Mountain pine beetle infestation of lodgepole pine in areas of water diversion Sharon L. Smolinski a, * , Peter J. Anthamatten a , Leo P. Bruederle b , Jon M. Barbour a , Frederick B. Chambers a a University of Colorado Denver, Department of Geography and Environmental Sciences, Campus Box 172, P.O. Box 173364, Denver, CO 80217-3364, USA b University of Colorado Denver, Department of Integrative Biology, Campus Box 171, P.O. Box 173364, Denver, CO 80217-3364, USA article info Article history: Received 11 July 2013 Received in revised form 21 January 2014 Accepted 23 February 2014 Available online 26 March 2014 Keywords: Mountain pine beetle Water diversions Lodgepole pine Rocky mountains Tree mortality Water management abstract The Rocky Mountains have experienced extensive infestations from the mountain pine beetle (Den- droctonus ponderosae Hopkins), affecting numerous pine tree species including lodgepole pine (Pinus contorta Dougl. var. latifolia). Water diversions throughout the Rocky Mountains transport large volumes of water out of the basins of origin, resulting in hydrologic modifications to downstream areas. This study examines the hypothesis that lodgepole pine located below water diversions exhibit an increased inci- dence of mountain pine beetle infestation and mortality. A ground survey verified diversion structures in a portion of Grand County, Colorado, and sampling plots were established around two types of diversion structures, canals and dams. Field studies assessed mountain pine beetle infestation. Lodgepole pines below diversions show 45.1% higher attack and 38.5% higher mortality than lodgepole pines above di- versions. These findings suggest that water diversions are associated with increased infestation and mortality of lodgepole pines in the basins of extraction, with implications for forest and water allocation management. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The mountain pine beetle (Dendroctonus ponderosae Hopkins) has severely impacted pine species throughout the western USA and Canada in recent years, resulting in large regions with damaged and dead pine trees (Raffa et al., 2008; Logan et al., 2010). Increased mountain pine beetle (MPB) populations are supported by increased temperatures, as well as increased stand density facili- tated by fire suppression (Raffa et al., 2008; Negron et al., 2009; Bentz et al., 2010; Logan et al., 2010; Kulakowski et al., 2012). These conditions are compounded by decreased resistance of host trees to bark beetle species due to factors such as drought, increased temperatures, and pollution deposition (Mattson and Hacck, 1987; Jones et al., 2004; Raffa et al., 2008; Bentz et al., 2010; Logan et al., 2010; McDowell et al., 2011). Drought can alter the chemical and physical properties of resin, a key defense mechanism, thereby reducing resistance of the host tree to infes- tation (Mattson and Haack, 1987; Raffa et al., 2008; McDowell et al., 2011). Specifically, drought impairs resin flow and pressure, prop- erties that can impede beetles, as well as the concentration of chemicals that are toxic to beetles (ibid). Climate change is contributing to both increased temperatures and decreased water availability, thereby increasing conditions that favor MPB infesta- tion (Raffa et al., 2008; Bentz et al., 2010; Logan et al., 2010; McDowell et al., 2011). Water diversion projects extend throughout the Rocky Mountain region, transporting significant volumes of water out of the basins of origin. In Colorado, numerous systems collect and transport water from the western side of the Continental Divide to the eastern side, servicing the Front Range (Colorado’s Decision Support System [CDSS], n.d.). In Grand County, CO, water is diverted from all major basins in the southern and eastern portions of the county using vast systems of dams, canals, and pipelines, based on data from Colorado’s Decision Support System (n.d.), as well as survey data gathered during this study. Dams function to block and collect water from streams, and funnel the water into the diversion canals and pipes. Canals function to transport water, and also collect surface and subsurface flow (Natural Resources Conservation Service [NRCS], * Corresponding author. Present address: University of Colorado Denver, The School of Public Affairs, 1380 Lawrence St., Suite 500, Denver, CO 80204, USA. Tel.: þ1 303 919 2806; fax: þ1 303 315 2229. E-mail addresses: sharon.smolinski@ucdenver.edu (S.L. Smolinski), peter. anthamatten@ucdenver.edu (P.J. Anthamatten), leo.bruederle@ucdenver.edu (L. P. Bruederle), jon.barbour@ucdenver.edu (J.M. Barbour), frederick.chambers@ ucdenver.edu (F.B. Chambers). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2014.02.034 0301-4797/Ó 2014 Elsevier Ltd. All rights reserved. Journal of Environmental Management 139 (2014) 32e37