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Daily To Decadal Patterns Of Precipitation, Humidity, And Photosynthetic Physiology Recorded In The Spines Of The Columnar Cactus, Carnegiea Gigantea, N. B. English, D. L. Dettman, D. R. Sandquist, David G. Williams

David G Williams

Isotopic analyses of cactus spines grown serially from the apex of long-lived columnar cactuses may be useful for climatological and ecological studies if time series can be reliably determined from spines. To characterize the timescales over which spines may record this information, we measured spine growth in saguaro cactus over days, months, and years with time-lapse photography, periodic marking, and postbomb radiocarbon dating and then analyzed isotopic variability over these same timescales and compared these measurements to local climate. We used daily increments of growth, visible as transverse bands of light and dark tissue in spines, as chronometers to develop …