Régimen histórico de incendios y su relación con el clima en un bosque de Pinus hartwegii al norte del estado de Puebla, México

The Pinus hartwegii forest in cooperative lands Rinconada, Chignahuapan, represents the region of highest risk of forest fires in the state of Puebla. In order to reconstruct the history of fires and determine their historical association with climate, we collected 43 cross-sections with fire scars and analyzed them by dendrochronological techniques. Two hundred and thirty five fire scars were dated in 40 cross-sections. The fire history was reconstructed for the period 1876-2011 (136 years). Most (91.7 %) fires occurred during spring and 8.3 % in summer. The Mean Fire Interval (MFI) and Weibull Median Probability Interval (WMPI) for all the scars were 5.6 and 5.0 years, respectively. Large or extensive fires occurred when fire scars were recorded in 25 % of samples or more with MFI and WMPI values of 9.2 and 8.5 years, respectively. On this site, fires have continued to the present, but after 1988 a significant drop in fire frequency was noted. A positive association between lower precipitation (drought) and fire occurrence was determined. Similarly, negative values of NIÑO 3 and PDSI (dry conditions), associated with drought conditions, have a positive influence on the modulation of the historical frequency of fires in this region of central Mexico.