It is still startling that the linkage should be so easily
demonstrated. There are plenty of indirect reasons to promote tree
culture and we have been out there cheer-leading. Yet to see a shift
in statistics cleanly related to the removal of trees is a little
unexpected. I would have expected a way more ambiguous signal.
The answer of course for cities everywhere is to build and plant as a
matter of course as we generally experience in Vancouver. This also
results in a huge bird population. It does not seem like much and
the cost is modest against most urban expenditures, but the
difference produced is literally night and day.
I recall flying into LA and looking at miles of backyards and streets
devoid of trees and a compelling argument for apartment dwelling. I
know it takes scarce water but the difference in living quality is
palpable. Cover that same valley with trees and you will even have a
restoration of rainfall at night.
Tree and human
health may be linked
by Staff Writers
Portland OR (SPX) Jan 18, 2013
The emerald ash borer
was first discovered near Detroit, Michigan, in 2002. The borer
attacks all 22 species of North American ash and kills virtually all
of the trees it infests.
Evidence is increasing
from multiple scientific fields that exposure to the natural
environment can improve human health. In a new study by the U.S.
Forest Service, the presence of trees was associated with human
health.
For Geoffrey Donovan,
a research forester at the Forest Service's Pacific Northwest
Research Station, and his colleagues, the loss of 100 million trees
in the eastern and midwestern United States was an unprecedented
opportunity to study the impact of a major change in the natural
environment on human health.
In an analysis of 18
years of data from 1,296 counties in 15 states, researchers found
that Americans living in areas infested by the emerald ash borer, a
beetle that kills ash trees, suffered from an additional 15,000
deaths from cardiovascular disease and 6,000 more deaths from lower
respiratory disease when compared to uninfected areas. When emerald
ash borer comes into a community, city streets lined with ash trees
become treeless.
The researchers
analyzed demographic, human mortality, and forest health data at the
county level between 1990 and 2007. The data came from counties in
states with at least one confirmed case of the emerald ash borer in
2010. The findings-which hold true after accounting for the influence
of demographic differences, like income, race, and education-are
published in the current issue of the American Journal of Preventive
Medicine.
"There's a
natural tendency to see our findings and conclude that, surely, the
higher mortality rates are because of some confounding variable, like
income or education, and not the loss of trees," said Donovan.
"But we saw the same pattern repeated over and over in
counties with very different demographic makeups."
Although the study
shows the association between loss of trees and human mortality from
cardiovascular and lower respiratory disease, it did not prove a
causal link. The reason for the association is yet to be determined.
The emerald ash borer
was first discovered near Detroit, Michigan, in 2002. The borer
attacks all 22 species of North American ash and kills virtually all
of the trees it infests.
The study was
conducted in collaboration with David Butry, with the National
Institute of Standards and Technology; Yvonne Michael, with Drexel
University; and Jeffrey Prestemon, Andrew Liebhold, Demetrios
Gatziolis, and Megan Mao, with the Forest Service's Southern,
Northern, and Pacific Northwest Research Stations.
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