SGER: Restoring Old-Growth Ponderosa Pine and Western Larch Stands in Western Montana

9814835沙拉自20世纪初S以来，西北内陆地区的防火和放牧导致疏松和西部落叶松林被密集的内部道格拉斯冷杉林所取代。防火可能会严重损害我们保护落基山脉北部古老森林的能力。演替森林更替的生态影响包括对老树残留林中老树的竞争压力、道格拉斯冷杉以外的物种更新不良以及水、碳和氮循环的改变。管理后果包括增加火灾危险、增加对病原体的易感性和降低森林健康。美国林业局山间火灾科学实验室正在计划一个项目，以恢复依赖火灾的老树黄皮松和落叶松。对于100年来未被烧毁的老树种残留林(约450a)，将采用几种处理：1)对照；2)林下燃烧；3)林下砍伐而不焚烧；4)覆被和林下焚烧间伐；5)覆被和林下砍伐间伐。这些处理提供了一个从实验上评估由于灭火而导致的生态系统属性变化的非同寻常的机会。研究人员将在处理前和处理后测量五个处理的林分水平用水量、木材产量、叶片产量、叶片氮环境、水分利用效率和土壤水分有效性。结果将确定与灭火相关的林分密度和树冠覆盖率的增加是否导致整个林分水平用水量的增加，但减少了老黄皮松和落叶松的用水量。

9814835 Sala Since the early 1900's, fire exclusion and livestock grazing in the interior northwest have resulted in a successional replacement of open ponderosa pine and western larch stands with dense stands of interior Douglas-fir. Fire exclusion may seriously compromise our ability to preserve old-growth forests in the northern Rocky Mountains. The ecological implications of successional forest replacement include competitive stress on the older trees in old-growth remnant stands, poor regeneration of species other than Douglas-fir, and alteration of water, carbon and nitrogen cycles. Management consequences include increased fire hazard, increased susceptibility to pathogens and decreased forest health. The Intermountain Fire Sciences Laboratory of the US Forest Service is planning a project to restore old-growth fire-dependent ponderosa pine and larch. Several treatments will be applied to an old-growth remnant stand (ca 450 years) which has not burned in about 100 years: 1) control; 2) understory burn; 3) understory removal but no burn; 4) thinning of overstory and understory burn; and 5) thinning of overstory and understory removal. These treatments provide an extraordinary opportunity to experimentally assess changes in ecosystem properties due to fire suppression. The investigators will measure stand-level water use, wood production, foliage production, foliage nitrogen context, water use efficiency, and soil water availability in the five treatments before and after treatment application. Results will determine whether increases in stand density and canopy cover associated with fire suppression has resulted in an increased whole stand-level water use, but has decreased water used by old ponderosa pines and larches.