rocks and water in forest
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Intern Experience: Appreciating the “evolutionary cleverness” of tree hydraulics

Andressa Viol is a senior at Rice University majoring in ecology and evolution.  Her focus has been on animal biology, and her interest specifically lies in herpetology.  In her recent Research Experience for Undergraduates with SERC’s Quantitative Ecology Lab, however, she turned her attention to tree vessels. Andressa described the focus of her internship as “turning black and white microscope images into numbers” – that is, to create and administer a protocol to identify the quantity and area of vessels present in micro-cores from American beech and tulip poplar samples that Jess Shue, Biological Science Technician, collected from SERC’s 16-ha plot in 2014.  Such data contributes to better understanding of how drought impacts trees, which, in turn, strengthens the representation of forests in global models. 

Photo caption below.
A zoomed-out slice of what’s inside a tree.  The rough edges are the edges of the bark.  The holes are the vessels, running lengthwise out of the image.  Photo Credit: Jess Shue
Photo caption below.
A black-and-white rendition of a portion of the above image.  This is the type of image that Andressa used to gather metrics, including the number of vessels present and the area of said vessels.  Photo credit: Jess Shue

Because of the global pandemic, Andressa’s internship had to adapt from an in-person to a remote experience. This necessitated a shift from a field-based focus to a computational one.  Recognizing that forest ecology was a new area of study for Andressa, her advisor, Sean McMahon (ForestGEO Temperate Program Coordinator) suggested she do some reading to orient herself in this new field and contextualize her vessel quantification work. 

With this guidance, Andressa started reviewing AP Biology textbooks for the basics and made her way to reading primary literature on a topic that caught her wholly by surprise – hydraulics.  She noted that trees possess an “evolutionary cleverness that’s amazing to witness” and was so captivated by trees’ unique capacity to transport water that she created a three-minute video full of pithy questions, whiteboard drawings, and substantive scientific explanations.


Eight colors of marker, three hours to draw, and one rather captivating video on the science of tree hydraulics. 

Reflecting on her internship, Andressa observed that its computational focus expanded her sense of what constitutes ecology.  She has a new appreciation for the labor of daily analysis and observed that it is capable of revealing “trends that are not visible in the field.”  We couldn’t agree more.