Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Siegert, Courtney

Committee Member

Keim, Richard

Committee Member

Renninger, Heidi J.

Date of Degree

12-8-2017

Document Type

Graduate Thesis - Open Access

Major

Forestry

Degree Name

Master of Science

College

College of Forest Resources

Department

Department of Forestry

Abstract

Stemflow creates biogeochemical hotspots at tree bases. Few studies examine bark structure effects on stemflow generation via stable isotopes. Stemflow volume and isotopic composition (δD, δ18O) were measured over 15 months to address three main objectives: to determine origins and pathways of stemflow, to identify differences in stemflow generation mechanisms between tree species, and to identify differences in stemflow generation mechanisms between meteorological events. Laser ablation spectroscopy showed that, compared to throughfall and precipitation, stemflow was isotopically enriched, signifying isotopic fractionation. A bark-wetting experiment showed bark water storage capacity to be greatest in species with thick, continuous bark. Isotopic composition of precipitation was significantly more enriched in convective storms compared to that of continental or oceanic origin. Therefore, isotopic fractionation of stemflow and stemflow generation mechanisms vary from that of throughfall and precipitation, by interspecific differences in bark, and by meteorological event, potentially influencing existing canopy water storage models.

URI

https://hdl.handle.net/11668/19679

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