基于多元回归树的常绿阔叶林群丛数量分类——以古田山24公顷森林样地为例

Numerical classification of associations in subtropical evergreen broad-leaved forest based on multivariate regression trees——a case study of 24hm^2 Gutianshan forest plot in China

常绿阔叶林植被分类一直是植被生态学研究中的难题,尤其是基本单位——群丛的分类。该文以地形因子和物种组成数据为变量的多元回归树方法,将浙江古田山24hm2森林监测样地的森林群落分为3个群丛。所得群丛既反映了群落在时间和空间上的相对间断分布,也符合植被分类基本单位的特点,为常绿阔叶林的群丛分类提供了新思路。并首次引入了指示值算法,解决了以往指示种无法量化的难题。最终以优势层优势种为主、下木层指示种为辅的命名原则,将3个群丛命名为:1)石斑木(Raphiolepis indica)+柳叶蜡梅(Chimonanthus salicifolius)-格药柃(Eurya muricata)+赤楠(Syzygium buxifolium)-木荷(Schima superba)+甜槠(Castanopsis eyrei)群丛;2)映山红(Rhododendron simsii)+满山红(Rhododendron mariesii)-短柄枹(Quercus serrata var.brevipetiolata)+灰白蜡瓣花(Corylopsis glandulifera var.hypoglauca)-马尾松(Pinus massoniana)+甜槠群丛;3)短尾越桔(Vaccinium carlesii)+毛花连蕊茶(Camellia fraterna)-杨梅叶蚊母树(Distylium myricoides)+浙江新木姜子(Neolitsea aurata)-木荷+甜槠群丛。

Aims A 24hm2 permanent plot in Gutianshan National Nature Reserve provided a valuable case for association classification in evergreen broad-leaved forest.Our objectives were to divide the forest community into associations to provide a new classification of evergreen broad-leaved forest and introduce the algorithm of indicator value for species in associations.Indicator species previously could not be quantified.Methods We used multivariate regression trees,based on topographic factors and species composition,for association classification.An indicator value was introduced to quantify the indicator species of associations.We named associations after the dominant species in the tree layer,followed by indicator species of lower tree layers.Important findings The forest community was divided into three associations that not only reflect temporal and spatial disjunctions of the community,but also correspond with features of the basic unit of vegetation classification.The three associations are 1） Raphiolepis indica＋ Chimonanthus salicifolius―Eurya muricata＋ Syzygium buxifolium―Schima superba＋ Castanopsis eyrei Association;2） Rhododendron simsii＋ Rhododendron mariesii―Quercus serrata var.brevipetiolata＋ Corylopsis glandulifera var.hypoglauca―Pinus massoniana＋ Castanopsis eyrei Association;and 3） Vaccinium carlesii＋ Camellia fraterna―Distylium myricoides＋ Neolitsea aurata―Schima superba＋ Castanopsis eyrei Association.