Field Survey of Growth 

and Colonization of 

Nonnative Trees on 

Mainland Alaska

John Alden

United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

General Technical 

Report

PNW-GTR-664

April 2006
Author

John Alden was a forest geneticist, U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station, Portland, OR, and is now 

Executive Director of the Alaska Reforestation Council, Inc., P.O. Box 

82163, Fairbanks, AK 99708-2163.

The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of 

multiple use management of the Nation’s forest resources for sustained yields of wood, 

water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide increasingly greater service to a 

growing Nation.

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activities on the basis of race, color, national origin, age, disability, and where applicable, sex, 

marital status, familial status, parental status, religion, sexual orientation, genetic information, 

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public assistance program. (Not all prohibited bases apply to all programs.) Persons with 

disabilities who require alternative means for communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice 

and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 

1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (800) 795-3272 (voice) 

or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.
Abstract

Alden, John. 2006. Field survey of growth and colonization of nonnative 

trees on mainland Alaska. Gen. Tech. Rep. PNW-GTR-664. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest 

Research Station. 74 p.

Six of nine nonnative boreal conifers in three genera (Abies, Larix, and Pinus) 

regenerated in 11 to 31 years after they were introduced to mainland Alaska. 

Lodgepole pine (Pinus contorta var. latifolia Engel.) and the Siberian larches 

(Larix sibirica Ledeb. and L. sukaczewii N. Dyl.) were the most widely introduced 

species and will likely be the first nonnative conifers to naturalize. Siberian larch 

grew up to six times more stem volume than white spruce in the first 40 years on 

upland sites, but was susceptible to the larch sawfly and a blue stain pathogen 

carried by bark beetles. On productive sites, lodgepole pine appeared to grow 

more stem wood than white spruce for about 35 years after planting. Snowshoe 

hares and moose were the most serious pests of the nonnative conifers. Balsam 

fir (Abies balsamea (L.) Mill.) was the only species to regenerate in an established 

moss understory. Growth and age relationships were negative for all adequately 

sampled nonnative conifers and positive for native white spruce (Picea glauca

(Moench) Voss). Data were insufficient to assess niche availability for commercial 

use of productive nonnative conifers in mixed stands in Alaska. Survey results 

indicate that introduction and naturalization of noninvasive tree species may 

improve the diversity, stability, and productivity of managed forest ecosystems.

Keywords: Alaska, nonnative conifers, adaptation, regeneration, 

colonization, growth rates, wood yields, animal damage.
1Mulder, Christa. 2003. Characteristics of successful plant invaders and vulnerable 

habitats. 5 pages. In: Introduced and invasive species in resource management. 

Workshop sponsored by The Yukon River Chapter, Alaska Society of American 

Foresters, Fairbanks, Alaska. December 4–5, 2003.

Preface

To successfully invade new habitats, all nonnative species must complete 

three phases of introduction before they can be judged as either invasive 

or noninvasive:1

1. Introduction. Nonnative tree species depend on dispersal of their seeds 

or other propagules to new habitats. Introductions can be deliberate, but 

they are often accidental resulting from increased global trade and travel 

among countries. 

2. Colonization. Successful colonization of nonnative trees depends on 

regeneration from production and local dispersal of propagules after they 

are introduced. Regeneration depends on favorable weather for meiosis, 

gamete formation, flowering, pollination, fertilization, and formation of 

viable embryos (seeds), or for vegetative reproduction. Favorable wind, 

water, and seed-gathering mammals and birds are usually necessary for 

dispersal of propagules such as seeds.

3. Naturalization. Naturalization is the permanent establishment and expansion of nonnative species without their reintroduction. Naturalization 

leads to expansion and the invasion of new habitats. If the nonnative 

species requires continual reinvasion for survival, it is not naturalized. 

Naturalization of nonnative species is noninvasive if the environment is not 

significantly affected, if native flora and fauna are not displaced, and if there are 

no economic losses or effects on human health. Most naturalized tree species are 

noninvasive. Among about 250 invasive weed species on a global scale, only a few 

are nonnative Pinus that replace native forest flora and fauna locally and cause 

economic loss. In their native range and other forest habitats, these same Pinus

are environmentally and economically beneficial. 

This paper is a field survey of introduced conifers planned and funded by the 

Alaska Department of Natural Resources, Division of Forestry Central Office, 

Anchorage, AK 99501, and carried out by the Alaska Reforestation Council, Inc., 

P.O. Box 82163, Fairbanks, AK 99708 in 2002 and 2003.
Summary

Six of nine nonnative boreal conifers in three genera (Abies, Larix, and Pinus) 

regenerated 11 to 31 years after their introduction to mainland Alaska. Lodgepole pine (Pinus contorta var. latifolia Engelm.) and the Siberian larches (Larix 

sibirica Ledeb. and L.sukaczewii N. Dyl.) were the most widely introduced 

species and will likely be the first nonnative conifers to naturalize in Alaska.

Siberian larch grew up to six times more stem volume than white spruce 

(Picea glauca (Moench) Voss) in the first 40 years on upland sites, but was 

susceptible to the larch sawfly (Pristiphora erichsonii Hartig) and a blue-staincarrying bark beetle (Dendroctonus simplex LeConte). On productive sites, 

lodgepole pine appeared to grow more stem wood than white spruce for about 

35 years after planting. Hares (Lepus sp.) and moose (Alces alces L.) were the 

most serious pests of the nonnative conifers. Most species regenerated on 

disturbed sites. Balsam fir (Abies balsamea (L.) Mill.) was the only species to 

regenerate in an established moss understory. The relationship of growth with 

age was negative for all adequately sampled nonnative conifers and positive for 

native white spruce.

Data are insufficient to assess niche availability for commercial utilization 

of productive nonnative conifers in mixed stands in Alaska. Survey results 

indicate that introduction and naturalization of noninvasive tree species may 

improve the diversity, stability, and productivity of managed forest ecosystems. 

Introduction of nonnative tree species may favorably alter the habitat for the 

indigenous wildlife as well. The plantings in this survey should be reexamined 

within 20 years to determine if more conifers are colonizing forest habitats in 

Alaska, and if some have naturalized.
Contents

1 Introduction

2 Procedures

2 Establishment and Growth of Nonnative Parental Populations

9 Regeneration Potential of the Nonnative Species

10 The Dispersal, Establishment, and Growth of Natural Regeneration

11 Results

11 Establishment and Growth

18 Regeneration and Potential for Naturalization

26 Insects and Disease

28 Animal Damage

32 Discussion

32 Relative Growth Differences Among Species

34 Lodgepole Pine

36 The Siberian Larches

39 Other Nonnative Species

42 Conclusions

43 Acknowledgments

44 Metric Equivalents

44 Literature Cited

49 Appendix


Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Introduction1

Exotic or nonnative tree species have been managed in forestry, landscaping, 

windbreaks, and for aesthetics and other amenity purposes throughout the world 

for centuries. The transfer of a western Siberian larch (Larix sukaczewii N. Dyl.) 

provenance 500 km southwest of its natural range on Russia’s White Sea to the 

Gulf of Finland in 1738 was one of the earliest and most successful examples of 

exotic forestry in the boreal region (Alden 2003, Lähde et al. 1984, Redko and 

Mälkönen 2005, Viherä-Aarnio and Nikkanen 1992). The introductions were 

made to grow decay-resistant timber for cargo shipbuilding in the 18th century. 

Long after wooden ships became obsolete in the 19th century, the introductions were found to be the most productive larch provenances north of 60°

latitude in Scandinavia and Iceland. The exotic seed source is widely known as 

“Raivola larch,” a cultivar or race named for a railroad station near the original 

introductions in the “Lintula Park” or “Lintula Larch Forest” near the Finnish 

border with Russia (Redko and Mälkönen 2005). The Raivola larch plantation 

is reported to be “the most magnificent stand in northern Europe and one of 

the most remarkable forest cultures in the whole of Europe” (Viherä-Aarnio and 

Nikkanen 1992).

Historically, the primary reasons for introducing nonnative species were to 

increase wood yields for industrial forestry. Introduced nonnative tree species 

can enrich the biodiversity and improve the productivity of low-diversity forests 

(Andersson and Rosvall 1999). Examples of forest areas with few tree species are 

the harsh sites found in northern Scandinavia, northern Russia, northern Alaska, 

Iceland, and isolated islands or desert regions of the world. In absence of productive native tree species, exotics may double growth and yields compared to the 10 

to 20 percent improvement per generation from conventional tree selection and 

breeding of the indigenous species.

But nonnative introductions may potentially spread uncontrollably, suppress 

indigenous species, and carry virulent pathogens or insect parasites of an indigenous species (Andersson and Rosvall 1999, Engelmark et al. 2001). The nonnative species may also be susceptible to indigenous pathogens or insect parasites, 

leading to a buildup of inoculums or insect populations that may cause epidemics. 

A foreign species may also cross with native species producing unstable hybrids, 

1This paper presents material revised from written reports presented to the Alaska 

State Board of Forestry, August 6, 2003, and to the Society of American Foresters—

Continuing Forestry Education workshop “Introduced and Invasive Species in 

Resource Management.” December 4–5, 2003, Fairbanks, Alaska.


GENERAL TECHNICAL REPORT PNW-GTR-664

contaminate species gene pools, change soil properties, and alter ecosystem 

processes. Results can be either negative or positive and are reasons for 

provenance research before species are introduced on a large scale.

This report presents the results of a 2002 survey of nonnative conifers 

introduced to 55 sites in northern Alaska. Most sites had small trial plantings 

without replication. Objectives of the survey were to determine if the introduced 

conifers (1) grew more rapidly than the native (indigenous) tree species, (2) if they 

were free of pests and winter injury, (3) if they had successfully reproduced, and 

(4) if they found satisfactory ecological niches in which to eventually naturalize, 

and either increase forest diversity and productivity or invade natural ecosystems 

by replacing native flora and fauna.

Lodgepole pine (Pinus contorta var. latifolia Engelm.) and the Siberian larches 

(Larix sukaczewii N. Dyl. and Larix sibirica Ledeb.), the most commonly planted 

nonnative conifers in northern Alaska, were the primary target species in this 

survey. Other less commonly planted nonnative species surveyed were Scotch pine 

(Pinus sylvestris L.), jack pine (Pinus banksiana Lamb.), Norway spruce (Picea 

abies (L.) Karst.), balsam fir (Abies balsamea (L.) Mill.), Siberian fir (Abies sibirica

Ledeb.), Dahurian larch (Larix dahurica Trucz.), and Rocky Mountain Douglasfir (Pseudotsuga menziesii (Mirb.) var. glauca (Beissn.) Franco). Data for planted 

white spruce (Picea glauca (Moench) Voss) and natural paper birch (Betula 

papyrifera var. neoalaskana (Sarg.) Raup) and aspen (Populus tremuloides Michx.) 

are also mentioned. The sites and trees measured for the native and minor nonnative species were limited.

To invade new habitats after introduction, each of the above species must first 

colonize (reproduce) successfully, and secondly naturalize by demonstrating longterm survival and ability to successfully spread to new sites (Mulder 2003, footnote 1). From Eric Hulten’s (1968) Flora of Alaska and Neighboring Territories, 

Ager and Brubaker (1985) reported that more than 200 nonnative vascular species 

were added to Alaska’s native flora during the past two centuries. European 

mountain ash (Sorbus aucuparia L.) was the only nonnative tree that naturalized 

in Alaska during this time (Little 1979).

Procedures

Establishment and Growth of Nonnative Parental Populations

One or more nonnative conifers were surveyed for tree survival, growth, and 

natural regeneration on each of 55 sites in interior Alaska (Tanana Valley), southcentral Alaska (Matanuska-Susitna, or Mat-Su Valley), western Kenai Peninsula 
Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 1a—Regions on mainland Alaska surveyed for nonnative conifers in 2002 and 2003, and locations of sites and plantings 

on 250-meter-resolution Modis 2003 satellite imagery for each region below.

