CI As the climate warms, it is predicted that more of Alaska’s precipitation could arrive as rain instead of snow. Are these trees a fire hazard? The recent loss of entire stands of long-lived, high-elevation whitebark pine, Pinus albicaulis Engelm., as a result of the mountain pine beetle (figure 4) underscores the need for greater understanding of climate change effects on complex interactions important to ecosystem resiliency and stability. Simulated past and future climates (1961–2100) were obtained from the Canadian Regional Climate Model (CRCM) version 4.2.0 runs ADJ and ADL (Music and Caya 2007). Joe Romm Apr 30, 2012, 9:00 pm. Fazekas Climate change has amplified eruptive bark beetle outbreaks over recent decades, including spruce beetle (Dendroctonus rufipennis). Bentz similar changes may occur north of the Alaska Range. The understory is becoming denser and more productive. JR Hydraulic failure may be further amplified when water transport is interrupted by symbiotic fungi inoculated into trees during the bark beetle attack process (McDowell et al. KF First question was what can we do? public that the costs of warming will be VERY REAL and VERY expensive. Even in the peak of summer as other trees grow and thrive, these dead trees can give the forest an eerie appearance. The mountain pine beetle and whitebark pine waltz: Has the music changed? Langor K . Campbell Nebeker Pörtner But even as these dead spruce trees loom over the current Brooks Camp landscape, more sunlight is now reaching the forest floor. RE T Stastny Kegley We used the Intergovernmental Panel on Climate Change A2 emissions scenario, which results in relatively high projected warming in 2100 among all scenarios (IPCC 2007), but which has been realistic thus far given emissions estimates in the last 20 years (Raupach et al. 2001). Klepzig KF . Spruce beetles and mountain pine beetles accumulate cryoprotectant compounds such as glycerol as temperatures decline during autumn (Miller and Werner 1987, Bentz and Mullins 1999). Christopher J. Fettig and Steven J. Seybold are with the USDA Forest Service, Pacific Southwest Research Station, in Davis, California. The ecological roles and temperature dependencies of the majority of bark beetle community associates are not well understood, which hampers full comprehension of the consequences of climate change on bark beetle population dynamics. Predicted probability of mountain pine beetle adaptive seasonality (a–c) and cold survival (d–f) in pine forests of the western United States during three climate normals periods: (a) and (d) 1961–1990; (b) and (e) 2001–2030; and (c) and (f) 2071–2100. Frequently referred to as aggressive bark beetles, these species can kill healthy trees and have the capacity to cause landscape-scale tree mortality (table 1). Termination of diapause in the Douglas-fir beetle, Journal of the Entomological Society of British Columbia, Model projections of an imminent transition to a more arid climate in southwestern North America, The enantiomeric composition of ipsdienol: A chemotaxonomic character for North American populations of, A Theory of Forest Dynamics: The Ecological Implications of Forest Succession Models, Temperature determines symbiont abundance in a multipartite bark beetle-fungus ectosymbiosis, The response of subalpine forests to spruce beetle outbreak in Colorado, Modeling the impacts of two bark beetle species under a warming climate in the southwestern USA: Ecological and economic consequences, Spruce beetles and forest ecosystems in south-central Alaska: A review of 30 years of research, Warming and earlier spring increase western US forest wildfire activity, Consequences of simultaneous elevation of carbon dioxide and temperature for plant-herbivore interactions: A metaanalysis, © 2010 by American Institute of Biological Sciences, Indigenous Systems of Management for Culturally and Ecologically Resilient Pacific Salmon (, Not All Nitrogen Is Created Equal: Differential Effects of Nitrate and Ammonium Enrichment in Coastal Wetlands, A Research Agenda for Urban Biodiversity in the Global Extinction Crisis, A Call to Action: Marshaling Science for Society. ing biotic agents affecting forests globally (Anderegg et al. But many more remain standing, their spines still upright and looking as skeletal as ever. JA The Alaskan landscape is covered with dead spruce trees after a major outbreak of spruce bark bettles in the arctic region in this file image. . The potential for adaptive seasonality in central Canada decreases dramatically from the historical period to the end of this century, with high probability of population success restricted to northern provinces (figure 3a, 3b, 3c). Huber . Franceschi TS GA Although little is known about specific temperature-dependent developmental processes of many bark beetle species, research suggests that at least two predominant strategies, diapause and direct temperature control, have evolved to maintain appropriate life-cycle timing. YJ Millar At the retreating and expanding margins of tree distributions, bark beetles may play a significant role in colonizing and killing stressed individuals as trees and their progeny strive to adapt to a changing environment. 