forest ecology - ucanr

Forest Ecology (Forest Distribution, Forest Change, and Forest Mgt)

Ryan DeSantis

University of California Cooperative Extension

• What is a “natural landscape”?

1990

1880

Swift River Valley (Western MA)

Forest land percent of total land: Maine 89% New Hampshire 85% Vermont 78% Massachusetts 63%

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Today’s forest is a result of:

• Previous human management

• “Natural” disturbance*

• Genetics

• Seed dispersal strategies • Seed size, shape, abundance

• Competition*

• Soils

• Geology

• Slope/aspect

• Climate*

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H

W

TC

Annual precipitation – H-Hayfork, W-Weaverville, TC-Trinity Center http://library.humboldt.edu/~rls/geospatial/nwcalmaps.htm

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California

Location, location, location

32 to 42o north/south latitude (Mediterranean, Australia, New Zealand, S. Africa)

Mediterranean climate – cool, wet winters and warm, dry summers

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West <<< >>> East

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• Riparian – Communities adjacent to water

– Big leaf maple, black cottonwood, dogwood, white alder, willow

– Important for terrestrial and aquatic wildlife

• Oak woodland – Xeric environment

– Associated with grass

– Adapted to frequent low-intensity fire

• Montane chaparral – Most extensive CA vegetation type

– Manzanita, ceanothus

– Wildfire important

– Drought resistant

Our local forest types

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• Mixed conifer – Middle elevations of Klamath-Cascade (3,000-6,000 ft)

– Greatest conifer diversity in the world

– Ponderosa pine, Jeffrey pine, sugar pine, incense cedar, white fir,

Douglas-fir, black oak, manzanita, ceanothus, bitter cherry, mountain

misery

– Periodic fires

– Some snow

– 20th Century fire suppression changed forest density and composition

• Douglas-fir-mixed evergreen – Douglas-fir dominant throughout much of Pacific Northwest

– Associated with mixed evergreen hardwood species including

California bay, coast live oak, canyon live oak, tanoak, Pacific madrone

– Adapted to frequent low-intensity fire


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• True fir

– Found along higher elevations in the Klamath-Cascade, between

mixed conifer and subalpine forests (6,000-8,000 ft)

– Heavy snowfall

– White fir, Jeffrey pine, lodgepole pine, juniper

• Subalpine

– Found at highest elevations of the Klamath-Cascade, just below

timberline (8,000-11,000 ft)

– Whitebark pine, mountain hemlock, lodgepole pine, juniper


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Tree species differ in their adaptation to:

Shade

Frost

Temperature

Drought

Fire

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Shade tolerance – most to least tolerant

white fir

red fir Douglas-fir

sugar pine incense cedar

ponderosa, jeffrey pine black oak

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ASPECT

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Frost tolerance (seedlings) – most to least

lodgepole, w. white pine

red fir ponderosa, jeffrey pine

incense cedar sugar pine

white fir Douglas-fir

madrone

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Temperature adaptation – warm to cold

ponderosa pine, black

oak, madrone Douglas-fir, sugar pine, incense

cedar, bigleaf maple red fir, lodgepole pine

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Ponderosa pine 2000 ft



Latitude

40o

38o

36o 16

Drought tolerance – least to most tolerant

red fir

white fir

sugar pine

Douglas-fir

lodgepole pine

incense cedar

ponderosa pine

jeffrey pine

black oak 17

Fire resistance –bark thickness, resin content, foliage flammability. Increasing resistance.

lodgepole pine

incense cedar, western white pine

sugar pine, white fir

Douglas-fir, ponderosa pine

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Ponderosa pine

Lodgepole pine

Knobcone pine, California

Jack pine, Minnesota

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Drastic changes to forest ecosystems: knobcone pine and jack pine require large, stand-replacing fires for regeneration

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Forest change

Changes to ecosystems occur due to….

