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Tree-Ring Evidence for Climatic Changes in Western North America

Reprinted from: Monthly Weather Review, Vo. 93, No. 7, Pp. 421 to 443, 1965 / The relationships between climatic factors and fluctuations in dated tree-ring widths are statistically evaluated. A wide ring indicates that the year's climate was moist and cool, and a narrow ring dry and warm. In general, ring width relates to a 14-month period from June through July but most tree-ring chronologies exhibit a closer relationship with autumn, winter, and spring moisture than with summer moisture. The climatic relationships for evergreen trees are attributed largely to the influence of environmental factors on photosynthesis and the accumulation of food reserves. Under abnormally dry and warm conditions, especially during the autumn, winter, and spring, little food is accumulated, new cells are formed more slowly during the growing period, and the resulting ring is narrow.
Relative 10 -yr. departures are calculated for the entire length of 26 tree -ring chronologies from western North America.
Those portions after 1500 are used to map areas of high and low moisture. Periods of widespread drought
are noted in 1576-1590, 1626-1635, 1776-1785,1841-1850, 1871-1880, 1931-1940. Periods of widespread and above average moisture occurred during 1611-1625,1641-1650, 1741-1755, 1826-1840, 1906-1920. The moist periods of 1611-1625, and 1906-1920 were most widespread and markedly above average.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/304606
Date07 1900
CreatorsFritts, Harold C.
ContributorsLaboratory of Tree-Ring Research, University of Arizona
PublisherAmerican Meteorological Society (Boston, MA)
Source SetsUniversity of Arizona
Languageen_US
Detected LanguageEnglish
TypeArticle, text
SourceLaboratory of Tree-Ring Research Archives. The University of Arizona.
RightsCopyright © Arizona Board of Regents. The University of Arizona.

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