Event Title

Hydrological Response of Western Subalpine Watersheds Following Mountain Pine Beetle Infestation

Event Website

http://www.nafew2009.org/

Start Date

23-6-2009 4:40 PM

End Date

23-6-2009 5:00 PM

Description

Mountain pine beetle (Dendroctanous ponderosae) has been infesting large areas of lodgepole pine dominated forests in the western US and Canada over much of the past decade. The US forest service predicts the current epidemic will kill approximately 90% of the lodgepole pine (Pinus contorta) overstory in Colorado. An outbreak of this size and intensity will influence watershed processes for decades to come but the magnitude of these changes is uncertain. Water supply in western North America is controlled primarily by snow accumulation and melt in forested headwater basins. Trees impact runoff through wintertime canopy interception losses of snowfall and summertime transpiration. Management studies suggest that changes in water yield will occur in response to beetle disturbance but there are significant differences between timber harvesting and pine beetle induced mortality. Hydrological responses in beetle killed forests are dependent on local climatology, forest age and species composition, understory response and severity of infestation. Long-term data records at the Fraser Experimental Forest provide an exceptional opportunity to examine the effects and recovery of insect disturbance on subalpine forest ecosystems. Changes in discharge measured at the watershed level are typically quantified using statistical methods applied to time series data. Critical analysis elements are stationarity, and a sufficient data record for statistically significant detection of change. Short-term studies comparing statistical properties of flow often lack these critical elements and should be examined with caution. We show why short-term studies related to pine beetle impact on hydrology are unreliable. During the past five years, approximately 80% of the lodgepole pine overstory has been killed by MPB at Fraser Experimental Forest, yet double mass plots using control basins and analysis of covariance show no significant response to date. A process-based modeling approach offers a realistic alternative to predicting beetle-induced watershed changes.

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Jun 23rd, 4:40 PM Jun 23rd, 5:00 PM

Hydrological Response of Western Subalpine Watersheds Following Mountain Pine Beetle Infestation

Mountain pine beetle (Dendroctanous ponderosae) has been infesting large areas of lodgepole pine dominated forests in the western US and Canada over much of the past decade. The US forest service predicts the current epidemic will kill approximately 90% of the lodgepole pine (Pinus contorta) overstory in Colorado. An outbreak of this size and intensity will influence watershed processes for decades to come but the magnitude of these changes is uncertain. Water supply in western North America is controlled primarily by snow accumulation and melt in forested headwater basins. Trees impact runoff through wintertime canopy interception losses of snowfall and summertime transpiration. Management studies suggest that changes in water yield will occur in response to beetle disturbance but there are significant differences between timber harvesting and pine beetle induced mortality. Hydrological responses in beetle killed forests are dependent on local climatology, forest age and species composition, understory response and severity of infestation. Long-term data records at the Fraser Experimental Forest provide an exceptional opportunity to examine the effects and recovery of insect disturbance on subalpine forest ecosystems. Changes in discharge measured at the watershed level are typically quantified using statistical methods applied to time series data. Critical analysis elements are stationarity, and a sufficient data record for statistically significant detection of change. Short-term studies comparing statistical properties of flow often lack these critical elements and should be examined with caution. We show why short-term studies related to pine beetle impact on hydrology are unreliable. During the past five years, approximately 80% of the lodgepole pine overstory has been killed by MPB at Fraser Experimental Forest, yet double mass plots using control basins and analysis of covariance show no significant response to date. A process-based modeling approach offers a realistic alternative to predicting beetle-induced watershed changes.

http://digitalcommons.usu.edu/nafecology/sessions/disease/5