As tree species ranges shifted, so did the ranges of phytophagous insects such as bark beetles as they tracked environmental changes and followed host tree species (Seybold et al. These historical patterns foreshadow large modifications to current forest ecosystem dynamics as climate change accelerates. GJ
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. Spruce beetle (Dendroctonus rufipennis Kirby) outbreaks are important disturbances affecting subalpine forests of Engelmann spruce (Picea engelmannii), subalpine fir (Abies lasiocarpa), and lodgepole pine (Pinus contorta) in the southern Rocky Mountains. Currently, spruce beetles are affecting over 400,000 acres in the Matanuska-Susitna Valley, resulting in widespread mortality of spruce trees. AV
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. Water, Air, Soil Pollution Focus, 4(2-3): 391-414. G
To avoid drought-induced hydraulic failure, plant stomates close to restrict transpiration. Le Quéré
As a individual who has experience with the removal of elm trees due . An outbreak started in the 1980s in Southcentral Alaska and continued until 2003 affecting over 1.3 million hectares of forest with >90% of the trees killed in many stands. .
While the spruce bark beetle is not a new arrival, it now poses a bigger threat because global warming is having a direct effect on the natural defenses against parasites. Warwell
The right conditions simply aligned for the beetle to thrive. 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). Macías-Sámano
And though it is a natural occurrence, the area around Brooks Camp was hit particularly hard in the middle of the previous decade. Cayan
2006), and mountain pine beetle in high-elevation forests (Bentz and Schen-Langenheim 2007). 2007). Taylor
By the end of the century, the change in temperatures across the boreal forests of central Canada may cause markedly higher probability of spruce beetle outbreak potential, based on developmental timing alone.
Female beetles excavate galleries in which to lay eggs. JD
As the climate warms, it is predicted that more of Alaska’s precipitation could arrive as rain instead of snow. Ongoing research in interior Alaska is suggesting that warmer and drier summers over the last three decades is stressing white spruce, setting the potential for widespread infestation by spruce bark beetle, spruce budworm, or perhaps other insects. Langor
Warming temperatures also have fueled successive outbreaks of spruce bark beetles that razed the region’s forests.
Response was a shock. To compensate, insects consume more but grow more slowly, a trade-off with the potential to disrupt phenological synchrony important to bark beetle survival, in addition to prolonging exposure to mortality agents. Further, a study done by the Kenai Wildlife Refuge in Southcentral Alaska has found no significant relationship between beetle-related die-off and wildfire occurrence in Alaska; in other words, beetle outbreaks have occurred more frequently than fire historically, and the loss of trees to beetle kill does not necessarily result in widespread wildfires.
Logically, concerned visitors may soon ask, “what caused this?” Rick G. Kelsey is with the USDA Forest Service, Pacific Northwest Research Station, in Corvallis, Oregon. Stinson
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. C
Therefore, although spruce beetle outbreak potential will be enhanced by higher temperatures throughout the century, reductions in the range of Engelmann spruce in the western United States, also as a result of climate change (Rehfeldt et al.
2008). Because bark beetle population survival and growth are highly sensitive to thermal conditions, and water stress can influence host-tree vigor, outbreaks have been correlated with shifts in temperature (Powell and Logan 2005) and precipitation (Berg et al. KF
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.
. . JS
The right conditions simply aligned for the beetle to thrive. . BJ
Ecological. A 2016 aerial survey conducted by the Forest Service showed a roughly 35% increase in spruce beetle activity as compared with new activity in 2015. RW
. Wish the press would force the government to act and inform the . In a rapidly changing environment, coniferous tree species will persist through migration or adaptation to new conditions, or they will go locally extinct.
During this same period, low temperature survival would have been high in coastal regions and other low-elevation forests across the current range, although quite low in high-elevation areas of the United States and Canadian Rocky Mountains (figures 2d, 3d). 2008, Raffa et al. These defenses are overcome only when a critical minimum number of beetles are recruited to the host tree. May 2, 2007 ; VRETA KLOSTER, Sweden — For Goran Samuelsson, the proud owner of 70 hectares of majestic spruce …
NPS Photo/A. Knight
We averaged model output over replicates. The mountain pine beetle and whitebark pine waltz: Has the music changed? 2006), can reduce the resistance of surviving trees to bark beetle attack. M
Spruce beetle eggs normally hatch by August, then spend the winter, dormant, in larvae beneath the bark. Adults average 4 to 7 mm in length.
