Plant species living in extreme environments express diverse ecological strategies: A case study from a Colombian inselberg

Lina Aragón, Natalia Atuesta-Escobar and Eloisa Lasso, Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia, Lina Aragón and Julie Messier, Biology, University of Waterloo, Waterloo, ON, Canada, Eloisa Lasso, Smithsonian Tropical Research Institute, Balboa, Panama

Background/Question/Methods
Inselbergs are isolated rock hills with harsh environmental conditions completely different from their surroundings. They are rich in endemic plant species, yet little is known about those species' ecology and physiology. We measured 22 anatomical, morphological, and physiological traits on the three most common endemic plant species from a Colombian inselberg to study their ecological strategies. Ecological strategies were defined using two approaches: The Grime's CSR strategy scheme and the resource-use strategy based on plant's functional traits. Given inselbergs' extreme environmental conditions (high radiation, low water availability, high temperatures, shallow soils), we expected all species to be stress-tolerant and have similar functional traits to cope with multiple stressors.
Results/Conclusions
We found that Acanthella sprucei is the only stress-tolerant, whereas Mandevilla lancifolia and Tabebuia orinocensis are stress-tolerant/competitors. A. sprucei has a conservative leaves production (high leaf mass per area (LMA) and small dense stomata) and water-use (low maximum photosynthesis per mass (AMmass)) strategy but a low light compensation point (LCP) typical of shade-tolerant plants. M. lancifolia has an acquisitive leaves production (low LMA and large scattered stomata) and water-use (high AMmass) strategy and a low LCP. T. orinocensis has an intermediate conservative leaves production (intermediate values of LMA and stomatal size and density) and water-use (low AMmass) strategy but a high LCP typical of light-demanding plants. By analyzing only three species, we identified two ecological strategies base on Grime's scheme and three contrasting ways of water- and light-use based on species functional traits. These results suggest that inselbergs can sustain a great diversity of functional strategies and that limiting similarity could be an important force in plant community assembly, even in extreme environments.