巨枝人工林灌木层优势种的种间联结性分析

种间联结的研究对于人工林群落的生物多样性保育和可持续经营与管理具有重要的意义，目前对巨桉人工林灌木层物种之间的作用关系知之甚少。根据野外60个样方的调查数据，运用x^2检验、Jaccard指数和Spearman秩相关系数研究了巨桉（Eucalyptusgrandis）人工林灌木层18个优势种的种间关联和相关关系。结果表明，灌木层优势种具有总体上的正联结性，但在153个种对中，具有显著正联结性的种对数约占总种对数的10％，绝大数种对表现为弱联结性或无联结性，种间关系较为松散，表明巨桉林下灌木种群具有相对独立分布的特性。研究种间关系时，种间关联结合种间相关得出的结果较好。根据分析结果将18个优势种划分为4个生态种组，生态种组内的种其资源利用方式和生态要求相似，而组间表现出明显的差异。生态种组的划分能为巨桉人工林林下灌木层的管理提供理论依据。

Interspecific association of dominant shrub species under Eucalyptus grandis plantation

The interspecific association analysis of undergrowth vegetation has important significance for biodiversity conservation and sustainable management of plantation. However, little is known about interspecific relationships of shrub species under Euca-lyptus grandis plantation. Based on the data of 60 plots obtained from investigation, the interspecific relationships among 16 domi-nant herbage species under Eucalyptus grandis plantation were studied by using χ~2-test, Jaccard's association index test and Spear-man's rank correlation coefficient test, respectively. The results indicated that dominant species had general positive interspecific association, but the species pairs with significant positive association were only ten percent of the total 153 species pairs, and most of the species pairs showed weak interspecific association or without interspecific association. That is, the investigated species had characteristics of relatively independent distribution. Indicators of interspecific association adding to correlation coefficient was an effective method to study the relationship between species. The 18 dominant species were classified into 4 ecological species groups. The Species in same ecological species groups had similar resource utilizing ways and ecological requirements, but those in different groups showed apparent differences. The classification of ecological species groups would provide a theoretical basis on managing herb layer of Eucalyptus grandis plantation.