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.

树轮火疤痕（tree-ring fire scars）、树木年代数据、历史影像与历史调查均证实，数个世纪以来，在陶斯谷流域的海拔梯度、森林类型与火制度（fire regime）梯度上，火曾发挥着各异的生态作用。至1899年，这三个相邻流域的火制度均已崩溃，所有样地均至少119年未发生火灾。历史影像与颤杨（Populus tremuloides Michx.）年代数据显示，如今的陶斯滑雪谷村范围内的多处高海拔亚高山样地中，历史上曾发生过高强度火烧，形成了面积超过640公顷的大面积高强度火烧斑块。所有流域内的南坡中海拔干旱针叶林区域，均发生过低强度、高频发（中位间隔9~29年）的地表火。火灾发生当年多伴随干旱，且火灾发生前多为湿润年份；在更为严重的干旱年份，大范围火灾通常会在多个流域同步发生，1664年、1715年与1842年的火灾便波及了全部三个流域。与之形成对比的是，近期的“大规模”野火仅在单个流域内蔓延，因此从历史语境来看，这些火灾并不算大规模。在这些流域的干旱针叶林中，推行重复低强度火干预以维持开阔林分结构的管理方式，符合该区域历史上的生态变异范围；但在高海拔亚高山森林中，则需采用差异化的管理手段，在兼顾生态与社会经济价值的同时保障公共安全。