| Tongguling Nature Reserve was located in the eastern part of Wenchang City east near the South China Sea, the west was connected the inland of Hainan Island. Geographical location was110°58’30"111°03’00" E,19°36’54" to19°41’21" N. It was a tropical marine monsoon climate. The soils in the region were characterized by latosols, thin layer. The mangrove forest, semi-mangrove forest, sandy vegetation, shrubs, tropical evergreen monsoon elfin forest and part of plantation were existed in this area, and tropical evergreen monsoon elfin forest was climax vegetation type.This research used path method and fixed bulk sample method to comprehensively study the species diversity of the Tongguling Nature Reserve, the results show that:there are1019kinds of plant species in this region, belonging to170families,651genus. The species richness index of the tropical evergreen monsoon elfin forest was higher than the evergreen shrub. Simpson index and Shannon-Wiener index size of tropical evergreen monsoon forest was higher than the evergreen shrub., and evenness index size based on Simpson index of the evergreen shrub was higher than tropical evergreen monsoon forest,but the evenness index size based on Shannon-Wiener index of the tropical evergreen monsoon was higher than evergreen shrub. Shannon-Weiner index of the tropical evergreen monsoon elfin forest in Tongguling Nature Reserve was5.647255, with high species diversity, protection of the plant species diversity of the Tongguling Nature Reserve is great significance.21small plots of10m×10m were seted at the main peak of the Tongguling Nature Reserve, which includes data of terrain factors such as angle of slope (ANG), slope aspect (ASP) and slope position (POS), soil factors such as soil moisture, pH value, organic matter, available nitrogen, available phosphorus and available potassium, species richness plant diversity factors including each plot species richness index(R).species diversity index (SW) and evenness index (E). Then we analyze the experimental data with principal components analysis (PCA). canonical correlation analysis (CCA), redundance analysis (RDA). correlate on analysis and stepwise regression analysis. And the result shows as follows:1) The species diversity of the tropical evergreen monsoon elfin forest was mainly affected by the slope of terrain factors, within the extent of slope range from3°to35.5°, species richness index and species diversity index are both positively linear correlated with slope. And among all the terrain factors, ANG influences the most on plant species diversity variation, followed by ASP and POS. Besides, species richness index and species diversity index both have a significant linear correlation with slope.2) The main soil factors to influence the community species richness and diversity of the tropical evergreen monsoon elfin forest are0-10cm soil layer soil moisture (SM1)、soil organic matter content (SOM1) and10-20cm soil layer available potassium content (K2) and soil moisture (SM2).The soil factor to affect the species richness was various, but the0-10cm soil layer of quick-impact phosphorus content (PI) was showed significant influence, which showed large negative effects on species richness. In addition, there was a signigicant negative correlation between species richeness index and the soil moisture (22.92%32.69%) of measured0-10cm in this area of study, but a positive corrrlation with SMI and signigicantly positively relationship with K2.3) The slope was the most important factor of soil environmental factors in the topographic factors. The ANG showed a signigcant negative correlation with SMI and a significant linear positive correlation with SOM1and K2. The ASP showed a significant positive correlation with SMI.4) Correlation analysis among terrain factors, soil factors and plants showed that the three factors interact with each other along mutual succession.Woody plants with its DBH≥1.5cm at a160×160m shrubbery permanent forest plot at Tongguling National Nature Reserve in Wenchang, Hainan, have been investigated., and those plants have been classified into7size classes based on DBH to determine the regulation of Thinning. Results showed that:1) Class I (DBH<4.5cm) occupied a maximum percentage (64%).The community was "Inverse-J type", the order of stands density was young trees> small trees> grow-up trees, the community was in a stable state. It has a typical phenomenon of thinning caused by the self-thinning and alien-thinning which caused by the individuals to compete for more living space and resources.2) Above ground biomass of each classes increased with the growth of density, in a small density range, above ground biomass increased swiftly with the growth of density, but changed slowly and tended to a constant value when the density tend to be0.6plant per square meter, and the power function equation was AGB=6×107N04626or lnAGB=0.46261nN+17.855.3) It had a negative correlation between the density and the average DBH of each class (larger the density, smaller the average DBH) and its power function equation was:N=70.1d-3.5506, R2=0.8808.4) We simulated the self-thinning law put forward by Yoda, and found that there was a significant coherence between stand density and average biomass, the correlation was:W=2219.1N-0.5374or InW=7.7048-0.53741nN, thinning index a value was0.5374, it was largely differ from the3/2index put forward by Yoda,did not satisfy the-3/2law of self-thinning.5)41common species (individuals more than or equals5per0.2hm2) and51rare species have been investigated. It has a certain discipline in terms of thinning of species of natural shrubbery.Based on the study of the relationship between species diversity and community thinning intensity of nine plots of80m×80m.It showed that:It was a negative correlation between thinning index and species diversity index of community, and it also had a significant negative correlation with the species richness index (R), Shannon-Wiener index (SW) and Simpson index (SP). The thinning index decreased with the increasing of species diversity, but the absolute value of the thinning index became larger,and the thinning intensity also became stronger.The thining of community provided a condition for the diversity and coexistence.of species. |
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