Landscape patterns of litter decomposition in alpine tundra

Area of Science:

• Ecology
• Soil Science
• Tundra Biogeochemistry

Background:

• Decomposition is a critical ecosystem process in tundra environments.
• Landscape heterogeneity, including snowpack and moisture, can significantly influence decomposition dynamics.
• Soil microarthropods play a role in nutrient cycling and decomposition.

Purpose of the Study:

• To investigate the effect of landscape factors on the decomposition of alpine avens (Acomastylis rossii) foliage in alpine tundra.
• To determine how snowpack amount and soil moisture gradients influence litter decay rates.
• To assess the relationship between microarthropod communities and decomposition patterns across different habitats.

Main Methods:

• A two-year field study measuring foliage decomposition rates across varying snowpack conditions.
• Analysis of annual decay constants (k-values) in relation to moisture gradients (dry, moist, wet).
• Microarthropod sampling and identification (oribatid and prostigmatid mites) in different habitats.
• A mushroom litterbag experiment using naphthalene to exclude fauna and evaluate invertebrate effects on decomposition.

Main Results:

• Litter decomposition was most rapid on sites with intermediate snowpack.
• Annual decay constants (k-values) ranged from -0.33 (dry) to -0.52 (moist) to -0.47 (wet).
• Faster decomposition occurred beneath the snowpack in late winter/early spring.
• Microarthropod densities did not differ significantly, but oribatid mite abundance increased in wetter areas.
• Mushroom decomposition was significantly faster in mesic sites with higher invertebrate densities; xeric sites lacked fauna.

Conclusions:

• Landscape factors, particularly snowpack and moisture, exert a strong influence on alpine tundra decomposition rates.
• Soil microarthropod community composition, not just density, varies with the moisture gradient and affects decomposition.
• The detritus-based food web's activity and composition are significantly altered by the alpine tundra's moisture gradient.