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Revising Southern Sierran Forest Management: The Implications for Plants Malcolm North, USFS Sierra Nevada Research Center, and Dept of Plant Sciences, UC Davis [email protected] 530-754-7398 Upper Yosemite Valley from Colombia Point 1899 1961 1994

Revising Southern Sierran Forest Management: The Implications for Plants

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Revising Southern Sierran Forest Management: The Implications for Plants. 1899. 1961. 1994. Upper Yosemite Valley from Colombia Point. Malcolm North, USFS Sierra Nevada Research Center, and Dept of Plant Sciences, UC Davis [email protected] 530-754-7398. Outline:. - PowerPoint PPT Presentation

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Page 1: Revising Southern Sierran Forest Management: The Implications for Plants

Revising Southern Sierran Forest Management: The Implications for Plants

Malcolm North, USFS Sierra Nevada Research Center, and Dept of Plant Sciences, UC Davis

[email protected] 530-754-7398

Upper Yosemite Valley from Colombia Point

1899 1961 1994

Page 2: Revising Southern Sierran Forest Management: The Implications for Plants

Outline:1. Some of the lessons from the Teakettle Experiment2.The current stalemate in Sierran Forest Management3.The proposed “Ecosystem Management Strategy for

the Southern Sierra”4.What are the implications for plants?

Page 3: Revising Southern Sierran Forest Management: The Implications for Plants

What are the best means of restoring forest ecosystems?Fire? Thinning? Both?

And if a forest is thinned, what kind of prescription?

2003Healthy Forests Restoration Act:

"In carrying out a covered project, the Secretary shall fully maintain, or contribute toward the restoration of the structure and composition of old growth stands according to the pre-fire

suppression old growth conditions”

1996Sierra Nevada Ecosystem Project:

Critical Findings“Although silvicultural treatments can mimic the effects of fire on structural patterns of woody vegetation, virtually no data exist on the ability to mimic ecological functions of natural fire.”

Restoration and Forest ‘Health’

Page 4: Revising Southern Sierran Forest Management: The Implications for Plants

1) Teakettle Experiment’slocation, design, and integrated sampling

scheme

bn1

un1

uc1

uc2

bs2

bs3

bn3

us1

bc3

bc2

bn2

bs1

bc1

un2

us2

us3

un3

uc3

bn1

un1

uc1

uc2

bs2

bs3

bn3

us1

bc3

bc2

bn2

bs1

bc1

un2

us2

us3

un3

uc3

Each plot is 200 by 200 mTotal plots = 18

Thinning Level: Unburned Burn

None Control (UN) Burn Only (BN)

Understory CASPO thin (25 cm < thin <76 cm)

Unburned/Thin from below (UC)

Burn/Thin from below (BC)

Shelterwood thin(25 cm < thin & leave 22 large t/ha)

Unburned/Overstory thin (US)

Burn/Overstory thin (BS)

Page 5: Revising Southern Sierran Forest Management: The Implications for Plants

Conceptual model used in the Teakettle Experiment

STRUCTURE FUNCTION AND COMPOSITION OF FUEL-LOADED FOREST

DIRECT EFFECTS OF TREATMENTS(FIRE/THINNING)

ALTER LITTER REDUCE BUFFERING REDUCE DENSITY

FORESTSTRUCTUREMICROCLIMATESOILS

PATHOGENSFUNGI

INVERTEBRATES PLANTSEPIPHYTES

DECLINERESILIENCEFOREST PRODUCTIVITY & DIVERSITY

CORE PROCESSES

DECOMPOSITION

NUTRIENT CYCLING

MORTALITY

HERBIVORY

EVAPOTRANSPIRATION

RESPIRATION REGENERATIONWATER USE

GROWTH

CO

MPO

NEN

T ST

UD

IES

ECO

SYST

EMRES

PO

NSE

MA

NIP

ULA

TIO

NS

STRUCTURE FUNCTION AND COMPOSITION OF FUEL-LOADED FOREST

DIRECT EFFECTS OF TREATMENTS(FIRE/THINNING)

