Post-drought growth responses of western juniper (Juniperus occidentalis var. occidentalis) in central Oregon

Call Number:

URL:

Keywords:

Abstract:

Increased atmospheric CO2 may affect the physiological response of natural trees to drought. We examined radial growth rates developed from five western juniper chronologies to determine whether post-drought growth responses have changed. Using prior year October to current year June precipitation from 1896–1998, we identified drought recovery years as having standardized scores (z-scores) > 0 and preceded by a year with a z-score < –0.6. We defined our analysis by an early period, 1896–1930, when atmospheric CO2 concentrations were close to preindustrial levels, and a late period, 1964–1998, when concentrations were substantially higher. Mean growth index values of recovery years between early and late periods were significantly greater (p < 0.05) for four of the five sites, and for all sites combined. These results are consistent with the drought-ameliorating effects of CO2 shown by controlled laboratory studies and suggest that rising levels of atmospheric CO2 may impact western juniper growth rates.

Notes:

ELECTRONIC FILE - Ecology

SWAP (2/19/2016) citation:
Knapp PA, Soulé PT, Grissino–Mayer HD. 2001. Post-drought growth responses of western juniper (Juniperus occidentalis var. occidentalis) in central Oregon. Geophysical Research Letters. 28(13):2657–2660