| Wugong Mountain meadow is one of the most representative mountain meadow in the subtropical region of southern China.Due to its low latitude,high altitude and large growing area,Wugong Mountain meadow boasts its uniqueness among the mountains of the same latitude and height in the world.However,the rise of tourism and the construction of infrastructure in recent years have accounted for the degradation of vegetation to grassless rock and the damage of biodiversity in some areas of Wugong Mountain meadow.It poses a serious threat to the maintenance of meadow biodiversity and a severe impact on the beautiful landscape and its sustainable and stable development.This paper regards as research object the mountain meadow in the core tourist site Jingding meadow.Based on remote sensing images,96 different plots in different altitudes and slope orientations are selected as quadrats during plants'maturity period(from September to October).As for research methods,the paper employs theoretical methods of Quantitative Ecology and statistics as the basis and combines spatial data and ground survey data.Arc GIS vector intersection method is used to obtain the position data and the area of meadow communities in all the altitudes and slope orientations.The paper probes into the correlations between the spatial distribution of vegetation communities and factors including terrain and soil in the quadrats,and meanwhile into the relations of vegetation types,the spatial distribution of vegetation communities,the spatial distribution of soil as well as the landscape of community distribution with terrain,soil and other factors.It aims to provide a theoretical and scientific reference for the regeneration of degraded meadow,the preservation of biodiversity and the sustainable and stable development.The research results are as follows:1.The total area of the selected meadow region is about 1,090,374 m~2.According to the values of importance of 23 plant species in the 96 quadrats,plant communities are divided into10,including 38.58%area of silvergrass and ancient wild grass community,24.85%area of pure silvergrass community,13.45%of silvergrass,ancient wild grass and wild green grass community,6.21%of ancient wild grass and silvergrass community,4.71%of silvergrass,wild ancient grass and big-tooth mountain celery community,3.36%of silvergrass,wild ancient grass and linear-leaf pearleverlasting herb community,2.90%of dichotomous fimbristylis herb and Carex chinensis community,2.77%of arrow bamboo community,2.14%of arrow bamboo and silvergrass community,0.93%of Carex chinensis,dichotomous fimbristylis herb and silvergrass community.The results show that there is a significant positive correlation between altitude and the number of plant communities.There are 9different communities at 1900m altitude and 5 at 1600m.In the selected region,silvergrass is the absolute dominant vegetation while wild grass is the second.The community of the two is the most widely distributed one in Wugong Mountain meadow area,while the community of dichotomous fimbristylis herb and Carex chinensis and that of dichotomous fimbristylis herb,Carex chinensis and silvergrass mainly lie at 1900m,rarely seen at other altitudes.2.In the low-altitude area(1600m altitude zone),the soil environment is less than satisfactory,featuring relatively high density and p H value,low nutrient content and effective porosity,as well as poor air permeability and ability to conserve water and fertility.As a result,the plant community types are few and the biodiversity is low.The types of plant are also relatively simple as silvergrass community occupies the absolute advantage in distribution area and the community of silvergrass and ancient wild grass takes the second,sparing less than10%for the other communities.In the high-altitude area(1900m altitude zone),the soil environment is more than satisfactory,featuring low density and p H value,high nutrient content and effective porosity,as well as good soil permeability and ability to conserve water and fertility.Hence more abundant plant communities,with Carex chinensis,dichotomous fimbristylis herb and silvergrass community only seen in this area,and high biodiversity.Silvergrass is still the main dominant species.However,compared with other altitudes,the community of silvergrass and ancient wild grass and the community of silvergrass covers less area at 1900m altitudes.Except for the northeast slope with acid soil,low water capacity,high total nutrient where the arrow bamboo community grows,the other communities distributed evenly in other slopes where the distinctions of area proportion are narrowed,and the soil factors vary slightly in different slopes.3.According to the redundancy analysis(RDA)of the meadow community distribution area and the influencing factors,the characteristic values of RDA1 and RDA2 are 20.11%and5.72%respectively.RDA1 axis shows an invert relationship with altitude,slope orientation and nutrient(except ammonium nitrogen and p H),and a positive relationship with the physical structure of soil;RDA2 axis is negatively correlated with altitude and nutrient(except p H),and positively correlated with the physical structure of soil(except non-capillary porosity and maximum water holding capacity).The stepwise regression analysis and path analysis show that altitude and microbial biomass of both carbon and nitrogen have a direct positive influence on the proportion of community distribution area.Among the three factors,while microbial biomass of carbon has the weakest direct function and the indirect effect impacted by microbial biomass of nitrogen through altitude is the strongest. |
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