Paper No. 88028 of the Water Resources Bulletin. Discussions are open until December 1, 1989.
DROUGHT INDICATED IN CARBON-13/CARBON-12 RATIOS OF SOUTHWESTERN TREE RINGS1
Article first published online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 25, Issue 2, pages 341–347, April 1989
How to Cite
Leavitt, S. W. and Long, A. (1989), DROUGHT INDICATED IN CARBON-13/CARBON-12 RATIOS OF SOUTHWESTERN TREE RINGS. JAWRA Journal of the American Water Resources Association, 25: 341–347. doi: 10.1111/j.1752-1688.1989.tb03070.x
- Issue published online: 8 JUN 2007
- Article first published online: 8 JUN 2007
- stable-carbon isotopes;
- pinyon pine;
- Pinus edulis;
- Palmer Drought Indices;
ABSTRACT: Stomatal closure during periods of moisture deficiency should theoretically lead to elevated 13C/12C ratios as reduction of available CO2 leads to diminished photosynthetic discrimination against 13C in favor of 12C. Stable-carbon isotope ratio chronologies developed from 5-yr tree-ring groups at 17 sites in six southwestern states were tested for a drought relationship by first fitting a spline curve to each chronology to remove the long-term trend and calculating indices as the ratio of actual to spline curve value. The time series of “Del Indices” so developed are significantly correlated with 5-yr mean Palmer Hydrological Drought Indices (post-1930 period) and reconstructed July Palmer Drought Severity Indices from respective areas. Overall, in the period since 1790, the driest pentads were 1900–04 and 1960–64, whereas the wettest were 1980–84 and 1915–19. Maps of drought represented for two pentads seem to be reasonable representations, although spatial correlations of Del Indices with PHDI were generally not significant. These Del Index drought reconstructions may provide a useful measure of past physiological response to drought (stomatal closure), although the present cost of analysis would prevent this from being a routine method.