Out on a Limb: Bella Wetzler Logs the Survival of Big Trees with Undergraduate Research Grant

If the proverbial tree falls in the forest, undergraduate forestry student Bella Wetzler isn’t so much concerned with the acoustics of the event as she is with discovering just why that tree fell, and what, precisely, will happen to it next. Wetzler, an undergraduate forestry student in Quinney College of Natural Resources, learned of this particular botanical avenue after taking a Forest Plant Identification class, taught that semester by Ph.D. student Sarah Germain. With a wealth of hours under her belt memorizing plant names and botanical structures, and a good dose of encouragement from the instructor, Wetzler was hired onto a crew from the laboratory led by Jim Lutz, and headed out to become more intimate with the trees she’d studied in the classroom.

It was late summer of 2020, and the Big Trees team was spending a full month among the sandstone hoodoos and forest-covered hills of Cedar Breaks National Monument, logging every log, surveying each and every live woody stem larger than the width of a finger. Every tree rooted in the rust-colored soil within their plot got a metal tag and a detailed once-over by the crew. Is the tree still alive and standing? Did the top break off since the last survey? Are there signs of stress, such as excessive sap or red needles? If the tree is newly dead, is there evidence of why?

August is monsoon season in southern Utah, so it wasn’t unusual that the day’s sunshine was cut one afternoon by a sudden splash of rain and the rumble of distant thunder. The crew was moving across their assigned plot for the day, locating ID tags placed by previous crews and working through the checklist of questions they carried on clipboards. Fast-moving monsoon thunderstorms occurred almost daily, so there weren’t plans to retreat to camp unless the weather became especially severe. Wetzler was moving up a steep slope toward a section of ground they called, for good reason, “The High Point.” 

The clay-heavy soil in the monument became remarkably slippery as it soaked up the rain, which was getting heavier. Wetzler was challenged to maintain her footing on the gooey terrain. She scrambled to the top of a boulder that offered better traction, and frog-jumped across to reach a newly downed subalpine fir next on her checklist inventory. Wetzler knew that the demise of the tree probably couldn’t be attributed to just one factor. It was more likely to be the result of a complex combination of environmental stressors; drought, insect invasion, the after-effects of wildfire, or perhaps fungal pathogens. Following protocol, she unsnapped her hatchet and began a post-mortem to search for evidence of bark beetle—the insect’s rambling route evident beneath the bark where it munched through the phloem. Or perhaps she’d find evidence of heart rot nearer the center of the log. 

That’s when it began to hail. She was being pelted with pellets of ice, clinging to the downed log and slipping through the mud, but she was determined to get the data. 

“So, I’m doing all these bouldering moves, and it’s hailing, and I have my hatchet out hacking into this tree trying to find which fungus killed it,” she said. “It got pretty hairy. I never realized I’d need these kinds of skills for this kind of job.”

It’s a good thing people like Bella are determined to get the data. Old growth forests are in decline; increasing frequency of severe forest fires, and climate change haven’t been good for forest health across the globe. The long-term research project that Wetzler supports is trying to get to the bottom of the downturn, examining the relationships between tree mortality, climate change, and other characteristics that make or break forests. There are a whopping 100,000 trees in this particular inventory. If an individual tree is struggling, it’s noted. If it dies, technicians like Wetzler do a post-mortem evaluation to find out why. Cumulatively, they are creating a treasure trove of information to allow researchers better understand the fate of these forests.

Her time at Cedar Breaks National Monument gave Wetzler a deep appreciation for the complex landscape of southern Utah. It might actually have been her favorite location of the forests she visits each summer—if it weren’t for a new crush. Wetzler is enamored with old growth Douglas-fir and hemlock, green carpets of moss, and the otherworldly lichen found in the Gifford Pinchot National Forest in Washington state.

It might also be an affection of investment. This is the site Wetzler recently used to complete a research project, the result of a QCNR Undergraduate Research Grant she won to study how big logs in the old growth Douglas-fir/western hemlock forest change the way new tree seedlings survive and grow. 

Even after they die, big trees are still an important part of forest ecology. When they finally come down, the long-term presence of logs can tweak all sorts of aspects of the ecosystem. The shade cast by big logs creates cool, wet microsites where seedlings have a better chance of establishing and surviving. Wetzler’s research took on the complexity and variety of log size and position, something earlier studies hadn’t quite been able to capture. Seedlings are more likely to survive in these microsites near logs, even with different widths and orientations of the wood structure, she said. Moss can work against that though, thriving in the moist microclimate and shouldering aside the young seedlings.

“I appreciate the hands-on work, getting to see the successional stages of a forest in real life, to notice the gradient on the mountain, the draw of a stream, get my hands on different species, and be in the middle of different ecosystems,” said Wetzler. “This kind of work really cements learning for me.