Download A Health Management Plan for Sitka Spruce By: Jeremy Greenwood

A Health Management
Plan for Sitka Spruce
By:
Jeremy Greenwood
April 27, 2007
Management Objective


Focus will be on southeast, Alaska
Management objective will be timber
production but on a multiple-use forest
(Tongass National Forest)
2
1
Introduction to the Species
Sitka spruce (Picea sitchensis)






Prominent along northwest coasts of N. America
Stands have some of the highest growth rates in NA
Commercially valuable species for lumber, pulp, &
specialty uses
World’s largest spruce
Large individuals yield 6-8MBF.
Typical heights are 180’-200’ and DBH of 4’ to 5’ (max. is
315’; 19’)
3
Photo: J. Greenwood
How to identify
5

Needles


Orange-brown, with ovoid buds
Bark


2” to 3.5”, fall in late autumn/early winter, thin & papery scales
Twigs


5/8”-1” long, flattened, yellow-green above, blueish white below, sharp
pointed, R. angles from all sides of twig
Cones


4
Thin, silvery gray to purplish gray elliptical scales
8
Form

Long, cylindrical boles with short, open crowns. Branches are
pendulous
7
Source: Hardin, J.W., D.J. Leopold & F.M. White. 2001. Harlow & Harrar's Textbook of Dendrology-9th Ed. McGraw-Hill. 534 p.
6
Tree Species Adaptations

Climate


Coastal Species that is tolerant of ocean spray
Wide range of precipitation rates





25” to 221” of precipitation
0.5” to 134” of snow
Moisture is year round & abundant
Mild winters & cool summers
Frost free days range from 295 days in OR to 111 days in
Cordova, AK
Tree Species Adaptations

Soils



Competes best on alluvial soils, sandy/coarse-textured
soils or soils with lots of organic matter
Soils with large amounts of calcium, magnesium &
phosphorus
pH ranging from 4 to 5.7 (acidic)
Tree Species Adaptations

Competition




Tolerant to intolerant
Develops best in gaps
Long-lived (up to 800 yrs)
Competitors include:





Western hemlock
Mountain hemlock
Western redcedar
Alaska cedar
Also several HW species (red alder, Sitka alder, & black
cottonwood)
Wind: An Abiotic Stress
9
Wind: An Abiotic Stress

The most dominant disturbance agent in southeast
Alaska



27% of annual timber loss on the Tongass NF is due to
wind
Little is known of the disturbance regime of
Alaska in comparison to other regions where Sitka
spruce is found (OR, WA, etc.)
Large storm systems in the fall



Development
Return interval (8 years)
Wind direction
Wind

Environment



Found throughout the range of Sitka spruce but
ranges from single trees to large-scale blowdown
Highest intensity on hill tops/ridges
Lowest intensity on stands on north or northwest
facing slopes
Wind

Predisposing Factors

Tree Adaptations



Height:Diameter
ratios
Vigor
Quantity of crown
H:D Ratios
•Useful measure of tree stability
•Measure each dimension in same units
(feet)
•The higher the ratio the more unstable the
tree becomes
Wind: Predisposing Factors
Heart Rot Fungi
-Primary factors leading to stem snap
-Transport mechanism
11
12
Phellinus pini
10
Wind

Degree of Stress




Time of year
Quantity of soil
Water holding capacity of
soil
Sitka spruce rooting
habits
13
14
Wind

Inciting Factors

Strong wind events
such as gales


Wind speed (up to
100 mph)
Storm
characteristics



Counterclockwise
spin (cyclone)
Wave development
in Gulf of Alaska
24 to 30 hour notice
prior to storms
reaching landfall
Wind Effects

Tree response



17
16
Wind snap
Wind throw
No Effect
18
20
Wind

Contributing Factors


Bark beetles
Fire
19
22
21
Wind: Control Options

Preemptive

Match silvicultural method to site



Stand replacing wind events=clear cut
Individual tree/Small gap windthrow= selection cuts
Increase species diversity
Wind Control Options (cont’d.)
Thin to foster high H:D ratios
Layout strip cuts in orientation to
the prevailing winds
23
Wind Control Options

