Pictures, Video, Lectures, and More:
Ellen Wohl gave a lecture titled “Messy Rivers are Healthy Rivers” at Boise State University as part of a series on The Idea of Nature. Watch the entire lecture here.
Large wood traps carbon flowing downstream
Portions of a river network with abundant large wood, whether single pieces or logjams, are more efficient at retaining particulate organic matter, which is about 50% carbon. When large wood helps to trap organic matter for even a few hours, the organic matter becomes more available to microbes and macroinvertebrates in the stream and floodplain. Examples are shown in the following three photographs:
Glacier Creek, Rocky Mountain National Park, CO
Ouzel Creek, Rocky Mountain National Park, CO
Biscuit Creek, Catskills, NY
Beaver dams and meadows retain carbon in river networks
Portions of a river network in which beaver build dams can also be sites of enhanced organic carbon storage. Beaver dams obstruct stream flow, enhancing overbank flooding and associated deposition of organic matter and infiltration of flood waters. The saturated, organic-rich sediments in these portions of the river corridor contain substantial amounts of organic carbon. Beaver commonly build multiple dams, creating a valley-bottom mosaic of dams and ponds of differing ages that is known as a beaver meadow.
An example of an active beaver meadow along North St. Vrain Creek in Rocky Mountain National Park, Colorado. This beaver meadow lies between lateral moraines of the Pleistocene valley glacier.
An abandoned beaver dam and pond along the southern valley margin of the North St. Vrain Creek beaver meadow.