| In this study, the configuration modes of tree-shrub allocations were compared with the tree-only mode in Antaibao Opencast Coal Mine South Dump, which had 17 years of vegetation restoration. The population dynamics, regeneration and succession trend of the trees and shrubs under different modes were analyzed, and the change of soil quality indicators was compared. Using regression and principal component analysis, the relationship between plant and soil were expounded to put forward the optimization mode of the ecological restoration and vegetation reconstruction and to further enrich the research on tree-shrub configurations and their effects on mining area reclamation. This thesis aims at contributing to the theoretical development and data on vegetation restoration. The main results were as follows:Mode 1 showed the highest ranking in total survival rate at initial stage, especially for Robinia pseudoacacia for its best survivorship and stable age structure. The total basal area at breast height of the trees in mode 1 was the maximum and the proportion of mature individuals was the highest. There were also a larger number of regenerated individuals of Ailanthus altissima and Ulmus pumila. However, the investigation found that the Ulmus pumila all died in initial phase. The growth trend of Ulmus pumila in mode 1 called for further continuous observation. Mode 2 also showed higher survival rate at initial stage with significant regeneration in Robinia pseudoacacia. However, no R. pseudoacacia individuals with 3cm<DBH<4cm was found, suggesting a bottleneck point. A few numbers of invasive Ulmus pumila was present, which may gradually disappear for its weak competitive ability. In mode 3 there were more regenerated individuals and the Robinia pseudoacacia and Hippophae rhamnoides all died at initial stage. The further observation to R. pseudoacacia and Ulmus pumila showed the regenerated individuals all in small age class with weak survival ability. There were more regenerated individuals of Caragana korshinskii with sufficient reserves, for which mode 3 was expected to gradually turn into C. korshinskii pure forest. In mode 4, higher initial mortality occurred in the trees of Robinia pseudoacacia and Hippophae rhamnoides, in contrast with the lower mortality in Ulmus pumila and Elaeagnus angustifolia. There are a larger number of regenerated individuals of Ulmus pumila which also shows stable age structure. Hippophae rhamnoides were mostly at small age with a great number of regenerated individuals. There were many mature individuals of Elaeagnus angustifolia but few regenerated ones.In brief, the modes of tree configuration (mode 1 and mode 2) developed better than the mixed configuration modes of trees and shrubs (mode 3 and mode 4). Mode 1 developed notably well among all modes.In comparison with the original landform near the South Dump, pH value in all modes were lower than that of the original landform, meanwhile, the content of organic matter, total N and available K were in excess of the original landform. Among the restoration modes, the content of total N, organic matter and available K in surface soil showed the following order: mode 4>mode 2>mode 3>mode 1. The content of available N and available P was lower than the original landform. For each mode, the content of the majority of soil nutrient decreased along with the increasing soil depth. The correlations among soil indices in 20-40cm depth were not significant.The stepwise linear regression fitted well with the mean density/DBH/height to all 5 soil parameters. The principal components analysis (PCA) showed that the effects of the 5 soil parameter on the population parameters in Robinia pseudoacacia and Ulmus pumila:available P>decomposed ammonia>organic matter>pH>available K. These models had guiding significance for the cultivation and reproduction of Robinia pseudoacacia and Ulmus pumila population. |
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