Study Of Community Ecology For Parakmeria Lotungensis Forests In Fujian Province

Parakmeria lotungensis is a kind of evergreen broad-leaved tree and a kind of endemic,rare and endangered species in China.It is distributed in several provinces,but wild populations and individuals are scarce.There are still several natural Parakmeria lotungensis communities well preserved in Fujian province.In this paper,we investigated four climax evergreen broad-leaf forests with Parakmeria lotungensis as the constructive species,located in Niuge mountain plot(hereafter referred to as PN),Qitai mountain plot(hereafter referred to as PQ),Huangtuling plot(hereafter referred to as PH),and Wanmulin plot(hereafter referred to as PW),in Fujian,and conducted a study on the community ecology analyzing community structures,biodiversity,niche width and overlap of dominant species,interspecific association etc.The main results are as follows:1.In terms of community habitats:The Parakmeria lotungensis forest in PN is distributed along both sides of the ridge with the slope aspect of northeast and southwest and with the average elevation of 792 m.The forest in PQ is mainly distributed on the northeast,northwest and north slopes with the average elevation of 629 m.The forest in PH is distributed on a gentle hill next to a village,with the average elevation of 726 m.The forest in PW is mainly distributed on the southwest upper slope close to the ridge,with the average elevation of 445 m.2.In terms of community structures:According to importance values,the Parakmeria lotungensis forest in PN is named Ass.Parakmeria lotungensis-Sarcandra glabra-Hicriopteris glauca.The forest in PQ is named Ass.Parakmeria lotungensisArdisia punctata-Dicranopteris dichotoma.The forest in PH is named Ass.Parakmeria lotungensis-Sarcandra glabra-Lophatherum gracile.And the forest in PW is named Ass.Parakmeria lotungensis-Maesa japonica-Woodwardia japonica.The ecological dominance in different layers from high to low are:herb layer>tree layer>shrub layer,consistent in all the 4 plots.Parakmeria lotungensis is more dominant in PQ and PH than in PN and PW.3.In terms of areal types of the families for seed plants,the tropic element is the main component in all the 4 plots,accounting for about 50%.Variations in the proportion of widespread and temperate elements are are slightly different in different plot,which are unconspicuously associated with altitude of plots.The proportion of temperate elements is higher in PW,where is at low altitude,while less in PN and PH,where are at high altitude.In terms of areal types of the genera for seed plants,the tropic element is more dominant than that at a family level,accounting for about 80%,then the temperate element accounting for about 16%.The widespread element accounts for a tiny proportion.The variation trends of geographical elements’ proportion are similar in different plots.In the tropical elements,the Pantropic has the largest proportion,followed by Trop.Asia and OW Trop.In the temperate elements,E.Asia&N.Amer.disjuncted has the largest proportion.In terms of endemic plants,there are 2 Chinese endemic genera and 47 Chinese endemic species in all of the plots,accounting for up to 23.3%of total species,indicating that the Parakmeria lotungensis community is worthy of preservation as a aggregate.4.In terms of species diversity,generally,Margalef index(hereafter referred to as R),Shannon-Wiener index(hereafter referred to as H’)and Simpson index(hereafter referred to as D)are higher in PN and PQ than in PH and PW,but the Pielou index(hereafter referred to as J)is higher in PW and PQ than in PN and PH.Analyzing from different layers in each community,R,H’,D of PN,PQ and PH are all shown as shrub layer>tree layer>herb layer while Jis shown as tree layer>shrub layer>herb layer.There is some particularity in PW.R in the shrub layer is the highest among three layers,while H’,D,J are all the highest in tree layer.All the species diversity indices of herb layer are the lowest in each community.5.In terms of community similarity,PQ and PH are the most similar and the Sorensen index value at the level of genus and species are 0.622 and 0.532.PN and PW are the most different and the Sorensen index values at the level of genus and species are 0.473 and 0.296,respectively.According to Pearson’s correlation test,the difference of altitude between plots has more impact on the community similarity than the distance.The common species among the communities are mostly shrubs and herbs while the tall trees account for a small proportion.6.In terms of ecological niche,Parakmeria lotungensis has the largest niche width and the strongest competence to utilize environmental resources comprehensively in all the 4 plots.Other trees with wide niche are different in each plot.30.56%of species pairs have the niche overlap values over 0.5 in tree layers of PN,PQ and PH.Much more species pairs,with 72.22%,have the niche overlap values over 0.5 in tree layers of PW.The overlap values between Parakmeria lotungensis and other dominant trees in PN are not very large,generally less than 0.4.Instead,Parakmeria lotungensis has the highest niche overlap values with other dominant trees in the PW,generally more than 0.6.The overlap values between Parakmeria lotungensis and other dominant trees in PQ and PH are at a medium level.7.In terms of interspecific association,the dominant trees are in significantly positive association in PN,while in not significantly negative association in PQ,PH and PW.Except for minority of species pairs,most of species pairs are in not significant association.Combining the results of X2-test,Jaccard index and Spearman rank correlation coefficient,Parakmeria lotungensis has significantly negative association with Meliosma rigida and Litsea pungens in PN,obviously negative association with Schima superba and Altingia chinensis and significantly positive association with Litsea elongate in PQ,obviously negative association with Castanopsis fabri in PH and no significant association with other dominant trees in PW.