Study On Distribution Patterns Of Rare Species And Their Impact On The Estimation Of The Species Diversity In Tropical Evergreen Monsoon Dwarf Forests In Tongguling, Hainan

Rare species refers to the species that appear with less or rare frequency in communities, at present, little research has been done in distribution patterns of rare species and the impact on forest biodiversity. The study taked Tongguling National Nature Reserve as example, and carried out working on this area. Based on the research of two permanent sample plots(2.56hm2each), by the methods of community composition investigation, O-ring univariate function calculation of point pattern analysis and species diversity indices calculation, we tried to explore the impact of species composition, distribution patterns, quantitative change of rare species on distribution pattern, and the impact of species number changes in different types of community members on species diversity indices calculation. The research results showed that:(1) The research found that the monsoon elfin forest community succession of Tongguling is already close to climax community, but the community continues in the shrub forest. There were74kinds of rare species in the plot of the tropical evergreen monsoon elfin forest, and68kinds of rare species in the shrub forest, the kinds of rare species of the plot were enormous, it was an important part of the species;(2) Univariate function calculation of O-ring was used to do point pattern analysis on different rare species in two plots. Then found that the rare species of the plots were obvious aggregated distribution on a small scale of1-4m, while as the scale increases, it gradually showed a significant aggregated distribution and uniform distribution on a larger scale which greater than20m, and it was mainly random distribution in whole plots;(3) The impact of quantitative change of rare species on its aggregated distribution on a small scale of1-4m was not obvious,and it had some impact on aggregated distribution and uniform distribution on a larger scale which greater than20m, and it was mainly random distribution in whole plots. If the investigation of rare species was ignored or not completed in the survey, it may affect the results of the analysis on a larger scale;(4) We found that Simpson index, Shannon-wiener index and Pielou evenness index in monsoon elfin forest were higher than shrub forest communities by calculating. Quantitative change of dominant species had a negative correlation with three indices in monsoon elfin forest; While in the shrub forest, it first had a negative positive correlation with the three indices, then showed a positive correlation; The quantitative change of dominant species had a positive correlation with three index in the two plots; Quantitative changes of rare species had a significant positive correlation with Simpson index, and Shannon-wiener index, while had a significant negative correlation with Pielou evenness index. The amount of rare species have little effect on the calculation of species diversity indices, some of the data seem closer, but actually it had a great difference to reflect the truly biodiversity. Therefore, in the research of biodiversity, we should pay more attention to the investigation of rare species, and combined the findings of rare species with the calculations of evenness index to assess biodiversity.