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)

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Introduction to the Species

Sitka spruce (Picea sitchensis)

Photo: J. Greenwood3

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’)

How to identify

Source: Hardin, J.W., D.J. Leopold & F.M. White. 2001. Harlow & Harrar's Textbook of Dendrology-9th Ed. McGraw-Hill. 534 p.

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Needles 5/8”-1” long, flattened, yellow-green above, blueish white below, sharp

pointed, R. angles from all sides of twig Cones

2” to 3.5”, fall in late autumn/early winter, thin & papery scales Twigs

Orange-brown, with ovoid buds Bark

Thin, silvery gray to purplish gray elliptical scales Form

Long, cylindrical boles with short, open crowns. Branches are pendulous

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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

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)

Tree Species Adaptations

Wind: An Abiotic Stress

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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

•Useful measure of tree stability•Measure each dimension in same units (feet)•The higher the ratio the more unstable the tree becomes

H:D Ratios

Phellinus pini

Heart Rot Fungi-Primary factors leading to stem snap-Transport mechanism

Wind: Predisposing Factors

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Wind

Degree of Stress Time of year Quantity of soil Water holding capacity of

soil Sitka spruce rooting

habits

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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 Wind snap Wind throw No Effect

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Wind Contributing Factors

Bark beetles Fire

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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

Wind Control Options (cont’d.)

Layout strip cuts in orientation to the prevailing winds

Thin to foster high H:D ratios

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Wind Control Options

Reactive Salvage harvest

Potentially controversial (Donato & Biscuit Fire) No harvest action

Risks associated with no harvest

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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)

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Spruce beetle Identification Adults

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.) Eggs

Oblong, white, 1/16” long Larvae

Cream colored legless grubs; ¼” at maturity

Pupae Opaque white, inactive, similar size/shape

to adults

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Spruce beetle

Life Cycle 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)

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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

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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)

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Spruce beetle

Predisposing factors Tree vigor & health (amount of pitch defense)

Slower than average growth rate=bad Mature, large trees (increased food source)

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

Inciting Factors Any event that increases CWM

Harvesting Wind events Landslides

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Spruce beetle

No important secondary/contributing factors The beetles are quite capable of killing trees by

themselves

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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

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)

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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

Salvage quickly to ensure highest profit Minimize spraying to high value stands

Ecological 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 spruceSitka spruce Management region: SE AlaskaManagement region: SE Alaska Wind is the primary disturbance agentWind is the primary disturbance agent Spruce beetles are the primary insect agent Spruce beetles are the primary insect agent

(linked with wind disturbance)(linked with wind disturbance) HMP PlanHMP 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-Grove-

3.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