Juneau

Anchorage

Fairbanks

I

II

III

IV

Region I

Region II

Region III

Region IV

White spruce

 tree limits

White Spruce Tree Limits

0 45 90 180 360

Miles

White Spruce Tree Limits

and Cook Inlet, and mid Copper River Valley on mainland Alaska (fig. 1, table 1, 

app. 1). Planting site and species characteristics considered for the survey were:

I. Site history:

A. Quality

B. Soils

C. Vegetation

D. Prior use

E. Site preparation

F. Present site conditions
GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 1b—Region I.

Fox

Tok

Healy

Minto

Beaver

Circle

Nenana

Central

Anderson

Cantwell

Dot Lake

Livengood

Fairbanks

Tanacross

North Pole

Birch Creek

McKinley Park

Stevens Village

Tetlin Junction

Chena Hot Springs

Circle Hot Springs

149°30'0"W

149°0'0"W

148°30'0"W

148°0'0"W

147°30'0"W

147°0'0"W

146°30'0"W

146°0'0"W

145°30'0"W

145°0'0"W

144°30'0"W

144°0'0"W

143°30'0"W

143°0'0"W

142°30'0"W

62°0'0"N

62°0'0"N

62°30'0"N

62°30'0"N

63°0'0"N

63°0'0"N

63°30'0"N

63°30'0"N

64°0'0"N

64°0'0"N

64°30'0"N

64°30'0"N

65°0'0"N

65°0'0"N

65°30'0"N

65°30'0"N

66°0'0"N

66°0'0"N

Delta

Miles

Highways

Cities and towns

Site locations

Region I ±

0 10 20 30 40
Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 1c—Region II.

151°0'0"W

150°30'0"W

150°30'0"W

150°0'0"W

150°0'0"W

149°30'0"W

149°30'0"W

149°0'0"W

149°0'0"W

61°30'0"N

61°30'0"N

62°0'0"N

62°0'0"N

62°30'0"N

62°30'0"N

Miles

Highways

Cities and towns

Site locations

Region II

0 4 8 12 16

±

Petersville

Talkeetna

Willow

Susitna

Houston

Biglake

Knik

Wasilla

Eklutna

Palmer

Sutton

Anchorage
GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 1d—Region III.

Hope

Knik

Kenai

Homer

Tyonek

Willow

Sutton

Palmer

Seward

Kasilof

Eklutna

Susitna

Houston

Wasilla

Nikiski

Whittier

Soldotna

Seldovia

Big Lake

Portlock

Nanwalek

Kachemak

Anchorage

Ninilchik

Salamatof

Clam Gulch

Chickaloon

Moose Pass

Nikolaevsk

Port Graham

Anchor Point

Cooper Landing

153°0'0"W

152°30'0"W

152°30'0"W

152°0'0"W

152°0'0"W

151°30'0"W

151°30'0"W

151°0'0"W

151°0'0"W

150°30'0"W

150°30'0"W

150°0'0"W

150°0'0"W

149°30'0"W

149°30'0"W

149°0'0"W

149°0'0"W

148°30'0"W

148°30'0"W

59°0'0"N

59°0'0"N

59°30'0"N

59°30'0"N

60°0'0"N

60°0'0"N

60°30'0"N

60°30'0"N

61°0'0"N

61°0'0"N

61°30'0"N

61°30'0"N

Legend

Highway

Towns

Site locations

Region III

Miles

Highways

Cities and towns

Site locations

Region III ±

0 6 12 24
Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 1e—Region IV.

Chitina

Tonsina

Kenny Lake

Lower Tonsina

145°30'0"W

145°30'0"W

145°0'0"W

145°0'0"W

144°30'0"W

144°30'0"W

61°30'0"N

61°30'0"N

62°0'0"N

62°0'0"N

Miles

Highways

Towns

Site locations

Region IV ±

0 2.5 5 10
GENERAL TECHNICAL REPORT PNW-GTR-664

Table 1—Sites and plantings surveyed for colonization of nonnative conifers in interior and south-central 

Alaska

 LPb	 SLb	 SPb	 Other

c

 plantings plantings plantings plantings

No. No. Average age With With With With

Region sites plantingsa and range No. regen. No. regen. No. regen. No. regen.

Years Percent Percent Percent Percent

Interior (Tanana Valley) 19 58 24 (10–48) 21 33 11 55 3 0 23 13

Mat-Su Valley 14 31 22 (10–50) 10 30 8 13 9 22 4 75

Kenai Peninsula–Cook Inlet 18 25 22 (13–36) 17 47 5 20 2 0 1 S 0

Copper River Valley 4 5 17 (15–18) 4 0 0 — 0 — 1 0

 Total (N. Alaska) 55 119 52 24 14 29

Average (Weighted) 23 34 34 14 21

aPlantings include nonnative conifers ranging from 10 to 50 years of age after planting and native trees of the same age and site as the 

introduced conifers. 

bLP = lodgepole pine; SL = Siberian larch (Sukachev’s and Siberian larch); SP = Scotch pine.

cOther plantings include nonnative jack pine (5), Siberian fir (2), balsam fir (2), Norway spruce (2), Douglas-fir (1), Dahurian larch (1), and 

native white spruce (7). Native paper birch (5), aspen (2), Alaska larch (1) and white spruce (1) regenerated naturally and were not planted.

2The use of trade or firm names in this publication is for reader information and 

does not imply endorsement by the U.S. Department of Agriculture of any product 

or service.

II. Species history:

A. Survival, growth, age, and health of parent trees

B. Cone production and seed dispersal distances from seed parents

C. Seedbed conditions: forest floor and vegetation inside and outside the 

plot

D. Height, diameter at breast height (d.b.h.), age, and condition of the 

offspring (natural regeneration)

E. Height, d.b.h., age, and condition of indigenous trees of the same age, 

especially white spruce

F. Stocking (density) and growth of the natural regeneration

G. Stocking and growth of the indigenous trees, especially white spruce

All known nonnative conifers were sampled other than occasional landscape 

plantings. One to 10 (average about 4) trees in the dominant crown class of each 

planting were selected and measured for age, height, and d.b.h. (4.5 ft or 1.37 m 

from ground level). Heights were measured with a Suunto clinometer, Haga 

altimeter, or a hand-held Impulse 200 laser hypsometer manufactured by Laser 

Technologies, Engelwood, Colorado.2 Stem diameters were measured with a 

diameter tape. Heights and diameters of trees less than 15 ft (4.5 m) tall and 3 in 

(7.5 cm) d.b.h. were usually estimated. Plantings less than 10 years old were not 

evaluated. Lodgepole pine and Siberian larch plantings were emphasized in the 

survey because they were more common than other nonnative conifers.
Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

3White spruce also regenerated naturally in T-Field Arboretum and was included in the 

analysis. Seven other sites in the comparisons were white spruce plantings.

To estimate tree ages for unknown planting dates, internodes between yearly 

branch whorls were counted from tree top to ground level. The ages were used to 

derive annual stem elongation and diameter growth. Age at d.b.h. was extrapolated from mean annual height growth. For reliable comparisons of height and 

diameter growth among species, rates must be independent of age between 10 

to 50 years. A simple regression of annual stem elongation and d.b.h. increment 

(dependent variables) on planting age (independent variable) was made for each 

species with more than 30 sample trees to determine if growth remained constant. 

A significant positive or negative change in the regression coefficient would 

indicate an increase or decrease in growth rate, respectively.

Annual volume growth per tree increases exponentially with increasing stem 

diameter and leader growth. Thus mean tree volumes were compared only for species of the same age and site that were planted or regenerated naturally (aspen and 

paper birch) for each of 13 plantings3 on 11 sites. Species in this survey included 

the four major conifers, lodgepole and Scotch pine, the Siberian larches, and white 

spruce, and the minor species, jack pine, Norway spruce, Douglas-fir, the true firs, 

aspen, and paper birch. The true firs included subalpine (Abies lasiocarpa (Hook.) 

Nutt.) and balsam fir. The Siberian larches were identified as Raivola larch and 

Siberian larch. White spruce, paper birch, and aspen on the same sites and age as 

the nonnative conifers were sampled for comparing tree volumes among species. 

Stem volumes were estimated from the volume of a cone (1/3πr 2h) where h = tree 

height and r = radius at the base of the tree. Radius at ground level was extrapolated from tree height and d.b.h.

Regeneration Potential of the Nonnative Species

The regeneration potential of each nonnative species was evaluated from the 

frequency of sites exhibiting natural regeneration. Natural seedlings in areas 

under and adjacent to the seed parents were inventoried. Frequency of planting 

sites with natural regeneration among the four regions was tested for significance 

of association with a Chi-square distribution test of the G statistic (Sokal and 

Rohlf 1969: 599).

To estimate the age of natural regeneration from seed germination, internodes 

were counted from the apex of the oldest or tallest offsprings to ground level. 

Age of the oldest offspring was subtracted from the age of its seed parents and 
10

GENERAL TECHNICAL REPORT PNW-GTR-664

averaged for all plantings to estimate the earliest reproductive age of each species. 

Natural regeneration was very recent and no attempt was made to estimate the 

number of seed crops.

Lodgepole and jack pine seed production and seed available for future 

dissemination were estimated from the numbers of closed cones retained in 

the crowns of the sample trees. The numbers of closed and open cones were 

estimated from cone counts on one side of each tree that was surveyed. The 

regeneration potential of lodgepole and jack pine was estimated from the number 

of offspring per site relative to the number and frequency of open cones per tree. 

Their future regeneration potential was estimated from the frequency of serotinous cones and the percentage of the total seed crop retained in the crowns of 

the parental populations.

The Dispersal, Establishment, and Growth of 

Natural Regeneration

The distance of the outermost offspring from its parents was measured at each 

planting site. Estimated seedling densities were plotted on transects from the seed 

parents to their most distant offspring. This was done only for sites with more 

regeneration than 1 tree per 4 m2. On sites with dense stocking, seedlings were 

counted in square meter plots at 5-m intervals on transects perpendicular to the 

seed parents. Stocking was calculated as seedlings per acre as well as seedlings per 

square meter. All seedlings were counted under and adjacent to the seed parents 

at stocking densities less than about 1 seedling per 2.5 ft2 (4 per m2).

Height of the tallest and age of the oldest offspring were measured and 

calculated, respectively, for each planting. Annual height growth was derived for 

the tallest offspring at each planting and averaged for each species and region.

The regeneration potential of the nonnative conifers was estimated from 

the frequency of sites with natural regeneration, numbers of natural offspring, 

offspring densities, and the earliest successful reproductive age. Success of the 

natural regeneration was assessed from seedling numbers and densities, distances 

of the outermost offspring from their seed parents, and the average age, height, 

and annual height growth of the tallest offspring for each species.

The average values of reproductive traits and seedling parameters were 

reported in a table of regeneration statistics. The SAS4 General Linear Models 

analysis of variance (ANOVA) procedure was used to test for mean annual 

differences in height and d.b.h. growth between species and for significance of 

4SAS is the registered trademark of SAS Institute Inc., SAS Campus Drive, 

Cary, NC 27513. 
11

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

species x region interactions. Differences among species for all growth, reproduction, and regeneration variables were tested for significance at 0.05 probability of 

error with the Least Significant Difference (LSD) t-test.5 Variables that failed to 

approximate a normal distribution including numbers and densities of offspring, 

height growth of the tallest offspring, and maximum dispersal distance were 

ranked in ascending order before the ANOVA procedure. 

