广西弄岗五桠果叶木姜子群落木质藤本空间格局及其与树种间的关系

Spatial pattern of lianas of Litsea dilleniifolia community and its relationship with main tree species in Nonggang,Guangxi

木质藤本是生物多样性的重要组成,木质藤本通过影响支持木进而影响群落的结构和功能,但在生物多样性丰富的北热带喀斯特森林中,木质藤本与支持木的关系鲜为人知。以喀斯特季节性雨林的五桠果叶木姜子(Litsea dilleniifolia)群落为研究对象,对木质藤本的密度、分布格局及其与主要树种的关系进行调查研究,分析木质藤本对树木的影响。结果显示:(1)五桠果叶木姜子群落内木质藤本平均密度为0.0913株/m2,木质藤本在0—20m空间尺度整体表现为聚集分布,且随着尺度增大,聚集强度逐渐减弱;不同径级木质藤本在不同尺度上的分布格局不同。(2)木质藤本对不同径级、不同种类、不同聚集强度的支持木选择表现以下体征:随着支持木径级增加,木质藤本攀附的比例和每木藤本数有增加趋势,且木质藤本胸径与支持木胸径呈极显著正相关;附藤率较高的支持木有紫葳科(Bignoniaceae)种类和东京桐(Deutzianthus tonkinensis),单木附藤数量多的是南方紫金牛(Ardisia thyrsiflora);物种的聚集强度与附藤率、附藤数量呈负相关。(3)木质藤本的密度与支持木死亡率关系不显著,而物种的附藤率与死亡率呈极显著负相关。以上结果表明,木质藤本密度在原生性喀斯特季节性雨林中并不高,且木质藤本对支持木具有选择性,但其对五桠果叶木姜子群落的死亡率并未产生显著影响。该研究可为喀斯特原生性季节性雨林的物种共存、极小植物种群保育提供理论依据,也可为石漠化区域的植被修复提供科学参考。

Lianas are an important part of biodiversity.Lianas have an impact on the structure and function of many forest communities by influencing on woods.However,little is known about the relationship between lianas and supporting woods in the biodiversity-rich northern tropical karst forest.For this reason,this study is mainly devoted to investigating the density and distribution pattern of lianas and their relationship with main tree species in Litsea dilleniifolia community,which is one of the unique types of karst seasonal rain forest in Nonggang,Guangxi;and the effect of lianas on the death of trees in the community was analyzed.The results were as follows:(1)the average density of woody vines in the plot was 0.0913/m2,and the woody vines showed an aggregated distribution pattern on the scale of 20 m,and the aggregation intensity decreased gradually with the increase of spatial scale,the distribution patterns of woody vines of different diameter at breast height(DBH)size-class structure were different at different spatial scales.(2)The selection of supporting woods of different DBH size-class structure,different types and different aggregation strengths of woody vines showed the following signs:with the increase of supporting wood of DBH structure,the climbing proportion of lianas and the number of vines per tree tended to increase,trees of larger diameter class were more likely to be attached to woody vines and held more woody vines,and the DBH of lianas was significantly positively correlated with that of supporting wood.The supporting tree species with a higher rattan rate were the species of Bignoniaceae and Deutzianthus tonkinensis.The Ardisia thyrsiflora had a large number of single wood attached lianas;the aggregation intensity of species was negatively correlated with the rate and number of vines.(3)The relationship between the density of woody vines and the mortality of supporting wood was not significant,and the correlation between the number of vines and the mortality of trees was not significant,but there was a very significantly negative correlation between the attachment rate of species and the mortality.The results showed that the liana density was not high in the primary karst seasonal rain forest,and the liana was selective to the supporting wood,but it had no significant effect on the mortality of Litsea dilleniifolia community.This study can provide a theoretical basis for species coexistence and minimal plant population conservation in karst primary seasonal rain forest,and can also provide a scientific reference for vegetation restoration in rocky desertification areas.