Fire, Fish and Food Webs

The frequency and severity of wildfire in North America has increased substantially in recent years, with relatively poorly understood impacts on aquatic systems. While these large-scale disturbances potentially pose a serious challenge for management and conservation of vulnerable species, these disturbances also can elucidate key biotic and abiotic linkages in watersheds. For example, the alteration of riparian habitat can reveal the strength of habitat coupling between the terrestrial and aquatic ecosystems. Here we examine the incipient impacts of a wildfire that burned 40% of the Scott Creek watershed in coastal California, August 2009. With extensive pre-fire data from study sites in both burned and unburned regions we are provided a “natural experiment” to investigate wildfire impacts on stream ecosystem processes and imperiled salmonids. We examined the short-term impacts of fire on abiotic conditions such as stream temperature, ecosystem processes such as algal accrual and leaf litter breakdown, and aquatic and riparian community dynamics. While fire did impact some of these response variables (e.g., stream temperature, aquatic invertebrate communities), other potential responses appeared unresponsive to this disturbance. Populations of imperiled salmonids in this system appear to be somewhat resilient to this disturbance. Given ongoing global change, it is increasingly imperative to understand how large-scale perturbations alter stream ecosystem and community dynamics.