PARENT SESSION
Poster Session #16: Fire Ecology.
Tuesday, August 7, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Downed woody material, projected leaf area index, and satellite index relationships in Chihuahuan Desert vegetation.

WHITE, JOSEPH¹, ¹

ABSTRACT- Low productivity systems such as deserts should show conservative relationships between the accumulation of downed woody material and above ground biomass in the absence of frequent disturbance. Downed woody material, projected plant area (PLAI), and cover were measured on more than 30 sites in Big Bend National Park to assess whether patterns of fuel buildup was associated with canopy structure characteristics. Overall, total downed woody material was linearly related to PLAI across different vegetation types, though some variation exists when all vegetation types were considered. Individual size classes of downed woody material showed sensitivity to vegetation type with larger fuels having a different relationship to PLAI in areas dominated by shrubs than areas dominated by grasses. In general, medium sized fuels increase exponentially with increasing PLAI in shrub communities, whereas in grass communities fuel accumulation reaches a maximum amount with small PLAI development. Among the canopy characteristics PLAI and cover were highly related, though exponentially. Satellite-derived vegetation indices (Landsat TM) were also found to be highly related to PLAI (r²=0.91). By utilizing these relationships and satellite data from 1986 and 1998, maps of potential downed woody accumulation were created. Correspondence between predicted fuel accumulation and location and size of recent fires illustrates the potential of these spatial data for modeling and management of desert fires.

KEY WORDS: fuels, satellite, cover, PLAI