Results

Establishment and Growth

Lodgepole pine was the most commonly planted nonnative conifer in Alaska 

with 1.4 times as many plantings as the Siberian larches and Scotch pine combined (table 1). Both lodgepole pine and the Siberian larch plantings averaged 

34 percent with natural regeneration, and 14 percent of the Scotch pine plantings 

had regeneration. Twenty-one percent of the other (minor) nonnative plantings 

also regenerated. Balsam fir at two plantings in Mat-Su Valley, and Siberian fir 

and jack pine at one site each in Tanana Valley were among the other nonnative 

species that regenerated, and they may have potential for colonizing site-specific 

habitats in Alaska.

The oldest nonnative plantings surveyed were 37-year-old (43 years from 

seed) lodgepole pine in T-Field Arboretum, Fairbanks, 50-year-old Siberian 

larches at Wasilla, and 48-year-old Scotch pine and Siberian larch at Fairbanks. 

The youngest plantings were 10-year-old lodgepole pine, Scotch pine, and Siberian larch. Average age was 22 years.

Average age and size statistics, and differences in both height and d.b.h. 

growth among the major species for all geographic regions are given in table 2. 

Differences in height and d.b.h. growth among the major species were highly 

significant (P < 0.0001). At average ages of 23, 20, and 26 years, the three major 

nonnative conifers grew more rapidly than did native white spruce that averaged 22 years of age. Average height growth of the Siberian larches exceeded the 

average height growth of lodgepole and Scotch pine, but d.b.h. growth of the 

Siberian larches was not significantly greater than the d.b.h. growth of lodgepole 

pine. Height growth of native paper birch and aspen (app. table 9) at five and 

three plantings, respectively, were comparable to the height growth of the major 

nonnative conifers.

5The LSD test reduces the chance of not identifying differences among populations 

(species) when the differences are real. The chance of accepting the species as different 

when they are actually from the same population is high with the LSD test, however. 
12

GENERAL TECHNICAL REPORT PNW-GTR-664

Differences in growth statistics among regions could not be assessed because 

each region was represented by different species and sample sizes. Likewise, 

growth comparisions among the minor species were considered unreliable because 

they were inadequately sampled and not uniformly distributed among the regions. 

Mean age, size, and growth statistics of the minor species are summarized in app. 

table 9. Only lodgepole pine, Scotch pine, and white spruce were found in five 

plantings on four sites in the Copper River Valley (Region IV), and Alaska paper 

birch is not an indigenous species in this region.

For all nonnative species combined, average annual height and stem-diameter 

growth declined significantly (P = 0.0003 and <0.0001, respectively) from 10 to 

50 years of age (figs. 2 and 3). The decrease was only 0.1 and 0.003 in (2.5 and 

0.08 mm) per year, R2 = 0.03 and 0.1, N = 354. Each of the major nonnative 

conifers displayed negative diameter and height growth relationships with age 

for trees from 10 to 50 years old (figs. 4 through 9), whereas native white spruce 

was positive for both diameter and height growth for trees from 10 to 36 years 

old (figs. 10 and 11, table 3).

The declines of height and stem-diameter growth rates with age for lodgepole 

pine were not significant (figs. 4 and 5, table 3), whereas the declines in both height 

(0.16 in or 4.0 mm, fig. 6) and stem diameter (0.0035 in or 0.09 mm, fig. 7) growth 

per year with age for the Siberian larches were significant (table 3). Only the 

decrease in stem-diameter growth with age for Scotch pine (0.003 in or 0.08 mm 

per year, figs. 8 and 9) was significant (P = 0.03). Both annual height and stemdiameter growth of white spruce increased from 10 to 36 years, but only the height 

growth increase (0.24 in or 6.1 mm per annum) was statistically significant (figs. 10 

and 11). 

Table 2—Mean age, size, and annual growth of the major nonnative species and native white spruce sampled 

in 2002 on mainland Alaska

Growth*

No. trees Mean age Mean d.b.h. Mean height Diameter at breast

Species sampled and range and range and range height outside bark Height

Years Inches Feet Inches/year Feet/year

Nonnative:

Siberian larch 88 23 (11–50) 6.9 (3.0–18.8) 39 (18–78) 0.357 a 1.77 a

Lodgepole pine 192 20 (10–43) 5.5 (0.6–14.4) 26 (8–64) 0.325 ab 1.30 b

Scotch pine 37 26 (12–48) 6.5 (2.0–14.5) 31 (10–46) 0.306 b 1.20 bc

 Average nonnative: 106 23 6.3 32 0.329 1.42

White spruce 32 22 (17–37) 3.9 (1.5–8.9) 24 (11–52) .216 c 1.08 c

Note: Growth means with same letter were not significantly different.

*As determined by the Least Significant Difference t-test, species with less than 0.2-ft and 0.03-in differences in height and d.b.h., 

respectively, are not statistically different at P = 0.05. 
13

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 2—Mean annual height growth of nonnative conifers.

Figure 3—Mean annual diameter growth at breast height for nonnative conifers. 
14

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 4—Mean annual height growth of lodgepole pine. 

Figure 5—Mean annual diameter growth at breast height for lodgepole pine. 
15

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 6—Mean annual height growth of Siberian larch. 

Figure 7—Mean annual diameter growth at breast height for Siberian larch. 
16

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 8—Mean annual height growth of Scotch pine. 

Figure 9—Mean annual diameter growth at breast height for Scotch pine. 
17

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 10—Mean annual height growth of white spruce.

Figure 11—Mean annual diameter growth at breast height for white spruce. 
18

GENERAL TECHNICAL REPORT PNW-GTR-664

Several species were established during the same year in 13 plantings at 12 

sites (table 4). With the exception of the 36-year-old T-Field and Tazlina Experimental Plantings, white spruce grew the least volume per tree relative to the 

nonnative conifers and aspen on six of the eight sites where they were planted 

or regenerated naturally. Among the nonnative conifers, only Siberian fir and 

Norway spruce among the older T-Field Arboretum plantings grew significantly 

less volume per tree than white spruce.

The largest nonnative conifers in Alaska and the first- and third-largest 

Siberian larches were found on the Alaska Department of Natural Resources 

(DNR) Compound (46 ft3 or 1.3 m3) and on Les Viereck’s Tree Farm (33 ft3 or 

0.93 m3) in Fairbanks. The Siberian larches at both sites regenerated naturally. 

However, because taper was excessive in the upper crown of the DNR larch, 

a tree 16.5 inches (42 cm) in d.b.h., 75 ft (23 m) tall and 43 ft3 (1.2 m3) with excellent form in Mat-Su Valley was probably the largest nonnative conifer in Alaska. 

Even as young as 14 years, the Siberian larches at Swain’s Tree Farm on Tanana 

Loop Road in Delta grew significantly more volume per tree than lodgepole pine 

at the same age (table 4). The fastest growing nonnative conifer was Raivola larch 

from a seed orchard in Norway and an experimental forest in Finland. Annual 

growth of four dominant trees averaged 2.9 ft (89 cm) in height and 0.63 in (16 

mm) in d.b.h. during each of the 14 years at the Wasilla Veterinary Clinic.

Regeneration and Potential for Naturalization

Interior, Mat-Su Valley, and Kenai Peninsula were not significantly different in 

frequencies of nonnative plantings with natural regeneration (P = 0.1745). Thirtyfour percent of both lodgepole pine (n = 52) and Siberian larch (n = 24) plantings 

regenerated naturally before they reached an average age of only 22 years (table 

1). Forty-seven percent of the Kenai Peninsula–Cook Inlet lodgepole pine plantings and 55 percent of the Siberian larch plantings in interior Alaska regenerated 

before average ages of 22 and 23 years, respectively. All four lodgepole pine 

Table 3—Simple regression statistics for growth rates versus age of species between 10 and 50 years old, 

and N > 30

Species Average age No. Trees Annual growth, height Annual growth, d.b.h.

Year Feet Probability R2 Inches Probability R2

Siberian larch 23 88 -0.013 0.0016 0.11 -0.0035 0.0001 0.16

Lodgepole pine 20 192 -0.003 0.3829 0.004 -0.0003 0.7446 0.0006

Scotch pine 26 37 -0.001 0.7605 0.003 -0.003 0.0344 0.12

White spruce 22 32 0.020 0.0003 0.36 0.0008 0.5331 0.01

All species 23 411 -0.008 0.0002 0.03 -0.003 <0.0001 0.09
19

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Table 4—Approximate mean stem volume1 per tree for native and nonnative species, by age and site

Species2

Site Region Age LP JP SP WS3 NS PB4 AS RL SL TF and DF5

Years Cubic feet per tree

Kratzer’s Tree Farm Interior 19 3.1a 0.9

Viereck’s Tree Farm Interior 36 11.4a 2.7b 17.6a 3.0b

T-Field Arboretum Interior 36 7.7a 5.0a 4.8a 5.3a 2.0b 11.8 6.0a 1.4b

T-Field Arboretum Interior 27 5.7a 6.6a 3.0

Rosie Plantation Interior 17 1.4a 0.4

Rosie Creek—Malone #1 Interior 18 1.1a 0.4 1.4a

Rosie Creek—Malone #2 Interior 18 1.6a 0.3 1.6a

Samuel’s Tree Farm Interior 18 1.6a 0.2 1.0b 1.5ab

Swain’s Tree Farm Interior 14 1.2 1.6a

DNR Compound— Interior 48 8.8a 6.6a 23.0

Fairbanks

Gonder’s Tree Farm South-central 35 9.4 2.9a 3.6a and 2.6a

 Alaska

Tazlina Experimental Copper River 18 1.2a 1.0a

Plantings Valley

Old Edgerton Highway Copper River 18 0.8a 0.5a

 Valley

Note: Estimated volumes with the same letter for species at identical sites were not statistically different at P = 0.05.

1Stem volumes were derived from the formula of a cone (1.074 r2h) where the base radius (r) was extrapolated from diameter at breast 

height and total tree height (h) in feet. Volumes were estimated from samples of 2 to 10 trees (mean = 4) selected at random from the 

dominant crown class of each species at each site. Bole form was not factored into the equation and actual volumes are underestimated. 

2Species abbreviations are: LP = lodgepole pine, JP = jack pine, SP = Scotch pine, WS = white spruce, NS = Norway spruce, 

PB = paper birch, AS = aspen, RL = Raivola larch (a selected variety of western Siberian or Sukachev’s larch, Larix sukaczewii

N. Dyl.), and SL = Siberian larch (Larix sibirica Ledeb.). TF and DF = true fir and Douglas-fir.

3The white spruce regeneration in T-Field Arboretum was natural seedlings that averaged 2.6 ft3

 (0.07 m3) per tree at 23 years of 

age. The volume was adjusted to 3.0 ft3 (0.08m3) per tree at 27 years.

4All paper birch and aspen were natural regeneration. Paper birch included coppice regeneration in Malone sites 1 and 2. 

5TF (true fir) includes Siberian fir in T-field Arboretum and balsam fir at Gonder’s Tree Farm. Dominant and co-dominant 

Douglas-fir averaged 2.6 ft3 (0.07 m3) per tree after 35 years at the Gonder Tree Farm.

plantings that ranged from 15 to 18 years of age in the Copper River Valley 

(table 2) failed to regenerate by 2002.

The earliest successful reproductive ages of all lodgepole pine and Siberian 

larch plantings were 11 and 12 years, respectively (table 5). The average reproductive age of lodgepole and Siberian larch populations were 17 and 22 years, respectively. Differences among species in average reproductive age were significant 

(P > 0.04), but differences among regions ranked for average age were not significant (P > 0.14). 

