Vegetation Restoration And Soil Seed Bank Characteristics Of The Abandoned Coal Mine In Wangping Town,Mentougou,Beijing

With the functional and steady industrial transformation of the capital along with the improvement of people’s ecological awareness,most of the mine sites in Beijing have been gradually closed in recent decades,leaving a large number of abandoned mining sites in the suburbs of Beijing.Among which coal mines are large at the number,meanwhile the complex mining methods and constitution lead to particularly severe damage to the surrounding ecological environment and a long-lasting restrictive impact on the recovery of vegetation,which is difficult to restore or manage and has a great impact on the land use and ecological conservation in the shallow mountainous areas of Beijing.In this study,the typical abandoned coal mine in Wangping Town,a shallow mountainous area in western Beijing,was selected as the research object,and its habitat characteristics,vegetation composition characteristics and soil seed bank characteristics were investigated and analyzed to explore their correlation characteristics,the vegetation succession direction and factors influencing its vegetation restoration were studied.The main research results are as follows:(1)The results of the physical and chemical property determination of the abandoned coal mine soil in Wangping town showed that the abandoned coal mine soil was neutral to weakly alkaline,with poor soil moisture,low soil N,P and K content,and high soil salinity,but good soil maturation.There are differences in the habitat characteristics of each microtopography.The soil capacity gradually decreases with the elevation,and the soil is more acidic in the sample site with larger slope.The gravel content is high in the sample sites on the convex side of the ridge and at the foot of the mountain.The conductivity of the sample sites on the convex side of the ridge is low and the soil is acidic,while the conductivity of the sample sites at the foot of the mountain is high.The organic matter content of the upper slope is higher than that of the lower slope.The overall nutrient content of the foot of the hill sample sites was higher.(2)In this study,a total of 110 species of ground vegetation plants belonging to 45 families and 99 genera were counted in the survey of coal mine abandoned land in Wangping Town.Among them,1species of gymnosperm,109 species of angiosperm,93 species of dicotyledonous plants and 16 species of monocotyledonous plants were observed.There are 28 species of 28 genera in 17 families of woody plants,including 1 species of evergreen coniferous trees and 17 species of deciduous broad-leaved trees.Herbaceous plants 32 families and 73 genera and 82 species,including 12 families and 17 genera and 17 species of 2012 herbs,25 families and 46 genera and 56 species of perennial herbs.There are 5 families and 6 genera and 6 species of vines.The vegetation in the study area showed an overall diversity index of herb layer > tree layer > shrub layer.The plants of Asteraceae,Gramineae,Leguminosae,Rosaceae,Liliaceae,Lauraceae,Corydalidae,Buttercups,Moraceae,Euphorbiaceae,Sapotaceae and Staphylinidae were dominant.The vegetation composition characteristics of each type of microtopography differed,and the plant density showed that the concave side of the valley > greater than the convex side of the ridge,the foot of the hill > the top of the hill,and the lower slope > the upper slope;the diversity index of ground vegetation was affected by a combination of factors,and did not show significant differences among microtopography,but was directly affected by habitat factors such as elevation,soil capacitance,soil conductivity,soil p H,soil organic matter content,soil fast-acting potassium content,etc.(3)The soil seed bank and above-ground vegetation in the study area showed large differences.The family Asteraceae,Primulaceae,Gramineae,Labiatae,Salicaceae,Caryophyllaceae,Rosaceae,Amaranthaceae,Spiniferae,and Lydiaceae were dominant.The overall seed bank density is concentrated between 887.91 ～ 2685.40 seeds/m~2 and is in the middle stage of community succession.Artemisia spp.have an important position in the composition.The spatial and temporal dynamics of the seed bank in the study area had significant characteristics.The seed bank species and reserves of the seed bank sampled before winter were significantly less than those before spring,and the seed reserves of the 0-2 cm surface layer were higher than those of the middle and lower layers of 2-5 cm and 5-10 cm,while the number of species did not differ significantly.Soil seed banks showed significant edge effects in the study area.The similarity index of each soil layer with the ground vegetation showed a pattern of large top and bottom and small middle.(4)Elevation directly affects the diversity of ground vegetation and also indirectly affects the diversity of ground vegetation by influencing soil capacitance,soil conductivity,seed bank diversity,and has an impact on the similarity of ground vegetation to the seed bank.Slope does not directly affect ground vegetation composition,but influences nutrient uptake and thus seed bank diversity by affecting soil p H.The diversity indices of seed bank and ground vegetation were significantly correlated,but different diversity indices influenced in different directions,and the dominance index usually had a negative influence on other diversity indices.