Organic matter (OM) decomposition is an important variable in determining the potential of forest soils to sequester atmospheric CO2. Studies using OM from a particular location gives site-specific decomposition information, but differences in OM type and quality make it difficult to compare results among soils and forest ecosystems. By using a “standard” OM in decomposition studies, OM quality is held constant, and decomposition is a function of soil abiotic (moisture, temperature, O2/CO2, redox potential, pH, N, P, etc), and biotic (microbial biomass, functional diversity) properties. Wood is a good standard material to use in soil OM decomposition studies, since it is a normal soil component (woody residue, coarse roots), and a slow decomposition rate allows wood to remain in the soil for a number of years. In 1998 a wood stake study was initiated on both public and industry land throughout the U.S., Canada, and Europe. These sites represent a variety of climatic conditions and forest types, which cover a wide range of soil chemical, physical, and biological properties. Wood stakes of two tree species are being used to contrast different lignin types present in wood: loblolly pine (Pinus taeda), and aspen (Populus tremuloides). The objectives of this study are: (1) to determine the effects of abiotic soil properties on wood decomposition, and (2) to assess how these soil properties affect microbial activity and diversity during wood decomposition. This paper will present an overview of the study protocols, field and laboratory methods used, and discuss preliminary results from several of the study sites in North America and Europe.

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