ibclogo XVI International Botanical Congess


Abstract Number: 3454
Poster No. = 1256


CHANGING ATMOSPHERIC CO2 CONCENTRATIONS DURING DEGLACIATION


P. K. Van de Water, S. W. Leavitt, J. L. Betancourt*, Univ. of Arizona, Tucson AZ, * U.S.G.S. Desert Lab., Tucson AZ


Atmospheric CO2 increased from 180 to 280 p.p.m.v. during the transition from the full glacial to Holocene conditions. The effect of DCO2 on the eco-physiology of selected species was determined through d13C and morphological analysis of macrofossils. The macrofossils were recovered from packrat middens collected in the southwestern United States and span 40,000 years determined through radiocarbon dating. They include both gymnosperms and angiosperms as well as representatives of C3, C4, and obligate along with facultative CAM physiologies Responses include changing water-use efficiency, stomatal density, and biomass . Samples of the same species were collected along elevation transects to characterize natural variability in modern communities for comparison.


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