Reactive

Salvage harvest


Potentially controversial (Donato & Biscuit Fire)
No harvest action

Risks associated with no harvest
24
Wind Control Options: Feasibility


Preemptive measures are more cost effective
than reactive measures
Difficulties with salvage harvests in this region


Political
Terrain
Spruce beetle
(Dendroctonus rufipennis)
24
25
Spruce beetle Identification

Adults




Eggs


Oblong, white, 1/16” long
Larvae


dark brown w. reddish brown wing
covers
Cylindrical; ¼” long by 1/8” wide
Can be confused w. Ips beetles
(wing covers are evenly rounded on
D.r.)
Cream colored legless grubs; ¼” at
maturity
Pupae

Opaque white, inactive, similar
size/shape to adults
27
26
Spruce beetle

Life Cycle



28
Varies due to temperature (1 to 3 years)
Adults emerge from May thru October
Most attacks occur in early summer






Females bore into tree & create egg galleries (2.5”-12”)
4 to 14 eggs/centimeter
Eggs hatch in August; Larvae bore out and feed as a group for the
1st two instars; the 3rd and 4th instars are characterized by individual
galleries
Overwinter as Larvae (but eggs and parents can still be present)
Larvae pupate one year after attack (pupation lasts 10-15 days)
Overwinter as adults either in Larvael chambers or in the bark near
the litter line (decreases predation by woodpeckers)
Spruce beetles

Signs




Red-brown boring dust on the
ground
Entrance holes in the bark &
crevices
Pitch at entrance holes
(dependent on tree health)
Woodpecker activity on stems
29
Spruce Beetle Components

What is diseased in trees?




Feeds on multiple spruce species (including Sitka, Lutz, &
white spruce)
Tissue functions affected are the phloem & cambium;
foliage turns orange-red in the second year of infestation
Potential impact on whole tree functioning is dependent
upon the population size of the beetles & tree health
Severe infestations create stands that are a complete loss
Spruce beetle

Tree Symptoms



None occur until the second summer of infestation
Needles turn yellow-green to orange-red
Needle drop due to wind/rain (leaving bare
crowns)
30
Spruce beetle

Predisposing factors

Tree vigor & health (amount of pitch defense)


Mature, large trees (increased food source)



Slower than average growth rate=bad
Usually attack trees larger than 18” initially
Average stand diameter greater than 12”
Proportion of spruce in the stand

Stands with 70% or more spruce are highly vulnerable
Spruce beetle
31

Inciting Factors

Any event that increases CWM



Harvesting
Wind events
Landslides
Spruce beetle

No important secondary/contributing factors

The beetles are quite capable of killing trees by
themselves
32
Spruce beetle Control Options

Preemptive

Maintain stand health & vigor



Thinning
Minimize CWM over 12”
Minimize number of dominant trees in a stand
Spruce beetle Control Options

Reactive





33
Dependent on scale of outbreak & forest objectives
Rapid salvage harvesting focusing on dominant
stems
Minimization of logging slash (chip/burn)
Antiaggregation Pheromones (as a control?)
Insecticides (Carbaryl & pyrethroids)
34
Health Management Plan
Preemptive
Monitor & Survey
 Reactive
 Feasibility


Preemptive Measures

In high value stands that are at risk

Antiaggregation pheromones (MCH)




Release must be properly timed to beetle flight
Minimize amount of CWM (over 12”)
Thinning from below to keep site vigor high and to
increase component of wind-firm trees with high
H:D ratios
Match silvicultural methods to site
Monitor & Survey

Aerial monitoring




Steep ground
Larger coverage area
Windfall monitoring should be done in spring
due to winter storms, but after any major storm
system monitoring should be encouraged
Bark beetle monitoring done in regions with
lots of blowdown
Reactive Measures

