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Title: A LARGE CO2-INDUCED SPRING GROWTH ENHANCEMENT IN SOUR ORANGE TREES

Author
item IDSO, CRAIG - CTR STY C02/GLOBAL CHG AZ
item Idso, Sherwood
item Kimball, Bruce

Submitted to: Association of American Geographers
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Resent research has documented a 7-day advance in the declining phase of the atmosphere's seasonal CO2 cycle since the early 1960s, which finding has been suggested to provide evidence for a lengthening of the "climatological" growing season, brought about by an increase in spring air temperatures. However, it is possible that the phase shift may also be the result of an earlier or more robust "biological" spring, brought on by earlier and/or more vigorous spring growth in response to the aerial fertilization effect produced by the increase in atmospheric carbon dioxide experienced over the same time period. To test the viability of this hypothesis, we measured a number of parameters related to spring growth rates of sour orange trees that have been growing in open-top chambers under controlled CO2 concentrations of 400 and 700 ppm at the U.S. Water Conservation Laboratory in Phoenix, AZ, for the past ten years. Results indicate a dramatic CO2-induced spring growth enhancement, which, if characteristic of other vegetation, could explain about one-third of the reported phase shift in the atmosphere's seasonal CO2 cycle since 1960.