[目的] 分析鄂西南森林动态样地内优势种群的结构及动态特征,为进一步深入研究亚热带常绿落叶阔叶混交林的更新动态及生物多样性维持机制奠定基础.[方法] 参照热带森林科学中心森林动态监测样地(大样地)建设与监测技术规范,于2014年在湖北木林子国家级自然保护区的亚热带常绿落叶阔叶混交林中建立15 hm2大样地,调查并鉴定胸径大于1 cm的所有木本植物,分析其种群结构及动态特征.[结果] 在垂直结构上,物种丰富度和个体多度都随着树木高度层次的降低而升高;在径级结构上,物种丰富度和个体多度都随着径级增大而降低,呈倒"J"形分布趋势;按所分布的径级数量不同可将群落内的物种分为10类,多数物种主要分布于小径级范围,但优势种群则集中分布于某个径级或均匀分布于各径级,表明优势种群可能有集中更新和连续更新2种方式;在胸径小于10 cm的径级内翅柃最占优势,而在其他径级内壳斗科物种占主要优势;群落中大部分种群有超过60%个体分布在最低的2个垂直层次内,且有超过85%的个体胸径小于10 cm,表明其具有良好的更新趋势,群落总体上处于进展演替中;对群落中径级和高度级上都占优势的25个种群的动态分析表明,16种属进展种群,3种属近期处于稳定状态但远期将趋于衰退状态,2种属衰退状态,4种属进展期与衰退期相间出现及个体数量存在波动的种群.[结论] 鄂西南亚热带常绿落叶阔叶混交林群落树体较小,大径级和高度级树木种类及个体较少,绝大多数优势种群及群落总体均处于进展演替阶段,群落具有良好的自然更新.%[Objective] The study was intended to understand the characteristics of community structure of the mixed forest of subtropical evergreen and deciduous broad-leaved trees in Mulinzi National Nature Reserve,Hubei Province.[Method] A 15 hm2 large plot was established following the field protocol of the CTFS in 2014 in Mulinzi National Nature Reserve,Hubei Province.All freestanding trees with diameter at breast height (DBH) ≥1 cm were mapped and identified to species.[Result] In the studied community,species richness and abundance increased with the decrease of tree heights in vertical layers,and decreased with the increase of DBH,,and the DBH classes showed an inverse J-shape.Ten species types were classified according to the diameter classes,most species were mainly distributed in the smaller diameters.Some dominant populations were clustered in one special class or evenly distributed in each class,this situation indicated that dominant species would have a concentrated or successive regeneration.Eurya alata was the dominant species of DBH<10 cm,and Fagaceae species were the dominant species in other DBH classes.Over 60% individuals of most populations were mainly distributed at the lowest tree layers,and the DBH of over 85% individuals was less than 10 cm,which suggested that these species have good regeneration,and the populations were in progressive succession.Based on the characteristics of height and DBH classes,the 25 dominant species were divided into 4 types.16 species such as Quercus engleriana,Padus avium,and Cyclobalanopsis multinervis showed expanding populations;3 species such as Betula luminifera,Populus adenopoda and Populus lasiocarpa were stabilizing recently but would become recession in future;2 species including Fagus lucida and Castanea henryi displayed declining population;and 4 species (Quercus fabri,Cyclobalanopsis phanera,Tilia chinensis and Fagus engleriana population) showed alternative increasing and declining and fluctuation of the number of individuals.[Conclusion] It is concluded that the freestanding trees were small in the mixed forest of subtropical evergreen and deciduous broad-leaved trees in Mulinzi National Nature Reserve,trees of large DBH and height classes were few.Most dominant populations and even the communities were at the stage of progressive succession with good natural regeneration.
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