Interactions of White Pine Blister Rust and Mountain Pine Beetle in Whitebark Pine Ecosystems in the Southern Greater Yellowstone Area Author(S) :Nancy K
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Interactions of White Pine Blister Rust and Mountain Pine Beetle in Whitebark Pine Ecosystems in the Southern Greater Yellowstone Area Author(s) :Nancy K. Bockino and Daniel B. Tinker Source: Natural Areas Journal, 32(1):31-40. 2012. Published By: Natural Areas Association DOI: http://dx.doi.org/10.3375/043.032.0105 URL: http://www.bioone.org/doi/full/10.3375/043.032.0105 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. R E S E A R C H A R T I C L E ABSTRACT: Whitebark pine (Pinus albicaulis) is a fundamental component of alpine and subalpine habitats in the Greater Yellowstone Ecosystem. The magnitude of current white pine blister rust (WPBR) infection caused by the pathogen Cronartium ribicola and mountain pine beetle (MPB; Dendroctonus ponderosae) impacts, combined with the effect of climate change on beetle population dynamics, are placing this foundation species in a precarious state. We collected stand- and tree-level data in three whitebark pine systems in the southern Greater Yellowstone Ecosystem to evaluate current conditions and • to determine how characteristics of individual whitebark pine trees, including the presence and severity of white pine blister rust, influence host selection by the MPB. Data revealed that 45% of all whitebark pine trees sampled were dead. In addition, 67% of all trees sampled were attacked by MPB, 83% were Interactions of White infected with WPBR, and 62% were affected by both. Whitebark pine trees that were selected as hosts by MPB exhibited significantly greater blister rust severity than trees that were not selected. Multiple logistic Pine Blister Rust regression analyses identified a complex set of tree characteristics related to host selection by MPB; in addition to rust severity, stand type (mixed species or pure whitebark pine) and tree diameter were also significant predictors of selection. The interaction among MPB selection patterns, blister rust severity, and Mountain Pine tree diameter, and stand type quantified in this study will likely continue to influence the disturbance pattern and severity in whitebark pine ecosystems in the Greater Yellowstone Area. Understanding these Beetle in Whitebark patterns is critical to successful management of whitebark pine forests in this region. Index terms: disturbance, Greater Yellowstone Ecosystem, mountain pine beetle, whitebark pine, white Pine Ecosystems in pine blister rust the Southern Greater INTRODUCTION ogy records from subalpine forests indicate Yellowstone Area that these events are historically infrequent Whitebark pine (Pinus albicaulis Engelm.) in whitebark pine ecosystems because is an important component of many high winter temperatures were too cold for ex- Nancy K. Bockino1,2 elevation ecosystems throughout the west- tensive episodes of MPB activity (Amman ern United States and Canada, including and Schmitz 1988; Perkins and Swetnam the Greater Yellowstone Ecosystem (GYE). 1996; Hicke et al. 2006). The current MPB 1 Department of Botany This keystone and foundation species plays outbreak is intense, severe, and extensive University of Wyoming a disproportionately large ecological role both within its historic host range and in 1000 E. University Avenue relative to its abundance, and it strongly high elevation whitebark pine ecosystems, Laramie, WY 82071 defines ecosystem structure, function, and in part attributable to altered temperature process (Tomback and Kendall 2001). and precipitation patterns (Logan and 2 Grand Teton National Park Whitebark pine regulates soil development, Powell 2001; Carroll et al. 2004; Bentz PO Box 9816 facilitates plant succession, provides car- et al. 2010; Logan et al. 2010). Jackson, WY 83002 bon storage, and captures and retains snow, thus increasing the quantity and duration of In contrast to MPB, white pine blister summer runoff (Arno and Hoff 1989). This rust (WPBR) is caused by a non-native Daniel B. Tinker1,3 protracted melting provides water to feed pathogen - Cronartium ribicola Fisch. - ac- streams and riparian communities longer cidently introduced into the eastern United into the growing season, as well as produc- States as early as 1897, to western North ing a consistent flow to downstream water America in approximately 1910, and which • users. In addition, many wildlife species spread to the GYE by the 1940s (Geils utilize the nutrient- and lipid-rich seeds of et al. 2010). Spores of the fungus enter the whitebark pine, including many forest trees through leaf stomata, and the fungal birds and rodents (Lorenz et al. 2008). mycelia grow through the living bark and 3Corresponding