ALTER LITTER REDUCE BUFFERING REDUCE DENSITY

FORESTSTRUCTUREMICROCLIMATESOILS

PATHOGENSFUNGI

INVERTEBRATES PLANTSEPIPHYTES

DECLINERESILIENCEFOREST PRODUCTIVITY & DIVERSITY

CORE PROCESSES

DECOMPOSITION

NUTRIENT CYCLING

MORTALITY

HERBIVORY

EVAPOTRANSPIRATION

RESPIRATION REGENERATIONWATER USE

GROWTH

CO

MPO

NEN

T ST

UD

IES

ECO

SYST

EMRES

PO

NSE

MA

NIP

ULA

TIO

NS

Results presented in 38 peer reviewed publications (Dec. 2007)

Page 6: Revising Southern Sierran Forest Management: The Implications for Plants

How do thinning, fire and their interaction affect the ecosystem processes/health?

Thin Only

Effect Possible Reason

Microclimate Increase extremes Reduction in canopy

Plant Diversity Significant decrease Litter and slash

Invertebrate Div. Significant decrease Litter and slash

Carbon Store/Respire Reduce/Big Increase Log removal/ Slash and litter

Decomposition Rate Slows Fragmenters work on slash

Tree Growth/Mortality Moderate increase/slight Reduced density/yarding

Food Chain Importance Generalists (chipmunk)—none

Specialists (flying squirrel)—decrease

Change in seed comp. but not abundance

Significant drop in truffles

Available Nitrogen Decrease Increase in soil decomposers from litter

and slash

Soil Moisture Increase Reduced tree density

Page 7: Revising Southern Sierran Forest Management: The Implications for Plants

How do thinning, fire and their interaction affect the ecosystem processes/health?

Fire Only

Effect Possible Reason

Microclimate No change No effect on overstory canopy

Plant Diversity Slight increase Limited impact on litter

Invertebrate Div. No change Limited impact on litter and slash

Carbon Store/Respire Slight Decrease/No change Some combustion/ Slash and litter

Decomposition Rate No change No increase in moisture

Tree Growth/Mortality No change Limited burn extent/low severity

Food Chain Importance No change Limited burn extent/low severity

Available Nitrogen No change Few ceanothus burned

Soil Moisture No change Little change in tree density

Page 8: Revising Southern Sierran Forest Management: The Implications for Plants

How do thinning, fire and their interaction affect the ecosystem processes/health?

Thin and BurnEffect Possible Reason

Microclimate Increase small scale variability Increased habitat heterogeneity

Plant Diversity Large increase Significant reduction in litter and slash

Invertebrate Div. Large increase Increased habitat heterogeneity

Carbon Store/Respire Immediate decrease than building/Reduced

Combustion than tree growth/ Less slash-litter

Decomposition Rate Increase Increase in moisture

Tree Growth/Mortality Large increase after 2 yrs/ Increase

Nutrient flush, increase moisture/ Burn

Food Chain Importance Generalist—no change

Specialist--decrease

No change in seed abundance/truffles

reduced

Available Nitrogen Large Increase Burned shrubs

Soil Moisture Large Increase Reduced tree density

Page 9: Revising Southern Sierran Forest Management: The Implications for Plants

|

H2O Oct < 14.2%

H2O Oct < 10.3%PPFD Direct < 14.1 PPFD Direct < 8.6

0.8%2.0% 4.2%9.7%50.8%

Total Herb Cover

4.2%

|

H2O Oct < 14.2%

H2O Oct < 10.3%PPFD Direct < 14.1 PPFD Direct < 8.6

0.8%2.0% 4.2%9.7%50.8%

Total Herb Cover

4.2%

|PPFD Diffuse < 1.93

H2O avg < 11.8%

H2O Oct. < 7.4%PPFD Direct < 18.3

10.9%

15.0%22.4%32.7%51.3%

Total Shrub Cover

|PPFD Diffuse < 1.93

H2O avg < 11.8%

H2O Oct. < 7.4%PPFD Direct < 18.3

10.9%

15.0%22.4%32.7%51.3%

Total Shrub Cover

Forest UnderstoryPresent Forest Conditions (Pre-Treatment):

