Effects Of Man-made Interference On Plant Diversity And Soil Physical Properties In The Lower And Lower Riverside Of The Yellow River

Riparian zone is a transitional zone between river ecosystem and terrestrial ecosystem.It is water environment and land for material transmission and energy.One of the most complex and diverse habitats on Earth,with unique features,is an important barrier,filter and corridor for transformation and information exchange.ecosystem structure and service functions.With the transitional development of the river by human activities and the expansion of agricultural land,agricultural land is used in the middle and lower reaches of the Yellow River.The ecological environment of the riverbanks is seriously damaged.Taking the riverbanks in the middle and lower reaches of the Yellow River as an example,according to the results of field investigation,the riverbanks with different degrees of human activity(mild,moderate and severe)were screened,and the natural environment,plant characteristics and soil physical properties of different types of riverbanks were investigated,sampled and analyzed:(1)In the middle and lower reaches of the Yellow River,there are more species of vegetation in the riparian zone,the number of plant species increases with the increase of the degree of disturbance,and the emergence of new species;among the three species of artificial disturbance,gramineous plants are the highest in plant species,average coverage,frequency and multiplicity,followed by Compositae,while the other genera have only a few or a single species.(2)In the middle and lower reaches of the Yellow River riparian zone,plant ?diversity was generally moderate>severe and mild with varying degrees of human disturbance,and there was no significant difference in plant evenness index at different distances from the riparian.Plant richness index,Shannon-Wiener diversity index and dominance were significantly lower than moderate and severe at 200 m from the riparian,and moderate and severe at 2 m from the riparian.(3)Plant ? diversity:the similarity index showed moderate>mild>severe overall,the similarity index was moderately significantly greater than severe among 100 vegetation zones,and there was no significant difference among the rest of the vegetation zones;the substitution index showed mild<moderate<severe in the different disturbance riparian zones,no significant difference in the substitution index between 100 vegetation zones,and mild disturbance riparian zones were significantly less severe among the remaining vegetation zones.(4)There was a significant positive correlation between a diversity of riparian plants under mild disturbance,positive correlation between a diversity of riparian plants under moderate disturbance and positive correlation between riparian plant a diversity under severe disturbance,with the exception of plant richness index and evenness index.(5)In the riparian zone of different man-made disturbance,soil moisture content generally showed severe<mild<moderate;soil bulk density and soil non-capillary porosity generally showed an increasing trend with the increase of disturbance;and soil maximum water holding,soil capillary holding,soil minimum water holding,The soil moisture content,soil water holding capacity,total soil porosity and soil capillary porosity decreased with the increase of soil depth in the riparian zone with mild and moderate disturbance trend;in the severe disturbance riparian zone,with the change of soil depth,soil moisture content,soil bulk density,soil water holding capacity,total soil porosity and soil capillary porosity in 0-30 cm the soil layer shows the trend of first decreasing and then increasing,and the soil non-capillary porosity shows the trend of first increasing and then decreasing.With the change of distance from the river bank,the soil moisture and non-capillary porosity change obviously,and the other physical indexes change less.(6)In the middle and lower reaches of the Yellow River riparian zone,the soil moisture content is positively correlated with soil water holding,total porosity and capillary porosity,and negatively correlated with soil bulk density and soil non-capillary porosity.(7)In the middle and lower reaches of the Yellow River riparian zone,the plant a diversity index is positively correlated with soil moisture content,soil water holding capacity and total porosity,capillary porosity,and negatively correlated with soil bulk density and soil non-capillary porosity.(8)In the middle and lower reaches of the Yellow River riparian zone,the contribution of soil total porosity to plant diversity was the greatest,with 80.2 being the main factor of plant a diversity driven by soil physical properties of riparian zone;37.6 being the main factor of plant a diversity driven by soil physical properties of riparian zone;42.8.It is a major factor driving changes in plant a diversity due to severe disturbance of the physical properties of riparian soils.