B064-0003
Bark Beetle Impacts on Forest Evapotranspiration and its Partitioning

Friday, 11 December 2020
Poster
John F Knowles1, Andrew Badger2, Max B Berkelhammer3, Joel A Biederman1, Nels R Bjarke4, Peter Blanken5, Mario Bretfeld6, Sean P Burns7, Brent E Ewers8, John M Frank9, Leanne Lestak10, Ben Livneh2, David E Reed11, Russell L Scott1 and Noah P Molotch12, (1)USDA-ARS, Southwest Watershed Research Center, Tucson, AZ, United States, (2)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (3)University of Illinois at Chicago, Chicago, IL, United States, (4)University of Colorado at Boulder, Civil, Environmental and Architectural Engineering, Boulder, CO, United States, (5)University of Colorado, Boulder, Geography, Boulder, CO, United States, (6)Kennesaw State University, Ecology, Evolution, and Organismal Biology, Kennesaw, GA, United States, (7)University of Colorado and National Center for Atmospheric Research, Boulder, CO, United States, (8)University of Wyoming, Botany, Laramie, WY, United States, (9)U.S. Forest Service, Fort Collins, CO, United States, (10)Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, United States, (11)Michigan State University, Center for Global Change and Earth Observations, East Lansing, MI, United States, (12)University of Colorado at Boulder, Geography / INSTAAR, Boulder, CO, United States
Abstract:
An open ecohydrological question concerns the impact of bark beetles on evapotranspiration (ET) due to uncertainties associated with differential and potentially counteracting responses of the abiotic (evaporation) and biotic (transpiration) components of the total ET flux. Given that changes in ET are linked to both groundwater and surface water recharge, these processes are directly relevant to the sustainability of downstream agricultural, industrial, and residential water consumption. As a result, this research combined satellite remote sensing, eddy covariance, and hydrological modeling approaches to quantify the impact of bark beetles on the magnitude of ET during the last two decades throughout the 144,462 km2 Southern Rocky Mountain ecoregion, USA. We leveraged recent advances in ET partitioning to further characterize and model changes in evaporation and transpiration over space and time before, during, and after the occurrence of a widespread bark beetle outbreak. Vegetation mortality and resulting overstory denudation have been shown to alter the surface radiation balance, wind regime, canopy interception, and understory growth; hence, our focus on ET partitioning allows for investigation of the relative magnitude and importance of each of these processes to biologically- and physically-mediated ET as well as the aggregate ET flux. To determine the effect of patch scale ecohydrological dynamics at larger spatial scales, changes in component and total ET fluxes were also translated through the water balance to evaluate regional streamflow using the Variable Infiltration Capacity (VIC-5) hydrological model. These results will benefit water managers tasked with forecasting water resources from insect disturbed areas both now and in the future.
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