Climatic influences on fire regimes in ponderosa pine forests of the Zuni Mountains, NM, USA

• The historic wildfire regime was characterized by frequent, low-severity fire.
• Wetter conditions typically occurred one to two years prior to fire.
• Drought typically occurred during the fire year.
• Fires were driven by interannual rather than multidecadal climate variability.

We characterized fire history and examined climate–fire relationships in dry ponderosa pine (Pinus ponderosa) forests in the Zuni Mountains of northwestern New Mexico. Our findings indicate that the historical wildfire regime for the study area was typified by high-frequency, low-severity surface fires. Climate–wildfire relationships were assessed using both Superposed Epoch Analysis (SEA) and Bivariate Event Analysis (BEA). SEA revealed that interannual variability of the El Niño–Southern Oscillation (ENSO) and the Palmer Drought Severity Index (PDSI) was a strong driver of widespread wildfires; wetter conditions often occurred one to two years prior to fire and were followed by drought during the fire year. BEA revealed statistically significant relationships only in the case of extreme PDSI events and widespread wildfire in the year of fire (t = 0). No relationship was found between either the Pacific Decadal Oscillation (PDO) or the Atlantic Multidecadal Oscillation (AMO) and widespread fire occurrence, signifying that shorter-term (i.e. interannual) oscillations between wet and dry conditions, rather than longer-term climatic variability, were historically most conducive to fire. Contextualizing these findings under ongoing climate and land-use change is challenging. Full restoration to historical conditions may be neither possible nor desired, but targeted efforts to promote a frequent, low-severity wildfire regime are generally consistent with our understanding of historical fire activity in this forest type and may foster ecological, economic, and/or societal goals.