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Effects of Oxidant Air-pollution on Needle Health and Annual-ring Width in a Ponderosa Pine Forest
Published online by Cambridge University Press: 24 August 2009
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More than 485,000 hectares of the Ponderosa Pine forests in the southern Sierra Nevada of California are diseased as a result of air pollution, while approximately 25% of the area of Sequoia-Kings Canyon National Park receives enough oxidant air-pollution to elicit symptoms of smog injury on Ponderosa Pine, the dominant mid-elevation tree.
In 1983 we re-examined four permanent study plots that had been established in 1974–75. Smog symptoms on current needles in 1983 occurred on 23.8% of the trees compared with 14.5% only in 1975. Second-year needles had 60.7% showing symptoms compared with 44.2% in 1975. Less than 0.5% of the trees retained 6-years-old needles, and 21% had only 2 years of needle retention. Mortality attributed to air pollution was observed.
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- Copyright © Foundation for Environmental Conservation 1986
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