Organization for Tropical StudiesAmeriFlux Florida International University

  Verano Project
Causes and implications of dry season control of tropical wet forest tree growth at very high water levels: direct vs. indirect limitations.

A study of dry season drivers of tree growth in old growth rainforest of Costa Rica

Recent research in Costa Rica has shown that the growth of tropical moist forest trees is strongly related to the strength of the dry season across a range of rainfall that by all standard measures would be considered more than sufficient for growth.  Understanding the basis for this finding is crucial because tropical moist forests play important roles in the global carbon and water cycles and therefore regional and global climate.  Predicted future warming and drying of tropical moist forests could have strong feedback effects on global climate.  However, recent satellite studies from the Amazon report that trees have their greatest leaf cover during the dry season, suggesting that the dry season does not affect production.  These two findings suggest a serious gap in our understanding of role of the dry season on tropical tree growth and carbon sequestration.  Dry-season controls on tree growth could result from both direct water limitation or via other indirect mechanisms.  The study will use both observational and experimental approaches test hypotheses of direct water limitation and indirect mechanisms to determine the basis for the dry season rainfall correlation with growth.  Measurements of growth and ecosystem carbon, water and energy balance will be used to evaluate the importance of dry season growth reduction for regional climate.


Steven Oberbauer- Florida International University
Joseph J. O'Brien- USDA Forest Service
Diego Dierick- Florida International University
Vinicio Paniagua - Organization for Tropical Studies
Danilo Villegas - Organization for Tropical Studies
Marilyn Veiman - Organization for Tropical Studies

This material is based upon work supported by the National Science Foundation. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.