Erosion and restoration of two headwater wetlands following a severe wildfire

Abstract

Wildfire can damage headwater wetlands, yet the value of post-fire restoration treatments in channels has been contested. Staff from the White Mountain Apache Tribe, students from the local Cibecue Community School, and researchers from the U.S. Forest Service collaboratively recorded channel responses over 13 years at two headwater wetlands lying within watersheds that were severely burned by the Rodeo-Chediski wildfire (Arizona, U.S.) in 2002. One site, Turkey Spring, was left largely untreated for 11 years following the fire, while the second site, Swamp Spring, was treated in 2005 by placing large rock riffle formations and vegetation transplants to prevent further incision and stimulate wetland development. The treatment was soon followed by cessation of channel incision and reestablishment of native wetland vegetation, while headcutting caused extensive erosion at the untreated site for eight years. Radio-carbon dating indicated that the eroding soils at Turkey Spring were over 8,000 years old. This study demonstrates that headwater wetlands in this region are vulnerable to extreme incision events following high severity wildfires, but that such impacts can be partially and gradually reversed. Targeted treatments of incising channels may be warranted to conserve wetlands, soils and associated values that have established over thousands of years.