Study On Quantitative Vegetation Ecology Of Pinus Tabuliformis Communities In Shanxi

Pinus tabuliformis is an endemic species to China and one of the important timber and ecological species in North China.Based on the dataset investigated from the field,P.tabuliformis forests in Shanxi were studied by numerical ecological methodology,including TWINSPAN,DCA and DCCA,species diversity and taxonomic diversity,in order to provide basic database and scientific fundamention for the biological conservation,managenment and utilization for P.tabuliformis forests.Totallly,113 stands of P.tabuliformis forests were investigated in Shanxi,and the species,communities and environment factors were studied by using TWNISPAN,DCA and DCCA.The results of TWINSAPN indiceated that the communities were classified into 17 Assoeiations,and there is a certain correlation between classification and environmental factors.The results of DCA reflected two environmental gradients obvious—temperature and moisture,among which temperature is leading factors.Moreover,the community types and stands occupied different positions in DCCA ordination diagram,and the longitude,altitude,precipitation,temperature,soil organic carbon and the latitude had greatly effects on the species and the comunities distribution.The species diversity of P.tabulaeformis forests were studied by using species diversity indices.The results showed that,species richness(R),Simpson index(D)and Pielou evenness(E)have same trend.There was an opposite change between Shannon-Wiener index(H')and D.All P.tabulaeformis associations have higher species diversity index,and it have big difference in the different association.It showed that the P.tabulaeformis forest have more complex structure,higher organization level and appropriate growth environment,in which R:16-33,H':1.62-2.35,D:0.66-0.78,E:0.56-0.74.The result of Spearman's rank correlation analysis showed that the relationships between H' and E and longitude were highly significantly positive correlation(P<0.05),but the effct of latitude on the 4 indices is not significant(P>0.05).Taxonomic diversity based on the phylogenetic system directly reflects species diversity with evolutionary information and consideres evolutionary and taxonomic hierarchies among species in a community.Moreover,it can also indirectly indicate that if community structure and components are affected by habitat and disturbance.Thus,it can indicate whether a community or ecosystem is degraded.Furthermore,taxonomic diversity is robust and minimally influenced by different sampling methods and sampling areas compared to the traditional species diversity indices(e.g.,Shannon index).To explore the taxonomic diversity of the P.tabuliformis communities,there were 357 species belonging to 227 genera,71 families,36 orders,4 classes,and 3 phyla in 113 stands investigated were recorded.The compositions of genera and species within families exhibited differences.The dominant family including the most genera and species was Compositae(31 genera and 50 species),among which most of the species belonges to the genus Artemisia(11 species).In addition,the taxonomic diversity of P.tabuliformis communities were analyzed by average taxonomic difference index(?+)and taxonomic difference variation index(?+),and the relationships between taxonomic diversity indices and environmental factors was discussed.The results indicated that the expected values of?+ and?+were 53 and 280,respectively.Based on the distributions of 113 stands in the confidence funnel,the?+ value of 89.5%and all the?+ values were above the expected values of?+ and?+,which suggested that species composition of the P.tabuliformis communities had more distant relatives and belonges to different taxa.The evenness of P.tabuliformis communities was lower,given that most species belonges to a fewer of families(e.g.,Compositae,Rosaceae,Leguminosae,Gramineae).The community factors(DBH,ensity,and number of species)and microtopography factors(aspect and slope position)were the most important factors influencing the taxonomic diversity index,followed by macrotopography factors(latitude and altitude).The DBH had a highly significant and positive correlation with?+ and?+(P<0.01);the relationship between slope,aspect,and?+ was highly significant(P<0.01).The slope position had a significant correlation with?+(P<0.05)and highly significant correlation with?+(P<0.01).The relationships between?+,total nitrogen,and soil organic carbon were highly significant and positive correlations(P<0.01).The correlation of macrotopography factors with?+ and?+ was not significant(P>0.05).We concluded that most P.tabuliformis communities in Shanxi were in the steady growth stage,and the species composition was relatively stable,although there were taxonomic differences to some degree within species distributed mainly in a few of the larger taxa.