Abstract
Epiphytes are common in tropical montane cloud forests (TMCFs) and play many important ecological roles, but the degree to which these unique plants will be affected by changes in climate is unknown. We investigated the drought responses of three vascular epiphyte communities bracketing the cloud base during a severe, El Niño-impacted dry season. Epiphytes were instrumented with sap flow probes in each site. Leaf water potential and pressure–volume curve parameters were also measured before and during the drought. We monitored the canopy microclimate in each site to determine the drivers of sap velocity across the sites. All plants greatly reduced their water use during the drought, but recovery occurred more quickly for plants in the lower and drier sites. Plants in drier sites also exhibited the greatest shifts in the osmotic potential at full saturation and the turgor loss point. Although all individuals survived this intense drought, epiphytes in the cloud forest experienced the slowest recovery, suggesting that plants in the TMCF are particularly sensitive to severe drought. Although vapor pressure deficit was an important driver of sap velocity in the highest elevation site, other factors, such as the volumetric water content of the canopy soil, were more important at lower (and warmer) sites.
| Original language | English |
|---|---|
| Pages (from-to) | 900-913 |
| Number of pages | 14 |
| Journal | New Phytologist |
| Volume | 219 |
| Issue number | 3 |
| DOIs | |
| State | Published - Aug 2018 |
Bibliographical note
Funding Information:The authors thank Alexander Darby, Andrew Glunk, Keylor Muñoz and Jessica Murray for the collection of data and the maintenance of sap flow stations. Keylor Muñoz is pictured in Fig. 1. We thank the Curi Cancha Reserve, the Monteverde Reserve and the University of Georgia field station for permission to conduct this research and for logistical support. We thank Willow Zuchowski, William Haber and Armando Estrada for help in the identification of species. We thank Cameron Williams, Autumn Amici, Nalini Nadkarni and four anonymous reviewers for providing valuable feedback on the manuscript. We acknowledge funding from the Franklin and Marshall College and the National Science Foundation (PI: S.G.G., IOS Award #1556289).
Publisher Copyright:
© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust
Keywords
- El Niño
- canopy water potential
- drought
- sap flow
- tropical montane cloud forest (TMCF)
- turgor loss point (TLP)
- vapor pressure deficit (VPD)
- volumetric water content
ASJC Scopus subject areas
- Physiology
- Plant Science