On the eastern coast of Tasmania, dry sclerophyll forests are sanctuaries for a diversity of plant and animal life — wallabies, wombats, and a number of understory shrubs. Mostly, these forests are thick with growths of acacia trees and the smell of eucalyptus. It's a picture of paradise.
But in 2017, when Chris Smith-Martin stepped into one particular grove in the aftermath of a devastating drought, she saw the exact opposite. The forest had suffered. Most of the trees wore a coat of drab, brown leaves, and many were dead.
“It struck me how fragile they were. Suddenly something pushed them over the edge,” says Smith-Martin, who took a trip to the drought-affected forest while working in Australia as a graduate student in the University of Minnesota’s Plant and Microbial Biology program. “It was extremely devastating.”
Now, as a new faculty member in the Department of Plant and Microbiology, Smith-Martin studies forest ecology and plant ecophysiology — the interaction between plant traits, processes, and their environment. But a huge part of her research examines how the unique traits of tree species among diverse communities make them more or less resistant to drought, as was the case with the forest in Tasmania, where several species survived, but others, including Eucalyptus were more affected.
“Why do some species die and others don’t?” asks Smith-Martin. She first connected with the University of Minnesota while working as a graduate student in Jennifer Powers’ lab. At the time, they were conducting research in the tropical dry forests of Costa Rica—where Smith-Martin grew up.“That’s what I’m after in my research.” She examines tree hydraulics and the physiological ways trees respond to heat and water stress. In particular, Chris-Martin studies tree species’ ability to transport water through root, trunk, branch, and leaf tissue.
“Trees that die from extreme drought stress typically accumulate so many embolisms and blockages that they just can’t move water anymore,” says Smith-Martin. “So embolisms are part of what we’ll be measuring. The other thing I look at is the wilting point. Some trees can withstand drought for a long time, and others wilt quite fast.”
At the University of Minnesota, Smith-Martin aims to take her research to a variety of Minnesota habitats — including at Itasca Biological Station and Laboratories’ ForestGEO sites, Cedar Creek Ecosystem Science Reserve’s Long Term Ecological Research (LTER) experiments, and on University campus. She hopes to cross-examine how certain Minnesota native tree species respond to temperature and water stress across a variety of landscapes — such as urban and protected areas.
Her work in Minnesota parallels the research she conducted during her graduate and postdoctoral years, studying woody species and drought effects across Puerto Rico, Panama, and Costa Rica. In particular, she focused on trees in the Luiquillo ForestGEO and LTER sites in the Caribbean during her postdoc at Columbia University, work she plans to continue as she establishes her home base in the midwest.
“We just finished installing this huge drought experiment in Puerto Rico, where we basically have installed giant roofs under trees in a forest to remove rainfall and measure all sorts of things,” says Smith-Martin.
As someone who grew up on a ranch in rural Costa Rica, Smith-Martin’s family is constantly surprised that she ended up in Minnesota doing work here. But with her network of people – including Powers and the connections she has at the long-term research sites – Smith-Martin is quite happy to brave the midwest winters and form a new appreciation for any and all ecosystems.
“I had a very unsupervised childhood,” says Smith-Martin, who was frequently seen barefoot, swinging from branches late into the evening. “It made me want to continue an outdoorsy life and understand plants in general. Like how do they survive? How do they live? I just want to understand them.” – Adara Taylor