Water most important to herb cover and richness

Indirect light and dry soil most important for

shrubs

Page 10: Revising Southern Sierran Forest Management: The Implications for Plants

 Control

Unburned / Understory

Thin

Unburned / Overstory

Thin

Burn / No Thin

Burn / Understory

Thin

Burn / Overstory

Thin

Bare ground (no litter layer; %) 7.82c 14.66c 11.61c 17.00c 38.77b 64.36a

Coarse woody debris (%) 8.61ab 13.16a 10.93a 4.94ab 3.34b 8.50ab

Litter depth (cm) 3.22a 2.89ab 3.61a 1.67c 1.80bc 0.71d

Transmitted direct light (mol.m-2.d-1) 24.38d 30.66c 39.85ab 24.89d 34.40bc 44.64a

Transmitted diffuse light (mol.m-2.d-1) 2.20d 2.94c 3.82b 2.14d 3.20c 4.22a

June soil moisture 0-15 cm (%) 13.9abc 15.6ab 19.1a 13.0bc 15.1ab 12.9c

Total N, 10-30 cm (%) 0.10ab 0.11ab 0.10ab 0.09b 0.12a 0.11ab

Total C, 0-10 cm (%) 5.42a 6.33a 5.28ab 4.36ab 4.94ab 4.24b

NH4, 0-10 cm (ppm) 7.33ab 11.17a 8.90ab 5.57b 7.97ab 8.64ab

NH4, 10-30 cm (ppm) 2.25c 4.00a 3.32ab 2.53bc 2.76abc 3.82ab

NO3, 0-10 cm (ppm) 1.12b 2.47ab 3.54a 0.90b 3.47a 4.19a

NO3, 10-30 cm (ppm) 0.13b 0.41ab 0.57ab 0.14b 0.41ab 1.55a

P (Bray method), 0-10 cm (ppm) 117.87ab 73.20b 124.91a 119.77a 127.53a 116.55ab

P (Bray method), 10-30 cm (ppm) 92.40a 41.87a 109.60a 73.64a 84.36a 59.01a

0.00

5.00

10.00

15.00

20.00

25.00

30.00

Control UU UO BN BU BO

1999 % Cover Shrubs

2003 % Cover Shrubs

1999 % Cover Herbs

2003 % Cover Herbs

4. How is the plant community affected by fire and thinning treatments?

Page 11: Revising Southern Sierran Forest Management: The Implications for Plants

What is the most effective restoration for the forest and its plant community?

• Get low-intensity fire back into the forest. Fire is essential. Thinning is a tool that should serve fire by increasing its extent and ‘work’.

• Reduce stem density and moisture stress. Currently plant diversity and many ecosystem processes are severely restricted by limited soil moisture

• Reduce litter and slash because it stalls most ecosystem processes and significantly reduces understory cover and richness.

• Provide for more large trees. Current forest, even old growth, has fewer large trees than under active-fire conditions.

Page 12: Revising Southern Sierran Forest Management: The Implications for Plants

Some of the road blocks:

•Concerns over thinning intermediate (20-30”) size trees? Does it affect fire behavior?

• Concerns over the impact of management practices on the Pacific Fisher

• Limited use of prescribed burning

Many fuels treatment projects are stalled or take a long time to implement. Why?

Page 13: Revising Southern Sierran Forest Management: The Implications for Plants

An Ecosystem Management Strategy for Southern Sierran Mixed-Conifer Forests

North, M., P. Stine, K. O’Hara, W. Zielinski and S. Stephens

• Much of current forest management is focused on landscape strategies intended to achieve immediate fuels reduction (e.g.., (SPLATs and DFPZs). These treatments have largely been developed with a short-term view, using fairly arbitrary diameter limits for mechanical tree removal.

