Document: MON-3-4-12

Effects of a fire-created landscape mosaic on ecosystem processes in Yellowstone National Park, Wyoming.

TURNER, M.G.* ¹, W.H.ROMME ², D.B.TINKER ¹, D.M.KASHIAN ¹ and D.H.KNIGHT ³

University of Wisconsin, Madison, WI 53706 USA ¹
Fort Lewis College, Durango, CO 81301 USA ²
University of Wyoming, Laramie, WY 82071 USA ³

Abstract:
Little is known about the long-term implications of a fire-created landscape mosaic for ecosystem processes. The 1988 fires in Yellowstone National Park produced a complex mosaic of early successional stands in response to variation in fire intensity and prefire serotiny in lodgepole pine. We studied spatial variability in these initial successional communities and its effect on aboveground net primary production (ANPP) and leaf area index (LAI). The spatial pattern of pine seedling density was mapped from 1:30,000 color infra-red aerial photographs obtained in August 1998. Postfire tree density ranged from 1000-5000 ha-1 across approximately 50% of the postfire landscape. Approximately 10% of the landscape was occupied by very high density (>50,000 ha-1) stands and 10% by very low density (< 100 ha-1) stands. We hypothesized that, for a given substrate, total LAI and ANPP would not differ among these postfire stands, although the contributions of herbaceous and woody LAI and ANPP would differ. ANPP and LAI were estimated from allometric relationships we developed and vegetation measurements made in 1999 at 88 widely distributed points. Total ANPP and LAI ranged from 0.9-12.6 Mg/ha/yr and 0.03-4.6 m2/m2, respectively. ANPP and LAI generally increased with pine seedling density, but both declined with pine densities >100,000 ha-1. Herbaceous biomass accounted for >80% of ANPP in low density stands and <10% in very high density stands. Pine seedlings accounted for >80% of total LAI except when pine seedling density was extremely low (e.g., <100 ha-1). Variation in post-fire succession produced substantial heterogeneity both in total ANPP and LAI and the contributions of herbaceous and woody ANPP and LAI. Large, infrequent fires may create a new vegetation mosaic that alters the spatial pattern of ecosystem processes.

Keywords: landscape heterogeneity, ecosystem processes, Yellowstone National Park, lodgepole pine

This abstract is being presented at: 2:45 PM in session:
Symposium # 10: Integrating Ecosystem and Landscape Ecology: Causes and Consequences of Spatial Heterogeneity in Ecosystem Processes.