Landscape patterns of CH₄ fluxes in an alpine tundra ecosystem

Abstract

We measured CH₄ fluxes from three major plant communities characteristic of alpine tundra in the Colorado Front Range. Plant communities in this ecosystem are determined by soil moisture regimes induced by winter snowpack distribution. Spatial patterns of CH₄ flux during the snow-free season corresponded roughly with these plant communities. InCarex-dominated meadows, which receive the most moisture from snowmelt, net CH₄ production occurred. However, CH₄ production in oneCarex site (seasonal mean=+8.45 mg CH₄ m⁻² d⁻¹) was significantly larger than in the otherCarex sites (seasonal means=−0.06 and +0.05 mg CH₄ m⁻² d⁻¹). This high CH₄ flux may have resulted from shallower snowpack during the winter. InAcomastylis meadows, which have an intermediate moisture regime, CH₄ oxidation dominated (seasonal mean=−0.43 mg CH₄ m⁻² d⁻¹). In the windsweptKobresia meadow plant community, which receive the least amount of moisture from snowmelt, only CH₄ oxidation was observed (seasonal mean=−0.77 mg CH₄ m⁻² d⁻¹). Methane fluxes correlated with a different set of environmental factors within each plant community. In theCarex plant community, CH₄ emission was limited by soil temperature. In theAcomastylis meadows, CH₄ oxidation rates correlated positively with soil temperature and negatively with soil moisture. In theKobresia community, CH₄ oxidation was stimulated by precipitation. Thus, both snow-free season CH₄ fluxes and the controls on those CH₄ fluxes were related to the plant communities determined by winter snowpack.