Evan Pugh, Geological Sciences, University of Colorado Boulder
Eric Gordon, Western Water Assessment, CU-NOAA

Since 1996, bark beetles have killed more than 600,000 km2 of conifer forest in western North America. These high-elevation watersheds are the source of much of our municipal drinking water.

A complex suite of processes affect the forest water and energy budgets. Click on a process to the right for more information.

(Click Below For More Info)

Canopy Snow Interception

Canopy Transmission

Canopy Albedo

Snowpack Albedo

Longwave Reemission

Wind Attenuation


Soil Infiltration


Hydrology research is conducted at a number of scales. Findings at one scale do not necessarily hold true at larger or smaller scales. At the tree stand scale, more snow accumulates under grey phase dead trees than comparable living trees.

So will there be more streamflow?

While additional snow accumulation under dead tree stands will lead to more water entering soil during snowmelt, this additional water will not necessarily make it to streams.

Why not? Because of a number of mitigating factors:

Height of the Groundwater Table

Presence of Regenerating Trees

Forested Area in the Watershed

Geographic Aspect and Slope


Even so, additional water from snowmelt coupled with dead trees that are no longer transpiring may produce additional streamflow. Because of interannual variation in streamflow due to weather and climate, the signal of increased streamflow wrought by forest mortality will likely have to be teased out by advanced computational models.


Pugh, E.T. and Gordon, E.S. (2012), A conceptual model of water yield effects from beetle-induced tree death in snow-dominated lodgepole pine forests, Hydrological Processes. doi: 10.1002/hyp.9312