木论喀斯特常绿落叶阔叶混交林群丛数量分类及稳定性

Numerical classification of associations and their stabilities of karst evergreen deciduous broad-leaved mixed forests in Mulun National Nature Reserve

加深对喀斯特顶极群落植物组成、群落结构和群落分布的认识可以为该区域生物多样性保护和森林管理提供参考。本文基于广西木论喀斯特常绿落叶阔叶混交林25 ha森林动态监测样地地形、土壤和物种组成数据,采用多元回归树对该群落进行群丛分类,并分析各群丛多样性和稳定性。结果表明,群落可分为6个群丛,分别为群丛I:长序厚壳桂+栀子皮+香叶树群丛(Ass. Cryptocarya microcarpa+Itoa orientalis+Lindera communis),群丛II:长序厚壳桂+灰岩棒柄花+罗伞群丛(Ass. Cryptocarya microcarpa+Cleidion bracteosum+Brassaiopsis glomerulata),群丛III:圆果化香树+密花树+齿叶黄皮群丛(Ass.Platycaryalongipes+Rapaneaneriifolia+Clausenadunniana),群丛IV:圆果化香树+滇丁香+齿叶黄皮群丛(Ass.Platycaryalongipes+Luculia intermedia+Clausenadunniana),群丛V:长序厚壳桂+罗伞+伞花木群丛(Ass.Cryptocaryamicrocarpa+Brassaiopsisglomerulata+Eurycorymbus cavaleriei),群丛VI:小叶栾树+长管越南茜+圆果化香树群丛(Ass.Boniodendronminus+Rubovietnamiaaristate+Platycaryalongipes)。除群丛I外,各群丛总体的多样性指数较高。Shannon-Wiener指数、Simpson指数以及Pielou均匀度指数表现出一致的变化趋势:群丛VI>群丛V>群丛IV>群丛III>群丛II>群丛I,而丰富度则为群丛VI>群丛IV>群丛V>群丛I>群丛III>群丛II,物种多样性在中海拔群丛最高。中上坡部位群丛稳定性最高,洼地群丛稳定性最低。海拔在群落结构及组成中起重要作用,可能是影响群落分布的重要因素。

Understanding plant composition,community structure and community distribution of karst climax communities can provide a reference for biodiversity conservation and forest management.Based on topographic factors,soil factors and species composition data of a 25 ha forest dynamic plot in Mulun,Guangxi,we numerically classified the association of karst evergreen deciduous broad-leaved mixed forests multivariate regression trees and a modified Godron stability analysis(Godron,1971;Zheng,2000)method to measure the stabilities of associations.The results showed that the forest community was divided into six associations.They were as follows:(I)Ass.Cryptocarya microcarpa+Itoa orientalis+Lindera communis,(II)Ass.Cryptocarya microcarpa+Cleidion bracteosum+Brassaiopsis glomerulata,(III)Ass.Platycarya longipes+Rapanea neriifolia+Clausena dunniana,(IV)Ass.Platycarya longipes+Luculia intermedia+Clausena dunniana,(V)Ass.Cryptocarya microcarpa+Brassaiopsis glomerulata+Eurycorymbus cavaleriei,(VI)Ass.Boniodendron minus+Rubovietnamia aristate+Platycarya Longipes.Except for Ass.I,diversity indices of each association were higher.Shannon-Wiener index,Simpson index and Pielou evenness index showed similar trends:Ass.VI>Ass.V>Ass.IV>Ass.III>Ass.II>Ass.I.Species richness did not follow this trend and decreased in the following order:Ass.VI>Ass.IV>Ass.V>Ass.I>Ass.III>Ass.II.Species diversities of these associations were highest at middle altitudes.The stabilities of associations were highest at medium-high slope positions,while associations were lowest in depressions.Elevation is critical for community structure and composition and may be an important factor affecting community distribution.