Characteristics Of Plant Community In The Early Stage Of Ecological Restoration Of Abandoned Slag Slope In Fangshan District,Beijing

The abandoned coal mines in Fangshan District of Beijing are widely distributed and have various site conditions.It is very important for land reclamation and ecological restoration to understand the characteristics of vegetation restoration and the relationship between vegetation restoration and environmental factors.In this paper,18 coal mine control areas in Fangshan District were selected for ecological restoration in the period of 2015-2017.By investigating and analyzing the natural restoration vegetation,topography,soil and other indicators of abandoned slag slope in the mining area,the preliminary succession characteristics of natural plant communities on the slope were systematically studied,including the characteristics of community composition,distribution and diversity.The correlation between site factors and community diversity was studied.The main results are as follows:(1)There are 73 species in the study area,belonging to 23 families and 60 genera.Herbs are the main species in the early stage of ecological restoration in mines.Among them,14 genera and 26 species belong to Compositae,12 genera and 12 species belong to Gramineae,6 genera and 6 species belong to Leguminosae,and 32 genera and 44 species belong to three families,accounting for 60%of the total species.This indicates that the three families occupy an important position in the initial succession of natural vegetation on the abandoned slopes of coal mines.TWINSPAN the Two-way Indicator Species Analysis method was used to divide 28 survey plots of abandoned slag slope in Fangshan Coal Mine into 4 groups of plant communities.Community ?:Artemisia annua-Artemisia scoparia;community ?:Artemisia sieversiana-Setaria viridis;community ?:Salsola collina-Setaria viridis;community ?:Saussurea japonica-Artemisia desertorum.(2)The CCA canonical correspondence analysis method was used to explore the distribution characteristics of natural plant communities in coal mine abandoned slag slope.The results showed that the distribution of community was affected by both topographic and soil factors,in which elevation,slope direction,total nitrogen,organic matter and soil bulk density played an important role.Community I was distributed under high habitat conditions(910?1149m,mean 101 7m)and soil nitrogen(0.95?2.59mg/kg,mean 1.73mg/kg).Community ? was distributed in the sunny slope,soil organic matter(2.00?42.58‰,mean 24.49‰)high content of habitat;community ? distributed at lower altitudes(253?976m,mean 394m),soil bulk density(1.32?1.72g/cm3,mean 1.51 g/cm3)under high habitat conditions;community IV distributed on the Yin slope,soil The bulk density(1.11?1.32 g/cm3,mean 1.23g/cm3)under low habitat conditions.(3)The species diversity characteristics of natural plant communities in coal mine abandoned slopes were analyzed by alpha diversity index and beta diversity index.The results showed that in the initial stage of vegetation succession,community ? had the highest diversity index and the best recovery effect,while the recovery effect of community ? was relatively poor.Community ?represents the most common direction of community succession in Natural Restoration Vegetation Communities on slopes.Community ? and community IV have different vegetation succession directions,and elevation and soil bulk density play an important role in many site factors.(4)Multivariate regression and grey correlation analysis were used to explore the correlation between species diversity and site factors.The results showed that the topographic factors most closely related to species diversity were altitude,soil factors were total nitrogen,organic matter and soil bulk density,and the high soil bulk density in the study area played a restrictive role in vegetation restoration.