Snag-fall patterns following stand-replacing fire vary with stem characteristics and topography in subalpine forests of Greater Yellowstone

We assessed the stem- and landscape-level drivers of snag persistence and snag-fall mode within the area burned as stand-replacing fire in the 1988 Yellowstone Fires in Yellowstone National Park, Wyoming, USA. Snags were sampled 14-15 years postfire (n = 131) and again in a separate set of plots 34 years postfire (n = 55). Stem characteristics such as species identity (e.g., lodgepole pine, whitebark pine, Engelmann spruce, subalpine fir, and Douglas-fir), diameter at breast height, whether the tree was alive or dead at the time of fire, and the mode of snag-fall (snapping or uprooting) were measured and used to explain patterns of snag persistence and modes of snag-fall. In addition, plot-level environmental variables (e.g., slope, aspect, elevation, stand density) were measured and related to the proportion of stems still standing as snags at 14-15 and 34 years postfire. Data collection is complete and is part of a forthcoming manuscript in revision at Forest Ecology and Management.

本研究针对美国怀俄明州黄石国家公园1988年黄石山火中发生全林分烧毁型火灾的区域，探究了枯立木（snag）留存规律与倒伏模式的个体尺度及景观尺度驱动因子。研究分别在火灾后14-15年（样本量n=131）与火灾后34年（基于另一组独立样地，样本量n=55）对枯立木开展调查取样。调查测定的个体尺度特征包括：树种组成（如扭叶松、美国白皮松、恩氏云杉、亚高山冷杉与花旗松）、胸径、火灾发生时树木的存活状态，以及枯立木倒伏模式（折断或连根拔起），并基于上述数据解析枯立木留存动态与倒伏模式的影响机制。此外，本研究还测定了样地尺度的环境变量，包括坡度、坡向、海拔与林分密度，并分析其与火灾后14-15年、34年仍保持枯立状态的林木占比之间的关联。目前数据采集工作已全部完成，相关研究成果正在《Forest Ecology and Management》期刊审稿阶段，即将发表。