PARENT SESSION
Poster Session #35: Decomposition and Soil Respiration.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
21
The spatial distribution of litter decomposition over a heterogeneous landscape of a Wyoming forest-alpine tundra ecotone.
Hiemstra, Christopher1, Reiners, William1, 1
ABSTRACT- Forest-alpine ecotones in the Rocky Mountains feature pronounced changes in ecosystem structure over short extents. This heterogeneity provides a convenient system for determining how ecosystem properties like decomposition vary. We tested the effects of dominant vegetation type, litter type (dominant or standard), snow-free date, and site characteristics on decomposition rates in a treeline landscape in southeastern WY. The litter types used included the particular dominant community species (open meadow, Geum rossii; willow stands, Salix planifolia; snow glades, Juncus drummondii; and tree islands, Picea engelmannii), as well as a standard species (Deschampsia cespitosa). Ten bags of each type were placed at 12 sites (3 replicates for each type) during October 1999. Half of the bags were retrieved after the site became snow-free in May-July, 2000; the remaining bags were retrieved in September, 2000. With all litter types, 24.6% of the mass loss occurred under snow, while an additional 7.4% was lost during the snow-free period. Among dominant litter types, G. rossii exhibited the largest overall percent loss of initial mass (43%) followed by J. drummondii (36%), S. planifolia (19%), and P. engelmanii (9%). D. cespitosa litter showed the greatest mass loss in willow patches and snow glades (39.3%), a 30.7% loss in the meadows, and a 28.0% loss in the forest. Spatial data on vegetation type, soil temperature and aspect were used to spatially distribute decomposition rates over this landscape.
KEY WORDS: litter, decomposition, alpine, Wyoming