湖北神农架中亚热带山地落叶阔叶林25 ha动态监测样地群落物种组成与结构特征

Community composition and structure in a 25 ha mid-subtropical mountain deciduous broad-leaved forest dynamics plot in Shennongjia,Hubei,China

神农架落叶阔叶林是中亚热带北缘山地保存较好的典型森林植被类型。为探究中亚热带落叶阔叶林的物种多样性维持机制和森林动态,中国科学院武汉植物园按照全球森林生物多样性监测网络(Forest Global Earth Observatory,ForestGEO)和中国森林生物多样性监测网络(Chinese Forest Biodiversity Monitoring Network,CForBio)的建设标准,于2022年在神农架南坡建设了一个25 ha的落叶阔叶林森林动态监测样地。本文基于样地内所有胸径≥1 cm的木本植物(不含竹、藤)调查数据,分析了其物种组成、植物区系特征、群落结构。结果表明:该样地海拔落差334 m,含木本植物149种(包含变种),61,054个独立个体(包括分枝共有97,664个体),隶属于44科79属,其中常绿和落叶树种分别为28种和121种;稀有种(<1株/ha)有44种(29.5%);有萌枝的个体占总个体数的26.8%,其物种数占样地物种总数的93.3%。样地科的分布以热带分布(19科,43.2%)占优势,属的分布以北温带分布(35属,44.3%)占优势。该群落乔木层以锐齿槲栎(Quercus aliena var.acutiserrata)和米心水青冈(Fagus engleriana)为优势种,其重要值分别占7.5%和6.6%。样地树种的平均胸径为7.71 cm,胸径≤10 cm的个体占优势(76.7%)。群落径级结构整体上呈倒“J”型,优势物种的径级结构主要呈现类倒“J”型和正态分布型。神农架中亚热带山地落叶阔叶林具有丰富的物种多样性,相较于纬度相近的样地,其物种多样性更高;植物区系多样;群落结构稳定,根萌比例高,物种更新良好。

Aims:The deciduous broad-leaved forest in Shennongjia is a typical ecosystem that is well preserved on the northern edges of the middle subtropical zone.In order to explore underlying mechanisms of species diversity maintenance and forest dynamics in a mid-subtropical mountain region,a 25 ha forest dynamics plot of deciduous broad-leaved forest was constructed on the southern slope of Shennongjia in 2022,following the protocol of the Forest Global Earth Observatory(ForestGEO)and the Chinese Forest Biodiversity Monitoring Network(CForBio).The establishment of this plot had complemented the forest dynamics monitoring network in China.Methods:Based on the survey data of all woody plants(omitting bamboo and vines)with diameter at breast height(DBH)≥1 cm,the plot was analyzed based on community composition,plant flora,and community structure.All of these individuals had been subjected to species identification,DBH measurement and coordinate measurement.Results:Results suggested that the plot,characterized by an elevation difference of 334 m,accommodated 61,054 surviving individuals(total 97,664 individuals including branches)belonging to 149 species(including varieties),79 genera and 44 families of woody plants.There were 28 evergreen and 121 deciduous tree species,respectively,and 44(29.5%)rare species(<1 ind./ha)were recorded in the plot.Individuals with sprouts accounted for 26.8%of the total population,while species with sprouts accounted for 93.3%of the total number of the plot.The plot had typical transitional characteristics from the middle subtropical zone to the north subtropical zone,dominated by both tropical families(43.2%,19 families)and north temperate genera(44.3%,35 genera).The canopy layer was dominated by Quercus aliena var.acutiserrata and Fagus engleriana,with importance values of 7.5%and 6.6%.The average DBH of trees species was 7.71 cm,and individuals with DBH≤10 cm were dominant(76.7%).The size class distribution of dominant species mainly showed both an inverted“J”type and a normal distribution type.Conclusion:Shennongjia mid-subtropical montane deciduous broad-leaved forest is rich in species diversity and diverse in flora,compared to plots at similar latitudes.The community structure is stable,with a high root sprouting ratio and successful regeneration.