Presentation on theme: "Historical Creation of Early Seral Habitat: Fire, Wind, Bugs … Fred Swanson USDA Forest Service Pacific Northwest Research Station."— Presentation transcript:
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) 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
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)
Stand-Replacing Disturbance in Western Washington, Fires Harvests Volcanic eruption
Age Class Distributions in Coastal Oregon Source: various CLAMS analyses (Spies et al. 2007) Early seral
What we dont 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?