Chemical, physical and biological factors affecting wood decomposition in forest soils

Abstract

Organic matter (OM) decomposition is an important variable in forest productivity and determining the potential of forest soils to sequester atmospheric CO2 (Grigal and Vance 2000; Kimble et al. 2003). 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 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 in the U.S., Canada, and Europe to: (1) determine the effects of abiotic soil properties on wood decomposition, and (2) assess how these soil properties affect microbial activity and diversity during wood decomposition. These study sites represent a variety of climatic conditions and forest types, which are being extensively monitored for soil moisture, temperature, and CO2/O2 (Appendix A). Soil chemical and physical properties have also been characterized on each of these sites. Stakes of two tree species are used to contrast different lignin types present in wood: southern pine (Pinus spp.) and aspen (Populus tremuloides). Two test stakes are cut from each 2.5 x 2.5 cm x 70 cm Amother@ stake, and divided into tree ring and weight classes prior to field installation.

Citation

Jurgensen, Martin; Laks, Peter; Reed, David; Collins, Anne; Page-Dumroese, Deborah; Crawford, Douglas. 2004. Chemical, physical and biological factors affecting wood decomposition in forest soils. IRG documents 2003; IRG 35; 6-10 June 2004; Ljubljana, Slovenia. Stockholm, Sweden: IRG Secretariat. 14 p.