Thursday, January 31, 2013

Implications of Sudden Aspen Death


Ever since the severe droughts in the early 2000’s, aspen trees have been experiencing “sudden aspen death.” Research now suggests that droughts may have weakened past and current trees through a process known as cavitation. Cavitation is a physiological byproduct of a plants response to drought, where they attempt to draw more water through their roots, as water loss through transpiration increases. The added suction can pull air bubbles into the xylem (water-moving pipes) of the tree, disrupting water flow. Trees respond to cavitation by creating bypasses within the xylem, allowing water to move around the air pocket. However, after years of stress, trees will exhibit cavitation-fatigue: where the xylem will tear at the seams, allowing increased incidences of cavitation.

While this process is devastating Aspen trees throughout the United States, the implications for forests around the world are more frightening. Climate change is expected to increase incidences of severe weather and climate events, including drought. If we experience severe droughts over the next few decades, we may be decreasing forest resilience, and ultimately decreasing its biodiversity. While this is difficult to accurately predict, the story our Aspen trees share is one of caution, and hopefully of preemptive action.


Further Reading
-http://www.newscientist.com/article/dn22589-dying-aspen-trees-sound-alarm-for-worlds-forests.html
-http://www.sciencedirect.com/science/article/pii/0160932794900620
-http://adsabs.harvard.edu/abs/2006CRPhy...7.1018C

Photo - Aspen Forests
http://shelledy.mesa.k12.co.us/staff/computerlab/ColoradoLifeZones_Montane_Forests_Plants.html



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