# Presentation: 239040

## Historical Creation of Early Seral Habitat: Fire, Wind, Bugs ...

**Fred Swanson**
***USDA Forest Service***
***Pacific Northwest Research Station***

## 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

## Creating early seral

- Many disturbance types
- Few types commonly create big patches
- Many processes create fine patterns

## 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

## Disturbance processes in PNW

- Big patch
**Fire**
**Forest cutting **
**Volcanic – tephra vs. **
**        ****lava flows**
- Small patch
**Landslides – fast**
**Landslides – slow**
**Wind**
**Bugs**
**Root rot**

## Non-forest openings

- Patch
- size

- Persistence of early seral (yrs)

- 0

- 50

- 100

- small

- large

- Mount St. Helens
- Blast  zone – planted

- Canopy
- gap

- Mount St. Helens
- Blast zone - unplanted

- Mesic meadows

- Xeric
- meadows

- Lava
- flows

- Mount St. Helens
- Primary succ. zone

- Clearcuts
- fast   (Yang et al)   slow

- Wildfire

- tropics

## Slide 7

## 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)

## Big, homogeneous disturbance – fine-scale complexity

## Slide 10

## Stand-Replacing Disturbance

**Stand-Replacing Disturbance**

- _Fires_

## Stand-Replacing Disturbance

**Stand-Replacing Disturbance**

- _Fires_

- _Harvests_

## Stand-Replacing Disturbance in Western Washington, 1972-2004

**Stand-Replacing Disturbance in Western Washington, 1972-2004**
**Fires****	****	****        Harvests**
- 	1972-1977
- 	1977-1984
- 	1984-1988
- 	1988-1992
- 	1992-1996
- 	1996-2000
- 	2000-2002
- 	2002-2004

- Volcanic eruption

## Age Class Distributions in Coastal Oregon

- Source: various CLAMS analyses (Spies et al. 2007)

**Notes:**
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.

## What we don’t know

**Character of pre-management early seral habitat**
**Character of current plantations we might call early seral**

## “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?

## 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?