Plant Community Characteristics And Plantation Health Assessment In The Reclamation Area Of Pingshuo Opencast Coal Mine

Pingshuo Antaibao Opencast Coal Mine is located in the north of Shanxi,where the eco-environment is extremely fragile.The large amount of waste rock and soil produced from the opencast mining had caused huge damage to the ecological environment.Since the middle of 1980's,the land reclamation and ecological rehabilitation have been made a great progress by the Coal Mine.The results indicated that relatively stable artificial forest communities and herbaceous plant communities have been established.However,there still exists doubts in the plant species diversity of artificial ecosystem in the reclamation area,the stability of the plant communities,and the health of the ecosystem.These are still important scientific issues to be answered urgently.In this paper,the plant species,analysis of the growth of plantation communities,and assessment of the health situation of plantations in the Coal Mine reclamation area were studied by TWINSPAN,DCA,RDA,PCA etc.It will provide data and theoretical basis for the ecological rehabilitation research and scientific management of the mining area.The main results were as follows:1.The Pingshuo Antaibao Opencast Coal Mine reclamation area?referred to as the reclamation area?had more plant species,with a total of250 species?including sub-species?,belonging to 42 families and 149 genera.Among the 250 species,Gramineae,Compositae and Papilionaceae were dominant families.Dominance of genus composition was not obvious.Life forms of the plants were relatively simple,among which the herbs were dominant,followed by the trees and shrubs,and the grassy lianas were the fewest.Among the areal-type of family was dominated by the world distribution,and that of genus was the temperate zone.The flora of this area has obvious temperate characteristics.2.The plant communities in the reclamation area were divided into 7forest communities and 12 herbaceous plant communities by TWINSPAN.Compared with natural communities,there were fewer types of plant communities in the reclamation area.Compared with the initial planting patterns,the forest community structure had not been changed significantly,but the herbaceous plant communities were opposite.The results from DCA showed that both the forest communities and the herbaceous plant communities were distributed along the gradient of soil moisture and altitude,which were the main environmental factor affecting the distribution of plant communities in the reclamation area.3.Compared with 2010,the stand structure of the plantations in the reclamation area changed significantly in 2015.Robinia pseudoacacia+Ulmus pumila+Ailanthus altissima plantation had the maximum tree density.Picea wilsonii+P.meyeri+Pinus tabulaeformis plantation had the minimum.Except for U.pumila+Salix cheilophila plantation which had the slight increase in total tree density,the tree density of all other plantations was decreased.Among them,the decrease of the tree density of R.pseudoacacia+U.pumila+A.altissima plantation was the most,while that of P.wilsonii+P.meyeri+P.tabulaeformis plantation was the least.R.pseudoacacia,being the edificator,had the highest number of death,while S.cheilophila had the lowest.R.pseudoacacia+P.tabulaeformis and U.pumila+S.cheilophila plantations had mainly medium age trees.P.wilsonii+P.meyeri+P.tabulaeformis and R.pseudoacacia+U.pumila+A.altissima plantations had mainly younger trees.R.pseudoacacia plantation had mainly medium and younger trees.The DGH?Diameter at Ground Height?of the seedlings were mostly in the shape of inverted"J"or unimodal curve,while the TH?Tree Height?also was unimodal curve.The lever of DGH increased together with the proportion of main levels.The average DBH?Diameter at Breast Height?and TH of the plantations were significantly different,and the interannual variation trend was the same.R.pseudoacacia+P.tabulaeformis plantation had the largest DBH and TH,and P.wilsonii+P.meyeri+P.tabulaeformis plantation had the smallest.The DBH of plantations increased by 0.38 cm per year,of which the growth of R.pseudoacacia+P.tabulaeformis plantation was the largest.However,the growth of