Document: DAN-3-69-23

Long term development of stand structure following catastrophic fire in Yellowstone National Park: Do landscape legacies persist?

KASHIAN, D.M.* ¹, M.G.TURNER ¹ and W.H.ROMME ²

University of Wisconsin-Madison, Madison, WI 53706 USA ¹
Fort Lewis College, Durango, CO USA ²

Abstract:
The 1988 fires in Yellowstone National Park (YNP) created a 250,000-ha landscape mosaic that contains tremendous variation in the density and spatial pattern of lodgepole pine (Pinus contorta var. latifolia) seedlings across the landscape. The initial spatial heterogeneity created by large, infrequent fires is often assumed to persist until the next stand-replacing fire, especially where serotinous species are dominant and postfire seedling establishment is episodic. However, the spatial and temporal dynamics of this landscape legacy are not well known. We examined tree age structure, size structure, and spatial pattern across a range of stand ages (50 to 300 years old) and densities (1300 to 4200 stems/ha) to quantify changes in stand structure over time. Our results indicate that stands of lodgepole pine in YNP experience a reduction in density through decades of self-thinning, but continuous seedling establishment is also common at all stand densities, even where serotiny is high. Furthermore, spatial pattern of trees in a young (53 years old), sparse (1220 stems/ha), non-serotinous stand characterized by continuous colonization was similar to that of a more mature (115 years old), moderately-dense (2070 stems/ha), moderately-serotinous stand characterized by self-thinning. Although old-growth stands of differing density and spatial pattern are found in YNP, these results suggest that some initial differences in stand density and spatial pattern may not persist through the fire-free interval. In this sense, the spatial heterogeneity within the perimeter of a large, infrequent fire may decrease over time, and the importance of landscape legacies is reduced with time since disturbance.

Keywords: stand structure, convergence, large infrequent disturbance, landscape legacies, lodgepole pine

This abstract is being presented at: 10:30 AM in session:
Poster Session #12: Disturbance Ecology.