Apr
08
2010

Why study dead tree roots?

Vivian Leung with tree roots: Vivian Leung in the field researching woody debris
Vivian Leung with tree roots: Vivian Leung in the field researching woody debrisCourtesy Vivian Leung
Every once in a while, I come across an area of scientific inquiry and I wonder what it's all about. I mean, why do scientists study what they study? For instance, why would one study the dead, upended tree roots that have become lodged in stream beds and stream banks?

Well, Vivian Leung, a Ph.D. student at the University of Washington, is doing just that, and she is so clearly fascinated by her work that I am fascinated with her.

Vivian studies woody debris (think dead logs sticking out into a stream) and how the roots interact with water flow and the movement of sediment to affect stream bed shape. The shape of a stream’s bed influences the presence of important fish habitat and the mobility of potentially dangerous hazards (like logs that can become dislodged and move downstream).

Whether or not roots are present on woody debris seems to be especially influential in determining stream bed shape. “Field studies have shown that having roots makes a big difference, I wanted to know which part of the roots is important” said Vivian.

So, down three flights of stairs at the University of Minnesota’s Saint Anthony Falls Laboratory (SAFL), steps from where the Mississippi River laps outside the door, lies an experimental flume that Vivian traveled across the country to work on. Vivian is using the flume to research how the presence, size, and permeability of roots influence the distribution of sediment on a stream bed. As I mentioned above, sediment distribution on the stream bed helps determine whether mobile elements stay put or dislodge and move down stream. It also helps determine whether there is suitable habitat for fish in the stream, an issue especially important to fishermen.

Vivian Leung's root research: Image of Vivian Leung's experiment about how tree roots influence the shape of a stream bed.
Vivian Leung's root research: Image of Vivian Leung's experiment about how tree roots influence the shape of a stream bed.Courtesy Vivian Leung
In a previous experiment, Vivian found that increased density of roots could potentially increase wood stability and decrease the likelihood that the woody debris would break free and move downstream. Through participation with the National Center for Earth-surface Dynamics (NCED), which is housed at SAFL, Vivian is going to do more experiments, this time using a flume with a mobile sediment bed to look at the fluid flow conditions under which model trees begin to be dislodged from the flume bed.

I think it is so neat that studying dead wood debris can help us understand things about fish habitat or potential natural hazards.

Post new comment

The content of this field is kept private and will not be shown publicly.
  • Allowed HTML tags: <a> <h3> <h4> <em> <i> <strong> <b> <span> <ul> <ol> <li> <blockquote> <object> <embed> <param> <sub> <sup>
  • Lines and paragraphs break automatically.
  • You may embed videos from the following providers vimeo, youtube. Just add the video URL to your textarea in the place where you would like the video to appear, i.e. http://www.youtube.com/watch?v=pw0jmvdh.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Images can be added to this post.

More information about formatting options