A windthrown stand is likely to become
infested therefore:



Salvage harvesting
Antiaggregation pheromones & pesticides in
high value stands that are too immature to
harvest or stands with high aesthetic value
(recreation sites)
Trap Trees
Feasibility

Economic



Ecological



Salvage quickly to ensure highest profit
Minimize spraying to high value stands
Decreasing amounts of CWM
Decreased wildlife habitat
Political

Political opposition is likely with most salvage
harvests

Be proactive in attempting to educate the public on the
importance of salvage harvests (to the economy & to the
forest)
Review





Sitka spruce
Management region: SE Alaska
Wind is the primary disturbance agent
Spruce beetles are the primary insect agent
(linked with wind disturbance)
HMP Plan
Will I ever grow to
be as old as Sitka
spruce…?
Photo by Thomas Magliery
Discussion Question

If you were a land manager in a region that had
frequent stand replacing disturbances, what
silvicultural method or methods would you use
and why?
Discussion Question

You are a district ranger for the USDA Forest
Service. Greenpeace is scheduled to make an
appearance to your district. You have recently
finished all of the necessary paperwork to
conduct a salvage harvest on a 150 acre wind
event. How do you think your guests will feel
about this and how would you rationalize your
timber crews actions?
Discussion Question

Jerry Franklin, a proponent of old-growth
structures and CWM in forests, is coming to
visit your forest. You have recently started a
management policy to decrease the amount of
CWM in your stands. How would you defend
your actions?
Discussion Question

You are a landowner who has been tending a
stand of highly valuable Sitka spruce for your
lifetime. The USDA Forest Service is
predicting massive spruce beetle outbreaks,
what actions would you take?
Discussion Question

Does Sitka spruce relate to other things we
have seen this semester and can we relate
those management practices to this
environment?
Discussion Question

You are a land manager for a large industrial
company. The new, hotshot forester from
New Zealand wants to implement pruning of
Sitka spruce. Would you encourage or
discourage his suggestion? Why?
Discussion Question

Given the few tree species in the region and
the importance of Sitka spruce, what would
happen if the climate regime changed and
blowdown no longer occurred as frequently?
Photo Credits















Unless stated, the photos found in this presentation were taken by the author (J. Greenwood)
1:
http://www.alaskatours.com/alaskamap.jpg
2:
http://www.snowgoosealaska.com/images/
alaska-map-big.jpg
3: Burns, R.M., & B.H. Honkala, tech. coords. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.
Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 p.
4: Washington State Department of Ecology
(http://www.ecy.wa.gov/programs/sea/coast/images/spruce_n2.jpg)
5&7: Farrar, J.L. 1995. Trees of the Northern United States & Canada. Blackwell Publishing, Iowa. 512 p.
6: BCadventure.com (http://www.bcadventure.com/adventure/wilderness/forest/sitka.htm)
8: Cathedral Grove/British Columbia Archives: (http://www.cathedralgrove.se/text/01-Cathedral-Grove3.htm)
9:USGS http://vulcan.wr.usgs.gov/Volcanoes/MSH/Publications/MSHPPF/MSH_past_present_future.html
10, 11, 16, 18, 19, 20, 21, 22, 25, 26, 29, 30, 31, 32, 33, 34: Forestry Images
(http://www.forestryimages.org/)
12: Hennon, P.E. 1995. Are heart rot fungi major factors of disturbance in gap-dynamic forests?
Northwest Science. 69: 284-293.
15: Mount Washington Observatory
http://www.mountwashington.org/education/center/arcade/wind/beaufort.html
17: Louis Morin
13, 14, 23, 24 Harris, A.S. 1999. Wind in the forests of southeast Alaska and guides for reducing damage.
U.S. Department of Agriculture, Forest Service, Gen. Tech. Rep. PNW-GTR-244. 63 p.
24, 27, 28: http://na.fs.fed.us/spfo/pubs/fidls/sprucebeetle/sprucebeetle.htm