Two students from Western Colorado University helped scientists collect data for the Colorado Headwaters Ecological Spectroscopy Study (CHESS) this summer. Conducted at RMBL in 2018 and 2025, it is designed to see how plants and ecosystems in the Upper Colorado River system are faring under our current extreme drought conditions. Dr. Ian Breckheimer is the principal investigator. 

CHESS combines data from airborne imaging spectroscopy with corresponding field data gathered by researchers on the ground. Bradley Sowder and Andres (Dre) Villa served among the boots on the ground. Bradley operated drones to supplement the spectral data on plants, and Dre was part of the tree team. 

Working on the project allowed each student to develop a theme for his master’s thesis. 

Dre’s tree team looked at the demographic of the trees, like health status, presence of parasites, and disease. They measured each tree’s diameter (using the diameter at breast height or DBH standard) and height and collected samples from the tree canopy — needles if it was a conifer or leaves if it was an aspen. 

From those samples, they took sub-samples, weighed them while still fresh, put them in a drying oven, and then weighed them again to determine their water content. The team also calculated the forest’s average leaf area index (LAI) based on data collected at 30 points within 100-square-meter plots. This showed the leaf density of each plot. 

Will trees stand up to drought? 

The thesis subject Dre found from his field research is: Can scientists use a conifer forest’s canopy water content to predict its vulnerability to drought stress? 

Dre is collecting post-mortem data on dead trees, getting the DBH and height, and speculating the cause of death — pests, mechanical damage, or something else. Then he’ll develop a mortality dataset by species if possible or, if the spectra signature yields insufficient delineation, a general mortality dataset. He hopes to have the demographics on 400 trees over 19 field sites. 

Finally, Dre will combine his mortality dataset with the CHESS spectrometer data from 2018 and 2025 to see if scientists can predict the forest’s vulnerability to drought stress using mortality and climate data. 

In other words: Will the trees survive drought stress? How much can they take? Does the species matter? And how much canopy water do they need to stay alive? 

Leave it to beavers? 

Bradley’s thesis weighs the costs and benefits of beaver dam analogs, which are pseudo-dams built by land managers to restore habitats and wetlands. Like beaver-made dams, BDAs slow down waterflow, create wet environments, mitigate flood damage, and attract more plants and animals. 

To find out if beaver dam analogs are as effective as the real thing, Bradley will measure the evapotranspiration of the ecosystems around BDAs and compare it to the evapotranspiration that occurs where the dam builders are beavers. 

Evapotranspiration is the amount of total water moving into the atmosphere. It’s the sum of two things: the evaporation of water from the soil, water surfaces, and plant leaves; and transpiration, the water that evaporates from plants living out their lives. 

Bradley will compare the level of transpiration in natural, beaver-built systems to that of ecosystems made from beaver dam analogs. He wants to see if BDAs are generating more evapotranspiration than what occurs at natural sites created by beavers. And if so, to what degree? 

In his last year at Western, Bradley is part of a three-year, two-degree track. He’s completed a master’s degree in environmental management, and he’s following that with a master’s in ecology. Then he’s job-hunting. 

Dre just finished his third year in WCU’s 3+2 program, which allows students to earn an undergraduate and master’s degree in five years. He’ll earn a bachelor’s degree in biology and a master’s degree in ecology. He plans to be a pilot for the Air Force or, if not that, an ecologist. 

While pursuing their degrees, both Dre and Bradley have contributed to an important scientific study involving more than 20 scientists at RMBL.  

In addition to generating a fruitful career for each, their participation will help us move closer to knowing what lies ahead for the Colorado River headwaters and for the river itself.   

-Article written by RMBL contributor, Carol St. George

Photo credit: Sophia Todorov – Bradley Sowder, a student researcher with the CHESS program, shows off the flight controller for the drone.