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The diverse vascular epiphyte community in tropical rainforests is at the interface between the atmosphere and the forest floor and dependent on rainfall, cloud water, and sparse canopy soil for nutrients and water. As such, predicted anthropogenic changes in nutrient deposition (pollution) and water availability will have profound effects on epiphyte ecology. We conducted a 24 month, ex situ, experiment to determine the impacts of predicted increases in pollution (+nitrogen, +nitrogen & phosphorus, + phosphorus) and reduced water availability (-30%) on life history in five cosmopolitan epiphyte species in 3 general (Guzmania (Bromeliaceae), Anthurium (Araceae), Elaphoglossum (Elaphoglossaceae)) in a lowland rainforest in Costa Rica. These taxa obtain nutrients and water differently: Guzmania absorbs nutrients and water through the tank surface; Elaphloglossum uses canopy soil roots; Anthurium uses aerial roots and canopy soil roots.

Not surprisingly, we found significant variation across life history in response to experimental treatments and species, namely leaf production, leaf longevity, and reproduction. For example, Elaphoglossum leaf longevity was significantly longer under nitrogen addition (11.0 +/- 1.1 months) compared to control and other treatments (The ability to alter life history and functional traits under various conditions is critical to success in the liminal canopy space; interestingly, these epiphyte functional groups respond differently, and often in opposite ways, highlighting niche partitioning. These shifts in life history and leaf functional traits inform our understanding of how the canopy community will respond to global change. These data are part of a larger experimental study examining both ex situ and in situ vascular epiphyte responses to changing nutrient and water regimes.

Keywords:

epiphyte, canopy, life history, demography

Catherine Cardelus, Carrie Woods

Presentation within symposium:

S-13 Vascular epiphytes: current knowledge and future challenges

Vascular epiphyte life history responses to anthropogenic change: An Experimental Approach

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