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Stand Structure and Ecological Restoration

Stand Structure and Ecological Restoration. Charles W. Denton Ecological Restoration Institute John D. Bailey, Associate Professor of Forestry, Associate Professor of Forestry, Northern Arizona University, School of Forestry. Today’s Topics. “Stand Dynamics” and the role of disturbance

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Stand Structure and Ecological Restoration

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  1. Stand Structure and Ecological Restoration Charles W. Denton Ecological Restoration Institute John D. Bailey, Associate Professor of Forestry, Associate Professor of Forestry, Northern Arizona University, School of Forestry

  2. Today’s Topics • “Stand Dynamics” and the role of disturbance • Single vs. multiple species • Density and basal area • Even-aged stands • Multi-aged stands • Special stand structures, living and dead • Scaling up spatially • Temporal variation and planning

  3. Stand Dynamics Regulates: • Age and size distribution = even-aged vs. multi-aged stands • Vertical canopy structure/layers • Horizontal arrangementissues Four basic stages: • Stand initiation • Stand replacing event, growing space • Stem exclusion (“thinning”) • Self-thinning, low diversity, zero g.s. • Understory reinitiation (“transition”) - shifting mosaic • Old-growth

  4. Presettlement Age Distribution in Northern Arizona 180 Mast et al. 1999

  5. Single vs. Multiple Species Mix and ratios based on: • Disturbance type (e.g., fire) • Shade tolerance • Initiation vs. transition • Management preferences • Spatial arrangement issues

  6. Presettlement Ponderosa Pine Spatial Distribution Gus Pearson Natural Area width of circle indicates age Covington et. al., 1997

  7. Current conditions at the Gus Pearson Restoration site

  8. Diameter DistributionFort Valley, Arizona

  9. Kathy Smith’s thesis 1999 S9 S10

  10. Interpreting Density Measures • Trees per acre • Little use in multi-aged • BA and SDI • Workable, particularly at extremes • Canopy closure • Aerial fuels and growing space

  11. Hypothetical Results of a BDQ 14-50-1.2 Treatment S9-10 Before Treatment S9-10 After Treatment

  12. Implications • Multi-aged is ‘historically accurate’ • Group selection created “clumpiness” relative to individual-tree selection • Must revisit the sites regularly - the 1919 cohort is now a real problem • VSS distribution • Mistletoe does not have to be a concern

  13. Special Structural Elements • Large, old trees • Not “old-growth” trees • Vigorous lower and mid-canopy trees • True advantage of multi-aged • Snags and aerial dead wood • Wildlife habitat value • Downed, coarse woody debris • Ecosystem value ALL have their limits!

  14. STIFH Treatment Gradient Unburned Burned Control Thinned Wildfire Thinned and Burned Disturbance Gradient

  15. Forest Health “Indicators” • Overstory structure and growth/vigor • Fuel loading • Understory composition • Insect diversity • Soil nitrogen • Ectomycorrhizal fungi • Wildlife use

  16. Scaling up spatiallywelcome to “ecosystem management” • Three fundamental scales for diversity: • Within stand • Among stands • Landscapes, watersheds and fragmentation • Stand inequality is good ALL have their role!

  17. Temporal Scales • Trees grow • Disturbance happens • Trees grow • Stands change somewhat predictably given stand dynamics, but often unpredictably • Trees grow …Adaptive Management!

  18. Fire mortality1999 data collection

  19. REGENERATION • Adequate in most decades • seed tree density and production • seedbed and germination • mortality, particularly with fire • More likely TOO MUCH • Some decades may be insufficient, but that’s OK

  20. Concluding Remarks:Structure and Restoration • It’s ALL about structure • Multi-aged is often the way, but more complicated • Promote small trees, too • Spatial heterogeneity • Diversity at all three scales

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