EROSIONAL RESPONSE TO A STAND REPLACEMENT FIRE, BOULDER COLORADO

On July 9, 1989, the Black Tiger fire burned 2,100 acres of predominately ponderosa pine forest, as well as 44 homes and other buildings, west of Boulder, Colorado. Watershed slopes are moderately steep, with an average slope of 23 percent, and with predominately sandy soils. With fireline intensities ranging from 50 to 1,600 BTU/ft/sec, this stand replacement fire consumed virtually all the light vegetation, forest litter and duff, leaving nothing but exposed soil and ash.

In the 13 years since the fire, a series of more than 30 sets of matched photographs has been taken throughout the burned area to document the changes in hill slope and gully erosion. This field study showed that the majority of material moved in the Black Tiger watershed was from sheetwash rather than channel incision, and the majority of the material moved in the first 14 months after the fire.

In addition to the movement of material down the slopes, the photos in this poster board session show the effectiveness of various erosion prevention methods used after the fire, including sediment fences, contour felling of logs, and water bars. Given the placement and techniques used for construction of these prevention measures, sediment fences were most effective at detaining sediment on hill slopes.