Researcher(s)
- Samantha Chittakone, Environmental Engineering, University of Delaware
Faculty Mentor(s)
- Yu-Ping Chin, Civil and Environmental Engineering, University of Delaware
Abstract
Stemflow—a hydrological process involving meteoric water intercepted by forest canopies and funneled down trees’ stems, trunks, and roots—is a significant but often overlooked pathway for dissolved organic matter (DOM) entering terrestrial ecosystems. This study provides insight into this under-studied process by examining stemflow’s part in the cycling of soluble lignin. Soluble lignin is a rich aromatic compound that enhances soil structure and is a source of nutrients for microbial activity. The analysis of stemflow DOM from three tree species, Liriodendron tuliprifera L. (yellow poplar), Fagus grandifolia Ehrh (American beech), and Betula lenta L. (sweet birch) revealed lignin concentrations an order of magnitude higher than those in surface water. Utilizing liquid chromatography-mass spectroscopy, concentrations of dissolved lignin phenol concentrations in stemflow DOM, including p-hydroxybenzaldehyde, p-hydroxyacetophenone, p-hydroxybenzoic acid, vanillin, acetovanillone, vanillic acid, syringaldehyde, acetosyringone, syringic acid, p-coumaric acid, and ferulic acid, were determined. These concentrations of individual phenols ranged from 0.16µM to 5µM (total concentrations ranging from 10 µM to 20 µM, varying from each tree species). Contrary to findings in surface waters, a strong positive correlation between the biological index (BIX) and lignin concentrations emerged, suggesting that BIX may reflect lignin content rather than microbial activity in these systems. Identifying stemflow’s role in transporting soluble lignin facilitates further investigation with an emphasis on understanding terrestrial carbon cycling and ecosystem responses to environmental changes.