| Shibing Karst World Natural Heritage Site has vast native forest vegetation and diverse ecosystems.It is rich in species and has unique natural landscape,aesthetics and scientific value.Since the official listing of Shi Bian Karst in the World Natural Heritage List in 2014,the development of mountain tourism in the heritage site has been further accelerated.Many new tourist facilities have become a new landscape of heritage sites.In recent years,many tourists have been pouring in to the heritage sites.Sexual protection has some negative effects.The increasing frequency of mountain tourism activities is becoming an inevitable challenge for the effective management and ecological environment protection of Shih-Hsien.Therefore,the study of plant community structure characteristics and species diversity and stability of plant communities under different tourism disturbances in Shibing Karst World Heritage Site can provide theoretical basis for plant resources protection and sustainable development of mountain tourism in the heritage site.In this study,the subtropical coniferous-broad-leaved mixed forest in the core area of Shibing Karst World Heritage Site was taken as the research object.The structural characteristics of the community were studied and analyzed.The species diversity of the plant communities under different intensity of tourism disturbance was compared and analyzed.On this basis,the plants under different intensity of tourism disturbance were evaluated and analyzed by M.Gordon stability test and principal component analysis.At the same time,the relationship between species diversity and stability was analyzed.In addition,through research and analysis,the maintenance mechanism of community stability in heritage sites was revealed,and some measures to maintain the stability of plant communities were put forward.The main conclusions are as follows:(1)Heritage sites are rich in plant resources,there are 186 species of vascular plants,belonging to 68 families and 145 genera,including 158 dicotyledons,13 monocotyledons,6 gymnosperms,9 ferns,59 trees,77 shrubs,46 herbs and 4 vines.Rosaceae,Lauraceae,Leguminosae and Rutaceae are the dominant families.The seasonal change of the community in the heritage site is not obvious.The life form of the community is dominated by high-position buds,followed by aboveground buds and ground buds,and less cryptophytes and annual plants.The community stratification is obvious,which can be divided into tree layer,shrub layer and herb layer.The dominant species in each layer of the community are more uniform.Most of the plants in the community are calcium-loving and drought-tolerant.(2)The Marglef richness index and Shannon-Wiener index of Simpson index under different tourism disturbance intensities showed as follows: weak interference > moderate interference > no interference > strong interference,while Pielou evenness index showed as follows: moderate interference > weak interference > strong interference > no interference.A certain intensity of tourism disturbance can improve the species diversity level of the community as a whole.The Marglef richness index,Simpson index and Shannon-Wiener index of different communities were characterized by arbor layer > shrub layer > herb layer,while the Pielou evenness index was expressed as herb layer > shrub layer > arbor layer.(3)M.Godron stability test found that the Gordon ratio of strong disturbance community generally deviated from the stable point,and the stability was poor.The Gordon ratio of other disturbance intensity communities was close to the stable point,and the stability was high.Principal Component Analysis(PCA)showed that the three most important factors affecting the community stability of primary coniferous-broad-leaved mixed forest in karst area were average tree height,the proportion of adult trees and the proportion of young trees.The results of stability index method showed that C2(Pinus massoniana + Rhododendron)community had the largest stability index,and A3(Caragana cremastoides + Rhamnus heterophylla)community had the smallest stability index.The number of sample plots with strong and strong community stability accounted for 80%,and the number of sample plots with poor community stability accounted for 20% of the total sample plots.The forest community in the heritage site was in a relatively stable state as a whole.The change trend of stability index and diversity index was similar among different communities,and there was a significant correlation between species diversity and community stability(P < 0.05).(4)Species diversity in plant communities in heritage sites is the basis for maintaining the stability of plant communities in heritage sites.The diversity of species causes stability to be the main maintenance mechanism for plant community stability in heritage sites.According to the different degrees of tourism disturbance and vegetation zonal distribution of different plant communities,the artificial cultivation of native species and natural restoration of vegetation can effectively maintain the stability of plant communities in the heritage sites. |
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