1. 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 sgrand@interchange.ubc.ca Faculty of Land and Food Systems Institute for Resources and the Environment

2. 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

3. 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

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

5. 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

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

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

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

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

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

11. 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

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

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

14. 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) Control23.23.6 Cleared29.14.8 Regenerating15.92.8

15. 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

16. 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

17. 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