Taxodium mucronatum Ten. USE TO DETERMINE THE SEASONAL RAINFALL VARIATION IN GUANAJUATO

Abstract

Increment cores were collected from two Taxodium mucronatum populations located in the Central-South of Guanajuato state and two ring-width chronologies of 128 and 237 year long were produced for Manuel Doblado and Jerecuaro sites, respectively. Principal Component Analysis determined a common response for both time series, so a composite chronology was developed for the whole region, covering the period 1700 – 2007 (308 years). To analyze the climatic response of the composite chronology, the ring width indices were compared to precipitation records representating regional climatic data from ten individual meteorological stations. The period of significantly correlation (r= 0.75, p<0.01) corresponds to the seasonal January-April total precipitation. Calibration-verification procedures indicated a significant response for the statistic tests involved, explaining 62 and 52% of the variance, respectively. A calibration procedure was run for the whole period, explaining a significant 56% of the variance, and then this model was used to reconstruct a seasonal precipitation for the total length of the chronology (308 years). The reconstructed winter-spring precipitation indicated high hydroclimate variability and severe drought periods were detected from 1778 to 1788, 1798 to 181, 1817 to 1839, and 1861 to 1904. Pluvials were present from 1789 to 1797, 1840 to 1860, 1905 to 1927, 1964 to 1969, 1987 to 1994, and 2003 to 2007.