Resumen de Cuatro siglos de variabilidad hidroclimática en el noroeste de Chihuahua, México, reconstruida con anillos de árboles
José Villanueva Díaz, Julián Cerano Paredes, Peter Z. Fulé, Citlali Cortés Montaño, Lorenzo Vázquez-Selem, Larissa L. Yocom, José Ariel Ruiz Corral
- español
En el noroeste de Chihuahua, sitio Mesa de las Guacamayas, catalogada como “Área Natural Protegida” para anidamiento de la cotorra serrana, se desarrolló una serie dendrocronológica con abeto Douglas (Pseudotsuga menziesii) con una extensión de 409 años (1600-2008). La cronología de anillo total mostró asociaciones significativas (r>0.40, p=0.000) con cronologías vecinas (no separadas más de 200 km), particularmente las ubicadas en la misma vertiente de la Sierra Madre Occidental, lo que implica la influencia de patrones climáticos comunes, cuyos frentes húmedos impactan simultáneamente una extensa área del noroeste de México. Un análisis espectral de potencia indicó que los índices dendrocronológicos estuvieron afectados por ENSO y por otros patrones circulatorios, como se deduce de los picos espectrales dominantes (<10 años) presentes en la cronología; también mostraron asociación significativa (r=0.52, n=111, p<0.000) con registros del PDSI para el suroeste de los EUA. Una reconstrucción de precipitación acumulada enero-julio para la misma región, mostró sequías prolongadas en los períodos 1772-1782, 1793-1803, 1999-2008 y períodos húmedos en 1742-1751 y 1809-1818. La proporción de años secos detectados en la reconstrucción, sugiere que existe 50% de probabilidad de su ocurrencia a nivel anual
- English
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 <200 km apart along the western slopes of the Sierra Madre Occidental (SMO) observing correlations as high as 0.69 (p<0.001). Association between chronologies decreased for those sites in the state of Durango along the SMO but separated more than 200 km in straight line and also for sites in nearby borderline in the USA side. The similar climatic response among distant chronologies implies the influence of common atmospheric circulatory patterns affecting a large portion of land simultaneously. ENSO is one of the most important factors in determining inter-annual and multiannual hydroclimatic variability in northern Mexico, increasing winter-spring precipitation in its warm phase and causing extreme droughts in its cold phase.
