西南喀斯特峰丛洼地木本植物群落结构与多样性变化

Changes of woody community structure and diversity in karst peak-cluster depressions in southwest China

为了阐明喀斯特峰丛洼地植物群落结构和物种多样性特征及其变化规律,选择西南喀斯特具有代表性的灌木林、次生林和原生林3种植被类型,基于2007年、2012年、2017年3次植被的系统调查,研究了木本植物群落物种组成、群落结构和物种多样性的动态变化。研究结果表明,灌木林2007—2012年减少1个种,2012—2017年减少7属5种;次生林2007—2012年减少1科1属,2012—2017年增加4科7属6种;原生林2007—2012年减少1科4属6种;2012—2017年增加1科3属3种。增加和减少的物种为偶见种或稀有种,引起群落中物种数量的波动。灌木林中黄荆(Vitex negundo)、八角枫(Alangium chinense)重要值均大于10,黄荆占绝对优势;次生林中菜豆树(Radermachera sinica)、灰毛浆果楝(Cipadessa cinerascens)、香椿(Toona sinensis)等物种重要值大于10,占主要优势;原生林的优势种不突出,为多优势种群落。3种植被类型群落的胸径各年份差异显著,平均树高在5年间的差异不显著,10年间达到了显著差异;群落总径级结构呈倒“J”形,群落更新状态良好。随时间推移,3种植被类型主要优势种重要值趋于降低;群落内部存在物种竞争,十年间群落结构及多样性变化较大。

In order to elucidate the characteristics of plant community structure,species diversity and their evolution in peak-cluster depression region,the representative vegetation types in southwest karst region,i.e.,shrub,secondary forest,and primary forest,were selected.Based on the systematic investigation of dynamic plots of three vegetation types in 2007,2012,and 2017,the changes of community composition,community structure,and diversity were studied.The results showed that one species of shrub disappeared in 2007─2012,while 7 genera and 5 species disappeared in 2012─2017.For the secondary forest,1 family and 1 genera disappeared in 2007─2012,and 4 family,7 genera,and 6 species increased in 2012─2017.Regarding the primary forest,1 families,4 genera,and 6 genera increased in 2007─2012,and 1 family,3 genera and 3 species increased in 2012─2017.The increased and decreased species were occasional or rare species,which would cause the fluctuations in population.The important values(Ⅳ)of Vitex negundo and Alangium chinense in shrubs were more than 10.In addition,Vitex negundo had an absolute advantage.The Ⅳ of Radermachera sinica,Cipadessa cinerascens,and Toona sinensis in the secondary forest were more than 10,which were the dominant species.The dominant species of the primary forests were not prominent and were multi-predominant species communities.The average diameter at the breast height(DBH)in the three communities differed significantly among the three periods.The average tree height was not significantly different between 2007 and 2012,and between 2012 and 2017,while differences were achieved significant level(P<0.05)between 2007 and 2017.The total diameter-level structure showed an inverted“J”shape,which indicated that the community was in a good state.The different strategies should be adopted according to different vegetation restoration stages,which provided scientific basis for vegetation restoration in karst region.With the passage of time,the important value of dominant species tended to decrease.The community structure and diversity changed greatly during ten years.