Trends in stomatal density and 13C/12C ratio of Plnus flexilis needles during last glacial-interglacial cycle.
by Van de Water P. K., Leavitt S. W., Betancourt J. L. (1994)
1Laboratory of Tree-Ring Research and Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA.
2Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ 85721, USA.
3U.S. Geological Survey, Desert Laboratory, 1675 West Anklam Road, Tucson, AZ 85745, USA.
in Science 264: 239–243. – Int. J. Adv. Biol. Res. Vol 5 (1) 2015: 23-28.-
Measurements of stomatal density and δ13C of limber pine (Pinus flexilis) needles (leaves) preserved in pack rat middens from the Great Basin reveal shifts in plant physiology and leaf morphology during the last 30,000 years.
Sites were selected so as to offset glacial to Holocene climatic differences and thus to isolate the effects of changing atmospheric CO2 levels. Stomatal density decreased ∼17 percent and δ13C decreased ∼1.5 per mil during deglaciation from 15,000 to 12,000 years ago, concomitant with a 30 percent increase in atmospheric CO2.
Water-use efficiency increased ∼15 percent during deglaciation, if temperature and humidity were held constant and the proxy values for CO2 and δ13C of past atmospheres are accurate. The δ13C variations may help constrain hypotheses about the redistribution of carbon between the atmosphere and biosphere during the last glacial-interglacial cycle.