Funding: National Park Service, U.S.G.S. Restoring natural forest structure: Relationships between forest type, fire severity, forest structure, and gap patterns in Yosemite National Park Van R. Kane1, James Lutz1, Susan L. Roberts2, Douglas F. Smith3, Robert J. McGaughey4, Matthew L. Brooks2 1University of Washington, 2U.S.G.S, 3Yosemite National Park, U.S. 4Forest Service Funding: National Park Service, U.S.G.S.
Using Fire to Restore Structure
Study Area: Yosemite N.P. Unburned Four fire severities No change Low Moderate High Three forest types Ponderosa pine White fir-sugar pine Red fir
LiDAR Data Point Cloud Canopy Surface Model 400 x 400 ft *Light Detection And Ranging Old-growth stand Cedar River Watershed
Measuring Forest Change MTBS Fire Severity (30 m) Forest Type (30 m) Fire Severity- Forest Type Patches (30 m & 1 m) Vertical Structure Classes (30 m) Canopy – Gap Structure (1 m) Change examined by each fire severity-forest type combination
Measuring Vertical Structure Dominant tree height - 95th percentile* Established tree density - Cover >16 m Dominant lower foliage height - 25th percentile* Structural complexity - Rumple Regeneration density - Cover 2-16 m *Returns ≥2 m
Vertical Structural Classes Open 1-2 Sparse 2-30 Shorter 3-48 Multistory 4-69 Top Story 5-94
Identifying Canopy-Gap Patterns Canopy Surface Model 1 m Canopy-gap Map Point Cloud
Canopy-Gap Patterns Found Patch/Gap Open/Patch Continuous gradient of canopy/gap proportion Three archetypes shown Each example 300x300 m with 30x30 m grid cell overlays
Example: White fire-Sugar pine Canopy-Gap Gaps 16% Unburned Multistory 60% Top Story 21% Vertical Horizontal Severity
Example: White fire-Sugar pine Canopy-Gap Gaps 16% Unburned Multistory 60% Top Story 21% Top Story 49% Multistory 32% Canopy-Gap Gaps 24% No Change Vertical Horizontal Severity
Example: White fire-Sugar pine Canopy-Gap Gaps 16% Unburned Multistory 60% Top Story 21% Top Story 49% Multistory 32% Canopy-Gap Gaps 24% No Change Top Story 59% Sparse 16% Canopy-Gap Gaps 36% Low Vertical Horizontal Severity
Example: White fire-Sugar pine Canopy-Gap Gaps 16% Unburned Multistory 60% Top Story 21% Top Story 49% Multistory 32% Canopy-Gap Gaps 24% No Change Top Story 59% Sparse 16% Canopy-Gap Gaps 36% Low Sparse 42% Top Story 40% Patch-Gap Gaps 59% Moderate Vertical Horizontal Severity
Example: White fire-Sugar pine Canopy-Gap Gaps 16% Unburned Multistory 60% Top Story 21% Top Story 49% Multistory 32% Canopy-Gap Gaps 24% No Change Top Story 59% Sparse 16% Canopy-Gap Gaps 36% Low Sparse 42% Top Story 40% Patch-Gap Gaps 59% Moderate Sparse 40% Open 34% Open-Patch Gaps 78% High Vertical Horizontal Severity
Identifying Changes in Structure Pond- erosa pine White fir- sugarpine Red fir
Identifying Changes in Structure Pond- erosa pine White fir- sugarpine Red fir
Identifying Changes in Structure Pond- erosa pine White fir- sugarpine Red fir
Identifying Changes in Structure Pond- erosa pine White fir- sugarpine Red fir
Identifying Changes in Structure Pond- erosa pine White fir- sugarpine Red fir
Change in Patch & Gap Structure Patches – solid line; Gaps – dashed line
Change in Patch & Gap Structure Patches – solid line; Gaps – dashed line
Key Findings Fire changes vertical and horizontal forest structure at multiple scales Even no change and low fire severity patches showed substantial structural changes Forest types had individual structural trajectories with increasing fire severity
Conclusions Each forest type responds differently to each fire severity Management plans need to take forest response to fire into account Combination of Landsat & LiDAR measurements proves to be a sensitive measure of forest structure response to fire
Backup Why did lower severity fire remove larger ponderosa pine trees? Less compacted ground fuels may lead to higher intensities Lower productivity sites may lead to lower vigor and greater susceptibility to fire mortality Sustained drought may have led to increased susceptibility in conjunction with beetle activity