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Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds

April 1, 2014

The recent climate-exacerbated mountain pine beetle infestation in the Rocky Mountains of North America has resulted in tree death that is unprecedented in recorded history. The spatial and temporal heterogeneity inherent in insect infestation creates a complex and often unpredictable watershed response, influencing the primary storage and flow components of the hydrologic cycle. Despite the increased vulnerability of forested ecosystems under changing climate1, watershed-scale implications of interception, ground evaporation, and transpiration changes remain relatively unknown, with conflicting reports of streamflow perturbations across regions. Here, contributions to streamflow are analysed through time and space to investigate the potential for increased groundwater inputs resulting from hydrologic change after infestation. Results demonstrate that fractional late-summer groundwater contributions from impacted watersheds are 30 ± 15% greater after infestation and when compared with a neighbouring watershed that experienced earlier and less-severe attack, albeit uncertainty propagations through time and space are considerable. Water budget analysis confirms that transpiration loss resulting from beetle kill can account for the relative increase in groundwater contributions to streams, often considered the sustainable flow fraction and critical to mountain water supplies and ecosystems.

Publication Year 2014
Title Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds
DOI 10.1038/nclimate2198
Authors Lindsay A. Bearup, Reed M. Maxwell, David W. Clow, John E. McCray
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Climate Change
Index ID 70141031
Record Source USGS Publications Warehouse
USGS Organization Colorado Water Science Center