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Stoichiometry of Forest Nutrient L imitation

Stoichiometry of Forest Nutrient L imitation. Melany Fisk, Miami University. Stoichiometry of Forest Nutrient L imitation. Dynamic context: Interacting elements Resource optimization by organisms Species traits Disturbance and ecosystem development Heterogeneous landscape.

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Stoichiometry of Forest Nutrient L imitation

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  1. Stoichiometry of Forest Nutrient Limitation Melany Fisk, Miami University

  2. Stoichiometry of Forest Nutrient Limitation • Dynamic context: • Interacting elements • Resource optimization by organisms • Species traits • Disturbance and ecosystem development • Heterogeneous landscape Bormann et al. 1977

  3. Rethinking limitation • What limits productivity in northern hardwood forests? • Theory predicts N limitation • Has N deposition induced P limitation? • Recent syntheses predict co-limitation • Does a resource allocation framework explain patterns of limitation or co-limitation? • At what time scales can resource allocation processes operate to minimize single-element limitation?

  4. Rethinking limitation • Regional approach incorporates forest succession, soil variation • Short-term experimental responses evaluated in context of longer-term pattern N x P fertilization experiment: 13 sites 30 kg N/ha/yr 10 kg P/ha/yr parent material, succession

  5. Examples of Resource Allocation Across Sites • Above vs belowground • Total soil respiration is negatively related to N availability (Bae et al. submitted) • Belowground: N vs P • N and P availability are coupled by phosphatase activity (Ratliff 2012)

  6. Examples of Resource Allocation Across Sites • Above vs belowground • Total soil respiration is negatively related to N availability (Bae et al. submitted) • Belowground: N vs P • N and P availability are coupled by phosphatase activity (Ratliff 2012) • Fine root allocation to acquire N vs P depends on N availability (Naples and Fisk 2010) • P enhances C mineralization, while N depresses it (Santangelo et al, in prep)

  7. Predictions of the multiple-element limitation model Rastetter et al. 2013 • Allocation shifts between N and P after large-scale disturbance • Colimitation occurs when allocation to N and P equilibrates

  8. Rethinking limitation • What limits productivity in northern hardwood forests? • Does a resource allocation framework explain patterns of limitation or co-limitation? Enzymatic feedbacks Allocation feedbacks Decomposer microbes mycorrhizae Available nutrients Maintain consistent N:P Geohydrologic template

  9. Rethinking limitation • What limits productivity in northern hardwood forests? • Does a resource allocation framework explain patterns of limitation or co-limitation? • Is co-limitation a long-term outcome of ecosystem development? • Or, is it a transient part of long-term, ultimate limitation, mediated by shifting resource allocation? Enzymatic feedbacks Community or ecosystem level? Allocation feedbacks Decomposer microbes mycorrhizae Available nutrients Maintain consistent N:P Geohydrologic template

  10. Forest Nutrient Limitation • Collaborators: Multiple element interactions in northern hardwood ecosystems • Joel Blum, geochemistry • Tim Fahey, trees • Melany Fisk, soil biota and processes • Christy Goodale, soils and nutrients • Ed Rastetter, modeling • Ruth Yanai, trees and modeling • And many others

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