Details

Autor(en) / Beteiligte

• Van de Water, P. K.
• Leavitt, S. W.
• Betancourt, J. L.

Titel

Trends in Stomatal Density and $^{13}$C/$^{12}$C Ratios of Pinus flexilis Needles During Last Glacial-Interglacial Cycle

Ist Teil von

• Science (American Association for the Advancement of Science), 1994-04, Vol.264 (5156), p.239-243

Ort / Verlag

United States: American Society for the Advancement of Science

Erscheinungsjahr

1994

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Measurements of stomatal density and δ$^{13}$C 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 CO$_2$ levels. Stomatal density decreased ∼17 percent and δ$^{13}$C decreased ∼1.5 per mil during deglaciation from 15,000 to 12,000 years ago, concomitant with a 30 percent increase in atmospheric CO$_2$. Water-use efficiency increased ∼15 percent during deglaciation, if temperature and humidity were held constant and the proxy values for CO$_2$ and δ$^{13}$C of past atmospheres are accurate. The δ$^{13}$C variations may help constrain hypotheses about the redistribution of carbon between the atmosphere and biosphere during the last glacial-interglacial cycle.