Loading of stream wood following the 2016 Chimney Tops 2 Wildfire: Great Smoky Mountains National Park, Tennessee, USA

Abstract

Large wood drives physical and ecological processes in river systems, but the relative roles of continuous individual tree mortality versus episodes of mass mortality in wood recruitment are not well understood. Here, the 2016 Chimney Tops 2 wildfire, a rare severe wildfire in the eastern United States, was used as a case study for examining the role of mass tree mortality in wood loads of streams in Great Smoky Mountains National Park (GSMNP), Tennessee. Wood surveys were conducted on four reaches in two drainage systems affected by the fire to ascertain the total frequency and volume of burned and unburned wood pieces and jams. Relative to unburned wood, the Chimney Tops 2 fire resulted in a major influx of burned wood to the study reaches, with large percentages of individual pieces (average of 47% by frequency, 48% by volume) and jams (average of 72% by frequency, 93% by volume) exhibiting burn marks. Burned wood pieces had a larger diameter than unburned pieces (p = .065). Results suggest that rare mass‐mortality events like the Chimney Tops 2 wildfire could play a major role in wood dynamics of mountain streams in humid forested regions.

Fire and geodiversity

“…For example, the varve thickness of lake sediments increased in the 15 years following fire events by 35% and 25% where fire recurrence was 60 years and 80 years, respectively (Swanson 1981). Further, stream-bound logs and woody debris influence downstream flow by collecting and depositing sediments and partially or fully restricting flow at multiple stream points (Praskievicz and Sigdel 2021). At the watershed-scale, this can impact the redistribution of sediments and depositional landforms, particularly where hydro-geomorphological processes have been altered, albeit there can be micro-topographical variance on finer scales where impacts to localised dependencies are equally important to understanding and accounting for shifts in fluvial environments.…”

Large wood loads in an urban stream: The role of recruitment limitation versus transport dominance

“…Wood abundance in channels is also affected by the age of forest, wood mobility, and instability of banks (Elosegi & Johnson, 2003). Wood load in streams can also significantly increase due to mass mortality of trees resulting from fire (Praskievicz & Sigdel, 2021), insect outbreaks (Wallace, Webster, Eggert, Meyer, & Siler, 2001), or severe storms (West et al, 2011).…”