Floristic structure and composition of Guadua forests in the Colombian coffee region1

ABSTRACT In the coffee region (900-2,000 m a.s.l.) of the Colombian Andes, the forest remnants correspond mainly to fragments dominated by the bamboo species Guadua angustifolia Kunth (Guadua). These highly fragmented forests are found in landscapes with a high degree of transformation due to the agricultural activity and urban expansion. With the purpose of contributing to the knowledge of the ecological characteristics of these forests, the floristic structure and composition (alpha, beta and gamma diversity) of seven forest fragments located in the middle (Quindío) and lower basins of the La Vieja river (Risaralda) were studied. A total of 70,961 individuals and 172 species belonging to 54 families were found. Fifty percent of the families were represented by only one species, and the families Araceae and Leguminosae showed the highest taxonomic richness, respectively with 21 and 14 species. The diversity indices for these forests revealed values comparable to those of tropical forest ecosystems (Shannon-Weiner values between 3,167 and 3,798). Likewise, the cluster analysis (based on Euclidean distances) showed that the stands present a similarity below 0.65 (65 %), associated with the 35 species reported, in seven fragments that characterize a varied floristic composition. This finding implies that these fragments should not be seen as isolated units, but as sites embedded in a diverse regional landscape. This represents important habitats for these species, which are capable of maintaining significant levels of diversity, even under management conditions.

摘要：在哥伦比亚安第斯山脉海拔900~2000米的咖啡种植区，森林残存片段主要由以狭叶瓜多竹（Guadua angustifolia Kunth，简称Guadua）为优势种的斑块构成。这类高度破碎化的森林分布于受农业活动与城市扩张导致景观发生高强度改造的区域中。为深化对该类森林生态特征的认知，本研究针对拉维耶哈河（La Vieja River）中、下游流域（昆迪奥省与里萨拉尔达省）内的7处森林残存斑块，开展了植物区系结构与组成（α、β、γ多样性）的调查分析。本次调查共记录到70961株个体，隶属于54个科的172个物种。其中50%的科仅包含1个物种，天南星科（Araceae）与豆科（Leguminosae）的分类学丰富度最高，分别包含21和14个物种。该类森林的多样性指数结果与热带森林生态系统的水平相当，香农-威纳指数（Shannon-Weiner Index）介于3.167至3.798之间。此外，基于欧氏距离（Euclidean Distance）的聚类分析结果显示，在这7个植物区系组成多样的斑块中，各林分的相似性低于0.65（即65%），且与本次调查记录的35个物种存在关联。该研究结果表明，这些残存斑块不应被视为孤立的单元，而是镶嵌于多样区域景观中的生境斑块。即便在人为经营条件下，此类斑块仍可维持较高水平的物种多样性，是极具生态价值的物种栖息生境。