New article in Oecologia

Our new article Dew‑induced transpiration suppression impacts the water and isotope balances of Colocasia leaves was just published in a special issue of Oecologia honoring the career of Jim Ehleringer. In collaboration with Paul Gauthier and my PhD advisor Kelly Caylor, this paper looks at the effects of dew deposition on the isotope composition of Colocasia esculenta leaf water. See the abstract below for a quick overview of the study and results or head over to Oecologia’s website to read the full paper.Abstract

Foliar uptake of water from the surface of leaves is common when rainfall is scarce and non-meteoric water such as dew or fog is more abundant. However, many species in more mesic environments have hydrophobic leaves that do not allow the plant to uptake water. Unlike foliar uptake, all species can benefit from dew- or fog-induced transpiration suppression, but despite its ubiquity, transpiration suppression has so far never been quantified. Here, we investigate the effect of dew-induced transpiration suppression on the water balance and the isotope composition of leaves via a series of experiments. Characteristically, hydrophobic leaves of a tropical plant, Colocasia esculenta, are misted with isotopically enriched water to reproduce dew deposition. This species does not uptake water from the surface of its leaves. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential and a more depleted water isotope composition than dry leaves, suggesting a ∼30% decrease in transpiration rate compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance: increase in albedo from the presence of dew droplets, decrease in leaf temperature from the evaporation of dew, and local decrease in vapor pressure deficit. Comparing previous studies on foliar uptake to our results, we conclude that transpiration suppression has an effect of similar amplitude, yet opposite sign to foliar uptake on leaf water isotopes.

First International Workshop on Advances in Observations, Models and Measurements Techniques of Atmospheric Water Vapor Isotopes

I gave a presentation at the First International Workshop on Advances in Observations, Models and Measurements Techniques of Atmospheric Water Vapor Isotopes hosted at the CNRS (French National Center for Scientific Research) in Gif-Sur-Yvette, near Paris, from October 16th to October 18th 2013. My talk presented the first results of her project on rain-vapor equilibrium in Central Kenya.

The workshop was organized by Hans Christian Steen-Larsen and Valérie Masson-Delmotte and had been designed to bring together the community involved in measurements and modeling of water vapor stable isotopes in order to review the state of the art, to stimulate new collaborations, and to formulate recommendations for future research. It was decided to write a white paper highlighting the added-value of isotope measurements for atmospheric science studies, the state of the art for each topic, the progress in different research directions allowed by recent water vapor isotopic composition measurements, and key recommendations.

Workshop’s website

My presentation