P.wilsonii+P.meyeri+P.tabulaeformis was the smallest.The TH of plantations increased by 0.19 m per year,of which the growth of R.pseudoacacia plantation was the largest,and the growth of R.pseudoacacia+P.tabulaeformis plantation was the smallest.Generally,the plantations in the reclamation area were gradually entering the end stage of development,and beginning to enter the stage of natural succession.4.There are 23 dominant herbaceous plant species of plantations in the reclamation area from 2010 to 2015 in total.The species number of Gramineae was the largest?10 species?,followed by Compositae?6 species?,Papilionaceae?5 species?,Labiatae?1 species?and Chenopodiaceae?1species?.The dominance of Artemisia sieversiana and A.annua became weak gradually in R.pseudoacacia+P.tabulaeformis plantation,while the dominance of Stipa bungeana,Elymus dahuricus and S.sareptana were enhanced.Bidens parviflora,Leonurus artemisia,Gueldenstaedtia stenophylla and Chenopodium album became dominant species gradually.The dominance of Roegneria ciliaris and A.annua declined gradually in R.pseudoacacia+U.pumila+A.altissima plantation,while the dominance of Saussurea amara increased.S.caucasica became dominant species gradually.The dominance of S.bungeana,R.ciliaris,Heteropappus altaicus,L.artemisia became weak gradually in R.pseudoacacia plantation,while the dominance of E.dahuricus increased.B.parviflora,A.annua,A.sieversiana,Agropyron cristatum became dominant species gradually.The dominance of S.bungeana,R.ciliaris,A.ordosica became weak gradually in P.wilsonii+P.meyeri+P.tabulaeformis and U.pumila+S.cheilophila plantations,and the dominance of E.dahuricus,Poa sphondylodes,Cleistogenes squarrosa increased,Medicago sativa,Lespedeza davurica,Melilotus albus and M.officinalis gradually became dominant species.5.There were significant differences in herbaceous plant species diversity between plantations and interannual?P<0.05?.The species abundance?R₀?and diversity?H??of P.wilsonii+P.meyeri+P.tabulaeformis plantation were the highest,and those of R.pseudoacacia+P.tabulaeformis plantation were the lowest.R.pseudoacacia+P.tabulaeformis plantation had the highest dominance???,but P.wilsonii+P.meyeri+P.tabulaeformis and U.pumila+S.cheilophila plantations were lower.The uniformity?E?of herbaceous plant varied opposite to the dominance.The species abundance and diversity of herbaceous plant in plantations were the highest in 2011,and the lowest in 2014.The inter-annual dynamics of herbaceous plant dominance was opposite to that of species diversity.In 2013,the uniformity of herbaceous plant in plantations was the highest,and the lowest in 2010.6.The results form correlation analysis between the plantation communities and environmental factors showed that DBH,TH,Patrick richness index,Shannon-Wiener index,Simpson index,Pielou index,soil bulk density,field moisture capacity,soil available phosphorus,soil moisture content,soil organic carbon,autumn precipitation,winter mean temperature,and spring precipitation were significant correlation?P<0.05?.Based on the results of RDA,the soil bulk density,autumn precipitation,field moisture capacity,winter mean temperature,and soil available phosphorus were the main environmental factors affecting plantation communities.The soil bulk density and autumn precipitation had the greatest influence.7.The results of plantation ecosystem health assessment showed that the broad-leaf plantations in the reclamation area were healthier than the coniferous plantation,and the plantations with higher stand age were also healthier.R.pseudoacacia+U.pumila+A.altissima and R.pseudoacacia plantations were high-quality.R.pseudoacacia+P.tabulaeformis plantation was healthy.P.wilsonii+P.meyeri+P.tabulaeformis,R.pseudoacacia+Caragana korshinskii,R.pseudoacacia+Hippophae rhamnoides,R.pseudoacacia+C.korshinskii+Elaeagnus angustifolia plantations were sub-healthy,and Populus simonii plantation was unhealthy.The plantation ecosystem health assessment is not only a survey of the health status of the plantations,but also a test of the ecological rehabilitation models of the Antaibao Opencast Coal Mine.From the assessment results,R.pseudoacacia+U.pumila+A.altissima and R.pseudoacacia models were the better model.