1. Effects of silvicultural practices on forest soil metabolism Claire Phillips FS 533 Winter 2007

2. “Soil Respiration” Mixture of CO 2 produced by roots, mycorrhizae, and soil decomposition Generally the single largest efflux of CO 2 from forests >70% of ecosystem respiration in temperate forests

3. Explanatory Variables Soil Temperature F = F 0 e T Soil Moisture Biomass Microbial respiration: Litter Quality, C:N Root respiration: Nutrient Limitations Phenology Silvicultural Practices: Thinning Rotation Length

4. Thinning Mixed-conifer forest, Sierra Nevada (Tang et al. 2005) Overall, no net effect of thinning on soil respiration Thinning increases soil temperature and moisture For a given temperature and moisture level respiration is lower under thinned treatment

5. Rotation Length Does soil respiration correspond with aboveground productivity? Chronosequence studies show relationship with fine root biomass (Ewel 1987, Bond-Lamberty 2004, Howard 2004) (Howard 2004)

6. Root biomass differs from aboveground biomass

7. Conclusions Short term effects of silvicultural treatments mediated by changes in temperature, moisture, live root biomass Long term effects mediated by fine root growth Fine root biomass not predictable from aboveground biomass or growth General trends lack predictive power