Vegetation Module Seth Bigelow, Michael Papaik, Malcolm North USFS Pacific Southwest Research Station

Vision and Goals Determine ecosystem effects of current silvicultural practices, especially those in Pilot Project Develop predictive models of tree growth and establishment Provide technical assistance to other modules

Vegetation Module Research 2010 PSW experiment, Meadow Valley: three-year post- treatment canopy and understory cover, fuel loads Seedling dispersion after disturbance: group selection openings Neighborhood and Climate Determinants of Big Tree Growth

PSW Experiment, Meadow Valley Treatments: - Control - Thin to 50% CC - Thin to 30% CC - Group selection with large- tree reserves - 3 replicates - Stands of ~ 22 acres

Canopy Cover, PSW Experiment Meadow Valley - Initial cover 70-80% - Cover reduced to 50-60% in thinned stands - Cover reduced to 10-20% in group openings

Understory Light, PSW Experiment Meadow Valley

Canopy Cover as Predictor of Area Available for Shade-Intolerant Regeneration

Light Study: Conclusions Understory light changes slowly: it’s the same three years after treatment as immediately after Fuels-reduction thinning provides poor conditions for Shade-Intolerant Regeneration (~15% of area at 40% canopy cover) Group selection provides enough light for SIR, even with large tree retention

Fuel Loads (dead ground and surface fuels) -Treatments did not change fuel loads -Some differences between survey years

Fuel Loads: Conclusions -Low repeatability of Brown’s lines: consider sticking to visual assessment (photo series) -Fuels-reduction thinning doesn’t reduce dead ground/surface fuels: further treatment (e.g., Rx. fire) needed

J. Katz

Understory Vegetation -4-m diameter plots -100 plots / stand -Visual assessment of cover by plant lifeform -Species identification of dominant of each lifeform -Pre-treatment and 3-yr post-treatment surveys

Understory Cover: Observations It is what it was: treatments did not change cover of any plant lifeform Its about the shrubs: they make up the largest cover class It’s a fir farm out there: conifer recruitment dominated by shade-tolerant species

Seedling Dispersion (with Michael Papaik) Goal: develop models that spatially predict seedling density after disturbance Requires seedling counts along transects in mapped stands “Disturbance” types: high & low severity fire, salvage, group selection

Density (#/m 2 ) Predicted Seedling Density, Group Selection Opening (provisional)

Seedling Density: Group Selection Openings, Meadow Valley landscape -High fir density at higher elevations -Ponderosa(Jeffrey) density similar to White fir at lower elevations

White fir annual growth and precipitation (Large trees) Annual precipitation (inches/yr) Ring width (microns)

Neighborhood and Climate Determinants of Big Tree Growth All species grew faster in wet years No species were sensitive to density of neighboring trees Temperature: White fir, Doug-fir, Cedar grow faster in warm winters, slower in warm springs Pines grew more slowly with warm late summer temperatures

Conclusions Cover and understory light change slowly Fuels-reduction thinning (FRT) is a stop-gap measure, doesn’t reduce ground/surface fuels FRT/GS does not hurt understory plants, or do them much good Group Selection is increasing shade-intolerant regeneration at lower elevation sites Large tree growth responds to climate

Acknowledgments Funding: USFS Region 5 & National Fire Plan Cooperators: Small mammal module (canopy photos), Gerrard (graphics), Parker, Fuller, Bednarski (NEPA), Baldwin (statistics), Caum (dendrochronology) Support: Stine, QLG Field work: Salk, Perchemlides, Livingston, many others

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