Effects of logging on soil organic carbon in the Coast Mountains of British Columbia, Canada Stephanie Grand and Les M. Lavkulich Soil Water Air Laboratory University of British Columbia, Vancouver, BC, Canada Faculty of Land and Food Systems Institute for Resources and the Environment

Objective Faculty of Land and Food Systems Institute for Resources and the Environment Document the effects of logging on:  Organic matter  Reactive mineral fractions  Available and labile nutrient pools

Measurements Soil organic matter Total C and N Exchangeable cations Reactive mineral fraction Faculty of Land and Food Systems Institute for Resources and the Environment

The field sites Faculty of Land and Food Systems Institute for Resources and the Environment

Roberts Creek study forest Faculty of Land and Food Systems Institute for Resources and the Environment  Control plots = mature (140 years) forest  Cleared plots = clear-cut 1 to 5 years prior to sampling  Regenerating plots = clear-cut 8 to 15 years prior to sampling

Faculty of Land and Food Systems Institute for Resources and the Environment

Soil type Albic Gleyic Podzol (Humo-ferric Podzol / Aquentic Haplorthod) Faculty of Land and Food Systems Institute for Resources and the Environment

C stock: control site Faculty of Land and Food Systems Institute for Resources and the Environment

Cleared plots Faculty of Land and Food Systems Institute for Resources and the Environment

Regenerating plots Faculty of Land and Food Systems Institute for Resources and the Environment

Indicators of bulk OM composition C:NC:SOMCEC e :C Control2450%0.9 Cleared2351%0.9 Regenerating2141%1.3 Faculty of Land and Food Systems Institute for Resources and the Environment

Principle component analysis Faculty of Land and Food Systems Institute for Resources and the Environment

Short-range order mineral phases Faculty of Land and Food Systems Institute for Resources and the Environment

Short-range order phases Faculty of Land and Food Systems Institute for Resources and the Environment g/kg ITM (SRO Al phase) FH (SRO Fe phase) Control Cleared Regenerating

Future work Faculty of Land and Food Systems Institute for Resources and the Environment Rate of precipitation and dissolution of short- range order phases Rate of formation of organo-mineral complexes

Conclusion Subsoil C is important 60% of the soil C found below 20 cm depth Deep C pool responsible for overall C trend Clear-cutting causes increase in mineral soil C Short-lived increase suggesting that new C is not stabilized or that older C is mineralized Indication that logging impacts podzolization process Reactive mineral phases dynamics C stabilization potential Faculty of Land and Food Systems Institute for Resources and the Environment

Acknowledgements PhD thesis advisory committee Dr. L. Lavkulich, Dr. H. Schreier, Dr. R. Hudson Lab technicians Carol Dyck and Keren Fergusson Field assistants Peter Shanahan, Marina Romeo and Bryan Forrest Faculty of Land and Food Systems Institute for Resources and the Environment Special thanks to the French Society for Soil Study (AFES) for financial support