Vegetation Distribution Pattern And Environmental Interpretation In Sphagnum Wetland Of Dajiu Lake,Shennongjia

Wetland vegetation pattern refers to the distribution position,layout and community structure of vegetation in a certain area,which has a certain indicating effect on the changes of the ecological environment in the area.we carried out the field investigation and sampling for both vegetation and environmental factors on August 2020,by setting belt transect and quadrats along the direction perpendicular to lakeshore in Sphagnum wetland of Dajiu Lake,Shennongjia.Record all the plant species and plant height and coverage of the plant in the sample plot;collect soil,groundwater,and Sphagnum palustre L.samples for determination and analysis in the laboratory.Through the analysis of the correlation between vegetation data and environmental factor parameters to explore(1)the vegetation distribution pattern and influencing factors of Sphagnum wetland of Dajiu Lake,(2)the distribution and formation mechanism of the key species of Sphagnum wetland of Dajiu Lake—Sphagnum palustre L.population.This study provides theoretical basis and scientific guidance for Sphagnum wetlands protection and restoration in subtropical mountain regions.The main findings are as follows:(1)There are certain differences in environmental factors along the vertical lakeshore.The largest coefficient of variation is the two stoichiometric ratios: soil TOC/TN,groundwater TN/TP;followed by groundwater TP,soil bulk density,soil solids ratio,groundwater TN,groundwater level;the physical and chemical factor with the smaller coefficient of variation is groundwater p H,Soil p H,soil porosity,soil liquid ratio.Among them,there is a strong correlation between groundwater level,soil TOC,soil TN,and soil AHN.(2)A total of 35 species of plants in the selected typical transects,belonging to 21 families and 32 genera.There is only 1 species of spiraea(Spiraea salicifolia),31 species of herbaceous plants,and 3 species of mosses.Among them,there are many plants in Cyperaceae,Compositae,Gramineae,Polygonaceae,and Rosaceae.There are three species of mosses: Sphagnum palustre,Polytrichum commune,and Aulacomnium androgynum.Among them,Sphagnum palustre L.is the main dominant species.The increase of the distance along the vertical lakeshore of Sphagnum wetland of Dajiu Lake forms 11 different community types,which have obvious zonal distribution characteristics in the spatial pattern.From the edge of the lake to the outside: Ass.Calamagrostis epigeios-Sphagnum palustre?Ass.Carex capilliformis-Sphagnum palustre?Ass.Euphorbia sp.+Carex capilliformis-Sphagnum palustre?Ass.Osmunda cinnamomea-Sphagnum palustre?Ass.Eriophorum comosum + Carex capilliformis-Sphagnum palustre?Ass.Veratrum nigrum + Carex capilliformis-Sphagnum palustre?Ass.Calamagrostis epigeios +Sanguisorba officinalis-Sphagnum palustre?Ass.Sanguisorba officinalis + Carex capilliformis-Sphagnum palustre?Ass.Carex argyi + Sanguisorba officinalis-Sphagnum palustre?Ass.Sanguisorba officinalis + Carex capilliformis?Ass.Spiraea salicifolia-Sanguisorba officinalis.(3)The increase of the Patrick?Shannon-Wiener?Simpson and Pielou four diversity indexes of the 11 association along the vertical lakeshore distance showed a trend of first increasing,then decreasing and finally increasing.The 4 diversity indexes in association I are all the smallest,and the 4 diversity indexes in association XI are all the largest.(4)The results of RDA analysis showed that the cumulative interpretation rate of the first two axes reached 45.82%.The first axis mainly reflects the changes of plants and communities along the soil p H and groundwater level,and the second axis mainly reflects the changing trends of soil TP,TOC,and TN.Taken together,the most critical environmental factors affecting the distribution of species and communities in the Dajiu Lake peat moss wetland are soil nutrients: TP,TOC,and TN;followed by soil p H and groundwater level.(5)With increasing vertical distance from lakeshore,each of the three growth indicators(number of capitula,coverage,biomass)of S.palustre and the height of the moss mound increased firstly and then decreased,with largest productivity of S.palustre population occur at about 40 m away from the lakeshore vertically and the moss mound reaches the highest at about 40 m from the lakeshore.(6)Water table have an influence on photosynthesis and respiration of S.palustre capitula,and soil TOC have an influence on C absorption and C assimilation in S.palustre tissue,that further affect its population growth and distribution pattern.Within the scope of this study,groundwater level,soil TOC,and tissue TC all promoted the growth of S.palustre.