Ecological Effects Of Planted Communities On Colliery Spoil Heaps In The Lu'an Mining Area,Shanxi

The synergistic restoration of vegetation-soil system is not only the core of ecological restoration of colliery spoil heaps,but also the key of the successful ecological restoration of coal gangue piles.In this study,based on the investigation of planted vegetation on the reclaimed colliery spoil heaps of two different reclamation time(2009a and 2014 a,respectively)in Lu'an mining area of Shanxi,the relationship between different planted communities and environmental factors,interspecific associations of dominant species,and soil nutrient and enzyme activities of different planted communities were studied by using the methods of quantitative ecology,soil biochemical analysis,and so on.The ecological restoration efficiency was evaluated by using principal component analysis(PCA),and the ecological restoration strategy was put forward.The aim was to provide scientific basis and technical guidance for quickly building up self-sustaining planted vegetation-soil ecosystem on the colliery spoil heaps.The key research findings were as follows:(1)Planted communities on colliery spoil heaps in the Lu'an mining area were classified into 6 associations,which were in the early stage of ecological restorationThe 60 quadrats on colliery spoil heaps in the Lu'an mining area were classified into 6 associations by TWINSPAN classification,the classification results well reflected the relationship between planted communities and environmental factors,and got well confirmed by the two-dimensional ordination diagram of DCA;DCA sorting axis reflected a gradient in reclamation time of colliery spoil heaps,soil water content and soil organic matter.And these results indicated that the reclamation time of colliery spoil heaps and soil water content were the dominant factors affecting the composition and structure of planted communities.With the increase of revegetation restoration time,the soil water condition and soil organic matter of the planted communities on the colliery spoil heaps were gradually improved.(2)The degree of interspecific associations of dominant species in planted communities on the colliery spoil heaps in the Lu'an mining area was lowThe study on the interspecific associations among planted communities in the colliery spoil heaps by using x2-test,Pearson correlation coefficients and Spearman rank correlation coefficients showed that there were no significant interspecific associations among most of the 13 dominant species and the interspecific associations were loose.These results indicated that the overall correlations of the planted vegetation on the colliery spoil heaps were weak,the maturity degree of the planted communities was low,the structure of the communities was not perfect,and the stability was poor.All of these situations stated that those dominant species were still in the early stage of restoration succession.According to Spearman rank correlation coefficient,13 dominant species were divided into two ecological groups,and the dominant factor of ecological differentiation was soil moisture.(3)Soil quality of 6 planted communities improved with the increase of revegetation time on the colliery spoil heaps in the Lu'an mining areaThe analysis of soil physical and chemical properties of different planted communities on the colliery spoil heaps showed that,compared with un-reclaimed bare soil(Control),soil moisture was significantly affected by slope pattern and vegetation planted pattern.From the shady slope to the sun slope,the content of soil moisture gradually reduced,and mixed forests were more conducive to the preservation of moisture than pure forests;Soil nutrient increased with the increase of restoration time,the leguminous plants played an obvious role in on the improvement of soil fertility.The Platycladus orientalis has better ability to maintain the soil nutrient than the Rhus typhina.With the increase of reclamation period,revegetation restoration can effectively improve soil quality.(4)Soil enzyme activities of 6 planted communities improved with the increase of reclamation time on the colliery spoil heaps in the Lu'an mining areaCompared with the control,different types of planted communities could improve soil enzyme activity,including soil alkaline phosphatase activity,invertase activity and urease activity,and the soil enzyme activity increased with the increase of reclamation time.The soil enzyme activity of mixed forest was higher than that of pure forest,and the overall level of soil enzyme in forest type with Amorpha fruticosa was higher than that of other forest types.(5)Ecological effects of 6 planted communities on the colliery spoil heaps in the Lu'an mining area had significant differences,and the leguminous plants played important roles in the process of revegetation restorationThe results of ecological effect evaluation of different planted communities on the colliery spoil heaps in the Lu'an mining area showed that,compared with the control,the effects of different planted community types on improvement of ecological environment of colliery spoil heaps were significant.The restoration effects of mixed forests were better than that of pure forests.The plant community with many leguminous plant species had great the ecological restoration effect.With the increase of restoration time,the ecological effect of planted community on the colliery spoil heaps was more significant.In summary,this study puts forward the ecological restoration strategy of colliery spoil heaps,mainly including vegetation and soil aspects: it should be adopted reasonable measures to regulate the balance of soil physical and chemical properties for soil improvement.It should be taken into account the ecological characteristics of plant species and special site conditions of colliery spoil heaps in the choice of plant speciess.The plant combinations should be based on interspecific associations among plant species.For the reasonable design of green landscape of colliery spoil heaps,a multi-level combination of grass,shrubs and trees should be adopted and the environment condition of mining area should also be taken into account.