The offspring of all reproducing nonnative conifers ranged from 2 to 19 years 

of age, and the oldest averaged 4 to 12 years of age (table 6). Because only 32 

percent of the plantings regenerated before 2002 and stocking levels were highly 

variable, differences in the regeneration statistics among the six reproducing 

nonnative conifers and regions were not significant. Six of nine nonnative conifers 
20

GENERAL TECHNICAL REPORT PNW-GTR-664

Table 5—Reproductive ages of the major nonnative conifers on mainland Alaska

Species1

Reproductive age LP JP SP SL DL SF BF NS DF

Earliest reproductive age (years) 11 28 27 12 >24 31 20 >36 >35

Average reproductive age and 17 a 28 ab 27 ab 22 ab — 31 b 25 ab — —

standard deviation (years) ±6 ±0 ±10 ±7

Plantings with regeneration 18 1 2 8 0 1 2 0 0

Total plantings 52 5 14 24 1 2 2 2 1

Note: Ages with the same letter are not statistically different at P = 0.05. 1LP = lodgepole pine; JP = jack pine; SP = Scotch pine; SL = Siberian larch; DL = Dahurian larch; SF = Siberian fir; 

BF = balsam fir; NS = Norway spruce; DF = Douglas-fir.

examined in this survey were in the colonization phase of introduction. None 

had entered the naturalization stage. 

Average height and annual height growth of the tallest offspring for all 

plantings of each reproducing nonnative conifer are reported in table 6. Average 

height of the tallest lodgepole pine and Siberian larch offspring were 3.4 ± 6.4 

and 9.8 ± 14.9 ft (104 ± 196 and 298 ± 454 cm), respectively. The tallest lodgepole offspring was 28 ft (853 cm) at 19 years, and was found in T-Field Arboretum. A probable Raivola offspring transplanted at Les Viereck’s tree farm in 

Fairbanks was the tallest Siberian larch. As a first-generation offspring, it was 

45 ft (13.7 m) tall, 6 in (15 cm) in d.b.h., and also 19 years old.

Table 6—Regeneration statistics for the nonnative conifers sampled on mainland Alaska

Average value and standard deviation

Seedling parameter LPa JP SP SL SF BF

Maximum offspring distance 72 ±82 66 89 ±62 102 ±98 36 49 ±13

from their parents (feet)

Oldest offspring (years) 6 ±4 6 12 ±0 9 ±6 4 6 ±1

Tallest offspring (feet) 3.4 ±6.4 2.3 9.5 ±7.9 9.8 ±4.9 1.5 0.6 ±0.5

Number of offspring per 69 ±240 0.2 ±.4 322 ±1,202 232 ±997 2 ±2 1,000 ±1,273

plantingb

Offspring density per plantingb 400 ±1,200 12 ±32 1,620 ±810 2,430 ±810 40 ±80 16,200 ±20,200

(number per acre)

Annual height growth of the 5.1 ±3.9 4.7 9.4 ±7.9 9.1 ±8.7 3.9 1.2 ±0.8

tallest offspring (inches)

Number of plantings with 18 1 2 8 1 2

regeneration

Number of plantings sampled 52 5 14 24 2 2

aLP = Lodgepole pine; JP = jack pine; SP = Scotch pine; SL = Siberian larch; SF = Siberian fir; BF = balsam fir.

bThe average is for all plantings with and without regeneration.
21

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Densities of nonnative pine regeneration ranged from 1 lodgepole or jack pine 

seedling on each of four sites in Interior Alaska to 40,000 Scotch pine and 20,000 

lodgepole pine seedlings per acre (10 and 5 seedlings per m2) in south-central 

Alaska, respectively. The latter offspring were established on disturbed soils under 

the canopies of 39-year-old Scotch and 25-year-old lodgepole pine plantings at the 

Gonder tree farm in Big Lake (figs. 12 through 15). Twenty thousand 1- to 3-yearold seedlings per acre (5 per m2

) were also documented on exposed gravel at the 

edge of the crowns of lodgepole and jack pine trees in 15-year-old plantings in the 

Houston City Park, south-central Alaska (fig. 16). The estimated 1,000 seedlings 

per balsam fir planting at the Gonder tree farm correspond to about 1 seedling 

per 2.5 ft2 (4 seedlings per m2). Maximum average dispersal distance was only 

50 ± 13 ft (15 ± 4 m) from the seed parents. The most stocking (89,000 seedlings 

per acre or 22 seedlings per m2) was found within 25 ft (8 m) of twelve 15-year-old 

Siberian larches on exposed gravel in Houston City Park (fig. 17). The seedlings 

were about 3 years old, and had been mowed frequently during City Park maintenance.

Maximum distance of natural Scotch pine seedlings from their seed parents 

was 150 ft (45 m) at Gonder’s Tree Farm in Big Lake, Mat-Su Valley. Siberian 

(Raivola) larch offspring were found 250 ft (76 m) and 266 ft (81 m) from the 

nearest possible seed parents at Les Viereck’s Tree Farm, and the Department 

Figure 12—Two- to 10-year-old natural seedlings of a Finnish seed source on exposed gravel 

under the canopy of 39-year-old Scotch pine trees at the Carl Gonder Tree Farm in Big Lake, 

Alaska, September 14, 2001. The dominant parents averaged 42 ft (12.8 m) tall and 13 in (33.5 cm) 

in d.b.h. Regeneration averaged nearly one seedling per ft2 (10 seedlings per m2) (see fig. 14).
22

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 13—Mrs. Gonder and Mike Lyne of the Alaska Urban and Community Forestry 

Council, Inc., Anchorage, surveyed natural lodgepole pine regeneration at the Gonder’s 

new garden site in Big Lake, south-central Alaska on May 12, 2001. The parents were 

transplanted as wild seedlings from Whitehorse, Yukon, in about 1977. Seedlings were 

distributed only 44 ft (13 m) from the nearest seed parents as shown in figure 15.

Figure 14—Scotch pine stocking in Gonder’s meadow extending 171 ft from the understory of 

39-year-old parents to an undisturbed forest edge on September 14, 2002. Stocking (y) was 

estimated from a polynomial distribution, y = -0.0177x3 + 6.77x2 – 851.1x + 35906, R2 = 0.79, 

and x was feet from the parents.
23

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 15—The distribution of natural lodgepole pine seedlings per acre from 25-year-old seed parents at the 

Gonder’s new Garden Site.

Figure 16—Distributions of lodgepole pine, jack pine, and Siberian larch seedlings on exposed gravel from 

15-year-old seed parents in Houston City Educational Park.
24

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 17—Numerous 1- to 3-year-old natural seedlings of Siberian larch (A) on exposed 

gravel within 35 ft (8 m) of their 15-year-old seed parents (B) in the Houston City Park. 

Seedling density within 35 ft of the seed parents was 2 offspring per ft2 (22 seedlings per m2, 

fig. 16). 

A

B
25

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

of Natural Resources Compound in Fairbanks. The most distant nonnative 

offspring was a lodgepole pine seedling that was 341 ft (104 m) from its nearest 

possible seed parent at the Hermansen Homestead on Cohoe Loop Road, Kasilof 

River, Kenai Peninsula. Average maximum offspring distance from each of the six 

reproducing nonnative species and plantings ranged from 36 to 102 ft (11 to 31 m) 

(table 6).

Open and closed cones were retained as long as 15 to 20 years on older lodgepole and jack pine trees. Differences among the three major regions in number of 

cones per tree were not significant (table 7). Cone production of lodgepole pine 

plantings in the Copper River Valley was not compared with cone production of 

plantings in the interior and south-central regions where plantings averaged 2 to 

5 years older and four times as frequent (table 1). In addition, closed cones were 

harvested from the dominant seed trees for seedling production in two of the four 

Copper River plantings. As a result, the percentage of open cones was higher in 

the Copper River region than in the interior and south-central regions.

Table 7—Average number of cones per tree and percentage of open cones for lodgepole and jack pine 

plantings in four geographic regions on mainland Alaska

Number Average number of cones Number of trees Average percentage of open 

Region of trees and standard deviation with cones cones and standard deviation

Interior (Tanana Valley) 93 128 ± 156 85 21a ± 25

Mat-Su Valley 22 140 ± 251 17 25ab ± 21

Kenai Peninsula–Cook Inlet 53 173 ± 172 39 34b ± 28

 Total 168 141

Weighted average 144 25

Copper River Valley 14 26 ± 28 11 36 ± 36

Note: values with a common letter are not statistically different at P = 0.05.

All nonnative regeneration was found on sites that were disturbed by logging, 

thinning, agricultural clearing, or site preparation before the seed parents were 

planted. Nonnative conifers had not regenerated on sites with undisturbed natural 

vegetation. One exception was 3- to 5-year-old lodgepole pine seedlings that were 

found on two sites in the Kenai Peninsula and Cook Inlet Region (fig. 18). The 

seedlings were growing in native understory vegetation that was recovering from 

logging and thinning disturbances in about 1980. Several balsam fir seedlings 

were also found in about 6 in (15 cm) of understory moss at the Gonder Tree Farm 

(fig. 19), indicating that shade-tolerant Abies can regenerate somewhat in recovering indigenous vegetation without recent surface disturbance.
26

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 18—A 4-year old lodgepole pine seedling on a moist microsite in association with 

Betula (Kenai birch), Vaccinium (blueberry), Viburnum (highbush cranberry), Empetrum

(crowberry), Rosa (prickly rose), Sphagnum moss, Cornus (bunchberry), Epilobium (fireweed), 

Menziesia (rusty menziesia), Ledum (Labrador tea), Spiraea (Beauverd spirea), Alnus (Sitka 

alder), Picea (Lutz spruce), Salix sp. (willow), Calamagrostis sp., and other indigenous flora 

at Congahuna Lake, Tyonek on September 13, 2002. The seed parents were planted in 1982, 

apparently without site preparation. Commercial-size virgin spruce was clearcut in 1980. 

Insects and Disease

Although the pines are susceptible to several bark beetles and rust pathogens in 

their natural range, insects and diseases were not observed in the pine plantings in 

northern Alaska. The larch sawfly, Pristiphora erichsonii (Hartig), was observed 

on the Siberian larches at several sites in interior Alaska, and on at least one site 

(Mat-Su College Arboretum in Palmer) in south-central Alaska. Minor defoliation and deformed branches and twigs from a budmoth of the Zeiraphera genus 

were observed on smaller Siberian larch in Brann and Samuel’s Delta species 

trials (Trummer 2003).

Trees weakened from defoliation appeared susceptible to an unknown bark 

beetle, probably the eastern larch beetle, Dendroctonus simplex LeC. The infested 

trees died from the tops downward similar to Ips-caused mortality of Pinus. 

Siberian larch mortality, apparently from the insects and a blue stain fungus, 

Leptographium abietinum (Peck) Wingf., was observed at four sites in interior 

Alaska. The blue stain fungus was identified in the bark galleries of one secondgeneration tree that died after bark beetle attack (McBeath et al. 2004). Phloem 

and cambium necrosis from the blue stain pathogen appeared to prevent recovery 

of the tree from insect attacks.
27

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 19—A 6- to 7-year-old balsam fir seedling was growing in 6 in (15 cm) of sphagnum moss 

under the canopy of an estimated 27-year-old balsam fir planting at the Gonder Homestead, 

Big Lake, September 14, 2002. Six seedlings were observed in understory moss up to 12 in (30 

cm) deep. High shade tolerance may enable balsam fir to colonize mesic sites in south-central 

Alaska regardless of the indigenous understory and overstory flora. 
28

GENERAL TECHNICAL REPORT PNW-GTR-664

Animal Damage

In the boreal forests, lodgepole pine was susceptible to injury and mortality from 

all vegetation-consuming animals, both herbivores and omnivores wherever their 

populations were high. Northern red-backed and Taiga voles (Clethrionomys 

rutilus Pallas and Microtus xanthognathus Leach, respectively) cut 1- to 2-year-old 

seedlings at the ground level in plantings in interior Alaska. Snowshoe hares were 

particularly destructive in the Copper River Valley, killing 90 percent of the trees 

planted at two sites and partially girdling most of the remainder (fig. 20). Trees as 

large as 3 in (8 cm) in d.b.h. were damaged or killed. The injured trees recovered 

only after their boles were enclosed in chicken wire. Red squirrels (Tamiasciurus 

hudsonicus Erxleben) cut branches of lodgepole pine causing extensive branch 

mortality and defoliation in gathering cones for winter middens in Bonanza Creek 

Experimental Forest, Fairbanks (fig. 21).

