Fire and Forest History at Mount Rushmore

Abstract

Mount Rushmore National Memorial in the Black Hills of South Dakota is known worldwide for its massive sculpture of four of the United States' most respected presidents. The Memorial landscape also is covered by extensive ponderosa pine (Pinus ponderosa) forest that has not burned in over a century. We compiled dendroecological and forest structural data from 29 plots across the 517-ha Memorial and used fire behavior modeling to reconstruct the historical fire regime and forest structure and compare them to current conditions. The historical fire regime is best characterized as one of low-severity surface fires with occasional (> 100 years) patches (< 100 ha) of passive crown fire. We estimate that only approximately 3.3% of the landscape burned as crown fire during 22 landscape fire years (recorded at > or = 25% of plots) between 1529 and 1893. The last landscape fire was in 1893. Mean fire intervals before 1893 varied depending on spatial scale, from 34 years based on scar-to-scar intervals on individual trees to 16 years between landscape fire years. Modal fire intervals were 11-15 years and did not vary with scale. Fire rotation (the time to burn an area the size of the study area) was estimated to be 30 years for surface fire and 800+ years for crown fire. The current forest is denser and contains more small trees, fewer large trees, lower canopy base heights, and greater canopy bulk density than a reconstructed historical (1870) forest. Fire behavior modeling using the NEXUS program suggests that surface fires would have dominated fire behavior in the 1870 forest during both moderate and severe weather conditions, while crown fire would dominate in the current forest especially under severe weather. Changes in the fire regime and forest structure at Mount Rushmore parallel those seen in ponderosa pine forests from the southwestern United States. Shifts from historical to current forest structure and the increased likelihood of crown fire justify the need for forest restoration before a catastrophic wildfire occurs and adversely impacts the ecological and aesthetic setting of the Mount Rushmore sculpture.

Impacts of fire exclusion and recent managed fire on forest structure in old growth Sierra Nevada mixed-conifer forests

“…2A, B, C). These findings are consistent with those from previous studies in the Sierra Nevada (Parsons and Debenedetti 1979, Ansley and Battles 1998, North et al 2007, Scholl and Taylor 2010 and in the Rocky Mountains (Fulé et al 1997, Brown et al 2008, Naficy et al 2010. Given that the forest of western YNP has not been extensively harvested and that livestock grazing has not taken place for 70 to 110 years, the changes in forest structure can largely be attributed to the disruption of the key ecosystem process for these forests, fire, which occurred frequently within our study area until 1899 (Scholl and Taylor 2010).…”

“…These reconstruction studies characterize the structure and composition of forests for a period in which low-to moderate-intensity fire was the dominant process. Under these conditions forests were largely resistant to extensive, high-intensity fire (Brown et al 2008), and were generally resilient to other disturbances and stressors (e.g., insects, disease, and drought) (Fulé 2008). However, there is evidence from some forest types that historical fires did occur at higher intensities as well, resulting in discrete patches of high tree mortality throughout the landscape (Beaty and Taylor 2001, Hessburg et al 2007, Beaty and Taylor 2008; such patterns continue today where wildfires have been managed for resource benefit .…”

“…Most historical forest reconstructions rely on information inferred from tree rings, which allows for temporal depth and spatial precision that often exceeds other historical data sources (e.g., written accounts, maps, plot data, and photographs) (e.g., Fulé et al 1997, Taylor 2004, Brown et al 2008, Scholl and Taylor 2010. However, tree-ring based reconstructions are subject to an inherent limitation brought about by only using extant data.…”

Larch forests of Middle Siberia: long-term trends in fire return intervals

“…We attribute this to the significant difference in the forest types studied. Stephens et al (2010) and Brown et al (2008) studied pine stands within arid areas, whereas we focused on northern larch communities. As Stephens wrote, "the degree of underestimation of [fire frequency] depends on the density of woody debris and rates of fuel accumulation".…”

Unsupported inferences of high‐severity fire in historical dry forests of the western United States: response to Williams and Baker

“…Despite W&B's assertions to the contrary, we are unaware of any fire ecologists who claim that dry western forests were uniform in composition, structure or fire regime. For example, in the southwest, historical patches of high-severity fire in ponderosa pine have been documented at scales of 1-100 ha and in South Dakota at scales of < 5% of the landscape (Brown et al, 2008b). But the spatial pattern of burning in modern wildfires is orders of magnitude higher, with large (10 3 -10 4 ha) contiguous fire-killed patches.…”