Study On The Relationship Between Vegetation Degradation And Soil Mechanism In The Dump Site Of Pingshuo Opencast Coal Mine

To study the vegetation degradation mechanism in the dump of Pingshuo opencast coal mine,clarify the change law and driving mechanism of physical and chemical properties of the soil of artificial forest in the dump,and understand the relationship between soil conditions and vegetation degradation,this research takes four kinds of vegetation cases as subjects,including single black locust,single Chinese pine,black locust + elm mix,and black locust + Chinese pine mix.By measuring the distribution characteristics of physicochemical properties of samples collected from depths of 0-20 cm and 20-40 cm in soil profiles,the relationship between physicochemical properties of different degraded vegetation are analyzed and evaluated.The results showed that the greater the soil moisture in lower layer,clay content,total porosity,organic matter,nitrogen,phosphorus and potassium,the smaller the sand and silt content,soil bulk density and alkaline hydrolyzable nitrogen content,and the less vegetation degradation.The mixed vegetation model of multiple trees outperforms the single model in restoration effect,in the order of black locust + Chinese pine mix > black locust + elm mix > single Chinese pine >single black locust.The degradation degree of vegetation restoration in different site types of the dump of Pingshuo opencast coal mine is shown in the order of slope top > middle of slope >slope toe.The correlation analysis shows that the forest dieback rate mainly relates to soil mechanical composition,which has a significant correlation with fast-acting potassium,unrelated to other physicochemical properties.To sum up,drought act as the main reason for vegetation degradation in the dump of Pingshuo opencast coal mine;The mixed vegetation model of multiple trees works better in terms of restoration effect;The forest dieback rate in the area is influenced by soil mechanical composition directly as well as soil fast-acting nutrients indirectly.The thesis has 14 pictures,26 tables and 96 references.