Key message: Highly variable nighttime transpiration, with higher rates generally observed after preceding fog, is prevalent in dominant tree species of the nutrient-poor tropical montane cloud forest environment of central Veracruz, Mexico.
Abstract: Although nighttime transpiration (En) is prevalent in a wide range of species from cloud-affected forests, its magnitude relative to total daily transpiration (Ed) as reported in the literature is generally small (En/Ed is 0.12 on average). In the present study, we observed high dry-season En/Ed ratios with large night-to-night variation in dominant species from the tropical montane cloud forest (TMCF) zone of central Veracruz, Mexico: 0.22 ± 0.18 for Quercus lancifolia (old-growth TMCF); 0.26 ± 0.14 and 0.16 ± 0.16 for Alchornea latifolia and Alnus jorullensis, respectively (regenerating post-fire TMCF); and 0.30 ± 0.20 to 0.12 ± 0.21 for Pinus patula (young and mature pine plantations). En was determined as the difference between observed nocturnal sap flow and estimated refilling of stem water storage, the latter of which was on average: 21–25 % of nocturnal sap flow for Q. lancifolia; 6 and 5 % for A. latifolia and A. jorullensis, respectively; and 21–23 % for P. patula. Night-to-night variation in En was mostly due to large variation in vapor pressure deficit (VPD) related in turn to the alternation of cold fronts (producing fog events) and high pressure weather (producing nights with VPD up to 2 kPa). Moreover, in the hours following fog events without concurring rainfall, En was often higher as compared to fog-free nights with similar VPD across all species examined. Low-nutrient availability and high water content of the soils in the study area suggest a nutrient uptake benefit associated with the relatively high En rates observed.
Bibliographical noteFunding Information:
Funding was provided by a National Science Foundation’s Ecosystem Science Panel grant (NSF/DEB-0746179 to H.A. and T.E.D.) and a grant from Consejo Nacional de Ciencia y Tecnología-Mexico (CONACyT-106788 to D.R.G.). M.S.AB. received graduate student support from Iowa State University and University of New Hampshire, USA, while collecting and analyzing data, as well as from a postdoctoral fellowship (DGAPA-Universidad Nacional Autónoma de México) while writing the manuscript. We thank the Municipality of Coatepec, Veracruz, and local landowners for granting access and allowing us to work in their properties. We also thank Edgar Hincapié for soil VWC sensors calibration. We would like to gratefully acknowledge the hard work of our field technicians Adán Hernández Hernández and Sergio Cruz Martínez. Comments and suggestions from two anonymous reviewers greatly improved the original manuscript.
© 2014, Springer-Verlag Berlin Heidelberg.
- Sap flow
- Tropical montane cloud forest
ASJC Scopus subject areas
- Plant Science