1. Historical Creation of Early Seral Habitat: Fire, Wind, Bugs …
Fred Swanson
USDA Forest Service
Pacific Northwest Research Station

2. Early seral – definition issues
And we thought we have problems with old growth definitions!
Easy to talk about the archtype
Dimensions for definition:
Precursor system
Temporal - persistence
Spatial – patch size, location in environmental gradients
Disturbance regime context

3. Creating early seral Many disturbance types
Few types commonly create big patches
Many processes create fine patterns

4. Controls on disturbance effects
Selective of vegetation structure class
Selective of species
Spatial heterogeneity – of disturbance process, of affected ecosystem
Species dominating post-disturbance
Persistence of effects of disturbance – biotic legacies, dispersal, soil properties change

5. Disturbance processes in PNW
Big patch
Fire
Forest cutting
Volcanic – tephra vs.
lava flows
Small patch
Landslides – fast
Landslides – slow
Wind
Bugs
Root rot

6. Non-forest openings Wildfire Patch size
large
Mount St. Helens
Blast zone – planted
Mount St. Helens
Blast zone - unplanted
Mount St. Helens
Primary succ. zone
Lava
flows
Patch
size
Wildfire
Clearcuts
fast (Yang et al) slow
Xeric
meadows
Mesic meadows
Canopy
gap
small 50
100
Persistence of early seral (yrs)
tropics

8. Root rot, wind, bugs Part of ecosystem disturbed
Species ready to occupy the site
After Phellinus weiri Holah et al. (1997) observed:
Coast Range – shrubs dominate site
Cascades – hemlock dominates site
After Bull Run windthrow – hemlock dominates
(Sinton et al 2000)

9. Big, homogeneous disturbance – fine-scale complexity

11. Stand-Replacing Disturbance
Fires

12. Stand-Replacing Disturbance
Fires
Harvests

13. Stand-Replacing Disturbance in Western Washington, 1972-2004
Fires Harvests
Volcanic eruption

14. Age Class Distributions in Coastal Oregon
Early seral
Relative to HRV in the coast range, we have no shortage of early-seral forest in current landscape. Slide compares age-class distributions in current landscape (‘initial’, 1996) with HRV (300 years pre-Euro-settlement) and 100 years from now (CLAMS simulation – ignore for now). ~30% of current forest is early seral, vs. 3-12% historically.
Source: various CLAMS analyses (Spies et al. 2007)

15. What we don’t know Character of pre-management early seral habitat
Character of current plantations we might call early seral

16. “Real”, complex early seral – More or less? Probably less!
Lack of cultural burning
Fire suppression
Reduced federal harvest
Forest encroachment in mesic meadows
Practices to hasten conifer canopy closure
Regime-scale effects – is there cumulative loss of structural complexity and biotic diversity over multiple cuttings?
But, does harvest do the early seral creation job? Do we have more wildfire?

17. Closing thoughts Next steps:
Synthesize existing knowledge of early seral condition and function
Confer about management options and impediments
Integrate thinking/management across landscapes and all age classes
Address geographic variation
What are the similarities/differences with development of old-growth science, policy, and management?