INVESTIGATING THE ROLE OF AVALANCHES IN CONTRIBUTING LARGE WOOD DEBRIS FOR FISH HABITAT IN HIGH ELEVATION STREAMS

The Animas River originates in the San Juan Mountains northeast of Silverton, CO. The Animas and its tributaries flow through a region of montane forests, underlain by Tertiary volcanic rocks. These forests are dominated by Spruce and Fir trees. In 2019, a series of large avalanches occurred, which brought a substantial amount of woody debris into these streams. The avalanches carried the woody debris from hundreds of meters away to deposit them in the streams or riparian area. As no large trees grow near these streams. Weakening of trees by insect infestation and drought may have added to the amount of tree debris produced by the avalanches. The objective of this study is to understand how the woody debris affects the morphology of these streams and the fish that live in them. Streams in Alpine areas are some of the last refugia for native Cutthroat Trout. Understanding how avalanches contribute large woody debris to streams, which may enhance trout survival and recruitment, may help trout conservation.