Current WRP Projects: Project 35

Impact of bark beetle outbreaks on forest water yield in southern Wyoming

  • Project Number:  35
  • PIs: 
    • Brent E. Ewers (Assoc. Prof. U. of WY,; 307-766-2625)
    • Elise Pendall (Assoc. Prof., U of WY; 766-6293)
    • David G. Williams (Prof., U of Wyoming; 766-2494)
    • Holly Barnard (U. of WY, Post-doctoral Fellow; 766-5407)
  • Status:  Ongoing.
  • Period:  March 10 - Feb 13


A Rocky Mountain Region outbreak of bark beetles and their associated fungi from British Columbia to New Mexico is having profound impacts on forest function and ecosystem services. These forests are key components of major river watersheds which could magnify any impacts on downstream users of water including those in Wyoming. Current and ongoing research is documenting the potential extent, causes and impacts on carbon exchange and evapotranspiration but less is known about how water yields will be impacted on short to long time scales. This project will enhance preliminary measurements on evapotranspiration and soil moisture from a mid-elevation lodgepole pine forest undergoing infestation by 1) reasonably closing stand water budgets to better quantify and thus predict water yield and 2) extending replicate measurements and analyses to post-infection management and two other forest types to facilitate future scaling to landscape water yield. New stands will be established in mid elevation former lodgepole pine that has been clearcut after infestation, lower elevation lodgepole pine forest that may be replaced by sagebrush steppe and high elevation spruce fir forest experiencing slower bark beetle infestation and much higher precipitation inputs. We will provide complete water budgets that are closed on a stand basis by measuring 1) spatially explicit snow accumulation and loss, 2) detailed liquid canopy interception and stem flow, 3) appropriately scaled transpiration from living, dying and dead trees' water use (or lack thereof) through sap flow and leaf gas exchange, 4) soil hydraulic characteristics and modeling and runoff for water yield and 5) stable isotopes of soil, plant and atmospheric water as a further test of water budget component closure. Our proposed data collection and analysis will provide highly probable predictions of water yield during the first 5 to 10 years of the outbreak and provide the basis for first order predictions of the next 10 to 100 years of impact. The results of this project will be communicated with State and Federal agency personnel, providing data necessary for future water management decisions in all areas of Wyoming impacted by the bark beetle outbreak.

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