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Beetle Infestation’s Affect on Ecohydrology

May 21, 2012

Mountain Pine Beetle Infestation in Colorado. Image from Wiki Commons

The arid regions of the Western United States are under attack.  This immense assault is aimed at pine trees and initiated by the Mountain Pine Beetle, or Bark Beetle, (Dendroctonus ponderosae  and many other species) (Wallin). These beetles have been fiercely devastating the pine tree population in the Western U.S. for nearly two decades with no sign of stopping. Millions of acres have been transformed from lush, green forests to seas of brittle, dead, rust orange.  My home, like many others has gone from having great views of tree covered mountains to a waiting game for when the next large forest fire comes along and threatens to burn my house along with the dead forest.

Crown Fire experiment in Canada. Image from Wiki Commons

Mountain Pine Beetles (MPB) have been attacking pine trees like Lodgepole Pine (Pinus contorta var. latifolia) and Ponderosa Pine (Pinus ponderosa) for hundreds or thousands of years.  In the past, the MPB attacks have caused about 2 percent of pine forests to die. However, in the last 100 years the invasions have intensified to cause nearly 100 percent death of infested forests. Over 2 million acres have been destroyed in Colorado and Wyoming alone with over 9 million acres across the western United States (Mikkelson, Carroll 2007) and over 7 million hectares in British Columbia (Nelson 2006).

Mountain Pine Beetle

Mountain Pine Beetle…the size of a grain of rice. Image from Wiki Commons

Infestations begin by one or more species of beetle entering a tree then releasing pheromones to attract more beetles (Wallin, Wood). These tiny beetles destroy mature pine trees, especially Lodgepole Pine, by burrowing under the bark into the veins of the tree and eating the yummy phloem tissue of trees.  This tissue delivers the sugary essentials made in the leaves to all parts of the tree needed for survival of those organs.  Yet, the beetles block the veins from moving this liquid because it will otherwise drown their larvae. Eventually the tree runs out of sugary sap and dies of fungus infection in the burrows or malnutrition.

Beetle infestation in Lodgepole Pine. Picture from wiki Commons

Mountain Pine Beetle attacks on forest is greatly influenced by wildfire control practices that have been put into effect in the last 100 years (Carroll 2007, Wallin, Safranyik).  This is allowing forests to reach an even, mature age just ripe for infestation.  If there are uneven aged stands, fewer trees will be impacted and the infestation kills a much smaller percentage of trees. Some management practices now include prescribed burning of small areas of forest or thinning of the canopy by cutting down trees and using them as firewood, furniture or other useful purposes (Safranyik, Carroll 2007).

These infestations are damaging forest health, scenery and the ecohydrology of the entire western United States region.  The entire water budget is under intense fluctuation and causing:

  • Higher snow pack
  • Earlier snow melt
  • Increased frequency and intensity of floods
  • Increased damaging impact of precipitation onto soil
  • Increased solar radiation onto the understory and ground
  • Increased canopy wind speed

Yet a possible benefit is greater groundwater recharge and evolution of the tree species.

However, trees will probably continue to die after the beetle infestation has left because of the altered soil moisture, decreased transpiration (water released from plants), and higher intensity and frequency of floods (Mikkelson). I also think that fewer seeds will survive germination because of the harsh radiation from the sun.  Unless humans manage to get these infestations under control and forests replanted species will be forced to evolve adaptations against the beetles or risk going extinct. Ultimately, in an extreme way, our human nature to have control over everything and have it look as specific way is causing the great destruction of our forests. We need to find better management policies or go back to letting nature manage itself, live with nature instead of killing everything in our path.

References and Further Research

Carroll, A.L., Regniere, J., Logan, J.A., Taylor, S.W., Bentz, B.J. & Powell, J.A. (2006) Impacts of climate change on range expansion by the mountain pine beetle. Mountain Pine Beetle Initiative Working Paper 2006-14. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC.

Carroll, A. L. “The Mountain Pine Beetle Dendroctonus Pon- Derosae in Western North America : Potential for Area-Wide Integrated Management.” The Mountain Pine Beetle Dendroctonus Pon- Derosae in Western North America : Potential for Area-Wide Integrated Management 4: 297-307. Mendeley. Springer Link, 2007. Web. 21 May 2012. <;.

Furniss, M. & Furniss, R. (1972) Scolytids (Coleoptera) on snowfields above timberline in Oregon and Washington. Canadian Entomologist, 104, 1471–1477.

Logan, J.A. & Bentz, B.J. (1999) Model analysis of mountain pine beetle seasonality. Environmental Entomology, 28, 924–934.

Logan, J.A. & Powell, J.A. (2001) Ghost forests, global warming and the mountain pine beetle (Coleoptera: Scolytidae). American Entomologist, 47, 160–173.

Nelson, T., Boots, B. & Wulder, M.A. (2006) Large-area mountain pine beetle infestations: spatial data representation and accuracy. The Forestry Chronicle, 82, 243–252.

Mikkelson, K. M., R. M. Maxwell, and Et. Al. “Mountain Pine Beetle Infestation Impacts: Modeling Water and Energy Budgets at the Hill-slope Scale.” Ecohydrology (2011). Wiley Online. John Wiley & Sons, Ltd. Web.

Raffa, K.F. (1988) The mountain pine beetle in western North America. Dynamics of forest insect populations: patterns, causes, and implications (ed. by A.A. Berryman), pp. 506–530. Plenum Press, New York.

Robertson, Colin, Trisalyn A. Nelson, and “Spatial–temporal Analysis of Species Range Expansion: The Case of the Mountain Pine Beetle, Dendroctonus Ponderosae.” Journal of Biogeography (2009): 1446-458. Print.

Safranyik, L., and Bill Wilson. The Mountain Pine Beetle: A Synthesis of Biology, Management, and Impacts on Lodgepole Pine. Victoria, B.C.: Pacific Forestry Centre, 2006. Print.

Taylor, S. W., and A. L. Carroll. Disturbance, Forest Age, and Mountain Pine Beetle Outbreak Dynamics in BC: A Historical Perspective. Publication. Natural Resources Canada, Canadian Forest Service, 2003. Web. 2012. <W Taylor… – Mountain Pine Beetle symposium: …, 2003 –>.

Wallin, Kimberly F., Thomas E. Kolb, Kjerstin R. Skov, and Michael Wagner. “Forest Management Treatments, Tree Resistance, and Bark Beetle Resource Utilization in Ponderosa Pine Forests of Northern Arizona.” Forest Ecology and Management 255.8-9 (2008): 3263-269. ScienceDirect. Elsiever, Jan. 2008. Web. 21 May 2012.

Wood, D.L., 1982. The role of pheromones, kairomones and allomones in the host selection and colonization behavior of bark beetles. Annual Review Entomology. 27, 411–446.

One Comment leave one →
  1. September 20, 2014 11:14 pm

    Excellent blog! Do you have any tips and hints for aspiring writers?
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    Would you propose starting with a free platform
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    Bless you!

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