The Mechanisms Of The Vegetation Restoration And The Reconstruction Model In The Hilly Area Of Taihang Mountains

The hilly area in Taihang mountains is an ecotone between the plain vegetation and the mountainous vegetation. As a result of the overexploitation to vegetation for a long time, ecosystems in the study area have degraded seriously, which are characterized by natural vegetation with lower coverage, lower height, even bare land in some parts, and mosaic patches with different types of artificial vegetations. The ecological protection functions of the vegetations have been declined. The biological productivity was lower. In order to provide the theoretical basis for the project of conversion of cropland to forestland and grassland and the ecological forestry environment construction in the near future, the major types of the natural and artificial vegetations in Taihang mountains have been selected as a case for study. The ecological mechanisms and approaches of vegetation restoration and rehabilitation have been explored.Based on the methods of continuous quadrat, random sampling, biomass measurement and photosynthesis measurement, the distribution characteristics and the causes of the major plant communities, the ecological mechanisms and ways for vegetation restoration in the hilly areas of Taihang mountains have been analyzed in this study. Meanwhile the intraspecific relationships between Staghorn sumac and native plant species, plant species diversity, the relationship between characteristics of the degraded vegetations and the small-scale spatial heterogeneity had been explored. The results were as follows:(1) The distribution characteristics of natural vegetation are influenced by the disturbance regime, the dispersal and spread mechanisms of plant propagulum, and the small-scale spatial heterogeneity. The natural shrub vegetation is composed of the tree species with the scattered distribution pattern, the shrub synusium with discontinuous distribution and the constant herb synusium. With the slope moving up, the results obtained by analyzing the data of neighbor sub-plot also showed that Shannon-wiener index reduced greatly and Pielou evenness index decreased a little. The species number of perennial weed, graminoid plant and therophyte decreased. Herb liana disappeared and the number of sub-plot for the succulent increased, but the species number of perennial weed, graminoidplant and therophyte on the whole slopes were the largest; the number of species belonging to the achene and the caryopsis was the most for the association of Vitex negundo var. heterophylla- Bathriochloa ischaemum, the number of species belonging to the caryopsis and the drupe was also the most for the association of Zizyphus jujuba - Bathriochloa ischaemum .The number of plant species belonging to the raceme, the panicle and the mesoxerophyte was the largest for the two associations above.The root-type spectrum was as follows: taproot type>root sprout type>rhizome type>tuft root type >bulbous root type. It was concluded that the plant reproduction strategy of shrub grass-land in the area of Taihang mountains was characterized by combining plants with the amemophilous flower, the entomophilous flower, the aerochorous seed and the taproot system to adapt to the modern environment in the hilly area of Taihang mountains.(2)The characteristics of natural vegetation degradation were summed up as follows: the vertical closure of natural community had been reduced. The cover and the plant species diversity in the natural community also reduced. The ecological dominance of alien species is increasing as time going. The combinatorial stresses of the degraded habitat have been strengthening.(3)According to the distinct features of the clonal growth of Staghorn sumac ramets which the front part of the lateral root diameter is much larger than the back part, and the growth rate of height and crown are faster, the following viewpoints are put forward for the first time. Staghorn sumac can form monodominant community in five years or so in the shrub-grassland, and spread outside. The deciduous shrub synusium and herb synusium in the shrub-grassland will...