On Kenai Peninsula, moose were destructive, especially during rutting 

season, when more than half of the lodgepole pine plantings in Tustumena Lake 

area were damaged or destroyed (fig. 22). Moose also heavily damaged Siberian 

larch in Brann’s 1984 species trial a few miles east of Delta Junction, and severely 

browsed Scotch pine plantings at Kingsberry and Porkorny Tree Farms in Talkeetna (fig. 23). Moose appeared to prefer Scotch pine to lodgepole pine as winter 

browse on both tree farms, causing extensive plantation loss. As a result of the 

damage, Scotch pine plantings were abandoned in preference for lodgepole pine 

plantings at the Porkorny Tree Farm (fig. 24). 

Figure 20—Snowshoe hare injury to 12-year-old lodgepole pine in the Old Edgerton Highway, 

Copper River provenance trial in May 1997. The trees were planted as 2-year-old seedlings in 

1985. Hares killed 90 percent of the trees from 1986 until 1998 when the surviving trees were 

enclosed in chicken wire to prevent further injury.
29

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 21—Branch and foliage mortality in lodgepole pine from squirrels cutting branches 

and cones (A) for lodgepole pine middens (B) in a 17-year-old provenance and family variation 

trial in Bonanza Creek Experimental Forest, Fairbanks. The injury was photographed in late 

May 2001 (A) and early June 2003 (B). 

A

B

Brown bears (Ursus arctos L.) observed in the Tyonek area consumed or 

stripped the bark of lodgepole pine plantings, apparently after emerging from 

winter hibernation (fig. 25). The North American porcupine (Erethizon dorsatum L.) also consumed the bark of about 500 11-year-old Siberian larch trees at 

Wasilla, killing some of the trees outright, and killing the tops in the remainder 

(fig. 26). Animal injuries are summarized for each site and species in the appendix 

table 8.
30

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 22—Moose damage to 19-year-old lodgepole pine plantings in the Tustumena Lake 

area of Kenai Peninsula, August 7, 2002. Moose seem to prefer the resinous odor of lodgepole 

pine during the rutting season. Stems and branches of young trees are typically broken as 

bull moose rub velvet from their antlers. Injuries to lodgepole pine from browsing were less 

common than the physical breaking of stems and branches. 
31

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 23—Alan Kingsberry standing by moose-browsed Scotch pine at his Birch Creek Ranch, 

Mastodon Road, Talkeetna, Alaska, September 15, 2002. The trees were planted in 1986 for 

Christmas tree production. Crowns of surviving dominant trees averaged 18 ft (5.5 m) tall and 3.7 

in (9 cm) in d.b.h., and appeared to be above the reach of most moose. Injury included stripped 

bark and browsed foliage and twigs up to 2 cm in diameter. 

Figure 24—Moose browse damage to 11-year-old Scotch pine raised for ornamental plantings at 

the Pokorny Tree Farm, Mastadon Road, Talkeetna, September 15, 2002. Nearly all Scotch pine 

were browsed or physically damaged, forcing the landowner to plant lodgepole pine. Lodgepole 

pine was not heavily browsed. 
32

GENERAL TECHNICAL REPORT PNW-GTR-664

Discussion

Relative Growth Differences Among Species

The nonnative conifers, especially the Siberian larches and the hard pines (lodgepole, jack, and Scotch), not only grew significantly faster in height and stem 

diameter than native white spruce, but they produced two to six times more stem 

volume at the same age from planting and on the same sites in seven of eight 

plantings (table 4). From the regression analyses, white spruce was the only conifer 

with significant height growth acceleration from 10 to nearly 40 years of age. 

With the exception of lodgepole pine (N = 192) and the Siberian larches (N = 88), 

samples for native white spruce (N = 32) and the other less common nonnative 

conifers were inadequate for reliable assessments of annual height and diameter 

growth rates. Nevertheless, if white spruce height growth increases 0.24 in 

(6 mm) annually, it would overtake the height growth rate of lodgepole pine at 

about 35 years of age and the Siberian larches at about 45 years of age. The 

assumption is that the height growth of the Siberian larches will continue to 

decline at about 0.12 in (3 mm) per year after they exceed their 22-year average 

age in this survey. Annual growth of the Siberian larches is long lasting, however. 

In the Raivola larch forest, mean annual increment (MAI) began to decline from 

more than 6 m3·ha-1·yr-1 only after 150 years (Redko and Mälkönen 2005). Eis 

et al. (1982) reported that the growth rate of spruce exceeds the growth of lodgepole pine on the best sites in Central British Columbia after about 40 years, 

very close to the above-35-years estimated for spruce in Alaska. Bonnor (1989) 

also found that pure lodgepole pine regeneration on a cleared site of moderate 

productivity (2.5 m3·ha-1·yr-1) in southeast Yukon grew faster than mixed pinespruce regeneration until the stands were about 40 years old. After 40 years, lodgepole grew slower than spruce. Mean annual increments appeared to culminate for 

pine and spruce at predicted rotation ages of about 80 and 110 years, respectively.

At what age white spruce overcomes the height advantage of lodgepole pine 

and Siberian larch in Alaska is unknown. Radial growth and probably height 

growth of interior white spruce are slowing in response to climate warming 

(Barber et al. 2000, Fitzgerald and Barber 2003, Juday et al. 2003). Managed-stand 

yield tables for British Columbia show that the mean annual increment of fully 

stocked white spruce stands begins to exceed the MAI of fully stocked lodgepole 

pine stands at about 70 years (Nigh 1995). Because lodgepole pine canopies closed 

before interior spruce canopies in central British Columbia, heights of spruce 

did not exceed those of lodgepole pine until trees were 88 years old on the most 

productive alluvium soils, 110 years on sites intermediate in moisture and nutrients, and 130 years on dry sites dominated by Cornus and moss species (Eis et al. 
33

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Figure 25—Bears stripped the bark from the boles of about 

10 percent of 18- to 20-year-old Whitehorse, Yukon, lodgepole 

pine in a 1982 planting on the northwest shore of Congahuna 

Lake, Tyonek, Alaska. Bears are known to feed on the inner 

bark and cambium of conifers after emerging from winter 

hibernation, especially when traditional foods are in short 

supply. Dominant trees averaged 33 ft (10 m) tall and 7.8 in 

(20 cm) in d.b.h. Lodgepole pine was colonizing the site on 

September 13, 2002 (see fig. 18).

Figure 26—Porcupines debarked the stems of 11-year-old 

Siberian larch saplings near Wasilla in 2001 and 2002. Limbs 

were uninjured. Dominant trees averaged 26 ft (8 m) tall and 4.1 

in (10 cm) d.b.h. July 18, 2002. An estimated 75 percent of the 

trees were damaged. Marc Lee, Area Forester, State of Alaska, 

reported similar injury in an unsurveyed 10-year-old lodgepole 

pine planting in Rosie Creek, Fairbanks, Alaska.

1982). Diameters of spruce and pine were equivalent at 75, 82, and 115 years of age, 

and volumes were equal at about 95, 110, and 135 years on the productive, intermediate, and impoverished sites, respectively. After 88 years, mean annual volume 

increment for spruce was larger than pine on the most productive sites, about the 

same on intermediate sites, and less than pine on impoverished sites. Under short 

rotations (e.g., 80 years) on intermediate sites, lodgepole pine grew up to 50 percent 

more volume than spruce of the same age. On impoverished sites, lodgepole pine 

always grew more volume than spruce of the same age.
34

GENERAL TECHNICAL REPORT PNW-GTR-664

Native white spruce may have difficulty in succeeding lodgepole pine after 

it naturalizes on fire-prone sites in interior Alaska (Johnstone and Chapin 

2003). Wildfire cycles are as frequent as 40 to <120 years in the eastern Yukon 

River lowlands (Foote 1983, Kasischke et al. 2002, Yarie 1981), and should favor 

lodgepole pine. Long fire cycles should favor white spruce, which regenerated 

successfully under the closed canopy of a 28-year-old lodgepole pine provenance 

study in T-Field Arboretum, Fairbanks, after more than 10 years of competition 

control (fig. 27). Competition control was terminated in 1985.

Lodgepole Pine

 Lodgepole pine was the most common nonnative species introduced to 

mainland Alaska before 1992. Seed and wild seedlings were readily available 

from neighboring Yukon Territory. In central Yukon, lodgepole pine showed 

consistent increases in seedling recruitment following wildfires at the edge of 

its northern range (Johnstone and Chapin 2003). These authors concluded that 

northern lodgepole pine populations had not reached their climatic limits, and 

that the northern populations “have a capacity for rapid local population expansion” in spite of the limited seed dispersal distance as shown in table 6. Except 

for uncommon wind events and human transport of seeds, the limited dispersal 

distance of lodgepole pine regeneration appears to be typical for the major nonnative conifers in Alaska (figs. 14 through 16).

Lodgepole pine is widely planted in Alaska because its natural range extends 

to about 64°15' N. latitude in Hamilton Creek, east of Dawson City, Yukon, and 

the Alaska border. Readily available seed sources in the Yukon are advantageous 

compared to seed sources of nonnative species indigenous to Europe and Asia. 

In addition, lodgepole pine produces serotinous cones, and seed is easy to collect 

and propagate at a young age. With the exception of herbivore injury, our experiments with northern lodgepole pine provenances in interior Alaska show that 

they are well adapted to permafrost-free upland sites.

Common pathogens and insect pests of lodgepole and jack pines such as the 

rust fungi, Cronartium and Peridermium species, have not arrived in northern 

Alaska to date, but western gall rust, Peridermium harknessii J.P. Moore is a 

common disease of shore pine, Pinus contorta Dougl. ex Loud. var. contorta in 

southeast Alaska (Wittwer et.al. 2004). The bark beetles, Ips and Dendroctonus

species, especially the mountain pine beetle, D. ponderosae Hopkins, are among 

the most destructive insect pests of lodgepole and jack pine forests of North 

America (Furniss and Carolin 1977), and will likely be future pests of the Pinus

in Alaska.
35

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Absence of lodgepole pine natural regeneration in the Copper River Valley 

may be attributed to the young age of the plantings, high mortality from hares, 

and the commercial harvest of almost all cones in two of the four major plantings surveyed. The cones were harvested for seeds to grow nursery seedlings. In 

spite of the earlier reproductive age for lodgepole pine (table 5), the approximate 

numbers of offspring per planting, and numbers of offspring per unit area for the 

nonserotinous Siberian larches and Scotch pine were more than three times the 

number of offspring for lodgepole pine (table 6). In T-Field Arboretum, lodgepole 

pine produced cones that averaged 5 to 6 viable seeds each at 5 to 7 years of age 

(Alden and Zasada 1983). Viable seed recovery was normal (20 to 25 seeds per 

cone) after the trees were about 10 years old.

