Warming temperatures causing large number of tree deaths in USJanuary 23rd, 2009 - 2:17 pm ICT by ANI
Washington, Jan 23 (ANI): A new study has indicated that tree deaths in the Wests old-growth forests in the US have more than doubled in recent decades, likely from regional warming and related drought conditions.
The study, led by U.S. Geological Survey and involving the University of Colorado at Boulder, documented tree deaths in all tree sizes in the West located at varying elevations, including tree types such as pine, fir and hemlock.
Significant die-offs also were documented in the interior West, including Colorado and Arizona, as well as Northwest regions like northern California, Oregon, Washington and southern British Columbia.
The researchers speculated higher tree deaths could lead to substantial ecological changes in the West, including cascading effects affecting wildlife populations.
The tree deaths also could lead to possible increases in atmospheric carbon dioxide levels contributing to warming, which could stem from lower CO2 uptake and storage by smaller trees and increased CO2 emissions from more dead trees on the forest floors.
The study shows the establishment of new, replacement trees is not keeping pace with climbing tree mortality in the study plots, according to CU-Boulder geography Professor Thomas Veblen, study co-author.
According to the researchers, This regional warming has contributed to widespread hydrologic changes, such as a declining fraction of precipitation falling as snow, declining water snowpack content, earlier spring snowmelt and runoff, and a consequent lengthening of the summer drought.
The increase in tree mortality rates documented in the study is further compelling evidence of ecosystem responses to recent climate warming, said CU-Boulder geography Professor Thomas Veblen, study co-author.
The findings are consistent with other well documented, climate-induced ecological changes, including increased wildfire activity since the mid-1980s and bark beetle outbreaks that are occurring at unprecedented levels in western North America forests, including Alaska, he added.
Veblen said that the study suggests increased tree mortality rates may be indicators of climate-induced stress that could increase tree susceptibility to more abrupt causes of tree deaths like bark beetle outbreaks.
Given the evidence that recent climate-induced ecosystem changes are now so abundant, society needs to discuss policies that will help humans adapt to the changes under way, said Veblen. (ANI)
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