Historical Creation of Early Seral Habitat Fire Wind

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 large Mount St. Helens Blast zone – planted Mount St. Helens Blast zone - unplanted Mount St. Helens Primary succ. zone Patch size Wildfire Lava flows Clearcuts fast (Yang et al) slow Xeric meadows Mesic meadows Canopy gap small 0 50 Persistence of early seral (yrs) 100 tropics

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

Stand-Replacing Disturbance Fires

Stand-Replacing Disturbance Fires Harvests

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

Age Class Distributions in Coastal Oregon Early seral Source: various CLAMS analyses (Spies et al. 2007)

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?