2001). The insects have chewed up 4 million acres of spruce trees. Climatic changes are predicted to significantly affect the frequency and severity of disturbances that shape forest ecosystems. Cold tolerance. Moore JA Hutchinson Music G Response was a shock. Later life stages (e.g., fourth instar larvae) have higher temperature threshold requirements for development than earlier life stages. DL 2006), and mountain pine beetle in high-elevation forests (Bentz and Schen-Langenheim 2007). CL TR JD Bark beetle response to climate change can be characterized by a high degree of complexity and uncertainty, as populations are influenced directly by shifts in temperature and indirectly through climatic effects on community associates and host trees. This incidence is potentially a result of an increase in climate suitability and the number of beetle generations per year (Waring et al. Download this stock image: Alaska. Fish species from warmer waters were showing up in fishing nets. Search for other works by this author on: Adaptation, migration or extirpation: Climate change outcomes for tree populations, Movement of outbreak populations of mountain pine beetle: Influences of spatiotemporal patterns and climate, Global genetic change tracks global climate warming in, Herbivory in global climate change research: Direct effects of rising temperature on insect herbivores, A rapid altitudinal range expansion in the pine processionary moth produced by the 2003 climatic anomaly, Ecology of mountain pine beetle cold hardening in the Intermountain West. Mountain pine beetle outbreak populations are currently restricted to pine forests in the western United States, central British Columbia and west-central Alberta. May 2, 2007 ; VRETA KLOSTER, Sweden — For Goran Samuelsson, the proud owner of 70 hectares of majestic spruce … Bentz . . Of the hundreds of native bark beetle species in the western United States and Canada, few species (< 1%) attack and reproduce in live trees. EM Carroll Climatic Change , 109, 695–718. KF More frequent extreme weather events will also likely provide abundant resources for some bark beetle species creating the potential to trigger localized outbreaks (Gandhi et al. Stahl 2008). An increase in low-temperature survival is predicted for spatially isolated areas in Canada, including west-central Alberta, where mountain pine beetle has recently been found attacking lodgepole/jack pine hybrids (Nealis and Peter 2009). . Further, a study done by the Kenai Wildlife Refuge. Soltis JA KF Moreover, observed genetic variability in response to temperature (Bentz et al. Significant tree mortality caused by mountain pine beetles, relative to historical records, has also recently occurred in high-elevation pine forests across the western United States (Gibson et al. Our model results suggest that without adaptation to increasing temperature, the probability of mountain pine beetle range expansion across jack pine forests and into eastern US pine forests will remain low to moderate throughout this century (figure 3c, 3f). Some species, such as the western pine beetle, Dendroctonus brevicomis LeConte, and the piñon ips, Ips confusus LeConte, produce more than one generation per year. In Alaska and the Yukon, spruce bark beetles have spread out over 4.2 million acres, noshing their way through Sitka and white spruce forests. Wood McKenney Mendoza We note that this insect's flexibility in life-history strategies appears greater than previously anticipated (Bentz and Schen-Langenheim 2007), and our working definition of adaptive seasonality and associated rules that drive the seasonality model may be too restrictive. When we arrived, I asked a ranger about what appeared to be Large areas of suitable host trees of susceptible vigor, age, and density are required for an outbreak to develop (Fettig et al. In some places, these gray, skeletal trees seem to outnumber the trees that are alive. Because changes in climate will not be uniformly distributed across years, and not all temperature-dependent processes will be equally affected, a mechanistic understanding is imperative for making predictions of direct effects of climate change on future population trends. 