Modeling Tree Growth Under Varying Silvicultural Prescriptions
Effects of silvicultural practices on forest soil metabolism
description
Transcript of Effects of silvicultural practices on forest soil metabolism
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Effects of silvicultural practices on forest soil metabolism
Claire PhillipsFS 533
Winter 2007
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“Soil Respiration”
Mixture of CO2 produced by roots, mycorrhizae, and soil decomposition
Generally the single largest efflux of CO2 from forests
>70% of ecosystem respiration in temperate forests
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Explanatory VariablesSoil Temperature
F = F0eT
Soil Moisture
Biomass
Microbial respiration:Litter Quality, C:N
Root respiration: Nutrient Limitations Phenology
Silvicultural Practices:
Thinning
Rotation Length
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ThinningMixed-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
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Rotation LengthDoes soil respiration correspond with
aboveground productivity?
Chronosequence studies show relationship with fine root biomass (Ewel 1987, Bond-Lamberty 2004, Howard 2004)
(Howard 2004)
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Root biomass differs from aboveground biomass
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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