US-IALE 2018 has ended
Back To Schedule
Monday, April 9 • 5:30pm - 7:00pm
POSTER: Canopy Structural Complexity and Light Use Efficiency: The Influence of Forest Species Richness and Stand Density on Resource Use

Sign up or log in to save this to your schedule, view media, leave feedback and see who's attending!

AUTHORS: Franklin Wagner*, Brady Hardiman, Elizabeth Larue, Doug Jacobs – Purdue University

ABSTRACT: Forest structure is an important driver of resource use and ecosystem functioning in forest communities. Canopy structural complexity (CSC) describes the vertical and horizontal variation of leaves and branches within a canopy, and is an important predictor of forest light use efficiency (LUE). Previous studies have focused on observational relationships between stand level measurements of CSC and LUE; However, a mechanistic understanding of how other factors, such as community composition and tree density, contribute to this relationship is lacking. Therefore, we used manipulative experiments to test how tree density and species composition influence CSC and LUE. We hypothesized that CSC is positively related to both species richness and stand density across treatments. That is, CSC increases with increased species richness and increased density. Furthermore, we hypothesized that CSC is positively related to LUE- LUE increases in stands with higher CSC. The experimental plots were constructed in 2007 and planted with different species compositions (Northern Red Oak, American Chestnut, Black Cherry) and densities (1 m, 2 m, and 3 m spacing) for a total of 21 unique plot variants, including both monoculture and mixed stands. The fraction of absorbed photosynthetically active radiation (fPAR), a proxy for LUE, was measured in 2017 under different light conditions (direct vs. diffuse) within each plot. Preliminary results showed significant differences in fPAR for the density treatments, but not across species composition treatments. Canopy height was also significantly different across composition and density treatments. Ongoing and future work will involve a more comprehensive investigation of differences in fPAR across treatments as well as integrating tree mortality, a potential confounding factor. Understanding the relationship between CSC and LUE will have important implications for how forest structure influences resource use, and can be further applied to model forest carbon dynamics under climate change.

Monday April 9, 2018 5:30pm - 7:00pm CDT
Monroe Room

Attendees (3)