2009, Bentz et al. 2008). From these data, 30-year normals were computed for each decade in the interval between 1961 and 2100, and the “delta” method (differences between modeled decadal normals and the reference period 1961–1990) was used to generate unbiased decadal sets of 30-year normals into the future. TE Across pine habitats in the central and eastern United States, adaptive seasonality remains low throughout the century. Thormann We explore the potential effects of changing climate on bark beetle outbreak dynamics using two case studies: (1) spruce beetle and (2) mountain pine beetle. In Katmai’s forests, the spruce bark beetle population increased a whopping 300% from 2005 to 2006, accorrding to data from the US Forest Service. As we move through the aftermath of the previous beetle outbreak, we should recognize that we will see another in the future. J 2008, Raffa et al. These historical patterns foreshadow large modifications to current forest ecosystem dynamics as climate change accelerates. Zogas Our assessment assumes no change in current tree distributions, and that thermal conditions conducive to bark beetle population success result in increased levels of tree mortality, although we do not explicitly model the impacts to forests. . A Host selection and colonization behavior by bark beetles are complex processes that involve both long- and short-range behavioral components (Graves et al. Little A Hebertson Aukema Global warming blamed for Swedish beetle-infestation. J Barbara J. Bentz (email@example.com) and E. Matthew Hansen are with the US Department of Agriculture (USDA) Forest Service, Rocky Mountain Research Station, in Logan, Utah. Fettig Jacques Régnière is with the Canadian Forest Service in Quebec, Canada. During the 21st century, mean annual global temperature is expected to increase between 1.8 and 4.0 degrees Celsius (°C) as a result of growing atmospheric greenhouse gas concentrations created by human activities. As temperatures rise throughout this century, the area suitable for both adaptive seasonality and low-temperature survival is predicted to grow, although results are highly spatially variable (figures 2b, 2e, 3b, 3e). Bark beetles that infest and reproduce in live trees are capable of causing landscape-wide tree mortality. The potential for bark beetle outbreaks to affect communities and management paradigms in regions that historically have not experienced severe beetle outbreaks is perhaps an eventual outcome of climate warming during the 21st century. Zhu . S Berg RW Raffa Driving to Wind Cave National park, I was shocked to see the tree The right conditions simply aligned for the beetle to thrive. DE Dale Though the dramatic outbreak has slowed since then, nearly a decade later we are still feeling its effects. KD Nowak Jorgersen The recent advance of the spruce bark beetle is having similar impacts on Kluane’s boreal forest, which is home to wolves, lynx, snowshoe hares, grizzlies, moose, and many nesting birds. In a rapidly changing environment, coniferous tree species will persist through migration or adaptation to new conditions, or they will go locally extinct. Higher probability of one-year life-cycle duration translates to higher probability of population outbreak and increased levels of spruce-beetle-caused tree Additional fitness parameters potentially affected include higher adult longevity and prolonged adult emergence and flight. Following mountain pine beetle attack, tree foliage turns yellow, orange, then red over a one- to two-year period. Fulé . Werner Conversely, an obligatory adult diapause initiated by low temperatures, as in spruce beetles and Douglas-fir beetles, could be disrupted by higher minimum temperatures. KM 99613. The European spruce bark beetle has a significant impact on both the ecological and economic environment of Norway spruce forests. Lawrence By the end of the century, about 48% of the western US landscape is predicted to experience climate profiles with no contemporary analog to the current coniferous vegetation (Rehfeldt et al. H Jose F. Negrón is with the USDA Forest Service, Rocky Mountain Research Station, in Fort Collins, Colorado. . These species are significant because of their potential to move northward with climate change by following range expansion of current hosts or by adapting to novel hosts. Bark Beetle IS! We used available population models and climate forecasts to explore the responses of two eruptive bark beetle species. Danks Upon colonizing a tree, bark beetles introduce an array of fungi, bacteria, nematodes, and mites that can significantly influence their fitness (Hofstetter et al. Their dry branches creak as they sway in the wind. For example, spruce beetles have specialized body structures to carry associated nematodes (Cardoza et al. et al. Mature adult beetles of the next generation tunnel outward through the bark and initiate flight in search of a new host tree. Y GW Beetle outbreaks have occurred in the past in Kluane. Photograph: Courtesy of Wally Macfarlane. Page St-Amant CJ K What I saw is LIVING PROOF. Monograph Series no. Bark beetles are inextricably linked to their host trees, and will undoubtedly influence the formation of new western North American coniferous forests as predicted broad-scale tree migrations occur this century. forests on and near the Kenai Peninsula, We also used the cold tolerance model developed by Régnière and Bentz (2007) to predict the probability of annual survival given a one-year temperature regime. 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