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.


New article in Agricultural and Forest Meteorology

Our new article, “Dew deposition suppresses transpiration and carbon uptake in leaves” was just published in Agricultural and Forest Meteorology. The work was a collaboration with Kelly Caylor, Sally Thompson’s lab at UC Berkeley, and Tony Rockwell at Harvard University. For this work, we built a leaf energy balance model to test the effects of dew and fog on the leaf water, carbon, and energy balances. We compared our model to data from UC Berkeley’s Blue Oak Ranch Reserve in CA. See the abstract below for a quick overview of the study and results or head to the A&FM website to read the full paper.

Abstract

Dew deposition occurs in ecosystems worldwide, even in the driest deserts and in times of drought. Although some species absorb dew water directly via foliar uptake, a ubiquitous effect of dew on plant water balance is the interference of dew droplets with the leaf energy balance, which increases leaf albedo and emissivity and decreases leaf temperature through dew evaporation. Dew deposition frequency and amount are expected to be affected by changing environmental conditions, with unknown consequences for plant water stress and ecosystem carbon, water and energy fluxes. Here we present a simple leaf energy balance that characterizes the effect of deposition and the evaporation of dew on leaf energy balance, transpiration, and carbon uptake. The model is driven by five common meteorological variables and shows very good agreement with leaf wetness sensor data from the Blue Oak Ranch Reserve in California. We explore the tradeoffs between energy, water, and carbon balances for leaves of different sizes across a range of relative humidity, wind speed, and air temperature conditions. Our results show significant water savings from transpiration suppression up to 25% for leaf characteristic lengths of 50 cm. CO2 assimilation is decreased by up to 12% by the presence of dew, except for bigger leaves in windspeed conditions below 1 m s−1 when an increase in assimilation is expected.


New paper out in pre-print

After thinking a lot about pre-print and how they fit in the world of plant research, I have decided to give it a try! My first pre-print entitled “Dew-induced transpiration suppression impacts the water and isotope balances of Colocasia leaves is now available on the bioRxiv: see the article!

The paper examines the effects of dew on transpiration suppression in Colocasia esculenta leaves using stable isotopes of water to track changes in the water status of the leaves. The article has been submitted to a peer-reviewed journal.

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 isotopic 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. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential (p < 0.05) and a more depleted water isotopic composition than misted leaves (p < 0.001), suggesting a ∼30% decrease in transpiration rate (p < 0.001) compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance. 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.

https://www.biorxiv.org/content/early/2017/08/30/178293
doi: https://doi.org/10.1101/178293


Fog, Fog Collection, and Dew conference

Last week, I attended the 7th International Conference on Fog, Fog Collection, and Dew hosted in Wroclaw, Poland. The conference is organized every three years and brings together scientists from all continents working on different aspects of non-meteoric water.

I gave a talk on my current project in collaboration with Pr. Sally Thompson from UC Berkeley  looking at transpiration suppression due to fog and dew. I was also very happy to learn more about some fascinating dew and fog collection projects, a topic I have thought about a lot before.

It was great to get to see old friends, like former Caylor Lab member Lixin Wang presenting his work on the use of stable isotopes to separate dew and fog water inputs for vegetation in the Namib desert, or Camille Duprat, former post-doc in the MAE department at Princeton University. In addition, I got to meet some of the most active people in the world of dew related research, like Daniel Beysens, Nurit AgamJürgen Burkhardt, and Simon Berkowicz

Finally, the conference was a unique opportunity to meet young and enthusiastic scientists from all across the world, and I am thrilled for the opportunities that this new network of friends and colleagues will bring in the future!

See the conference website HERE.
See the full conference program HERE.
See the live tweets from the conference using the hashtag #FFCD2016.

PS: Can you find me on the official conference picture above?


Visit to UC Berkeley

Last week, I went out to California to initiate a new collaboration with Pr. Sally Thompson at UC Berkeley. Pr. Thompson has been collecting leaf wetness data at multiple sites across California, and I will be using her dataset together with my leaf energy balance model to estimate the reduction in transpiration associated with dew and fog formation. I got the chance to visit one of the field sites, the Blue Oak Ranch Reserve, located up in the hills above San Jose. See the gallery below to see some pictures of my trip!


EEWR Seminar March 27th 2015

I gave the EEWR (Environmental Engineering and Water Resources) departmental seminar on Friday, March 27th 2015. My talk focused on the latest results from the lab experiments I conducted last summer and fall, looking at the impact of dew deposition on Colocasia esculenta‘s energy balance. Please contact me if you would like to hear more on the topic!

See the flyer and abstract here.