Response Of Plant Community Functional Traits To Karst Mountain Tourism And Its Maintenance Mechanism

Guizhou Shibing Dolomite Karst has a globally outstanding value in its natural geological aesthetics,natural karst forest aesthetics and biodiversity.It was officially listed in the World Natural Heritage List in 2014,and the karst mountain tourism developed with it became Shi Bing.The threat to the plant community in the heritage site,and under the general trend of mountain tourism development,the threat is gradually rising.Plant functional traits can reflect the response of plants to changes in the growth environment.Exploring the variation of plant functional traits can help to predict large-scale environmental changes from small-scale changes,and explore the evolution of plant communities and ecosystems from individual species growth.This study takes the dominant species of plant population in the Shibing Karst World Natural Heritage Site in Guizhou as the research object.According to the basic theory of plant geography,the typical plot survey method and the standard method(Cornelissen JHC,2003)are used in 2018.From September to September,a field survey and a sample survey were conducted at the Shibing Karst World Natural Heritage Site.A total of 31 fixed plots were delineated.Sample collection and investigation of plant species composition and dominant species in the heritage site were carried out.The functional traits of plants were carried out.The variation characteristics of functional traits of different plants under different disturbances and different topography were compared and analyzed.The response of plant functional traits to mountain tourism in karst heritage sites and its maintenance mechanism were explored.(1)The study found that the forest vegetation is broad-leaved forest dominated by the family Fagaceae,Polygonaceae and Magnoliaceae,and the coniferous and broad-leaved mixed forest composed of Pinaceae and Polygonaceae,and the coniferous forest dominated by Damingsong and Masson pine.And the mountain shrubs dominated by Astragalus and Haitong,and the floodplain shrubs dominated by mosquito mother trees and sphagnum.The vegetation succession tops the mid-subtropical evergreen broad-leaved forest and the evergreen deciduous broad-leaved mixed forest.The community structure is obvious,the species is rich,and the vegetation coverage is high.It is a natural habitat of plants.There are many rare and endangered plants,such as Taxus chinensis(Pilger)Rehd and Amentotaxus argotaenia(Hance)Pilger.Wait.There were 81 species of trees in the plot,with an average height of 9.46 m,an average height of 3.14 m under the branches,an average DBH of 12.30 cm,216 species of shrubs,an average height of 1.2m,an average base diameter of 1.39 cm,and 82 species of herbs with an average height of 0.28 m.(2)In general,there are 8 species of 12 plant functional traits in the dominant species of arbor,which have significant differences in different degrees of interference.The chlorophyll of the arbor layer was significantly higher than that of the strong,weak and non-interference areas in the moderate interference zone.The leaf fresh weight and leaf dry weight were significantly lower in the weak interference zone than in the non-interference zone,and the twig length was strong > weak > medium > no The strong interference area is significantly higher than that of the non-interference area.The cross-sectional area of the branch is significantly lower in the non-interference area than in the strong,medium and weak areas.Correlation analysis indicates that the chlorophyll of the tree is positively correlated with the leaf fresh weight,and the leaf dry matter There was a significant negative correlation(p<0.05).There was a significant positive correlation between leaf fresh weight and dry weight(p<0.01),but it was significantly negatively correlated with leaf dry matter content.Leaf fresh weight was in strong interference and medium disturbance.The growth rate is higher than the leaf dry weight;the regression analysis shows that the leaf fresh weight and leaf dry weight of the tree are most sensitive to the response intensity,and the leaf fresh weight gradually increases as the interference becomes weaker and stronger.The weight also gradually increases,and in order to ensure the ability of plants to obtain resources,plants need larger leaf dry matter content,and plants should rapidly increase the dry weight of the leaves to achieve balance while being disturbed seriously;leaf dry weight and specific leaf area Significantly negatively correlated It indicates that when the plant is subjected to moderate or strong interference,not only the rapid increase of the dry weight of the blade but also the reduction of the blade area is required to ensure a small specific leaf area and improve the defense ability of the blade.The dry matter content of shrub layer from high to low is no interference > weak > medium > strong,no leaf area is weak < medium < strong,small branch cross-sectional area is not < weak < strong < medium,in the same community and trees In contrast,the response of the shrub to the degree of disturbance is more representative of the gradient change,and the regression analysis shows that the specific leaf area and the cross-sectional area of the branch are the sensitivity of the shrub layer to the change of the disturbance intensity,and the interpretation of the interference intensity.For the cross-sectional area of the branchlets,the cross-sectional area is gradually increased and the specific leaf area is gradually increased with the interference,free,weak,medium and strong sequence.Although the branchlets become thicker and provide more mechanical support,the gradually smaller leaf area,even if it has a high leaf strength,cannot change the leaf dry weight and the larger specific leaf area which are less interfered by the disturbance.Degradation trend.In the same interference degree area,the trend of the trait value is consistent with the trend of large-scale topographical parts.(3)There were 9 significant differences in the 12 plant functional traits of shrubs in different terrains.From the top to the middle of the shrubs,the leaf traits increased,the branch traits decreased,the function of the vegetation changed from weak to strong,the vegetation utilization rate of the community increased,and the trait value stabilized,but the twigs The trait value generally showed a downward trend,and the leaf strength decreased.The results of regression analysis showed that the arbor was most sensitive to the change of the topography by the cross-sectional area of the branchlets,the diameter of the branchlets,the number of leaflets and the strength of the leaflets.The diameter of the branches was small + the number of leaflets or the branchlet cross-section + the branchlets The combination of strength traits,that is,the change from the top of the mountain to the valley,the branchlets become thicker,the number of leaflets increased,and photosynthesis is enhanced;the shrubs have four sensitivities of chlorophyll,leaf dry matter content,twig diameter and twig cross-sectional area,along with the mountaintop— The topographical changes of the valley,the chlorophyll and leaf dry matter content gradually increased,and the branchlet diameter and branchlet cross-sectional area decreased gradually.This functional trait variation strategy is adapted to the weaker light intensity and less nutrient environment in the middle and lower parts of the mountain,increasing photosynthetic capacity and competitiveness of nutrients.(4)The leaf traits of plants and the variation characteristics of the current twigs are reflected in the photosynthesis ability of plants and the ability to acquire resources such as soil nutrients and space.During the development of Shibing Karst mountain tourism,tourism construction and post-tourist traffic The impact is the most important interference performance,including tourism trails,service area construction,and drifting rivers.In order to maintain normal ecological functions,in mountain tourism,controlling the scale of tourism planning can increase the illumination time and light intensity of plants in the area,reduce construction waste and rational planning trails,reduce water stress,improve soil nutrient fixation and survival.Space,even larger leaf area and smaller leaf dry matter content and plants with slender shoots can maximize their available resources and maintain normal growth.