CR 22:237-244 (2002)  -  doi:10.3354/cr022237

ABSTRACT: The state of Chihuahua lies in an arid to semiarid zone in the NW central plain of Mexico. Its agricultural economy is highly vulnerable to frequent droughts. In this study, we reconstruct winter-spring precipitation from 1647-1992 using 6 earlywood width chronologies of Douglas fir from around Chihuahua. The tree-ring data explain 56% of the winter-spring precipitation variance in a linear regression for 1949-1992, and there is strong correlation between the tree-ring reconstructed precipitation data and the observed precipitation data not used for calibration (r = 0.74, p < 0.01). The 5 driest years in the reconstructed precipitation record were 1974, 1954, 1742, 1980, and 1820 in order of severity, and the longest dry period in the 346 yr record lasted about 17 yr (1948-1964) during the severe 1950s drought that also affected the SW United States. The reconstructed precipitation record has a statistically significant 4 yr spectral peak in the El Niño/Southern Oscillation (ENSO) frequency band and is significantly correlated with indices of ENSO (tropical rainfall index; r = 0.58, p = 0.001). The correlation between the ENSO and Chihuahuan reconstructed precipitation varied in strength when computed for non-overlapping 18 yr sub-periods (ranging from r = 0.43 to r = 0.68), which may reflect changes in the ENSO teleconnection to climate in northern Mexico.

KEY WORDS: Chihuahua · Mexico · Reconstructed precipitation · Tree-ring chronologies · Earlywood · Douglas fir · ENSO · Tropical rainfall index