The Characteristics Of Endemic Plant Communities And Ecological Characteristics Of Endemic Populations And Their Responsest To Environmental Factors In The Coastal Area Of Pingtan Island

As Pingtan Island’s native vegetation,the endemic plant communities and populations can adapt to the harsh environment such as wind,salinity and high temperature,and play an immeasurable ecological benefit in preventing wind,fixing sand and conserving water and soil.With the rapid development of pingtan island in recent years,the original vegetation has been gradually replaced by artificial vegetation due to the development of tourism projects based on coastal landscape and the coupling of natural disturbance.Therefore,it is timely and necessary to strengthen the protection of the diversity of endemic plant communities in coastal areas.At present,there are relatively few studies on the plant community and population in the domestic,so it is of practical significance to carry out the research on the endemic plant community and population.This article aims at 7 types of coastal plant communities and 17 types of endemic plant populations.From the aspect of the plant community and population,it analyzed the species composition and floristic characteristics of coastal endemic plants,differences and correlations between species diversity and functional diversity,biological interaction among endemic plants and dominant species,and its response to the environment.In the view of the distribution pattern of different endemic plant populations combined with different environmental factors,we will get a better understanding of coupling and heterogeneity of endemic leaf functional traits,and how it adopts the survival strategy of combing functional traits in response to the environment.It reveals the ecological characteristics and responses to environmental factors of endemic plant communities and populations in coastal areas,and provides theoretical basis for the restoration and protection of endemic plant communities and populations.The main conclusions are as follows:This article aims at 7 types of coastal plant communities and 17 types of endemic plant populations.From the aspect of the plant community and population,it analyzed the species composition and floristic characteristics of coastal endemic plants,differences and correlations between species diversity and functional diversity,biological interaction among endemic plants and dominant species,and its response to the environment.In the view of the distribution pattern of different endemic plant populations combined with different environmental factors,we will get a better understanding of coupling and heterogeneity of endemic leaf functional traits,and how it adopts the survival strategy of combing functional traits in response to the environment.It reveals the constructive mechanism of the coastal endemic plant community and population and provides the theoretical basis and scientific measures for restoring and protecting the plant community and population.The main conclusions are as follows:1.Species composition and floristic characteristics of plant community and population(1)The research of community and statistic analysis of data: There were 107 species of endemic plant vegetation communities,belonging to59 families and 97 genera.Among them,≥5 species are Compositae(15genera,15 species),Gramineae(9 genera,9 species),and Liliaceae(6genera,6 species).Compared with various families and genera,only one family or genera accounted for a large proportion,respectively 66.10%and 38.61%,indicating that the phylogeny of the plants was more distant.Among the genera distribution,the distribution types of 107 seed plants in 15 genera all over the country accounted for 11(5 variants),indicating that the geographical composition had a certain degree of origin complexity.2.Characteristics of Species and functional diversity and relationship with the environment(1)Statics analysis of species diversity indicates: Among the seven community types,the Elaeagnus pungens shrubs had the highest richness index(R)and diversity index(H),while the lowest one is Ixeris repens grass,and the Simpson index(λ)showed the opposite trend.Its richness index(R)was 3.71 and 0.71,the diversity index(H)distribution is 2.19 and 0.89,the Pielou index(J)0.77 and 0.55,and the Simpson index(λ)was 0.18 and 0.52.This showed that the Elaeagnus pungens shrub had the highest species diversity among the seven community types,and the lowest was the Ixeris repens grass.(2)Statics analysis of function diversity indicates the levels of functional richness indexes(FAD、MFAD)and functional evenness index(FEve)of Elaeagnus pungens shrub was the highest,while the level of functional divergence indexes of Vitex trifolia shrub is the highest,and the three functional diversity indexes of the Ixeris repens grass were the lowest.The functional richness indexes(FAD 、 MFAD)of Elaeagnus pungens shrub and Ixeris repens grass was 208.383 and 38.695 and 8.480 and 3.409,respectively,and the functional evenness index(FEve)was0.560 and 0.375.The quadratic entropy index(Rao)and functional dispersion index(FDis)of Vitex trifolia shrub and Ixeris grass were10.578 and 4.315 and 3.169 and 1.730,and the functional divergence(FDiv)were 0.877 and 0.80.In conclusion,the Elaeagnus pungens.shrubs had the highest species diversity among the seven community types,and the lowest was Ixeris grass.