If the water is sufficient,healthy growth is basically no problem.In view of the water consumption problem,the proportion of arbor should be appropriately controlled on the basis of ensuring the normal function of windbreak and sand fixation to reduce water resources loss.