Diversity pattern of epiphytic Bromeliaceae in the northwestern Andes of Colombia.
Diversity pattern of epiphytic Bromeliaceae in the northwestern Andes of Colombia. BENAVIDES, Ana Maria. Corporación para Investigaciones Biologicas, Colombia. The northwestern Andes of Colombia is a diverse area in species of Bromeliaceae. The Catalogue of Vascular Plants Flora de Antioquia recorded 183 species, of which 70% have an epiphytic habit. In this study we examined the in situ diversity and distribution of vascular epiphytes, as well environmental variables (annual rainfall, temperature, rainfall in wet and dry months and wet and dry seasons) at 10 forest stands located between 62 and 2,887 m.a.s.l. in Antioquia, Colombia. Following SVERA methodology, a total of 850 species of vascular epiphytes were identified to species or morphospecies. The orchids were the most diverse group with 159 species, followed by bromeliads (105 species). Here, we present the results for Bromeliaceae. Bromeliaceae exhibited an elevational diversity gradient with a middle elevation richness peak at 2,100 m.a.s.l. However, correlations between elevation and environmental variables suggest that the elevational diversity gradient is affected by temperature and rainfall. For wind-dispersed species (anemochory) richness decreased with increasing rainfall, possibly because of deficient dispersion in wet environments, indicating that richness patterns differ among groups with different dispersal modes. Forest stands at middle elevations with lower rainfall present lower richness. At the forest stand level, matrix correlations between anemochory (wind dispersed) and zoochory (animal dispersed) Bromeliaceae composition and spatial-environmental variables (host tree structure and host spatial distribution) exhibited no patterns. Nevertheless, species showed vertical stratification, suggesting that mechanisms related with microenvironmental factors may lead to local distribution. In Colombia bromeliads are considered under threat and all species are protected. Legislation requires compensation strategies in the case of any intervention for species of this family. Currently, most compensation strategies involve transplanting plants to other forest. Results as presented in this study (that microenvironmental factors related with vertical stratification are key to species distribution) help improve compensation strategies.
Key-words: anemochory; rainfall; vertical stratification
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