• Displacement

• Site alteration

• Colonization

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Forest change

How fast does change occur? Depends on…

• How much change must occur

• Productivity of organisms

• Longevity of organisms

• Degree of dominance of site by seral stage

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Forest change

Ecological succession: Temporal changes in types, numbers and groupings of organisms occupying an area and concomitant changes in the physical environment

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Ecological succession

• Primary – following catastrophe, start with physical abiotic environment, no biological legacy, e.g. island building in ocean, retreating glacier, volcanic eruption

• Secondary – follows disturbance that leaves a significant biological legacy, e.g. fire, windstorm, clearcut

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Successional gradients

Light or shade: high low

Water: xeric mesic

Nutrients: low high

Species diversity: low intermediate high 25

Pioneer species: bare/exposed areas (ponderosa pine)

Gap-phase species: under closed canopies and later released by opening of a gap (redwood)

Seedling establishment

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Stages of succession

• Pioneer

• Consolidation

• Subclimax

• Climax

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Competition

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Suppressed seedling Released seedling 30

Diameter growth with competition control. 9 yrs.

Diameter growth slows with increasing competition. 23 yrs

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17 rings

17 rings

Effect of thinning, competition reduction

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How did your forest develop?

Use tips such as:

• Current overstory & regeneration

• Stumps

• Dead trees (oak, manzanita, etc.)

• “Wolfy” (dead, large, understory) limbs

• Fences

• Understory vegetation (grass? woody plants?)

• One or many ages, one or multiple species

• Opening size

• Fire scars

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Disturbances

• Fragmentation

• Weather (wind, drought, hail, flood, ice/snow)

• Fire

• Alteration of fire regime

• Diseases

• Invasive insects

• Invasive plants

• Global climate change

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Natural disturbances: wind damage

Forest before… ...and after wind damage

Lee Frelich Roy Rich

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Natural disturbances: wind damage

Affects….

• Energy capture, transfer and storage

• Biogeochemical cycles

• Light, temperature, water

• Soil

• Species>Population>Community>Ecosystem

Disturbance

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Natural disturbances: insect damage

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Natural disturbances: insect damage

• Photosynthesis:

CO2 + H2O + energy cellulose + O2

• Fire:

O2 + cellulose + energy CO2 + H2O + energy

• Similar to organic matter decomposition, but much faster.

Fire= photosynthesis in reverse

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• Cool/wet Winters grow fuels, warm/dry Summers fuel annual fire season

Mediterranean Climate

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California’s Mediterranean Climate

30%+ of U.S. national wildland fire management

expenditures

• Cool/wet Winters grow fuels • Warm/dry Summers fuel annual fire season

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Fire Climate - Precipitation Patterns

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0

2

4

6

8

10

12

14

16

18

20

NORTH PLATTE, NE


0

2

4

6

8

10

12

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FLAGSTAFF, AZ


0.0

0.5

1.0

1.5

2.0

2.5

YELLOWSTONE LAKE, WY


0

5

10

15

20

REDDING, CA

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Three parts of the fire triangle

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Fuel (something that will burn)

CA: historically, fires maintained a variety of vegetation types

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Affects energy, competition, succession… + & -

• Fire

• Wind

• Drought

• Ice

• Insects and disease

• Anthropogenic (forest management) – Harvesting trees, shrubs, other forest products

– Clearing space for trails, houses, agriculture

– Prescribed burning, thinning, etc. to control brush, fire hazard, wildlife habitat

Disturbance

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Forest management affects energy in the forest

• Pest control

• Clearcutting

• Site preparation

– Preparing site to promote future forest

• Prescribed burning

• Fertilization

All related to natural disturbances…

Energy capture, transfer and storage

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Ryan DeSantis Forestry Advisor UC Cooperative Extension Trinity, Shasta, and Siskiyou Counties (530) 224-4900 [email protected]

UC Cooperative Extension in… Trinity County: http://cetrinity.ucanr.edu/ Shasta County: http://ceshasta.ucanr.edu/ Siskiyou County: http://cesiskiyou.ucanr.edu/

mailto:[email protected]

mailto:[email protected]

http://ceshasta.ucanr.edu/





forest ecology - ucanr

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