1. US Army Corps of Engineers BUILDING STRONG ® Impact of Beetle Infestation on Hydrology Dr. Christopher A. Hiemstra Cold Regions Res. and Engr. Lab. (CRREL) U.S. Army Corps of Engineers Fort Wainwright, AK Christopher.A.Hiemstra@usace.army.mil office: (907) 361-5488 mobile: (907) 347-1028 November 2010

2. BUILDING STRONG ® Favorable Conditions for Beetles  Even-aged forests  Drought-stressed trees  Warmer winters (higher beetle survival)  Lodgepole pine trees are experiencing high mortality, as seen by their red coloration. In this August 2007 aerial image of the Fraser Experimental Forest, Colorado, dead reddened trees cover vast areas.

3. BUILDING STRONG ® Widespread Impact Raffa et al. 2008

4. BUILDING STRONG ® Kelly Elder

5. BUILDING STRONG ® Interception Litter Transpiration Snow Melt Infiltration Runoff Interception Precipitation Throughfall Wind Speed Sublimation

6. BUILDING STRONG ® Potential Impacts  Pre-disturbance ► Canopy intercepts ~20-36% of snow ► transpiration is ~38% of precipitation ► higher shading, slower spring melt  Post-disturbance ► lower interception ► higher sublimation, evaporation, and radiation ► faster runoff, earlier hydrograph peak  Unknowns ► Transpiration (forest floor compensation?) ► Runoff (greater or lower; spatially variable?)

7. BUILDING STRONG ® Watershed Research (Uunila et al. 2006)

8. BUILDING STRONG ® Snow Modeling (Bewley et al. 2010)  Baker Creek, BC, Canada (1570 km 2 )  Lodgepole pine with 50-80% mortality  10-20% increase in peak SWE  10-15% faster melt rate