Stanford University

Geological Sciences Seminar: Tyler Doane, Indiana University

When:
Tuesday, Feb 15, 2022 12:15 PM
Where:
Zoom
More Info:

Free

Audience:
Faculty/Staff, Students, Alumni/Friends
Sponsor:
Department of Geological Science

Theory, measurement, and process-based information of topographic roughness on forest floors

Tree throw is a consequential and recognizable sediment production and transport process when a tree topples and excavates a pit and deposits an adjacent mound. The pit-mound signature of tree throw is a uniquely clear and measurable topographic signature for hillslope processes. But quantifying the rate of tree throw is challenging because recurrence intervals are long relative to human timescales, which frustrates direct human observation. We have developed a theory that explains the topographic roughness of forest floors as a result of the competition between roughness creation by tree throw and destruction by creep-like processes operating within the soil mantle. We then use the theory to answer several questions. First, we rearrange theory to yield a dimensionless variable that is the ratio of sediment fluxes of tree throw versus creep-like processes, which is an entirely topographic variable and can be mapped using high-resolution topographic data. The variable is mapped across a county in southern Indiana. Second, we define relationships between statistical moments of topographic roughness and tree throw occurrences, which we use to identify a candidate probability function of tree throw production rates. Third, we develop a mechanical model for tree throw that combines the statistics of wind speeds, topographic roughness, and root and soil strengths. I end the presentation by suggesting other processes and settings where the overall concept might be applied.

Tyler received his bachelor’s degree in Geology from Colorado College in 2010 and a Ph.D. in Earth and Environmental Sciences from Vanderbilt University in 2018. Since then, he has been a postdoc at the University of Arizona and a postdoc at Indiana University.

Email Rey Garduño, rgarduno@stanford.edu, for Zoom link and password.

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