Distribution Of Soil Water And Salt In Shelterbelt System And Its Effect On Plant Communityin Desert Salt Lake Region

As an important environmental factor affecting the stability of windbreak and sand fixation forest in arid area,the distribution pattern of soil water and salt restricts the formation,succession and distribution of species.Taking Jilantai Salt Lake shelter forest system as the research object,this thesis investigated the soil water and salt content and typical plant community characteristics in the area by using the methods of field sampling and indoor analysis,analyzed the distribution law of soil water and salt content under different soil layers,and revealed the main water and salt factors affecting the plant community characteristics of the shelter forest system,so as to provide reference for the tending of Jilantai Salt Lake shelter forest system It provides a theoretical basis for management.(1)There are 17 species in 17 genera of 8 families in the study area,including 5 species of Chenopodiaceae,4 species of Leguminosae,2 species of Gramineae and Tamaricaceae,and 1 species of Compositae,nitrariaceae and Elaeagnaceae.On the whole,the plant species composition of shelterbelt system is relatively poor.The average density and coverage of shrub plants in different site types of shelterbelt system decreased gradually from beach to mobile sand ridge,while the average height change was opposite to the height.The results showed that the average density of herbaceous plants varied from large to small in shelterbelt,windbreak and sand blocking belt,semi fixed sand ridge and beach,and the variation of average height was similar to that of average density;The diversity index of herbaceous and shrub plants was the highest in shelterbelt,the lowest in beach,and the lowest in moving sand ridge.The results show that the artificial vegetation configuration has a certain influence on the characteristics of shelterbelt vegetation community.(2)The soil water and salt factors in different site types in horizontal direction were significantly higher than that of shelterbelt,wind and sand barrier zone,semi fixed sand ridge and floating sand ridge(P<0.05).In vertical direction,soil water content and total salt content increased with the increase of soil depth,but the soil p H and soil water soluble salt ions were not significantly different under different soil depth(P > 0.05).The results of geostatistics show that the spatial distribution of soil water content in the forest system shows the trend of high in the middle and low sides,and the spatial variability is mainly caused by random factors and structural factors.The total salt content and the soil salt base ions are decreasing gradually.Spatial variation is mainly caused by structural factors.(3)RDA analysis showed that the explanation of soil water and salt factors to the characteristics of herbaceous plant community was 72.9%,79.9%,69.3% and 59.4%,respectively.Among them,the soil water content,total salt content and soil HCO3-were the main environmental factors to inhibit the growth and distribution of herbaceous plants(P<0.05).The shrub community characteristics were mainly affected by soil water content and soil cation content in 40-60 cm and 60-80 cm,and the soil water and salt factors under beach,shelter belt,wind and sand prevention belt,semi fixed sand ridge and mobile sand ridge had little effect on the shrub community characteristics,which ranged from 37.4% to 53.2%,indicating that the artificial vegetation configuration and soil water and salt were the main factors affecting the plant community types and their components Cloth is an important factor.