Spotlight on Teaching: BISC 307: Ecosystem Ecology
In BISC 307: Ecosystem Ecology, a new course taught by Jaclyn Hatala Matthes, assistant professor of biological sciences, students are trying to determine what role humans play in managing ecosystems and how Wellesley’s campus ecosystem can be sustainably managed.
To reach those goals, the students are studying how ecosystems modify climate and how ecological restoration might improve the habitat for biodiversity at several sites—or microclimates—in an area of the College’s arboretum that will be restored next year. The restoration work is part of the Paulson Initiative for the Ecology of Place, which strives to engage students in studying and appreciating campus ecosystems.
Early in the semester, the 11 students in the course, who are among the first to be involved with the Paulson Initiative, installed a micrometeorology tower in the arboretum’s dell area, the lowest point on Wellesley’s campus. The tower records air temperature, humidity, incoming sunlight, soil temperature and moisture content, and the energy exchange between the ecosystem every minute. Students also performed spatial surveys, for which they collected data for air temperature, humidity, soil moisture content, and canopy and ground vegetation cover at 10 locations that transect different ecosystem types across the College’s botanic gardens and arboretum.
Together, these two studies will provide insight into the daily temporal patterns of energy exchange between the ecosystem and the atmosphere, which create the microclimate effects, and will provide data for the variety of different ecosystem microclimates across the campus landscape.
“Understanding the differences among various microclimates is important because a diverse suite of microclimates provides different types of habitat to support biodiversity,” explained Matthes, who served on Wellesley’s Sustainability Committee. “For example, some species, like amphibians, thrive in cool and humid microclimates, but other species are well adapted to warmer and drier conditions.”
Microclimates also have an impact on future global warming, because they can either weaken or intensify broad climate patterns on a local scale. Those patterns are influenced by the way ecosystems use energy from the sun or re-radiation from greenhouse gases to either evaporate water, which cools the surrounding microclimate, or increase convection and conduction, which warms the surrounding microclimate. The balance between evaporation and convection or conduction depends largely on ecosystem characteristics like the number of leaves on trees and the vertical complexity of plant canopies.
“Collecting data this year gives us a baseline for comparison after the restoration of the dell area, so that when we measure microclimate in future years, we can better understand how the ecosystem might be changing to support additional amphibian species [there],” said Matthes.
When students began analyzing the data, they were surprised by how clearly they could see daily cycles and lags among variables with the time-series data as well as differences between sites. For example, on one sunny day with a high of 75 degrees Fahrenheit, there was a difference of six degrees in air temperature between the warmest and coolest sites. Students also confirmed that the microclimate in the Science Center parking lot is up to six degrees warmer than the microclimate in the arboretum’s dell habitat, which is about 200 feet beyond the parking lot.
Matthes will leave the tower running throughout the semester, and she plans to reinstall it in the spring to collect additional data. “Through my teaching, I work to engage students in a process-based understanding of ecology where they develop an appreciation for the scientific method by which data are collected, analyzed, and presented to either support or refute theories,” she said. “Although I know that many of the students I teach will not become ecologists, I hope to impart to all of them skills for analyzing complex systems and appreciation for the critical role that humans play within ecosystems.”
Those skills have included constructing the tripod tower, programming the datalogger that stores the data collected by the sensors, and learning how and where to place sensors. Students also learned to write computer code in R (open-source statistical software), analyze their data, and test hypotheses. They will also produce a lab report written in the style of a scientific research article, with an introduction, methods, results, and discussion sections, as well as recommendations.
Irina Chen ’18, a biological sciences major, appreciates those lessons as well as the broader understanding of ecology she has gained from the class. “This course has given me insight into how extremely dynamic and diverse ecosystems are!” she said. “I continue to be surprised and amazed by interactions in ecosystems that I was not aware of previously.”