格氏栲林林窗物种多样性动态规律的研究

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 kawakamii 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 80～160m 2,and occurred a higher peak in those with a size of 240～320m 2 again,and became lower in the gaps of above 400m 2.Diversity index in shrub layer reached the lowest in the gaps with a size of 80m 2,the highest in those with a size of >200m 2,and occurred a higher peak in those with a size of 80～160m 2.Diversity index in herb layer reached the lowest in the gaps with a size of 80～160m 2,the highest in those with a size of >400m 2.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 in the gap ages of about 10～20 years and reached the lowest in 40～50 years of gap formation.The change trend of diversity index 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.

林窗对格氏栲天然林更新层物种多样性和稳定性的影响

采用物种多样性指数和改进的M.Godron稳定性法研究林窗干扰对格氏栲(Castanopsis kawakamii)自然保护区天然林更新层物种多样性和稳定性的影响。结果表明:林窗干扰改善了微环境,表现在林窗和林下乔灌层树种重要值和多样性存在差异。林窗乔木层中丰富度指数R、优势度指数D、Shannon-Wiener指数H、均优多指数Z均高于林下,均匀度指数Js和群落优势度指数C低于林下;灌木层中R、D、H、Js、Z指数均高于林下,群落优势度指数C低于林下,林窗物种多样性更为丰富,生态优势种不明显,群落向复杂化和均匀化方向发展。林窗与林下乔木层Jaccard相似性系数Cj、Sorenson相似性系数Cs、Bray-Curtis指数CN相对较低,Morista-Horn指数CmH较高,林窗对树种更新具有促进作用;灌木层相似性系数Cj、Cs、CN、CmH均较高,物种组成基本一致。根据M.Godron稳定性原理拟合出稳定性模型,林窗和林下乔木层分别为对数模型与二次函数模型,林窗和林下灌木层最佳拟合模型均为对数模型。林窗乔木层植物处于稳定状态,林下乔木层植物不稳定;林窗和林下灌木层植物均处于稳定状态。林窗和林下乔木层树种中以桂北木姜子(Litsea subcoriacea)重要值最高,说明其在森林更新中占有重要地位,可能对格氏栲种群更新产生较大影响。林下乔木层中格氏栲重要值较低,格氏栲更新存在困难,而林窗干扰促进了格氏栲的向上生长和重要值的提升,可有效实现格氏栲种群的更新和恢复。

茂兰喀斯特森林林隙物种多样性的动态规律

分析了茂兰喀斯特森林不同大小和发育阶段林隙物种多样性的动态变化规律。结果表明:林隙中乔木、灌木、草本和藤本植物的多样性指数H′在140～210 m2时最大,随林隙面积的进一步扩大,H′呈下降趋势。乔木、灌木和草本的多样性指数H′在林隙形成的20～30 a间达最大值,随林隙年龄的增加而减小。藤本植物的多样性指数H′在林隙形成初期至40 a时逐渐增加,在40 a时达最大值,最大值出现时间较其他生长型滞后。各生长型物种丰富度指数R1和均匀度指数J的变化趋势总体上与物种多样性指数相一致,生态优势度λ值与物种多样性指数几乎相反。乔木和藤本植物的多样性指数随林隙大小和年龄的变化趋势较灌木和草本植物和缓,灌木和草本植物对林隙环境的时空变化最为敏感。