By Carl Carman, Guest Blogger/Ex-officio RORG Team collaborator/Volunteer
The Red Oak Rain Garden (RORG) team planted approximately 9,000 plants and recorded the species, number, and geospatial location of each plant. Given the plethora of plants, the team thought it might be cool to estimate the environmental impact of the garden in the context of terrestrial carbon sequestration. First a definition: carbon sequestration is “capturing and storing atmospheric carbon dioxide”. It helps reduce atmospheric carbon dioxide with the goal of reducing climate change.
But, how to quantify this for a rain garden?
Enter the Dragon Carl Carman. I’m Carl. By day, I’m an environmental geologist at the Illinois State Geological Survey, a unit of the Prairie Research Institute at the University of Illinois. I specialize in geologic carbon sequestration, geospatial analysis, data analytics, and making fake nametags for my coworkers’ offices. Since I began working with the RORG team and the shelter-in-place order, I have developed proficiency in Skype, Webex, Zoom, Discord, Microsoft Teams, Google Hangouts, and GoToMeeting. Please don’t ask about other videoconferencing software packages.
Carl Carman at his day job, prior to shelter-in-place, slicing aluminum pipes for carbon storage.
From my home office, my cat and I are processing the RORG dataset (number, type, geometry, and geospatial location) to estimate the biomass of plants, and thereby an approximation of the carbon sequestered by the project. The RORG Team and I hope that this work can provide an outline or starting point for similar efforts involving small-scale terrestrial sequestration. However small, these impacts add up!
We grouped the plants into three categories: trees, shrubs, and groundcover, in order of their predicted contribution to the total carbon sequestered. I conducted an in-depth literature review to evaluate methods for estimating biomass of a wide variety of plant species. Using generalized allometric equations for the plants in all three categories, we will soon have a rough estimate of the total carbon terrestrially sequestered in the Red Oak Rain Garden.
There are a couple of obstacles in achieving a scientifically accurate estimate for this. Given that most of the plant life in the Red Oak Rain Garden is new, these plants have a long and full life ahead of them, during which they will, if raised right by their parents, continue to draw carbon from the atmosphere and incorporate into their corporeal forms. To overcome this non-linear growth, the equations used to calculate biomass must rely on allometric plant measurements which must occur each time a new estimate is desired. Another obstacle involves the large variety of species in the garden: without specific allometric measurements for each, we must use general equations for each subgroup.
Presently, I’m developing a software package which will eventually be turned over completely to the RORG team for periodic updates and maintenance. The package includes the dataset itself, carbon sequestration computations, and interactive web content available to the public to explore.
After this work is complete, I plan to go back to my other part-time gig as a devoted cat dad.
Check out his new blog: https://carlcarman.com/
redoakraingarden.org 
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