(3)The analysis of functional diversity indexes,the correlation between species diversity indexes and environmental factors Pearson,curve fitting: Two functional richness indexes(FAD 、 MFAD)and richness index(R)and diversity index(H)had a very significant correlation,and the fitting relationship showed a strong correlation.the quadratic entropy index(Rao)and the functional dispersion index(FDis)had extremely significant correlations with the four species diversity indexes.This showed that the difference in functional diversity was largely caused by the difference in the number and composition of species.(4)Response of species diversity and functional diversity to environmental factors: The species diversity index and functional diversity index of coastal endemic plant communities were mainly affected by the island slope,aspect,soil water content,and soil salt content.As the slope direction becomes smaller,Simpson index(λ)decreases,while soil moisture content,soil bulk density,and slope increase,then richness index(R)and diversity index(H),Pielo index(J),two functional diversity indexes(FAD 、 MFAD),functional evenness index(FEve)increased.Soil salinity,soil Ph value,and soil porosity decreased,while altitude increased,and then the Functional divergence indexes decreased.3.Inter-species correlation,correlation with two diversity indexes and ecological species group division(1)The interspecific correlation analysis of the coastal endemic plant community showed that: 53 positive species within the same plant community type or based on 7 coastal endemic plant communities had positive or negative correlation ratios that were less than 1 or close to 1.In addition,there was no significant correlation between the various pairs,indicating that the interspecific associations of endemic plant communities were loose and their independence was relatively strong.(2)Analysis of the relationship between environmental factors and species showed that: According to CCA analysis combined with the results of inter-species relationship,the 53 dominant species of coastal endemic plant community were divided into 4 ecological species groups.They were 1)Species group of Eurya emarginata and Elaeagnus pungens,2)species group of Spinifex littoreus,Calystegia soldanella 3)species group of Vitex trifolia 4)Species group of Cocculus orbiculatus and Crepidiastrum lanceolatum.(3)The relationship between species diversity and functional diversity and species was analyzed: The optimal fitting relationship between positive and negative species contrast ratio and richness index(R),diversity index(H),Simpson index(λ),two functional diversity indexes(FAD 、 MFAD),and functional evenness index(FEve)was presented as a binomial curve function,And its positive contrast ratio decreases with the growth of the six kinds of indexes after reaching the peak.The comparison of negative species showed the opposite trend.Although the optimal fitting relationship between the contrast ratio of positive and negative species and functional evenness index(FEve),quadratic entropy index(Rao),functional divergence(FDiv),and functional dispersion(FDis)presented a binomial curve relationship,it reached its peak and tended to be flat.The comparison of negative species showed the opposite trend.4.Distribution pattern of coastal endemic plant populationsWe used multiple indicators to detect the distribution pattern of the endemic population: The distribution patterns of 17 endemic plant populations in different communities all obey the aggregation distribution.Endemic plant populations were mostly herbaceous,and their fruits were mostly mini fruits of caryopsis,achenes,and capsules.The propagation method of fruits was mainly by wind and ants.5.Relationship between the leaf functional traits of endemic plant population and environmental factors(1)The leaf functional traits of endemic plant: The 17 endemic plant populations showed a significantly negative correlation between specific leaf area,leaf dry matter,leaf tissue density,and leaf thickness.The content of leaf dry matter and the intensity of leaf tissue showed a very significant positive correlation.Leaf thickness showed a significant negative correlation with leaf dry matter content,leaf tissue density,and leaf area.The combination of leaf dry matter content and leaf tissue density was opposite to the leaf area.In different communities,various endemic plants showing the combination of the traits of the opposite trend of leaf length and leaf width,leaf area and leaf dry matter content and leaf tissue density.(2)Analysis of the correlation between the functional properties of endemic plant leaves and environmental factors: In areas with high water content and high salinity,the leaves were longer,leaf area and leaf tissue have large density,dry matter content is high,leaf thickness is small,and leaf area was low.While in areas with large soil density and slope and high attitude,The content of leaf area greatly in contrast with leaf area,and leaf width.