Flood Disturbance in a Forested Mountain Landscape

R ecent flooding in the Pacific Northwest vividly illustrates the complexity of watershed and ecosystem responses to floods, especially in steep forest landscapes. Flooding involves a sequence of interactions that begins with climatic drivers. These drivers, generally rain and snowmelt, interact with landscape conditions, such as vegetation pattern and topography, to determine the capability of a watershed to deliver water, sediment, and organic material to downstream areas (Figure 1). Land-use practices can affect watershed responses to flooding through the influences of managed vegetation patterns and roads on delivery of water, sediment, and wood to streams. Watershed responses to floods include geophysical processes, such as landslides and channel erosion, and related disturbances of aquatic and riparian organisms and their habitats. We explore these geophysical-ecological interactions using a recent flood in