author: cambial tissue. This destroys the trees’ wa- [email protected]; 307-766-4967 Large-scale outbreaks of mountain pine ter and nutrient transport system, and forms beetle (MPB; Dendroctonus ponderosae cankers or spore-producing fruiting bodies Hopkins), an insect native to coniferous on branches and the bole (Woo and Martin forests of western North America, are 1981). Not only can severe WPBR infec- not uncommon in many pine forests, par- tions lead to the mortality of mature white- ticularly in lodgepole pine (Pinus contorta bark pine trees, the disease dramatically Dougl. ex Loud. var. latifolia Engelm. Ex decreases recruitment by extensive damage Natural Areas Journal 32:31–40 Wats.) ecosystems (Romme et al. 1986; to cone-bearing branches, seedlings, and Taylor and Carroll 2003). Dendrochronol- saplings; and these impacts are not char- Volume 32 (1), 2012 Natural Areas Journal 31 acteristic of most disturbance regimes in included the quantification of: (1) the spa- vary with outbreak phase and other fac- whitebark pine ecosystems (Tomback et al. tial extent and severity of MPB activity and tors, it should be noted that this study is 1995; McKinney et al. 2009). Blister rust WPBR infection in whitebark pine forests a single spatial and temporal description incidence and severity continue to increase on our study sites in the southern the GYE of patterns in MPB activity in whitebark across the western United States and within during the summer of 2006; (2) the rela- pine stands in the southern GYE. the GYE (Schwartz et al. 2007; Bockino tionship between individual whitebark pine Field Methods 2008; Bockino and McCloskey 2010; tree-level WPBR severity and selection as GYWPMWG 2010; Larson 2011). a host by the MPB; and (3) the influence At each of our study sites, we identified of multiple tree- and stand-level predictor two stand types. The first stand type, Both MPB and WPBR are widespread in variables on the probability of selection of referred to hereafter as PURE, was distin- whitebark pine ecosystems in the GYE, individual whitebark pine by MPB. guished by whitebark pine as the dominant yet an understanding of their interaction METHODS canopy species (90% of total stand basal and subsequent impacts is limited, yet area). The second stand type, referred to essential to successful management ac- hereafter as MIX, was characterized by tivities (Larson 2011). Two MPB events Study Area a canopy composition of whitebark pine occurred during the 20th century in mixed with subalpine fir (Abies lasiocarpa whitebark pine ecosystems; however, the Our study was conducted in the Greater (Hook.) Nutt.) and/or Engelmann spruce extent and intensity of the current MPB Yellowstone Ecosystem (GYE), which (Picea engelmannii Parry ex Engelm.). In outbreak combined with high incidence encompasses portions of southwestern these stands, whitebark pine comprised at and severity of WPBR has resulted in Montana, northwestern Wyoming, and least 20%, but no greater than 80%, of the historically unprecedented whitebark pine eastern Idaho. Two national parks, Grand canopy tree total stand basal area. Within mortality (Bentz 2008; Macfarlane et al. Teton and Yellowstone, as well as portions each stand type, we identified a polygon 2009; Logan et al. 2010). In portions of of seven national forests, three National of relatively homogenous forest structure the northern Rocky Mountains, mortality Wildlife Refuges, and Bureau of Land and species composition using digital rates of whitebark pine trees are as high Management, state, and private properties vegetation maps and field observations. as 90% (Gibson et al. 2007), while in the lie within this extensive region. The cli- To minimize the influence of topography, Interior Columbia Basin whitebark pine mate, characterized by warm, dry summers elevation, and aspect on our dataset and populations have declined by at least 45% and long, cold winters with continuous final model, we targeted areas that were (Kendall and Keane 2001). Data from the snow pack and mean temperatures below similar for these variables. 2009 Landscape Assessment aerial survey freezing are influenced by pacific, polar, in the GYE indicate that approximately and continental weather systems (Despain Twenty-four plots were sampled in each 90% of whitebark pine stands in the GYE 1990). The growing season is two to of the two stand types, PURE and MIX, contained some level of beetle activity, and three months in length at high elevation at each of the three sites (Table 1; n = 50% of these stands had experienced high whitebark pine sites. The GYE represents 144 plots). Within each site/stand type levels of overstory whitebark pine mortal- one of the most extensive whitebark pine combination, we established a random ity (Macfarlane et al.