Ecological And Environmental Effects Of Patch Like Shrub Vegetation In The Desert Oasis Transition Zone Of The Middle Reaches Of The Heihe River

The desert oasis transition zone widely exists at the edge of the desert in the arid region of northwest China.Unlike other ecosystems,the desert oasis transition zone is very fragile due to its unique climate and ecological environment.Moreover,due to its geographical location,the desert oasis transition zone has become a frontier area for preventing and controlling desertification.In fragile ecological environments,there is a very close connection between vegetation,soil,and other ecological environmental factors.Studying the ecological environment improvement effects of patch like shrub vegetation in the desert oasis transition zone,analyzing the interrelationships and feedback mechanisms among various ecological environment factors,is of great significance for a deeper understanding of the ecological environment improvement effects of patch like shrub vegetation in the desert oasis transition zone and the prevention and control of land desertification.In this study,patch shrub vegetation in the desert oasis transition zone in the middle reaches of the Heihe River was taken as the research object,and the wind blocking effect,sand blocking effect,physical and chemical properties of root soil,nutrient content,and the relationship with other meteorological environmental factors of shrub vegetation in the desert oasis transition zone were studied by using field observation tests,indoor sample tests,mathematical statistics analysis and other methods to explore the internal mechanism of shrub plants to improve the ecological environment in the transition zone,The aim is to provide scientific basis for the restoration and reconstruction of vegetation in the desert oasis transition zone,as well as theoretical basis for future vegetation construction in sandy areas.The main research findings are as follows:(1)The overall wind blocking effect of shrub plants is as follows: Haloxylon ammodendron>Calligonum mongolicum>Bubble thorn,with the maximum effective protection distance of Haloxylon ammodendron;The overall performance of the near-surface sand blocking effect of shrub plants is as follows: Haloxylon ammodendron>Bubble thorn>Calligonum mongolicum.The sand blocking efficiency is 60.7% for Haloxylon ammodendron,46.3% for Calligonum mongolicum,and 51.0% for Bubble thorn.The sand transport rate of shrub plants increases with the increase of wind speed,and the correlation can be described by an exponential function or a polynomial function.When the wind speed is within the range of 5.0 to 7.0m /s,the sand transport rate slowly increases with the wind speed.When the wind speed exceeds 7.0m /s,the sand transport rate increases faster with the increase of wind speed.The intensity of wind sand erosion in the study area increases from negative to positive.Due to the growth and development of patch like shrub vegetation in desert oases,the wind erosion effect in the study area continues to increase and decrease.(2)The soil moisture content in the root zone of shrub plants shows an overall trend of increasing first and then decreasing.The horizontal comparison of soil moisture content in the root zone of the three types of shrub plants is as follows: Bubble thorns>Calligonum mongolicum>Haloxylon ammodendron;The soil bulk density in the root zone of Haloxylon ammodendron and Bubble thorns showed an overall trend of decreasing first and then increasing,while the soil bulk density in the root zone of Bubble thorns showed an overall trend of decreasing first,then increasing,and then decreasing.The horizontal comparison of soil bulk density in the root zone of the three shrub plants showed that Haloxylon ammodendron>Bubble thorns>Calligonum mongolicum;The porosity of the soil in the root zone of three types of shrub plants is greater at a depth of 0-20 cm than at other soil layers.The horizontal comparison of the soil porosity in the root zone of shrub plants is as follows:Calligonum mongolicum>Bubble thorn>Haloxylon ammodendron;As the depth of the soil layer increases,the soil p H shows a decreasing trend,and the soil conductivity shows a trend of first increasing and then decreasing.The overall horizontal comparison of soil p H in the root zone of shrubland plants is as follows:Bubble thorn>Calligonum mongolicum>Haloxylon ammodendron,while the overall horizontal comparison of conductivity is as follows: Calligonum mongolicum>Haloxylon ammodendron>Bubble thorn.(3)The soil organic matter content in the root zone of shrub plants shows a trend of first increasing and then decreasing.The horizontal comparison of soil organic matter in the root zone of shrub plants is shown as Haloxylon ammodendron>Bubble thorns>Calligonum mongolicum;The total nitrogen and phosphorus content shows a decreasing trend,and the overall horizontal comparison between the total nitrogen and total phosphorus content in the root zone soil of shrub plants shows that the content of Haloxylon ammodendron>Bubble thorn>Calligonum mongolicum.(4)The mechanical composition of the soil in the root zone of shrub plants is characterized by the highest content of ultra-fine sand,followed by the content of fine sand and medium sand,and the lowest content of coarse sand,and the content of coarse sand is far less than the content of ultra-fine sand,fine sand and medium sand.(5)The effects of soil moisture content,porosity,soil p H,organic matter,and total phosphorus content in the root zone of shrub plants on the wind speed decrease were significant;The effects of soil moisture content,bulk density,soil p H,organic matter,and total phosphorus content in the root zone of shrub plants on sand blocking efficiency are significant.(6)Shrub vegetation can effectively improve the climatic conditions in the desert oasis transition zone,which is manifested by effectively reducing air temperature and surface temperature in the middle of May to September,and effectively improving the relative humidity of the air in the desert oasis transition zone.