5. Past Changes in Climate and Tree Growth in the
Western Americas
Rosanne D. D'Arrigo and Gordon C. Jacoby
The AMIGO project has been termed "An interhemispheric and interdisciplinary research program to measure and understand ecosystem
responses to global change" (Committee on AMIGO) . Its goals include
the development of comparative studies of ecosystem response in western
North and South America, regions that have many parallel geobiospheric
features (Fuentes, Kronberg, & Mooney, 1991). It is hoped that these
interhemispheric comparisons will help distinguish natural from anthropogenic change and aid in policy making and monitoring of natural
systems. Evaluating tree rings are one means by which past climatic
change and forest ecosystem response can be compared between the
Northern Hemisphere and the Southern Hemisphere.
Dendroclimatic techniques have been employed in numerous studies to
reconstruct or extend the instru mental record of climate, based on oldaged trees from selected climatically stressed sites, and to document
forest-growth variations. Site-sampling strategies, cross-dating and quality
control, standardization (to process raw measurements into final chronologies), and rigorous calibration and verification methodologies for
climatic reconstruction are all basic elements of dendrochronology (Cook,
1985; Cook & Kairiukstis, 1990; Fritts, 1976; Holmes, 1983; Stokes &
Smiley, 1968). These techniques have been devised in order to minimize
errors in dating and measurement and to maximize the signal of interest
(e.g., climate).
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Western Americas
Rosanne D. D'Arrigo and Gordon C. Jacoby
The AMIGO project has been termed "An interhemispheric and interdisciplinary research program to measure and understand ecosystem
responses to global change" (Committee on AMIGO) . Its goals include
the development of comparative studies of ecosystem response in western
North and South America, regions that have many parallel geobiospheric
features (Fuentes, Kronberg, & Mooney, 1991). It is hoped that these
interhemispheric comparisons will help distinguish natural from anthropogenic change and aid in policy making and monitoring of natural
systems. Evaluating tree rings are one means by which past climatic
change and forest ecosystem response can be compared between the
Northern Hemisphere and the Southern Hemisphere.
Dendroclimatic techniques have been employed in numerous studies to
reconstruct or extend the instru mental record of climate, based on oldaged trees from selected climatically stressed sites, and to document
forest-growth variations. Site-sampling strategies, cross-dating and quality
control, standardization (to process raw measurements into final chronologies), and rigorous calibration and verification methodologies for
climatic reconstruction are all basic elements of dendrochronology (Cook,
1985; Cook & Kairiukstis, 1990; Fritts, 1976; Holmes, 1983; Stokes &
Smiley, 1968). These techniques have been devised in order to minimize
errors in dating and measurement and to maximize the signal of interest
(e.g., climate).
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