Research On The Interspecies Of The Dominant Species Form Different Plant Successional Stages On Road Cut-slopes

Road cut-slope is a new type of bare surface formed by excavation and translocation of rocks and soils on terrestrial surface in road construction and mining. Ecological restoration of these surfaces has become an important and urgent practical task for not only disaster prevention and control but also natural landscape restoration. Therefore, understanding the processes and mechanisms of plants succession in road cut-slopes, and the interspecies of dominant species form different successional stages, will become the pivotal steps for plant rehabilitation on them.Objective: Use of a space-for-time substitution, the successional sequences consisting of different cut-slopes resulted from roads construction in different times around Chengdu area were selected to investigate the processes of plant succession in this study. The simulation experiments were used by collecting seed rain, substrates (soils, litters) to reveal the interaction mechanisms of dominant species at each succession stage. It probably provide theoretical basis for species choice in restoration practice.Methods: Combined field and laboratory investigations were conducted in the study. The former was used to investigate the species change of the successional sequence in road cut-slopes; the latter was used to study the interspecies of the dominant species at different successional stages.Results: The results of field investigation indicated that Pielou index reached maximal in the successional stage of 20 years period in the sequence, while Margalef index, Shannon-Wiener index and Simpson index reached maximal in successional stage of 50yr peroid. Afterwards both species and amount of plants had some decline. Although species diversity had somewhat decline in the 65yr successional stage, the community's layer structure consisting of wood, shrub and grass had formed. Indicating plant succession on the road cut-slopes approached climax community under climate conditions of study area.The results of simulation show that the dominant species form different successional stages had different response to nutrient factors under addition N,P,NP. Vitex negundo Linn. from early successional stage had markedly higher in total biomass than one in the control under N,NP (both p < 0.05), while did not have difference occurring between treatment of P and control. Similarly, Bauhinia purpurea L. had also higher in total biomass than the control in all treatments, and there was not significant difference. The total biomass of Cupressaceae did not have obviously different among all addition nutrient conditions (all p > 0.05).Under the conditions of adding nutrient, all dealt base diameter, inside the roots, and outside the roots (Pot experiments selected species the roots of the parts contacting root positive for internal roots while the rest is outside roots) has a slight difference compared with the reference. However, treatment inside and outside the roots the same plant all have significant difference (p <0.05 on average).The biomass of Vitex negundo Linn, Bauhinia purpurea L and Cupressaceae planted individually are higher than that when they are planted mixed with each other. For example, when fertilized NP, the biomass of Vitex negundo Linn, Bauhinia purpurea L differs significantly (p=0.05),when fertilized P, significant difference(p=0.049). While Cupressaceae has no difference when when fertilized P and NP, when fertilized N, no significant difference. When planted individually, the Root diameter of Vitex negundo Linn (base diameter, outside the roots, inside the roots) is bigger than that when mixture sowing. Which is the same to that of Bauhinia purpurea L and Cupressaceae. However, Bauhinia purpurea L is significantly different when fertilized P(P<0.05).However, there is no difference for Cupressaceae.Main conclusion: Different dominant species response to different Main nutrient elements in different Succession stages. The species without Nitrogen-fixing ability (Vitex negundo Linn) are more sensitive to the Exogenous nutrient that those with Nitrogen-fixing ability (Bauhinia purpurea L, Cupressaceae). For the effect of nutrition, the effect of N is the biggest, which may be one of the Major limiting factors in the Wound vegetation succession.There exists the obvious competition between the Superiority species in different succession stages in which the species will distribute the photosynthesis product by itself for the public room or nutrition in the earth.