Applications of acanthochronlogy on the Altiplano cactus Echinopsis atacamensis...or how I learned to love the bomb (pulse).

Cactus on the Altiplano of South America contain an archive of useful climate, physiological and demographic information in the isotopes of their spines. As demonstrated on saguaro cactus in Tucson, Arizona, spines emerge from the apex of the cactus, cease growth, and then are retained in time-ordered sequence on the side of the cactus as the stem continues to grow upward. Thus, time ordered sequences of spines contain diurnal, seasonal, and annual information in the oxygen and carbon isotope ratios of the robust spine tissue. Additionally, bomb-pulse radiocarbon from measured spines can be used to infer cactus growth rates in previously unmonitored populations of cactus. On the Bolivian Altiplano in the Salar de Uyuni, isotopic evidence from E. atacamensis cactuses provide estimates of cactus age that place these cactus among the longest-lived cactus in the world (>400 years old) and also suggest that the modern Salar de Uyuni region is influenced by the Gran Chaco climate regime with respect to nighttime, growing season temperatures. This talk covers the development of acanthochronology at University of Arizona and the LTRR, its challenges and some of the questions it's begun to answer.