热带低地雨林板根树木分布特征及其对林下植物多样性的影响

Patterns and effects of buttress distribution on understory biodiversity in tropical lowland forests

以海南吊罗山低地雨林1 hm^(2)样地内板根树木为研究对象,分析其物种组成、空间结构及林下植物多样性组成.结果表明:样地内共有板根树73株,隶属17科23属28种,株数最多的为壳斗科,单种株数最多的为青梅,板根主要发生在DBH>10 cm以上的树木;板根树径阶分布与群落树木径阶分布明显不同,呈中间高两侧低的近正态分布状,所占同级树木比例随胸径的增大而增加,主要处于群落的乔木层,呈集群分布;板根的存在提高了下坡位乔木树种和草本植物的丰度,板根区乔木、灌木、草本植物和板根区下坡位藤本植物的均匀度,以及乔木和草本植物下坡位的Shannon-Wiener指数;降低了上坡位乔木树种、草本植物以及板根区灌木和藤本植物的丰度,以及灌木和藤本植物板根区的Shannon-Wiener指数.

In order to explore the relationships between species composition,spatial pattern and understory biodiversity in tropical forests,we investigated buttress areas in lowland forests in Diaoluo Mountain,Hainan Province.The results showed that there were 73 trees with buttress roots,belonging to 28 species,23 genera and 17 families.Fagaceae was the dominant family,and the species Vatica mangachapoi Blanco had the largest quantity in this forest.Buttress root mainly occurred in trees with diameter at breast height(DBH)over 10 cm.The distribution of diameter class varied between trees with buttress roots and the main tree population.DBH distribution for buttressed trees showed a near-normal distribution,which was high in the center and low on both sides.Buttress trees mainly belonged to the arborous layer and were distributed in a clustered pattern.Buttress roots enhanced the abundance of trees and herbaceous in the downslope position of the buttress area while reduced the abundance of trees and herbaceous in the upslope area,as well as shrub and liana around buttress area.Buttress also improved the evenness of trees,shrubs and herbaceous in both buttress area and downslope of buttress area.Shannon-Wiener index of tree and herbaceous in the downslope of buttress was found to be increased,while that of shrub and liana was decreased.As a functional group,trees with buttress roots play an important ecological role in tropical forests.The results provides theoretical support for biodiversity conservation in tropical forests.