Spatial distribution and structure of the population of Pitcairnia huilensis (Bromeliaceae) in the upper valley of the Magdalena river (Huila, Colombia)

Abstract

We studied the spatial distribution pattern and the population structure of Pitcairnia huilensis (Bromeliaceae), a species critically endangered (CE) within the Magdalena river high valley of the Colombian Andean. We determined its spatial distribution with the K Ripley function. To understand the population structure, we established four size categories: seedlings, juveniles, sub-adults and reproductive adults, which were supported statistically by means of morphometric variables. In order to know which of the morphometric variables presented the greatest variability, we performed a Principal Component Analysis. To examine if there were significant differences between the morphometric variables by size categories with greater variability (total height), a Kruskal Wallis test was carried out and, subsequently, a Tukey test was applied to identify the differences between the size categories with respect to thisvariable. Additionally, to determine if there was a relation between the dry weight and the total height, we performed a linear regression. We found 289 patches that showed a pattern of aggregate spatial distribution and 2695 individuals. The density of individuals per m2 varied between 0.1 and 3.9. There were significant differences between the morphometric variables, with the total height being the one that best explains the variation. Total height also was the variable that most closely relates to the total dry weight. This paper indicates the importance of the data obtained for the management and conservation of P. huilensis in the area of study.