Graduate Exit Seminar - John Brett

Plan to join John Brett's graduate exit seminar on July 7, 2023, at 1:30 pm in Kottman Hall 245 or via Zoom. John will present, "Comparison of LiDAR, Allometry, and Photogrammetry Structural Measurements of Northern Red Oaks in Columbus, Ohio."

Abstract: Urban forests are important infrastructure in cities that hope to mitigate the worst effects of urbanization and climate change. Trees are shown to remove pollution, reduce surface temperature, intercept stormwater, sequester carbon, and secure other ecosystem services. These beneficial forest processes can be modeled and quantified using environmental conditions and tree characteristics. Among these characteristics, crown structure and leaf metrics are important factors to be quantified in efforts to estimate ecosystem services provided by urban forests. Considering the methods available to measure tree structure, this research examined the capability of various techniques to measure crown volume and crown surface areas of Northern Red Oaks from the Franklinton neighborhood in Columbus, Ohio. The methods to measure tree structure compared in this study included photogrammetry (a complex mesh and a convex hull representation), LiDAR analysis, and urban tree allometry (two regional allometric equations and one national allometric equation). The methods represented the crown across three levels of geometric specificity: a perfect geometric solid (i.e. ellipsoid), an irregular but simple geometric solid (convex hull), and a complex mesh. Results of this research showed significant differences between methods. Allometric models regionalized to the Lower Midwest United States and LiDAR data from 2019 showed the highest agreement with the Convex Hull from Photogrammetry for both crown volume and crown surface area measurements. Comparisons between the normalized vertical profiles of LiDAR and Convex Hull from Photogrammetry revealed consistency in crown shape across methods and heights. To enhance understanding of Northern Red Oaks growing in urban environments in Columbus, Ohio, allometric models were developed. This research has implications for the choice of method used for structural assessment and subsequent ecosystem services estimates. 

Advisor: Dr. Steve Lyon