Four centuries of reconstructed hydroclimatic variability for Northwestern Chihuahua, Mexico, based on tree rings

A Douglas-fir chronology with a length of 409 years (1600-2008) was developed for northwestern Chihuahua in Mesa de las Guacamayas, a “Natural Protected Area” known as an important nesting habitat for the thickbilled parrot (Rhynchopsitta pachyrhyncha) an endangered neotropical bird. Increment cores and cross-sections from selected Douglas-fir trees (Pseudotsuga menziesii) in a mixed conifer forest were obtained with an increment borer and a chain-saw. Standard dendrochronological techniques were used to process and date each one of the rings to their exact year of formation. The quality of dating of the measured series was analyzed with the COFECHA program, while biological trends not related to climate (age differences, stem-size increases, and disturbances) were removed by standardization procedures in the ARSTAN program. Tree ring series of earlywood, latewood and total ring width were developed for the last four centuries. The total ring-width chronology was significantly associated (r>0.40, p=0.000) with nearby chronologies, particularly those located