Habitat moisture is an important driver of patterns of sap flow and water balance in tropical montane cloud forest epiphytes

Alexander Darby, Danel Draguljić, Andrew Glunk, Sybil G. Gotsch

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Microclimate in the tropical montane cloud forest (TMCF) is variable on both spatial and temporal scales and can lead to large fluctuations in both leaf-level transpiration and whole plant water use. While variation in transpiration has been found in TMCFs, the influence of different microclimatic drivers on plant water relations in this ecosystem has been relatively understudied. Within the TMCF, epiphytes may be particularly affected by natural variation in microclimate due to their partial or complete disassociation from soil resources. In this study, we examined the effects of seasonal microclimate on whole plant water balance in epiphytes in both an observational and a manipulative experiment. We also evaluated the effects of different microclimatic drivers using three hierarchical linear (mixed) models. On average, 31 % of total positive sap flow was recovered via foliar water uptake (FWU) over the course of the study. We found that precipitation was the greatest driver of foliar water uptake and nighttime sap flow in our study species and that both VPD and precipitation were important drivers to daytime sap flow. We also found that despite adaptations to withstand seasonal drought, an extended dry period caused severe desiccation in most plants despite a large reduction in leaf-level and whole plant transpiration. Our results indicate that the epiphytes studied rely on FWU to maintain positive water balance in the dry season and that increases in dry periods in the TMCF may be detrimental to these common members of the epiphyte community.

Original languageEnglish
Pages (from-to)357-371
Number of pages15
Issue number2
StatePublished - Oct 1 2016

Bibliographical note

Funding Information:
The authors thank the Monteverde Cloud Forest Reserve for the use of laboratory facilities, access to the park and logistical support. We also thank the Monteverde Institute, especially Maricella Solis, for logistical support and help in obtaining research permits. Sarah McGraw aided greatly in the construction of sap flow sensors and in training undergraduate researchers at Franklin and Marshall College. Lynx Guimond provided assistance in the field. Willow Zuchowski and Bill Haber provided assistance in species identification. Erica Hample created Fig. . Ram Oren, Janet Fisher, Jaime Blair, Z. Carter Berry and two anonymous reviewers provided valuable suggestions to improve the manuscript. Financial support for this research was provided by Franklin and Marshall College.

Publisher Copyright:
© 2016, Springer-Verlag Berlin Heidelberg.


  • Drought tolerance
  • Foliar water uptake
  • Hemi-epiphytes
  • Microclimatic drivers
  • Water balance
  • Water relations

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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