10 years of counting campus trees – and growing

Research calculates ecological, economic and emotional value of UTRGV’s urban forest at more than $5M

By Karen Villarreal

Every five years, UTRGV students in hard hats and neon yellow vests hug trees for the sake of science. As they wrap their arms and measuring tapes around the trunks, they transform the campus grounds into their classroom and lab.

Their professor encourages them to enjoy this bonding moment with nature – and to ensure they collect accurate data for future generations of arboreal-minded students. Dr. Alex Racelis, director for the Agroecology program at UTRGV, focuses on the knowledge and care of trees in this Community Forestry course.

“We’re trying to get students to experience both,” Racelis said. “You care about what you know.”

He noted classes like this foster the innate sense of social responsibility of many UTRGV students.

“Some of them come from a culture of care where you are required to be responsible for your home, siblings and elders,” he said. “We try to extend it into their community and to their region’s natural resources – in particular, an appreciation of trees.”

The group of 20 undergraduate and graduate students get to know and appreciate UTRGV’s urban forest very well. One of their first exams involves identifying the 15 most common trees on campus, while a later exam focuses on pruning and maintenance. As part of their “homework,” they are tasked, in teams, with measuring 40 of the nearly 2,000 trees on the Edinburg campus.

Racelis stated the students’ work has produced valuable information, leading to a 10-year streak of recognition by the Arbor Day Foundation.

“The research informed the Office for Sustainability in drafting UTRGV’s inaugural Tree Care Plan and fulfilled one of the requirements for the university earning its first Tree Campus USA designation in 2014,” Racelis said.

The latest survey will contribute to an updated Tree Care Plan, and re-submission to Tree Campus USA.

THE VALUE OF TREES

Working with Texas A&M Forest Service, Racelis trains students to measure tree dimensions, like height and canopy volume, and to conduct an evaluation of tree health and maintenance needs. They log the measurements in a program called I-Tree Eco, which analyzes the data and quantifies environmental effects.

“Our research shows that when you increase tree canopy, land surface temperatures go down – so trees also help with the reduction of energy use,” Racelis said. “We can calculate the energy saved from shade cast on nearby buildings.”

I-Tree Eco similarly allows Racelis and the forestry students to calculate carbon sequestration, rainwater retention and airborne particulate sequestration.

In 2014, the last complete tree survey calculated these ‘ecosystem services’ and the trees’ standing value at more than $5,735,000.

Although the current assessment isn’t complete, Racelis said that they have already observed significant growth over the last 10 years, which contributes to the campus forest’s ecosystem.

For example, Live Oaks, the most common type of tree on campus, have increased in volume by more than 60 percent since the last assessment.

“According to our preliminary calculations, mature oak trees on campus absorbed nearly 6,000 pounds of CO2 over the last 10 years, absorbed more than 45,000 gallons of stormwater and removed pollution from the air equivalent in weight of 100 smartphones,” Racelis said.

Additionally, Racelis explained the beautification of the campus with an urban forest has aesthetic, spiritual and emotional benefits that are substantial – though a little bit more difficult to evaluate.

Racelis mentioned that former graduate students started asking questions about the campus’s cultural ecosystem services as part of their research.

Their surveys, conducted 10 years ago, revealed that students overwhelmingly appreciate the campus trees and their cooling shade. One favored campus spot was the tree-lined walkway to the Sundial where the canopies arch overhead.

“And our campus urban forest provides educational benefits, like the unique learning experience the students are getting right now,” Racelis said.

CONTINUING A LEGACY OF CARE

Juliete Gonzalez, a graduate student in her first semester of the Master of Science (MS) in Agricultural, Environmental, and Sustainability Sciences (AESS) program, wears a silver hard hat and carries a laptop instead of measuring tools.

Along with Racelis, she supervises to ensure students are collecting data from the correct tree; each tree is identified with a metal tag, which can fall off over time.

She plans to use the decade-long data for her thesis on the role of urban forests in mitigating climate change factors such as carbon pollutants, stormwater and extreme heat.

“I’m really appreciative of the team that took the initiative to carry out this project here on campus,” Gonzalez said. “Based on their work, I’m able to continue on and learn about the ecosystem benefits of trees.”

Although it will take time to see the cumulative impact of the trees, Gonzalez said she knows they are worth the wait and effort.

“Just because they’re stationary, people don’t make the connection that they are contributing to the ecosystem too,” she said. “These are living beings that we need to take care of.”