According to the principle of bio-diversity conservation,the change pattern of the species diversity in gaps of different sizes and developmental stages in Castanopsis kawakarnii forest was measured and analyzed by means of Margalef index, Shannon-Wiener index, Pielou index,Simpson index and Evenness dominance diversity index.The results showed that the general trends of species richness index were correspondent with those of species diversity index,evenness dominance diversity index and species evenness index,which were in opposite to those of ecological dominance index.The species diversity influence in shrub layer by gaps of different sizes and developmental stages was the strongest,the one in arbor layer was stronger,and the one in herb layer was the weakest.The species diversity index (Shannon-Wiener index) in ardor layer reached the highest in the gaps with a size of 80-160m2,and occurred a higher peak in those with a size of 240-320 m2 again,and became lower in the gaps of above 400m2.Diversity index in shrub layer reached the lowest in the gaps with a size of 80m2,the highest in those with a size of>200m2,and occurred a higher peak in those with a size of 80-160m2.Diversity index in herb layer reached the lowest in the gaps with a size of 80-160m2,the highest in those with a size of>400m2.Diversity index in arbor layer showed the high change trend in the middle period and the low one in two periods following the ages of gaps,which the index were the highest in the gaps about 40-50 years,and the lowest in the first 10 years after gap formation.The change trend of diversity index in shrub layer was the most evident,which formed a peak value inthe gap ages of about 10-20 years and reached the lowest in 40-50 years of gap formation.The change trend of diversityindex in herb layer increased following the ages of gaps formation,and diversity index in herb layer reached the highest after 50 years of gap formation and the lowest in the first 10 years after gap formation.Gap formation can increase species diversity and is one of the most important mechanisms for the maintenance of species diversity in C.kawakamii forest.The study will provide a reference for the protection of biodiversity and the natural regeneration in C.kawakamii forest.
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