Seeing the Forest for the Streams: Upper Trophic Level Consumer (Coastal Cutthroat Trout and Coastal Giant Salamander) Responses to Riparian Forest Thinning Across Seasons and Riverscapes

Contemporary forest management practices often prescribe riparian buffers to mitigate impacts associated with timber harvest on aquatic ecosystems. Although buffers have proven effective in providing shade and potential sources of large wood to streams, more active management of riparian forest conditions may also have benefits. Our work is focused specifically on the potential of selective harvest of riparian forests to boost instream productivity by increasing light availability. To address this question, we are evaluating the effects of selective harvest in riparian forests in headwater streams located in coastal northern California. The objectives of our research include quantifying the influence of riparian forest structure and composition on: 1) Light availability and stream temperature across stream networks; 2) The seasonality of riparian and instream pathways of production; and 3) The effect of these changes on the growth and bioenergetics of dominant upper trophic level consumers – Coastal Cutthroat Trout (Oncorhynchus clarkii) and Coastal Giant Salamander (Dicamptodon tenebrosus). We will evaluate the effects of riparian conditions through empirical spatial/seasonal models of site influences in networks and by applying a new mechanistic model of instream productivity that will allow us to explore a host of scenarios and cumulative effects of riparian forest management.