•We have learned much in recent years, however, that can contribute to re-evaluating Sierran forest management strategies. We believe a more complete understanding of the ecological role of fire, fuel dynamics, sensitive wildlife habitat, and the importance of forest heterogeneity can help revise current silvicultural practices.

• A central premise of this paper is that the risks of carefully considered active management are lower than the risks of inaction in the Sierras’ fire-prone forest types.

Page 14: Revising Southern Sierran Forest Management: The Implications for Plants

An Ecosystem Management Strategy for Southern Sierran Mixed-Conifer Forests

North, M., P. Stine, K. O’Hara, W. Zielinski and S. Stephens

•THE ECOLOGICAL IMPORTANCE OF FIRE: Mixed-conifer forests should be prescribed burned whenever possible. If an area cannot be burn, documenting the reasons for no burning may help inform the public about current limitations and the need for remedies

• LIMITED USE OF CROWN SEPARATION FUELS TREATMENTS: Reducing crown bulk density and increasing tree crown separation should be sparingly applied only to key strategic zones.

• SPATIAL VARIAION IN FOREST STRUCTURE:. Produce different forest conditions and use topography as a guide for varying treatments. Within stands, important stand topographic features include concave sinks, cold air drainages, moist microsites. Landscape topographic features include slope, aspect, and slope position.

Page 15: Revising Southern Sierran Forest Management: The Implications for Plants

An Ecosystem Management Strategy for Southern Sierran Mixed-Conifer Forests

North, M., P. Stine, K. O’Hara, W. Zielinski and S. Stephens

•STAND-LEVEL TREATMENTS FOR SENSITIVE WILDLIFE: Areas of dense forest and high canopy cover will be needed for California spotted owls and Pacific fishers. We suggest identifying those areas as places where fire would have burned less frequently or at lower severity, due to cooler microclimate and moister soil and fuel conditions.

•SILVICULTURAL MODEL/STRATEGY: The frequency distribution of tree diameters in Sierran mixed-conifer forest subject to frequent low-intensity fire was highly variable but generally flat due to periodic episodes of fire-induced mortality and subsequent recruitment. Stand treatments should strive to significantly reduce the proportion of small trees and increase the proportion of large trees as compared to current stand conditions.

Page 16: Revising Southern Sierran Forest Management: The Implications for Plants

An Ecosystem Management Strategy for Southern Sierran Mixed-Conifer Forests

North, M., P. Stine, K. O’Hara, W. Zielinski and S. Stephens

TOPOGRAPHIC FEATURES CREATE DIFFERING CIRCUMSTANCES FOR STAND DENSITY AND THUS HABITAT CONDITIONS: Basic topographic features result in fundamental differences in vegetation composition and density producing variable forest conditions across the Sierra’s landscape. •TREATMENT OF INTERMEDIATE SIZED (20-30”) TREES: In most cases thinning these trees will not affect fire severity and therefore other objectives for their removal should be clearly identified. Silvicultural prescriptions would only remove intermediate-sized trees when they are shade-tolerants on mid or upper slope sites.

FIELD IMPLEMENTATION OF SILVICULTURAL STRATEGY: Marking rules are based on crown strata or age cohorts (a proxy for size/structure cohorts) and species rather than uniform diameter limits applied to all species.

Page 17: Revising Southern Sierran Forest Management: The Implications for Plants

White-flowered hawkweed  

Pyrola picta

Corallorhiza maculata Pterospora andromedea ‘Pinedrops’

Some plants were sensitive to all disturbances

Page 18: Revising Southern Sierran Forest Management: The Implications for Plants

Malcolm NorthUSFS Sierra Nevada Research Center1731 Research Park Dr.Davis, CA [email protected]

Website: http://teakettle.ucdavis.edu