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Biomass Harvesting and Forest Site Productivity. Eric D. Vance National Council for Air and Stream Improvement (NCASI) Biomass/Bioenergy Workshop February 24-25, Houston, TX. Biomass Harvesting. Emerging markets for bioenergy Removal of biomass previously left on site Shorter rotations

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Biomass Harvesting and Forest Site Productivity

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Biomass Harvesting and Forest Site Productivity

Eric D. Vance

National Council for Air and Stream Improvement (NCASI)

Biomass/Bioenergy Workshop

February 24-25, Houston, TX


Biomass Harvesting

  • Emerging markets for bioenergy

  • Removal of biomass previously left on site

  • Shorter rotations

  • Concerns over site productivity, water, wildlife


Sustaining Site Productivity by Manipulating Site Resources

  • Water, nutrients, sunlight

  • Allocation of existing site resources

    • Competing vegetation, root growth

  • Increasing site resources

    • Artificially removing biomass and nutrients

    • Cannot always rely on natural replacement


Management Intensity and Site Resources

Intensive

Extensive

Available

Resources

Resource

Capital


Intensive Utilization of Harvest Residues in Southern Pine PlantationsM.H. Eisenbies, E.D. Vance, W.M. Aust, J.R. SeilerBioenergy Research (2009) 2:90-98

  • 32 million Mg yr-1 residues available in the South

  • 50-85 Mg ha-1 on site after stem-only harvest

  • 45-60% increase in mid-rotation fertilization may be needed to replace nutrients if residues removed


South Carolina Wet/Dry Harvest Study (Virginia Tech, MeadWestvaco, NCASI)Residue-Soil Disturbance Matrix


Ten-Year Effects of Harvest Residue Removal on Relative Rank of Stand Biomass


Fall River Long-Term Soil Productivity ProjectUniv. of Washington, Weyerhaeuser, USFS, NCASI

  • Conventional bole-only removal

  • Total stem (bole-only to a 5cm top)

  • Total-tree removal

  • Total-tree + legacy-wood removal

  • All cable-yarded


Fall River StudyDouglas-fir Age 5 Tree Volume Index


Forest Service Long-Term Soil

Productivity Network

Core Sites

Affiliated Sites


Competing Vegetation: A Critical Factor


Lake States AspenNutrient Depletion and Rotation Length

  • Deficiencies rare

  • Older studies

    • Multiple, short-rotation cycles

    • Concluded 10-15 yr rotations sustainable

  • Reduced soil/foliar Ca on some sites

  • Indices underdeveloped


Aspen in the Lake StatesNutrient Budgets for Whole-tree Harvesting over 50 years(Mineral soils (lb/ac); Minnesota GEIS, Grigal 2004))

Ca capital = 15,125


Short Rotation Aspen on Sandy Soils: A Worst-Case Scenario?

  • < 1% Ca drain

    • (Grigal, 2004)

  • Three 20-yr rotations

    • < 5% Ca removed

  • 1 ton/ac wood ash


The Forest Calcium Cycle(Likens et al. 1998)


Over a Century of Forest Nutrition Management in Scandinavia

  • Science-based

  • Forest productivity

  • Forest health

  • Nutrient imbalances

    • Foliar, soil analysis

  • Biomass harvesting


Intensive Harvest and Site Productivity: What Do We Know?

  • Many sites remarkably resilient

  • Little evidence for productivity declines

  • Preconceived notions often incorrect

  • Managers often know best


But, More Work is Needed!

  • Sensitive sites

  • Fundamental impacts

  • Long-term, repeated removals

  • Indicators

  • Prevention, mitigation


A Range of Management Intensities to Meet Society’s Needs


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