| Syzygium odoratum is a native species and typical vegetation in tropical coast.It is distributed in a small forest area around countrysides.Syzygium odoratum is also a"Geomantic forest",protecting the village from typhoon.Therefore,Syzygium odoratum is an important tree for coastal ecology.In this study,we focused on typical forest community in Wenchang,Hainan.We using Ecological statistics methods to research structural characteristics,species diversity,spatial pattern,soil environment,and establish step-forward multiple regression between species diversity and soil factors.This paper aims to reveal the community characteristics of Syzygium odoratum,as well as to provide theoretical basis for the recovery of coastal shelter-forest in China.The results showed that:(1)A total of 26 families,33 genera,36 species of plants are recorded,including 22 species in the arbor layer,13 species in the shrub layer,10 species in the herb layer.Syzygium odoratum is dominant species in the arbor layer,Its important value covers more than 40%.The dominated distribution of arbor presented approximate inverted "J".The height of trees in the community are mainly concentrated in the range of 2 to 9 m.The best Model of Syzygium odoratum between diameter and height is a cubics function:H=2.769+0.267D-0.004D2+0.000006D3(R2=0.439,p<0.01).(2)Compared with the Shenzhen Dapeng Peninsula,species diversity index is low.Margalef species richness index showed the following trend:tree layer>shrub layer>herb layer.It shows that trees are more,shrubs and herbs are relatively rare.Spatial distribution pattern of Syzygium odoratum manifested aggregated distribution on small scale and random distribution in large scale.(3)Tree layer Syzygium odoratum population spatial distribution pattern in small scale showed strong aggregation,in large scale performance for stable random distribution.The shrub layer Psychotria rubra population spatial distribution pattern and the dominant species of tree layer Syzygium odoratum is similar.Herb layer advantage of Panicum repens showed different distribution characteristics at different scales,the spatial distribution pattern characteristics of overall performance is not stable.Not only compete between Syzygium odoratum and Psychotria rubra,but also exist mutual symbiotic relationship.Panicum repens of Syzygium odoratum is larger,the dependence of the overall performance are associated.(4)Inter-specific association in the arbor layer is not significantly positive.For the 171 tree species,although there is a certain relationship,but a stable and harmonious collocation has not been formed.Syzygium odoratum has not associated with other tree species.It is strongly independent.The inter-specific association of Casuarina equisetifolia and Pittosporum tobira are in significant positive correlation.The inter-specific association of shrub layer has significant positive correlation,and Its proportion is 43.6%.Compared with the tree layer,Inter-specific association of the herb layer is strongly negative.(5)The soil is acidic.The soil nutrient content is low,and concentration in the soil surface layer(0-20cm).Species diversity index changes along with the change of soil nutrient,it verified the nutrient equilibrium hypothesis.The soil pH value was the key factor to community diversity in this forest.The optimal regression equation between diversity index and soil factors were very significant(P<0.01).The decision coefficient R2 is close to 1,and the reliability of regression model is high,which has guiding significance for practice. |
PDF Full Text Request