Structural Characteristics And Environmental Interpretation Of Typical Shrub Community In Haitan Island

Shrubs are widely distributed in Haitan Island,from the bedrock coastline to the coastal slopes,from the coastal mountains to the seamounts.It is an important part of the Haitan Island vegetation community,maintaining and stabilizing the Haitan Island ecosystem.It is of great significance.In order to understand and recognize the structural characteristics of the shrub community in Haitan Island and its relationship with environmental factors,this paper takes Haitan Island shrub as the research object,and in the early stage,through the three kinds of line method,12 hills of different sizes and sizes in Haitan Island.Carry out a tracing,record the plant species and vegetation group distribution of the mountain,and then select three representative mountain bodies to further investigate the shrub community,and analyze the structure,quantity characteristics and vegetation of the shrub community by statistics and analysis methods.Geographical distribution research,using SPSS for oneway analysis of variance and multiple comparisons to test the differences of different mountain environmental factors(altitude,slope,soil physical and chemical factors),and finally using SPSS for Spearman rank correlation analysis to obtain shrub community species diversity Correlation between average plant height,average ground diameter and environmental factors of dominant species.The main conclusions are as follows:1.A total of 137 species,121 genera and 64 families of vascular plants were surveyed in the Haitan Island shrub community.There are 46 species of 42 genera and 28 species of shrub layer,18 families,24 genera and 26 species of inter-layer plants,and 65 species of 60 genera and 31 species in herbaceous layer.The total number of species is herbaceous layer > shrub layer > interlayer.There are 46 species of shrubs in the shrub community of Haitan Island,which can form few dominant species.Moreover,among the 27 sample survey results,the proportion of single dominant species in the construction of the group accounted for half,and this situation was also found in the actual investigation of Haitan Island.Or some species of plants form dominant species,the more environmentally harsh areas,the more common,because the plants form dominant species can compete in the community for nutrients,light,and other environmental factors to compete for the environment Resources.The main community types are Ass.Eurya emarginata-Cynodon dactylon;Ass.Eurya emarginata+Dodonaea viscosa-Imperata cylindrica;Ass.Ficus erecta.var.beecheyana+Litsea rotundifolia.var.oblongifolia +Eurya emarginata;Ass.Ficus erecta.var.beecheyana+Litsea rotundifolia.var.oblongifolia+Paeonia delavayiLiriope spicata;Ass.Eurya emarginata+ Litsea rotundifolia. var.oblongifolia + Ficus erecta.var.beecheyana+ Pteris fauriei.The geographical distribution of plant genera in the shrub community of Haitan Island is dominated by tropical distribution,followed by world distribution and northern temperate zone distribution.2.In the environmental factor analysis of the shrub community sample survey in Haitan Island,according to the soil pH value of the shrub community sample,the soil of the Haitan Island shrub community is all acidic,including strong acid soil(pH<5).There are 9 sample squares.The soil pH average of Jiangjun Mountain was significantly higher than that of Junshan at the level of(P<0.01),and the soil pH average of Tianshan Mountain was significantly higher than that of Junshan at the level of(P<0.05).From the analysis of organic matter(SOM),total nitrogen(TN)and total phosphorus(TP),Tianshan and Junshan were significantly(P<0.01)larger than Jiangjunshan.Based on the results of soil physical and chemical factors in the three mountains,the soil fertility of Tianda Mountain>Junshan>Jianjun Mountain.3.The calculation of species diversity index of shrub species showed that the species richness index(R)of shrub layer,interlayer layer and herb layer of Junshan had the smallest variation range and the largest value compared with the other two mountains,indicating Junshan shrub plants.The number of species in the community is relatively rich and the species distribution is more uniform.Shannon-Winner diversity index(H) and evenness index(JSW)of Junshan's shrub layer and herb layer have the smallest variation range and the highest mean value,indicating that the species diversity of Junshan shrub layer and herb layer is relatively rich,and interspecific species.The distribution is more uniform.4.The analysis of important values and environmental factors of shrub species by CCA ranking showed that pH(p<0.01),available potassium(p<0.01)and total salt content(p<0.05)were the main factors affecting the composition and distribution of island shrub species..The variance decomposition of the environmental factor interpretation indicates that the interpretation of the species composition of the shrub community by the three environmental factors is 31.33%,indicating that 68.67% of the unknown factors still affect the species composition of the shrub community,which may be attributed to some environmental factors.Choose such as wind,light,rainfall,etc.5.The relationship between shrub diversity and environmental factors in Haitan Island was analyzed by RDA.It was found that species diversity and environmental factors were not significant,and the minimum P value was 0.0570.Using Spearman rank correlation analysis,the relationship between shrub community species diversity index,average plant height,average ground diameter and environmental factors of dominant species showed that Shannon-Winner diversity index(H)and organic matter(SOM)of shrub community There was a significant positive correlation between alkaline nitrogen(AN)and(P<0.01),and a significant negative correlation with slope(SI)at(P<0.01).The uniformity index(JSW)was(P<0.05).There is a significant positive correlation with organic matter.The average plant height and pH value,available potassium(AK),total salt(SA)and altitude(ELV)of dominant species were significantly negatively correlated(P<0.05),and total potassium(TN)was There was a significant negative correlation at the level of(P<0.01)and no significant correlation with other environmental factors.There was a significant negative correlation between the average ground diameter of the dominant species and total potassium(TN)at(P<0.01)level,and no significant correlation with other environmental factors.The species diversity of shrub community in Haitan Island increases with the increase of organic matter,soil total nitrogen content and soil alkaline nitrogen content,and decreases with the increase of slope.N is a large amount of elements necessary for plant growth,and the lack of N It will affect the growth of plants,and will inevitably affect the diversity of the community.The majority of N in the soil is derived from organic matter,so organic matter and total nitrogen have an important influence on the diversity of shrub communities.