Análisis morfofuncional de tres bambúes leñosos del ecotono selva nublada-páramo en Los Andes Venezolanos

Chusquea purdieana, C. serrulata and C. spencei represent the three most common woody bamboos of the Venezuelan Andes; the first two are climbers that grow in the cloud forest-subparamo forest ecotone, whilst the third is a shrub associated to the subparamo forest-paramo shrubland. With the purpose of determining the influence of life-form, habitat, morphoanatomical traits and altitude on the ecophysiology of these three species, a comparative multivariate analysis was carried out, involving water relations, leaf-gas exchange traits, foliage leaf nitrogen content and nitrogen use efficiency. The morphoanatomical traits studied were: specific leaf area, xylem vessel diameter and stomatal density. The ecophysiological studies and microclimate measurements in the two climbing species were carried out at 2450 m, and in the case of the shrub, at 3025 and 3320 m. Multivariate analysis based exclusively on ecophysiological traits revealed a pronounced ecophysiological uniformity in this genus that impedes differentiating climbers from shrubs, as well as between populations and species growing at different altitudes. However, when the analysis included both morphoanatomical and ecophysiological traits, it was possible to separate both life-forms and species. The physiological homogeneity observed in this group was related in the first place, with their close association to conditions characterized both by elevated humidity and cloudiness, and in second place, to the fact that Chusquea represents a relatively new group; therefore, morphological diversity is not yet reflected on a physiological leve.