1. 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.

2. Using Fire to Restore Structure

3. 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

4. LiDAR Data Point Cloud Canopy Surface Model 400 x 400 ft
*Light Detection And Ranging
Old-growth stand Cedar River Watershed

5. 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

6. 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

7. Vertical Structural Classes
Open
1-2
Sparse
2-30
Shorter
3-48
Multistory
4-69
Top Story
5-94

8. Identifying Canopy-Gap Patterns
Canopy Surface Model
1 m Canopy-gap Map
Point Cloud

9. 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

10. Example: White fire-Sugar pine
Canopy-Gap
Gaps 16%
Unburned
Multistory 60%
Top Story 21%
Vertical
Horizontal
Severity

11. 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

12. 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

13. 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

14. 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

15. Identifying Changes in Structure
Pond-
erosa
pine
White fir- sugarpine
Red
fir

16. Identifying Changes in Structure
Pond-
erosa
pine
White fir- sugarpine
Red
fir

17. Identifying Changes in Structure
Pond-
erosa
pine
White fir- sugarpine
Red
fir

18. Identifying Changes in Structure
Pond-
erosa
pine
White fir- sugarpine
Red
fir

19. Identifying Changes in Structure
Pond-
erosa
pine
White fir- sugarpine
Red
fir

20. Change in Patch & Gap Structure
Patches – solid line; Gaps – dashed line

21. Change in Patch & Gap Structure
Patches – solid line; Gaps – dashed line

22. 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

23. 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

24. 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