Aspen and pine leaf litter decomposition in laboratory microcosms. I. Linear versus exponential models of decay

摘要

Leaf litter of trembling aspen (Populus tremuloidesMichx.) and lodgepolendash;jack pine (Pinus contortaLoud, times;P.banksianaLamb.) was decomposed in laboratory microcosms at 2, 10, 18, or 26 deg;C and three watering rates (15, 30, or 60ensp;mL∙weekminus;1) for 16 weeks. Aspen litter lost 5.0ndash;37.3 of original mass, and pine litter lost 7.8ndash;14.9. Decay curves fit a sample linear model equally as well as the negative exponential model regardless of temperature or moisture conditions or species of litter. A general explanation of circumstances promoting apparently linear mass loss from decaying plant litter is derived from these data, a survey of the literature, and the assumption that all decay curves are ultimately curvilinear. Mass loss rates are expected to appear linear from slowly decaying substrates such as bole wood or when decay of rapidly decomposing substrates is not followed past the inflection point of the curve. Climatic variables that favour decomposer activity are hypothesized to increase the concavity of decay curves, while adverse conditions do the opposit