The “critical zone” refers to the planet’s permeable, near-surface layer — that level of the environment where rock, soil, water, air and living organisms interact and shape the Earth’s surface.
This summer, with the support of a $19,927 grant from Susquehanna Shale Hills Critical Zone Observatory (CZO) and the National Science Foundation, Assistant Professor of Environmental Studies Kristen Brubaker and three students spent a month conducting intensive research on the critical zone outside State College, Pa.
At the CZO — which promotes understanding of how a forested, first-order catchment of shale bedrock evolves over multiple time scales in a temperate climate — Brubaker, Kate Boeding ’16, Russell Symmes ’15 and Chad Tokowicz ’18, began work on a project to explore how carbon storage changes throughout a watershed, and how it differs between shale and sandstone dominated watersheds.
Brubaker earned her Ph.D. in forestry from Penn State, with a focus on light and radar – referred to as LiDAR – as well as remote sensing. She has conducted previous research using landscape scale LiDAR to model canopy height across the entire Bureau of Forestry in Pennsylvania.
Using LiDAR, which measures distance by illuminating a target with a laser and analyzing the reflected light, the team examined the Shale Hills and Garner Run watersheds near State College. This work was funded by the NSF Critical Zone Observatory program, with grant EAR 13-31726. They measured and calculated fine-scale, aboveground carbon pools in the hopes of linking robust ecological metrics to current understandings of geologic and hydrological processes occurring within these watersheds.
“Healthy forested ecosystems have the ability to be a major carbon sink globally, meaning they can take carbon out of the atmosphere and store it in the ecosystem,” Brubaker says. “Through this work, we are trying to gain a better understanding of what factors influence carbon storage across a landscape.”
In examining, for example, the percentage of stored carbon in trees, the percentage in shrubs, and the change in percentage across forests that develop over different types of bedrock, Brubaker says she hopes to “prioritize forest protection, management, and restoration to provide the maximum benefit to carbon sequestration for the money.”
In the spring, Boeding took Brubaker’s senior capstone course as a junior, which led to her joining the project team.
“I had an amazing time,” says Boeding, an environmental studies and architecture double major. “I loved being outdoors, collecting data in the field, being out of my comfort zone. I might be focusing on landscape architecture or urban ecology, so it was a great experience to learn about different species of trees and shrubs that will help when I go to apply design.”
Last summer Quincey Johnson ’16 worked in the same watershed, collecting tree data through a Research Experience for Undergraduates at Penn State focusing on forest ecology.
Now working on her Honors project under the direction of Brubaker, Johnson is “hoping to quantify and compare the ecosystem services of two deciduous forests with varying bedrock. Through this, I will be able to determine the impact that deciduous forests play in the mitigation of climate change through the sequestration of atmospheric carbon. Not only did the field work prepare me for my Honors project, but also the entire process of collecting, analyzing and synthesizing data for a greater scientific purpose.”
Brubaker suspects “an inverse relationship between the amount of carbon stored in trees and the amount of carbon stored in shrubs. In areas with less biomass in trees, there will be more in shrubs, and vice versa. What I don’t yet know is the relative amounts of these different carbon pools.”