| Taking the desert oasis transitional zone in the middle reaches of Heihe as an example,the characteristics of plant communities and the physical and chemical properties of the soil in the study area were analyzed based on field investigation and laboratory test.The relationship between species diversity and soil physical and chemical properties was analyzed by grey correlation analysis method.The experimental plot is located in the arid area of the northwest.Due to the enclosure policy,there is less human interference,coupled with its special geographical location and climatic conditions.It is used to study the plant community and soil development in the desert-oasis transition zone of the inland river region in the northwest arid area.Ideal place.Compared with other desert-oasis transitional zones,the desert-oasis transitional zone of Linze County has special soil formation process,soil physical and chemical properties,plant community properties,plant species composition,habitat characteristics,spatial structure and dynamic succession,etc.There are obvious differences.The soil has poor water storage capacity,poor soil quality,and low nutrient content,resulting in a simple plant community structure in this area,with very few species,and poor ecological stability.Compared with other research areas,it is more susceptible to damage and disturbance.Therefore,there is an urgent need to study the characteristics of the plant community,the physical and chemical properties of the soil,etc.,so as to provide a scientific basis for the restoration and reconstruction of the vegetation in this area.The main conclusions obtained from the experiment are as follows:(1)The soil physical and chemical properties of the plant root zone in the northern desert-oasis transition zone of Linze County have small coefficients of variation on the spatial scale and are generally relatively stable.The degree of variation of chemical property indicators is generally smaller than that of physical property indicators.Among them,bulk density,total porosity,total nitrogen,total phosphorus,and p H show weak variability.Capillary porosity,non-capillary porosity,saturated water holding capacity,capillary water holding capacity,field holding The water content,natural water content,organic matter content,and electrical conductivity show a moderate degree of variation.The soil porosity,soil p H and electrical conductivity of the plant root zone increase with the increase of soil depth.Total nitrogen and total phosphorus generally decrease with the increase of soil depth.Organic matter first decreases and then increases.Plant root zone soil bulk density,total porosity,capillary porosity,non-capillary porosity,saturated water holding capacity,capillary water holding capacity,field water holding capacity,and natural water content are1.16?1.69g/cm3,29.34%?57.56%,21.19,respectively %?53.01%,2.04%?13.66%,0.50%?5.12%,19.25%?51.52%,12.74%?45.28%,15.81%?49.00%;organic matter,total nitrogen,total phosphorus,p H,conductivity are 1.21 respectively %?2.44%,0.17%?0.20%,0.34%?0.44%,7.45%?9.01%,9.55?45.15?s/cm.(2)There are certain differences in the soil physical properties of the root zones of the three sand-fixing plants.Among them,the soil bulk density is as follows: Calligonum mongolicum>Nitraria sphaerocarpa> Haloxylon ammodendron,and the soil porosity and soil water holding capacity are as follows: Haloxylon ammodendron> Nitraria sphaerocarpa>Calligonum mongolicum;the soil chemical properties of the root zones of the three sand-fixing plants have significant differences only in electrical conductivity.Among them,organic matter,total nitrogen and electrical conductivity are in the order of prickly Nitraria sphaerocarpa > Haloxylon ammodendron> Calligonum mongolicum,and total phosphorus is expressed as: Calligonum mongolicum> Nitraria sphaerocarpa> Haloxylon ammodendron,and the p H performance is as Nitraria sphaerocarpa> Calligonum mongolicum> Haloxylon ammodendron.(3)The soil chemical properties of the desert-oasis transition zone fluctuate with seasonal changes,and the change trends of soil chemical properties of the root zone of different sand-fixing plants are different.The soil nutrient content in the root zone of the three sand-fixing plants is generally autumn>spring>summer,the soil p H is spring>autumn>summer,and the soil electrical conductivity is spring>autumn>summer.(4)There is a significant negative correlation between soil bulk density and physical property indicators in the study area.Soil porosity can significantly affect the value of total nitrogen and electrical conductivity in the soil.The total porosity has a significant positive correlation with total nitrogen,and has a significant positive correlation with electrical conductivity.There is a significant negative correlation,and the non-capillary pores are the opposite.It shows that the degree of soil porosity is a key factor affecting the physical and chemical properties of soil.It plays an important role in the improvement of soil quality and also plays a key role in the process of material circulation.(5)There is a significant negative correlation between soil bulk density and physical properties in the study area.Soil porosity can significantly affect the values of total nitrogen and electrical conductivity in soil.Total porosity has a significant positive correlation with total nitrogen and a significant negative correlation with electrical conductivity,while non capillary porosity has the opposite.The results show that soil porosity is a key factor affecting soil physical and chemical properties,and it also plays a key role in the process of material circulation.(6)The indexes of plant species diversity in the study area were affected by soil physical and chemical properties,and the natural water content,field water capacity and total phosphorus content had the greatest impact on Shannon diversity index;Total phosphorus,field capacity and electrical conductivity had the greatest impact on Simpson dominance index;Total phosphorus,field capacity and electrical conductivity had the greatest impact on Pielou evenness index;Natural water content,total phosphorus and electrical conductivity had the greatest impact on Margalef richness index.To sum up,the smaller the soil bulk density,the larger the porosity and the looser the soil are,which will affect the water holding capacity and chemical properties of soil and indirectly affect the plant community.In addition,this study also found that the soil quality of the root zone of three kinds of sand fixing plants is as follows: Haloxylon ammodendron>Nitraria sphaerocarpa> Calligonum mongolicum.Therefore,Haloxylon ammodendron should be a more suitable sand fixing plant to be widely planted in the practice of sand control engineering in the study area. |
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