The climatic response of baldcypress (Taxodium mucronatum Ten.) in San Luis Potosi, Mexico

Key message Baldcypress, a long-lived species of riparian habitats, is sensitive to interannual climate variability. The annual radial growth is associated with the Standardized Precipitation Evaporation Index (SPEI) and Palmer Drought Severity Index (PDSI), both depending on a water balance. The baldcypress (Taxodium mucronatum Ten.) is a long-lived species and Mexico's national tree. The objective of this study was to analyze the dendroclimatic response of baldcypress at sites located on the transitional zone between the semiarid and subtropical regions of Mexico, known as the Middle Zone of the state of San Luis Potosi, Mexico. The first site, Los Peroles (LPO), is a wetland where the oldest known baldcypress specimens in Mexico are found. The second site, Rio Verde (RVDE), is a riparian site located along a tributary of the Moctezuma River that drains into the Gulf of Mexico. Two ring-width chronologies were analyzed. The first one from LPO with a length of 633 years and the second one from RVDE with a length of 423 years. The species responded positively to the seasonal January-July precipitation (r = 0.52, p = 0.001) and negatively to the maximum monthly temperature of January, May, and June (r = - 0.42, -0.46, and -0.34; respectively). The average chronology was significantly associated with the mean January-August Standardized Precipitation Evaporation Index (SPEI) (r = 0.62, p = 0.000). An SPEI reconstruction was developed for the period 1575-1996 where the most prolonged and severe droughts were found at 70-year peaks in the El Nino Southern Oscillation frequency band. The annual radial growth of the species is a suitable indicator of the January-August water availability, and is important information that can be used to establish water management strategies for this semiarid environment and to preserve millennial baldcypress specimens.