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Overstory and understory vegetation management to meet fire resilience and wildlife habitat objectives Eric Knapp, Becky Estes, and Carl Skinner U.S. Forest.

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Presentation on theme: "Overstory and understory vegetation management to meet fire resilience and wildlife habitat objectives Eric Knapp, Becky Estes, and Carl Skinner U.S. Forest."— Presentation transcript:

1 Overstory and understory vegetation management to meet fire resilience and wildlife habitat objectives Eric Knapp, Becky Estes, and Carl Skinner U.S. Forest Service Pacific Southwest Research Station, 3644 Avtech Parkway, Redding, CA 96002

2 Outline Developing vegetation objectives from historical stand data: an example –Historical stands were fire resilient and biodiverse –Research plots, Stanislaus NF, CA 80 years of overstory and understory changes from before logging to present –Using historical stands as a guide: thinning prescriptions for restoring forest complexity & resilience to fire Similarities in scale of within-stand organization across dry forests with history of frequent fire

3 “Methods of Cutting” study plots Established in 1929 Stanislaus-Tuolumne Experimental Forest Heavy cut Light economic thin USFS thin Stanislaus National Forest

4 10 acre stand maps with vegetation transect

5 Change in density, basal area, and composition after logging and fire suppression Trees/ac (>11.5 in) Saplings/ac (4 – 11.5 in) Basal area - ft 2 /ac % pine3620

6 Change in structural heterogeneity

7 Methods of Cutting Plots, Stanislaus NF “The virgin forest is uneven-aged, or at best even-aged by small groups, and is patchy and broken; hence it is fairly immune from extensive devastating crown fires.” “fire creates a patchy scattered distribution of reproduction” (Show and Kotok 1924)

8 1929 Spatial structure of stand (trees > 10cm dbh) 2008

9 DBH 1929 (in) DBH 2008 (in) Live trees in 1929 prior to logging Plot 9 – USFS thin Live trees in 1929 post-loggingLive trees in 2008

10 Basal area heterogeneity MC Plot Low - High POTENTIAL ADVANTAGES resistance to crown fire spread surface fuel discontinuity nesting and foraging habitat for wildlife understory biodiversity – high and low light environments 2008

11 Shrub change

12 Structure in 1929 Mitigating crown fire hazard: - Reduce ladder fuels - Raise height to crown base - Space crowns of overstory trees

13 Developing prescriptions for restoring complexity

14 Create gaps & groups –Size & number based on historical stand data Among group variation –Thin to variable basal area/ SDI/ density targets Within group variation –Retain largest/best trees regardless of crown spacing Ideas for generating within stand complexity

15 Metolius Research Natural Area, OR Youngblood et al Wenatchee NF, WA Harrod et al Similarities with stand maps for dry forests of the eastern Cascades

16 Group size in historical old-growth forests with history of frequent fire Group size (acres) LowAveHigh LocationAuthor Mixed conifer, CAStanislaus MC plots – this study Ponderosa pine, WAHarrod et al Ponderosa pine, OR & CAYoungblood et al SW ponderosa pine, AZCooper 1961, SW ponderosa pine, AZWhite Sequoia/ mixed conifer, CA Bonnickson and Stone 1981, 1982

17 Beaver Creek Pinery, Lassen NF, CA burned 5 times since 1900 last fire in 1994 highly heterogeneous with group & gap structure

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19 Conclusions Historical stands provide one model for vegetation management objectives –Structural complexity Fuel discontinuities = fire resilience Habitat for a diverse array of species Heterogeneity - more resilient to climate change? Dry forests structured at similar spatial scales –vegetation management principles may apply across forests with a history of frequent fire

20 Change in resilience to fire Fuel model2, 8, 9 10 Fuel moisture (1-1000hr) 3-10% 20 ft windspeed, temp 20 mph, 75 o Torching index (mph) Crowing index (mph) BA remaining 96% 11%

21 fuel loading after fire suppression with historic fire regime Minimum depth to carry fire surface fuel continuity over time: even vs. variable overstory


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