NOAA/WDS Paleoclimatology - Johnson fire data from Middle Rio Pueblo, northern New Mexico - IMPD USMRP002

Tree-ring fire scars, tree ages, historical photographs, and historical surveys demonstrate that fire played different ecological roles for centuries across gradients of elevation, forest, and fire regime in the Taos Valley Watersheds. Fire regimes collapsed across these three adjoining watersheds by 1899, leaving all sites without fire for at least 119 years. Historical photographs and quaking aspen (Populus tremuloides Michx.) ages indicate that high-severity fire historically burned at multiple high-elevation subalpine sites in today’s Village of Taos Ski Valley, with large high-severity patches (> 640 ha). Low-severity, frequent (9 – 29 year median interval) surface fires burned in nearby mid-elevation dry conifer forests on south aspects in all watersheds. Fires were associated with drought during the fire year, preceded by wet years, with widespread fires commonly burning synchronously in multiple watersheds during more-severe drought years, including within all three watersheds in 1664, 1715, and 1842. In contrast, recent “large” wildfires have burned within single watersheds and therefore are likely not large in a historical context. Management to promote repeated low-severity fire and associated open forest stand structures is within the historical range of variability in the dry conifer forests of these watersheds, but in the high-elevation, subalpine forests different management approaches are required that balance ecological and socio-economic values while providing for public safety.