Phytocoenosis Of The Early Permian Tuff Flora From Southern Region Of Wuda Coalfield,Inner Mongolia

An area of 535 m2 of the "Wuda Tuff Flora"(the Chinese "vegetational Pompeii")from the lower Permian of the southern part of the Wuda Coalfield has been analyzed about community ecology,based on quantitative quadrat taphonomic investigation.In addition to previous research on this peat-forming flora,the present investigation promotes the diversity of the Wuda Tuff Flora and its plant community ecology,and as a result adds solid data on the actual reconstruction of the whole in situ preserved vegetation.Fossil plants in the studied area include 54 species of 24 genera,including 13 new species.It consists of Lycopsida(2 genera,2 species),Sphenopsida(3 genera,6 species),Filicopsida(13 genera,35 species)and Pteridospermopsida(1 genus,3 species),Noeggerathiales(3 genera,5 species),Cycadopsida(1 genus,1 species),Ginkgopsida(1 genus,1 species)and Cordaitopsida(1 genera,2 species).The new species includes Sigillaria arciformis sp.nov.?Bowmanites hallei sp.nov.?Corynepteris wudensis sp.nov.?Scolecopteris florentissimae sp.nov.?Polymorphopteris multinervis sp.nov.?Polymorphopteris densifolia sp.nov.?Sphenopteris nemejci sp.nov.?Sphenopteris calcarus sp.nov.?Sphenopteris nervosa sp.nov.?Tingia dentatifolia sp.nov.?Pseudomariopteris orbicularis sp.nov.?Pseudomariopteris falciformis sp.nov.?Taeniopteris wudensis sp.nov..On the basis of detailed systematic description of all the taxa,the community ecology has been analyzed according to the actual reconstruction.The number of standing stems represent the quantity of upper-storey trees and lower-storey trees.When stems are not observed,the scatter branches and leaves of same species in successive quadrats might indicate the existence of an upper-stroey or lower-storey tree in a particular location.The number of herbaceous plants and vines is deduced based on the number of scattered quadrats,along with the biomass for each quadrat.In the present research,the analysis of the plant community includes three major aspects.First,the vertical structure of each group is analyzed,and the allocation of individuals and biomass of each level are interpreted based on frequency,relative frequency,and density.Second,the species abundance and individual contributions to each level of each group are counted.The Simpson formula and Shannon and Weaver formula are tested,and the results are 0.965 and 3.5.The value of former formula is always less than 1;the closer the value is to 1,the richer the species diversity of the community is.The value of the latter formula falls within the normal range of modern phytocenosis and indicates level of high biodiversity.In addition,Sorensen and Jaccard index formula is used on a comparison of species composition similarity between this area and the nearby investigated area.The values are 0.244 and 0.139,which as a small value indicates a lower similarity.Finally,the life form and the minimum area of the community has been detected.The species-area curve has been obtained by using the cluster sampling method,which shows that the present studied area has not reached to its minimum area.Comparing with the forest community of a nearby area(Q2015),the present community shows a significant difference in landscape.This present community is dominant by tree ferns and herbaceous plant,whereas the community of Q2015 is dominant by tree ferns and Cordaitopsida.The biomass unit of each quadrat in the present community is 1.14,which in the nearby forest is 2.24.These significant differences show the spatial heterogeneity of the "Wuda Tuff Fora".