These changes in climatic conditions over the next century will significantly affect the condition, composition, distribution, and productivity of multiple ecosystems (Easterling et al. Climatic Change , 109, 695–718. KF
Based solely on the modeled response of mountain pine beetle to temperature, results suggest that by the end of this century probability of range expansion across
Given assumptions of the seasonality model, these results suggest that substantial warming would disrupt the emergence timing and generation duration required for population success. 2006), and mountain pine beetle in high-elevation forests (Bentz and Schen-Langenheim 2007). Werner
Diapause not only offers a mechanism to keep insects synchronized with their environment and food availability but also provides tolerance to environmental extremes (Tauber et al. . C
In the period 2001–2030 and again from 2071 to 2100, we would expect substantial increases in spruce forest area with high probability of spruce beetle offspring produced annually rather than semiannually (figure 1b, 1c, 1e, 1f). Nitrogen turnover and nitrate leaching after bark beetle attack in mountainous spruce stands of the Bavarian National forest Park.
2008), undoubtedly will also be influenced by abiotic factors associated with climate change. .
2006, Nealis and Peter 2009). Gilmore
Their dry branches creak as they sway in the wind. Wood
Climatic changes are predicted to significantly affect the frequency and severity of disturbances that shape forest ecosystems. .
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). J
Though the dramatic outbreak has slowed since then, nearly a decade later we are still feeling its effects.
High summer temperatures are correlated with a rising proportion of beetles that complete a generation in a single year rather than in two years, contributing significantly to population growth (Hansen and Bentz 2003) and to greater levels of spruce-beetle-caused tree mortality (Berg et al. Moser
Modeling cold tolerance in the mountain pine beetle, Stochastic simulation of daily air temperature and precipitation from monthly normals in North America north of Mexico, Empirical analyses of plant-climate relationships for the western United States, Mountain pine beetle-associated blue-stain fungi are differentially adapted to boreal temperatures. Developing mountain pine beetle larvae acquire vital nutrients not found in plant tissue by feeding on two fungi, Grosmannia clavigera and Ophiostoma montium, the hyphae of which spread throughout the phloem and sapwood following inoculation into the tree by attacking beetles. . Bentz
Is global warming real? Aber
In response to an approximately 2°C increase in temperature, significant changes in community composition occurred over the past several thousand years, including the formation of new communities, many of which no longer exist today (Shugart 2003).
Fish species from warmer waters were showing up in fishing nets.
. Host-tree physiology. Yeaman
However, a comprehensive synthesis of the direct and indirect effects of climate change on the population dynamics of bark beetles is lacking. Rebertus
In undisturbed forests, bark beetles serve the purpose of hastening the recycling and decomposition of dead and dying wood and renewing the forest. Grelet
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. Two recent studies shed light on how climate change is helping fuel the assault of bark beetles on U.S. forests, and what’s likely to happen in a world that continues to warm. Warming trends have been associated with shifts in generation duration for populations of spruce beetle in Alaska, Utah, and Colorado (Hansen et al. 2007).
1000 Silver Street, Building 603 JR
2008). In some places, these gray, skeletal trees seem to outnumber the trees that are alive. Canada and into central and eastern US forests will be low to moderate. .
Proceedings of the Conference Whitebark Pine: A Pacific Coast Perspective, Bark Beetle Outbreaks in Western North America: Causes and Consequences, Spruce beetle outbreaks on the Kenai Peninsula, Alaska, and Kluane National Park and Reserve, Yukon Territory: Relationship to summer temperatures and regional differences in disturbance regimes, Seasonal variation in pheromone-associated behavior and physiology of, Annals of the Entomological Society of America, Dietary benefits of fungal associates to an eruptive herbivore: Potential implications of multiple associates on host population dynamics, Parasitoids and dipteran predators exploit volatiles from microbial symbionts to locate bark beetles, Evolutionary response to rapid climate change, Regional vegetation die-off in response to global-change-type drought, Proceedings of the National Academy of Sciences, Comparative phylogeography of northwestern North America: A synthesis, Integrating Ecology and Evolution in a Spatial Context.
2006). Models that incorporate genetic variability in bark beetle temperature-dependent parameters are also needed. In this way climate change will continue to alter the makeup and appearance of Katmai’s forests. AL
As Alaska continues to experience a warming climate recent studies also indicate that spruce bark beetle outbreaks may become more frequent.
. mortality. JS
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