Absence or low stocking of lodgepole and jack pine regeneration at all sites 

may be attributed to the high percentage (74 percent) of closed cones in the 

crowns of seed-bearing dominant and codominant trees. In Alberta, lodgepole 

Figure 27—After more than 10 years of competition control, natural white spruce invaded the 

understory of a closed lodgepole pine canopy in T-Field Arboretum. The lodgepole pines were 

planted as 2-1 seedlings at 6-ft intervals in June 1974 from provenance collections provided by 

the International Union of Forest Research Organizations. On June 4, 2002, dominant trees in 

four superior provenances averaged 46 ft (14 m) tall and 7.5 in (19 cm) in d.b.h. after 27 growing seasons. White spruce in the understory averaged 4.2 ft (1.3 m) tall after 16 years, whereas 

dominant white spruce natural regeneration outside the 1974 study averaged 32.5 ft (10 m) tall, 

5.7 in (14.5 cm) in d.b.h. and 23 years old. On productive upland sites in Alaska, the annual 

growth and tree volume of native white spruce are expected to exceed the annual growth and 

tree volume of lodgepole pine in about 35 and 70 years, respectively. On xeric sites, however, 

lodgepole pine volume may exceed the volume of native white spruce even at maximum rotation 

age (Eis et al. 1982). 
36

GENERAL TECHNICAL REPORT PNW-GTR-664

6 Johnstone, J.F. 2005. Personal communication. Dr. Jill Johnstone is a Research 

Fellow, Department of Geography, Carleton University, Ottawa, Canada, and is in 

residence at the Division of Arts and Science, Yukon College, Whitehorse, YT Y1A 

6P8. E-mail: jjohnstone@yukoncollege.yk.ca.

pine trees lose about 3 percent of their cones annually, retaining about 50 percent 

of each cone crop for 15 years (Hellum 1983). Cones of trees less than 20 years 

old are generally less serotinous than older trees. Serotinous cones retained in 

the crowns of older trees open to disseminate their seeds slowly over time, or 

when heated to high temperatures for short periods such as during wildfires. 

Oven-drying temperatures of only 40 to 60 °C overnight will open most lodgepole and jack pine cones. With nearly three-fourths of their seeds available in 

about 50 percent of all cones produced for 30 years, lodgepole and jack pine have 

potential for abundant regeneration in Alaska. In the Yukon, natural regeneration 

of lodgepole pine is usually associated with fire and rarely includes understory 

regeneration without site disturbance6 (Stanek and Orloci 1987).

The relatively high percentage of open cones in the Cook Inlet Region may 

result from a high frequency of wet and dry weather cycles. The extensive harvest 

of closed cones in the Copper River region increased the percentage of open 

cones observed on the cone-bearing trees.

Jack pine is closely related to and hybridizes naturally with lodgepole pine. 

Recent natural hybrids are often unstable in new enviroments. For this reason, 

jack pine should not be introduced on a large scale in Alaska until the performances of jack pine and its lodgepole pine hybrid are fully investigated.

The slow establishment and height growth (1 to 9 inches or 3 to 24 cm per 

annum, table 6) of the nonnative regeneration relative to their parents may be 

caused by competition from the parent population and native vegetation that 

was recovering from preplanting disturbances. In addition, natural regeneration 

usually grows slower than planting stock, especially when the planted seedlings 

are young and establish a vigorous root system in 3 or 4 years.

More plantings in forest settings would help to fully test hypotheses concerning seed production, regeneration success, and growth of the nonnative species 

in Alaska. Operational forest plantations older than 10 years do not exist for 

nonnative species, thus it is difficult to determine the preferred sites and accurate 

growth and yields of the nonnative conifers. At this time, lodgepole pine and the 

other nonnative conifers do not appear to displace the indigenous flora.

From the early regeneration successes, growth rates, and relative shade 

tolerances of the nonnative conifers, I believe that lodgepole pine will eventually 

naturalize in Alaska. On productive sites in unmanaged forests, lodgepole pine 
37

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

will likely require fire cycles of 100 years or less to compete successfully with the 

indigenous Picea. On dry permafrost-free marginal sites, the indigenous Picea

may have difficulty competing successfully with lodgepole pine. A mosaic of 

intermixed or nearly monospecific stands of white spruce and lodgepole pine frequently populate dry areas in Yukon Territory. Although lodgepole may dominate 

specific sites, there is little evidence for competitive exclusion of white spruce at 

the landscape scale (see footnote 6).

Siberian Larches

On exceptional sites in Alaska, native white spruce is unlikely to overcome 

the faster early growth of the Siberian larches. Both western Siberian and 

Siberian larch grow rapidly to 150 ft (45 m) tall and more than 40 in (1 m) in 

d.b.h. at maturity (>100 years) on well-drained upland sites in Russia and Siberia 

(Bukshtynov 1959, Popov and Rozhkov 1966). Old-growth trees are reported to 

achieve 195 ft (60 m) in height and 78 in (2 m) in d.b.h., and occasionally survive 

more than 1,000 years. Similar rapid growth occurred in Alaska on 10 Raivola 

larches at Les Viereck’s Tree Farm in Fairbanks. The trees averaged 68 ± 6 ft 

(20.7 ± 2 m) tall after only 36 growing seasons from planting (fig. 28).

Western Siberian larch appears likely to maintain superiority on productive 

upland sites in Alaska because in its natural range, trees grow rapidly for 100 

years, achieve large size, and survive more than five centuries (Popov and Rozhkov 1966). But the indigenous Norway spruce and Scotch pine succeeded western 

Siberian larch on inferior lowland sites before 150 years in the Raivola plantation 

(Ilvessalo 1923), and on poor-quality sites in Sweden (Martinsson 1995). Thus, 

in spite of the early slower growth and smaller size, native spruce and deciduous 

species in Alaska may similarly replace the Siberian larches on poor to average 

sites where site indices of native species may exceed those of the Siberian larches. 

In the Raivola Forest, Siberian larches are more productive managed as pure species than managed in mixed pine, spruce, and birch stands (Redko and Mälkönen 

2005). In addition, 110 foliage insects (32 percent of all Siberian larch pests) are 

known to attack the Siberian larches in their natural range (Verzhutskii and 

Raigoredskaya 1966). Two foliage insects, a bark beetle, and a blue stain pathogen 

were found in this survey, less than 50 years after the first introductions.

On productive sites in their natural range, the Siberian larches replaced the 

more tolerant conifers only after wildfires (Popov and Rozhkov 1966). Seed crops 

averaged about 1 million seeds per hectare annually, but during rare heavy seed 

years 18 million seeds were produced per hectare. Thick bark (10 in or 25 cm) 

on tree trunks near the ground protects old-growth trees from ground fires. In 
38

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 28—A 36-year-old “Raivola strain” of western Siberian larch (A) at Les Viereck’s Tree 

Farm on Red Fox Drive, Fairbanks, Alaska, June 13, 2002. On productive sites, western Siberian 

larch outgrew all boreal conifers surveyed on mainland Alaska. The largest tree was 75 ft (23 m) 

tall and 16.5 in (42 cm) d.b.h. in 50 years. (B) The tree, shown by Stanley Vlahovich of the Alaska 

Department of Forestry, was planted in a partial birch-spruce overstory on Schrock Road, 

Wassila in 1953. 

absence of permafrost and on productive sites, the Siberian larches have deep 

root systems that are protected from cold and fire. On sites with shallow soils and 

active layers, root growth is restricted and trees are subject to windthrow.

The Siberian larches are excellent carbon sequestration species. In its natural 

range, Siberian larch absorbs 2.5 and 1.5 times as much CO2 during the growing 

season as Siberian spruce and pine, respectively (Popov and Rozhkov 1966). At 

about 500 kg/m3, wood density of Siberian larch is intermediate between the wood 

densities of spruce and birch (Gonzalez 1990), and contains about 50.5 percent 

carbon by weight (Matthews 1993). The heartwood is heavily lignified (lignin is 

66.7 percent carbon) and highly decay resistant, especially in moist environments. 

Seasoned wood requires special moisture treatments to prevent checking, and the 

low cellulose/lignin ratio is undesirable for wood pulp and paper manufacturing.

In this survey, the Siberian larches appeared more shade tolerant than the 

Pinus. The Siberian larches were precocious, produced many seedlings, and 

survived tenaciously at close spacing. How well the Siberian larches compete with 

the indigenous Picea on productive upland sites is unknown, but I believe white 
39

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

spruce is not likely to overtop the Siberian larches once they are established on 

productive upland sites in interior Alaska. However, white and black spruce (P. 

mariana (Mill.) B.S.P.) may compete successfully in the understory of the Siberian 

larches. Larch loses its foliage in winter, and provides less shade and competition 

during spring and early summer than during late summer. In addition, unlike the 

toxic phenol contents of Picea and Pinus needles, Siberian larch foliage provides 

organic amendments and nutrients for soil microflora and shade-tolerant understory vegetation, especially on mesic habitats. More than 90 species of fungi were 

described in the understory of Raivola larch in the early 1920s (Ilvessalo 1923). On 

dry habitats where decay is inhibited, needle cast from the Siberian larches may 

accumulate and prevent the regeneration of understory flora.

Other Nonnative Species

Balsam fir is another nonnative conifer that was capable of dense regeneration 

on disturbed sites, and limited regeneration in recovering understory mosses 

(fig. 19). Balsam fir is more shade tolerant than the indigenous Picea in Alaska, 

and is associated with white and black spruce in eastern Canada where it is the 

climax species (Frank 1990). It is a small to medium tree, and is not likely to overtop native white spruce on high-quality sites in Alaska. In addition, balsam fir has 

many insect and fungal enemies among which the spruce budworm (Choristoneura 

fumiferana Clemens and other species) is a common defoliator of white spruce 

in Interior Alaska. Balsam fir is highly valued for pulpwood and timber, and its 

wood may be stronger than white spruce.

Only two balsam fir plantings were found in Alaska, and both had regenerated naturally. At 1 seedling per 2.5 ft2

 or 4 seedlings per m2 (table 5), balsam 

fir regeneration was dense, but distances of its seedlings from their seed parents 

were limited to less than 50 ft (15 m) (fig. 29). Limited offspring dispersal distance 

(table 6) is typical of most conifers with wind-dispersed seed. As a result, population spread will probably be very localized for balsam fir and most other conifers 

except for rare natural dispersal events or human transport of seeds.

Future naturalization surveys of nonnative species should consider the relative contributions of cone crop heights, seed weights, wind events, and site disturbances on the distances and densities of offspring distributions. For open cone 

species, the frequency of seed crops can be estimated from the age distributions 

of their offspring.

Because of its shade tolerance, balsam fir could be a major competitor of the 

indigenous Picea on mesic and wet sites in south-central Alaska where wildfires 

are less common than in interior Alaska. Balsam fir is intolerant of wildfire, 
40

GENERAL TECHNICAL REPORT PNW-GTR-664

Figure 29—Four 1- to 5-year-old balsam fir seedlings per square meter 

on mineral soil within 50 ft (15 m) of their seed parents at the Gonder 

Tree Farm in Big Lake, September 14, 2002. Yellow flags mark each 

seedling. The parents were planted at 6 ft (2 m) spacing in about 1974. 

Dominant parents averaged 36.7 ft (11 m) tall and 5.5 in (14 cm) in 

d.b.h. Balsam fir is highly shade tolerant, and grows best on moist sites.

extreme cold, and short, dry growing seasons. Therefore, it is unlikely to naturalize in interior Alaska. If balsam fir and its close relatives adapt to cold dry habitats in interior Alaska, they could be major fire hazards.

Balsam fir is closely related to subalpine fir, and hybridizes with Siberian fir 

(Frank 1990). The three species have similar habitat and shade requirements, and 

the latter species also have potential for naturalizing in northern Alaska. Natural 

subalpine fir populations are found at 5,000 ft above sea level in central Yukon 

at 64° latitude (Keno Hill), and on the Stewart River only 125 mi (200 km) east 
41

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

of the Alaska border (Viereck and Little 1972). In southeast Alaska, subalpine fir 

is found naturally at the head of Lynn Canal and at other coastal sites extending 

to the mountains southeast of Ketchikan. Spruce-fir associations are common 

in eastern boreal forests, but their relation with the indigenous Picea should be 

investigated before they are widely introduced in Alaska.

Scotch pine is the most widely planted nonnative conifer in North America. 

