Species abundance and diversity in tropical hemiepiphytic plant communities

    Understanding patterns in species abundance, distribution, and diversity are fundamental to both ecology and conservation, yet the mechanisms maintaining diversity are highly debated.   The complex dynamics of tropical plant communities illustrate the need for a multivariate approach to address the importance of multiple mechanisms driving patters of species diversity.  Factors influencing species abundance, distribution, and diversity of secondary hemiepiphytic plant communities in Araceae and Cyclanthaceae were investigated at La Selva Biological Station, Costa Rica.  Secondary hemiepiphytes a poorly understood, but ecologically unique plant functional type in the neotropics.  Species abundance and diversity were censused in primary wet tropical forest across four different habitat types: swamp, stream associated, residual soil, and alluvial soil. While species rank abundance curves indicate a similarity in community structure between stream associated, residual soil, and alluvial soil habitats; swamp habitats differed notably in both diversity and abundance. High species abundance and diversity in both swamp habitats indicate moisture may be influential in species distribution and community diversity.  Across all habitats, Cyclanthaceae species were much less abundant than Araceae.  Manipulative shadehouse experiments investigated ecological equivalence in species response to different shade environments.  Comparatively lower growth, conductance, and gas exchange rates in Cyclanthaceae species could indicate a greater sensitivity to environmental conditions, which may explain the significantly lower abundance and diversity of this family compared to Araceae.