More than 10 million trees have been harvested for Christmas trees in the United 

States annually (Skilling 1990). As a result, Scotch pine has naturalized in the 

Northeast and Lake States regions of the United States, and in Ontario, Canada, 

where regeneration is prolific and spreads on disturbed gravel and light sandy 

soils. In New York, the stem and branch canker caused by Gremmeniella abietina

(Lagerb.) Merelet., an indigenous pathogen of native red (Pinus resinosa Ait.) and 

jack pines, keeps Scotch pine regeneration in check (Skilling 1981). Scotch pine is 

shade intolerant and has little chance of naturalizing extensively in Alaska except 

perhaps on disturbed sites, and on sand dunes that are unfavorable habitats for 

the indigenous species. Scotch pine is a highly variable species geographically and 

morphologically (Tseplyaev 1961). Latitudinal clines for growth and survival of 

the Scandinavia variety (P. lapponica Fries.) are steep and negative (data on file for 

a 1984 species trial in Delta, Alaska). In northern Sweden, native Scandinavian 

provenances grow 35 to 40 percent less volume than introduced lodgepole pine 

from the Yukon (von Segebaden 1993).

Norway spruce, Dahurian larch of Far East Asia, and Douglas-fir produced 

seed cones, but they failed to regenerate. A Norway spruce planting in Mat-Su 

Valley was vigorous and had high-quality trees, but three unsurveyed plantings of 

a Baltic Sea seed source in interior Alaska sustained frequent winter injury during 

the 1980s. Douglas-fir of a probable Rocky Mountain seed source developed 

poor form and appeared least likely among the conifers surveyed in south-central 

Alaska to compete successfully with the indigenous species.

Other boreal conifers were introduced to mainland Alaska in demonstration 

or species trials before 1990, but they were not investigated in this survey. They 

include subalpine fir, Siberian spruce (Picea obovata Ledeb.), Siberian pine (Pinus 

sibirica Du Tour), Japanese stone pine (Pinus pumila (Pall.) Regel), and limber pine 

(Pinus flexilis James). Each of these species has economic value in industrial or 

urban forestry. The Siberian and stone pines have additional value because their 

seeds are valued as a food crop for both human and wildlife consumption.

These conifers are among more than 300 exotic broadleaf and needle-leaf 

species that have industrial or urban forestry value and potential for introduction 

to mainland Alaska (list on file). Nearly one-third already survive as single trees 
42

GENERAL TECHNICAL REPORT PNW-GTR-664

or in small plantings in Alaska from introductions before 1990. Performances of 

the most promising should be studied in arboretums and replicated field experiments before they are introduced on a landscape level.

Growth and yields of the nonnative conifers in well-managed operational 

plantations for industrial forestry are unknown in Alaska. The potential for 

disruption of natural forest ecosystems from naturalization of nonnative conifers is a concern of some resource managers and scientists. Boreal forests are 

naturally lower in biodiversity and productivity than temperate and tropical 

forests. The performance of nonnative conifers mixed with boreal tree species, 

and of subsequent forest ecosystems are also unknown.

Conclusions 

Lodgepole pine and Siberian larch provenances reproduce after only 10 years 

on disturbed sites in Alaska. Lodgepole pine and the Siberian larches colonized 

at one-third of their introduction sites, and may soon be the first conifers to 

naturalize on mainland Alaska.

Lodgepole pine and the Siberian larches are shade intolerant relative to 

Alaska’s Picea species, and are not likely to dominate or replace the native 

conifers in undisturbed forest ecosystems. The prolific regeneration and shade 

tolerance of balsam fir indicate that it could naturalize on moist sites in southcentral Alaska.

On productive sites, annual stem-diameter, height, and volume growth of 

lodgepole pine and Siberian larch are likely to exceed the growth of native white 

spruce until they are at least 35 and 45 years of age, respectively. In absence of 

disturbance on productive upland sites, white spruce should succeed lodgepole 

pine in 100 years or less, but white spruce is not likely to replace adapted western 

Siberian larch until after the first generation when it recaptures a dominant 

crown position.

The western Siberian larches grow as fast as lodgepole pine in diameter, 

and faster in height. The larch sawfly, an unknown bark beetle and a blue stain 

fungus that is a pathogen could limit western Siberian larch as a forest crop 

species in Alaska.

Animal damage may limit lodgepole pine’s potential as a crop tree in eastern 

Alaska. Lodgepole pine remains susceptible to hare damage at peak population 

cycles until it is at least 3 in d.b.h. Large moose populations cause extensive 

injury and mortality. Animal damage is especially severe where (1) plantings 

are small and animals concentrate, (2) habitats are favorable for large animal 

populations, (3) natural browse is inadequate, and (4) migration is limited, i.e., 
43

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

by deep snow. Large plantings would distribute the damage over wider areas and 

reduce losses.

Data is insufficient to determine the productivity of pure and mixed forests of 

spruce, fir, pine, and larch in Alaska. Well-planned species and provenance trials 

of sufficient size and design to yield satisfactory results are necessary to evaluate 

the productivity of pure and mixed-species forests on mainland Alaska.

Acknowledgments

Assistance in locating and evaluating plantings of nonnative species in southcentral and interior Alaska was provided by Al Peterson, Wade Wahernbrock, 

and Rick Jandreau of the Kenai-Kodiak Area, Alaska Division of Forestry 

(DOF), Department of Natural Resources, Soldotna; Jim DePasquale of the 

Kachemak Nature Conservancy, Homer; Earl Breyfogle of the Kenai Peninsula 

Borough, Kenai; Jim Gladish, Northwest Cutters Inc., Homer; Cal Kerr, Northern Economics, Inc., Anchorage; Dr. Jeff Graham and Stan Vlahovich, Stewardship and Extension Foresters, Mat-Su Area, DOF, Palmer; and Martin Maricle, 

Copper River Area, DOF, Glennallen. Dr. Jeff Graham initially suggested the 

survey and reviewed an early draft of the results. Scott McDonald, contract 

Forestry Technician, provided assistance with the early measurements. Gordon 

Worum, DOF, Fairbanks, mapped the regions and sites that were surveyed.

I am grateful for the funding and logistical support provided by the Division 

of Forestry, Alaska Department of Natural Resources. Finally, site access and 

planting records provided by more than 50 landowners made this survey possible 

and were greatly appreciated.

Metric Equivalents

When you know: Multiply by: To find:

Miles (mi) 1.609 Kilometers

Feet (ft) .3048 Meters

Inches (in) 2.54 Centimeters

Square feet (ft2) .0929 Square meters

Cubic feet (ft3) .0283 Cubic meters

Acres (ac) .4047 Hectares

Trees per acre 2.471 Trees per hectare

Trees per square feet 10.7639 Trees per square meter
44

GENERAL TECHNICAL REPORT PNW-GTR-664

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47

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Skilling, D.D. 1990. Pinus sylvestris L., Scotch pine. In: Burns, R.M.; Honkala, 

B.H., tech. coords. Silvics of North America. Volume 1. Conifers. Agric. 

Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest 

Service: 489–496.

Sokal, R.R.; Rohlf, F.J. 1969. Biometry. San Francisco, CA: W.F. Freeman 

and Co. 776 p.

Stanek, W.; Orloci, L. 1987. Some silvicultural ecosystems in the Yukon. 

Info. Rept. BC-X-293. Victoria, BC: Canadian Forestry Service, Pacific 

Forestry Centre. 56 p.

Trummer, L. 2003. Disease assessment of dead and declining Alaska larch near 

Delta Junction. 3 p. Unpublished report. On file with: USDA Forest Service, 

State and Private Forestry, Forest Health Protection, 3301 C St., Anchorage, 

AK 99503-3956. 

Tseplyaev, V.P. 1961. [1965]. The forests of the U.S.S.R. [Translated from 

Russian by Prof. G. Gourevitch] New York: Daniel Davey and Co., Inc. 

521 p.

Verzhutskii, B.N.; Raigoredskaya, I.A. 1966. [1970]. Conifer foliage pests. 

In: Rozhkov, A.S., ed. Pests of Siberian larch. Academy of Sciences of 

the USSR, Siberian Department, East Siberian Biological Institute. 

[Translated from Russian] Washington, DC: U.S. Department of Commerce. 

393 p.

Viereck, L.A.; Little, E.L., Jr. 1972. Alaska trees and shrubs. Agric. Handb. 410. 

Washington, DC: U.S. Department of Agriculture, Forest Service. 265 p.

Viherä-Aarnio, A.; Nikkanen, T. 1992. [1995]. Siberian larch (Larix sibirica

Ledeb.): a successful exotic in Finland. In: Schmidt, W.C.; McDonald, K.J., 

Comps. Ecology and management of Larix forests: a look ahead. Gen. Tech. 

Rep. INT-GTR-319. Ogden, UT: U.S. Department of Agriculture, Forest 

Service, Intermountain Research Station: 507–508.

von Segebaden, G. 1993. Lodgepole pine in Sweden—a situation report. In: 

Lindgren, D., ed. Pinus contorta—from untamed forest to domesticated 

crop. IUFRO WP 2.02.06 and Frans Kempe Symposium. Report 11. Umeå, 

Sweden: Department of Forest Genetics and Plant Physiology, Swedish 

University of Agricultural Sciences: 8–23.
48

GENERAL TECHNICAL REPORT PNW-GTR-664

Wittwer, D., comp. 2004. Forest health conditions in Alaska—2003. Gen. Tech. 

Rep. R10-TP-123. Anchorage, AK: U.S. Department of Agriculture, Forest 

Service, Alaska Region; State of Alaska, Department of Natural Resources, 

Division of Forestry. 82 p.

Yarie, J. 1981. Forest fire cycles and life tables: a case study from interior 

Alaska. Canadian Journal of Forest Research. 11: 554–562.
49

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Appendix

An inventory of sites examined from June to October 2002 (and 2003 as indicated) for colonization and 

potential naturalization of nonnative species on mainland Alaska

Location and date planted Date checked

Interior and Copper River:

1. T-Field Arboretum 1964 to 1974 6/25, 9/24/03

2. Bonanza Creek Experimental Forest lodgepole pine provenance/family trial, 1985 7/03

3. Rosie Creek lodgepole pine prov./family trial, 1985 6/26

4. Rosie Creek lodgepole pine container seedling trial, 1986 8/15

5. Rosie Creek lodgepole pine operational seedling trial, 1985 and 1986 8/15

6. Malone Rosie Creek sites I and II 10/3

7. Samuel’s lodgepole pine provenance, provenance/family, and species trials, 1982–86 7/5

8. Brann’s lodgepole pine provenance/family and species trials, 1984 8/1

9. Tanana Loop Road lodgepole pine and Siberian larch plantation, ~1988 8/1

10. Tok Rifle Range lodgepole pine provenance/family and species trials, 1989 8/22

11. Lodgepole pine stocking study, Red Fox Drive, Tok, AK, 1992 8/21

12. Glennallen Division of Forestry Tazlina Experimental Planting, 1984 8/22

13. James Luebke’s lodgepole and Scotch pine 0.25 mi Copperville Rd., mi 112 Richardson 

 Highway planting, Glennallen, 1985–87 8/23

14. Nick Zerbinos’ Rose Av. ~1987 lodgepole pine planting on Tazlina Terrace, Glennallen 8/22

15. Old Edgerton Highway lodgepole pine provenance/family trial, 1984 and 1985 8/23

16. Don Kratzer’s Tree Farm, Nenana, 1982–87 6/20

17. Georgeson Botanical Garden and Irving Bulding Siberian larch, 1974 6/11

18. Les Viereck’s lodgepole pine, Scotch pine, Siberian larch, Norway spruce, and Siberian fir 

 plantings on Red Fox Drive, Fairbanks, 1966–82 6/12–13

19. Lodgepole pine and Siberian larch at Al and Robin Near home, and J. Zasada’s former home, 

 1555 LaRue Drive (Farmers Loop), Fairbanks, 1975–~1985 6/13

20. Lodgepole pine at 24 mile Chena Hot Springs Road, 1967 6/25

21. Siberian larch seed orchard, Delta Agriculture Experimental Farm, 1984 and 1985 8/21

22. Siberian larch, former Bureau of Land Management Office, Airport Way, ~1955 9/25

55. Alaska Tree and Garden Center, ~1978 7/1/03

South-Central Alaska:

23. Mat-Su College Arboretum (Pinus, Larix, Picea, Abies, Pseudotsuga), 1985 7/18

24. Gene Holmberg’s northwest field of Siberian larch, Schrock Road, Wasilla, 1991 7/18

25. Gene Holmberg’s understory Siberian larch, Schrock Road, Wasilla, 1953 9/16

26. Gene Holmberg’s south field of Siberian larch, Schrock Road, Wasilla, 1991 9/16

27. Houston City Educational Park, Houston, 1986 and 1987 7/18

28. Mike Peacock Demonstration Forest (Willow Experimental Forest), Houston City Landfill, 1986 7/18

29. Siberian larch at Wasilla Veterinary Clinic, 40 mi Parks Highway, 1988 7/18–19

30. Point Mackenzie tree farms: Scotch pine, T15 N, R5W, E1/2 S26, ~1985 7/19

31. Point Mackenzie tree farms: lodgepole pine, Scotch pine, Siberian larch, Guernsey Road, ~1991 7/19
50

GENERAL TECHNICAL REPORT PNW-GTR-664

Location and date planted Date checked

32. Point Mackenzie tree farms: lodgepole pine, Point Mackenzie and Airstrip Roads, ~1982 7/19

33. Gonder Homestead (Pinus, Abies, Pseudotsuga, Picea), Gonder Road, Big Lake, 1964–95 7/19, 9/14-16

 Lodgepole pine at 5 mi Goose Bay-Knik Road, ~1990 Not found

 Pinus and Larix at northeast end of Yarrow Rd., Wasilla, or Palmer, T18N, R2E, Sec, 6, 1988 Not found

34. Lodgepole pine at former Alaska Forest Tree Nursery, Eagle River, ~1983 7/19

35. Siberian larch, Scotch pine, and lodgepole pine at Pokorny Tree Farm, Talkeetna, ~1990 9/15

36. Lodgepole pine and Scotch pine at Kingsberry Tree Farm, Talkeetna, ~1985–90 9/15

Picea, Pinus, Abies, and Larix on University of Alaska Anchorage Campus, ~1975–95 Not examined

Picea and Larix in the University of Alaska Fairbanks Palmer (Babb) Arboretum, 1949–85 Not examined

Kenai Peninsula:

37. Division of Forestry Area Office lodgepole pine and Arboretum, Soldotna, 1978–85 8/6–7

38. Division of Forestry Area Arboretum, Soldotna, 1978–2000 8/7

39. Lodgepole pine and Siberian larch plantings on power line road extending from Tustumena 

 Lake Road, ~1980 8/7

40. Lodgepole pine on Richard Stingley Farm, 3 mi North Fork Road, Anchor Point, 1977 5/29

 Scotch pine at seismic line crossing, 2.4 miles southwest of 2 mi Falls Creek Road, T1N, R13W, 

 Sec 25, Kenai Peninsula, ~1985 Not examined

41. Arc Loop Road, south of Soldotna, ~1973 8/6

42. Lodgepole pine and Siberian larch on a burned site in Moose Pass, 1988 8/8

43. Curly Wynkoop home, Strawberry Road, Soldotna-Kenai, 1975 8/6

44. Southeast of Curly’s, Strawberry Road, Soldotna-Kenai, 1978 8/6

45. Funny River State Recreation Area, 1987 8/6

46. Dean Glick, Lake Street, Soldotna, 1989 8/6

47. Siberian larch and Scotch pine at 2.5 mi Falls Creek Road, 1988 8/7

48. Mossy Kilcher’s Seaside Farm, East Homer Road, ~1977 9/10

49. East Hill Road lodgepole pine, Homer, ~1977 9/10

50. Lodgepole pine in the Homer Demonstration Forest, ~1982 9/10

51. Milepost 54.1 Seward Highway lodgepole pine, ~1968 9/11

52–3. Two lodgepole pine of six plantings on Division of Forestry salvage sites at Tyonek, ~1975 9/12–13

54. G. Hermansen lodgepole pine on Cohoe Loop Road, Kenai Peninsula, ~1969 7/17/03
51

Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous ainterior and south-central AlaskaSite GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

Interior Alaska:

1. T-Field Arboretum 64.8740229N; 

147.8647104W; 219M

Larix sukaczewii N. Dyl. and 

L. sibirica Ledeb. 

0.1 1964 Yes 

(64.8739012N; 

147.5638589W; 193M—escape)

Pinus contorta Dougl. ex Loud. 

var. latifolia Engelm.

0.1 1964 Yes 

64.8733984N;

147.8636730W; 188M

Pinus contorta Dougl. ex 

Loud. var. latifolia and Pinus banksiana Lamb.

0.5 1974 No Broken tops 

and branches

37 

Pinus sylvestris L. 0.05 1966 No Broken roots 

at ground

15 

Pinus banksiana 0.05 1966 Yes Browse Hare 10 P. sibirica Du Tour, P. pumila

(Pal.) Regel, Picea abies (L.) Krast., Abies sibirica Ledeb.

0.1 1966–78 No None 

2. Bonanza Creek 

Experimental Forest, Rep 6

64.7414780N;

148.2909996W;236.6M

Pinus contorta var. latifolia

and P. banksiana

2 1985 No Bark, 

branches

Squirrel 1 

3. Rosie Creek Prov./

family Trial, Rep 8

64.7780558N; 

148.1828052W;235M

Pinus contorta var. latifolia

and P. banksiana

2 1985 No Bark

stripping, top and branch kill

Moose 30 

4. Rosie Creek 

Container Trial

64.7753584N; 

148.1592672W; 235M

Pinus contorta var. latifolia 0.25 1986 No None 

observed

6. Malone’s Rosie 

Creek trial No. 2 

64.7748192N; 

148.1899687W; 212M

Pinus contorta var. latifolia 0.5 1985–86 No Browsed 

tops

Moose 5 

Malone’s Rosie 

Creek trial No. 1

64.7737949N; 

148.1940113W; 217M

Pinus contorta var. latifolia 0.5 1985–86 No Browsed 

tops

Moose <5 
52Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous a

interior and south-central Alaska (continued)Site GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

7. Samuel’s lodgepole 

pine prov./family test, Delta Junction 

64.0063942N;

145.5554455W;381M

Pinus contorta var. latifolia 1 1982 Yes 

(in 2003)

Cut stems, 

branches

Hares 1 

Samuel’s lodgepole 

pine prov./family and species trials

64.0102363N;

145.5530110W;387M

Pinus contorta var. latifolia, 

Larix sukaczewii and L. sibirica, L. laricina var. 

alaskensis (W.F. Wright) Raup, Pinus sylvestris, P. banksiana, P. flexilis James, Picea abies, P. obovata Ledeb.

6 1984, 

1987

Yes 

(in 2004)

Cut stems, 

branches

Hares 

andvoles

0–50 

8. Brann’s lodgepole pine 

prov./family and species trials

63.9705751N;

145.5325712W;389M

Pinus contorta var. latifolia 4 1984 Yes Cones 

stripped; cut stems and branches

Squirrels Hares

50

Brann’s species trial 63.9705751N;

145.5325712W;389M

Pinus contorta var. latifolia, 

Larix sukaczewii and L. sibirica, L. laricina var. alaskensis, Pinus sylvestris, P. banksiana, P. flexilis, Picea abies

4 1984 No Broken 

tops and branches

Hares 

and moose

As above 

9. Swain’s Tanana Loop 

plantation

64.1179010N;

145.6659476W;338M

Pinus contorta var. latifolia; 

Larix sukaczewii

2 ~1988 No None Squirrel 

cutting larch cones

0 

10. Tok Rifle Range 

lodgepole pine prov./family and species trials

63.3590475N; 

143.2740616W;490M

Pinus contorta var. latifolia, 

Larix sukaczewii and L. sibirica, L. laricina var. alaskensis, L. dahurica Turcz., Pinus sylvestris, P. banksiana, P. flexilis, Picea abies

3 1989 No Branch 

pruning on pines

Hares 10 

11. Malone’s Stocking 

Study, Red Fox Drive, Tok

63.3519755N; 

142.9792464W; 494M

Pinus contorta var. latifolia 6.5 1992 No Branches 

clipped, browsed

HaresMoose

10

0

12. Division of Forestry 

Tazlina Experimental Planting, Glennallen

62.0484757N;

145.4575409W; 421M

Pinus contorta var. latifolia 4 1984 No Stems to 4 in 

diameter girdled and branches cut

Hares voles 5 

13. J. Luebke’s Copperville 

plantings, 112 Rich Highway, Glennallen

62.0713223N; 

145.4244732W;364M

Pinus contorta var. latifolia, 

P. sylvestris

0.1 1982–87 No None Hare 
53

Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous ainterior and south-central Alaska (continued)Site GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

14. N. Zerbinos’ Rose 

Ave., Tazlina Terrace planting, Glennallen

62.0636783N; 

145.3981067W; 348M

Pinus contorta var. latifolia 1 ~1987 No Forked Hare 5 

16. D. Kratzer’s Tree 

Farm, Nenana

64.6344257N; 

149.0365430W; 115M

Pinus contorta var. latifolia 1 1983 Yes Broad crowns 

Pinus contorta var. latifolia 4 1984–85 Yes None observedPinus contorta var. latifolia ~18 1986–87 No None observedP. sylvestris, Larix sukaczewii ~10 1985, 

1992

No None observed

17. Georgeson Botanical 

Garden and IrvingBuilding

64.8567760N;

147.8535984W;166M

Larix sukaczewii 0.1 1974 Yes None noted

18. Les Viereck, Red Fox 

Dr., Fairbanks

64.8998033N; 

147.8109484W; 245M

Larix sukaczewiiAbies sibiricaPinus contorta var. latifolia, 

P. sylvestris, Picea abies

0.1 

(10 trees)

(2 trees)

0.75

1966

1986

1966, 

1982

YesYes

No

None notedNone notedNone noted

19. Al and Robin Near, 

and J. Zasada, 1566 LaRue Dr. (Farmers Drive), Fairbanks

64.8929488N; 

147.7967253W;325M

Pinus contorta var. latifoliaPinus contorta var. latifoliaLarix sukaczewii

(1 tree)

(8 trees)

(5 trees)

1975

~1985

1980

Yes

NoNo

None notedNone notedNone noted

33. At Gonder home 61.5079739N; 

149.8759461W; 45M

P. sylvestris 0.25 ~1965 Yes None

Naturals back 40 61.5069775N; 

149.8808315W; 46M

Abies balsamea 0.1 1997–99 Yes None

Gonder driveway Douglas-fir on 

ridge south of Norway spruce below

P. pungens Engelm., 

Pseudotsuga menziesiivar. glauca, Pinus ponderosaDougl. ex Laws

0.6 1964–70 No None

Gonder Ridge 61.5072910N;

 149.8739658W;  54M

Picea abies 0.2 ~1970 No None

Original Gonder 

access road 

61.5072038N; 

149.8721514W;  46M

Abies balsamea 0.2 1968 Yes None
54Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous a

interior and south-central Alaska (continued)Site GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

34. Former Alaska Forest 

Tree Nursery, Eagle River

61.3009417 N; 

149.5835821W; 142M

Pinus contorta var. latifolia, 

P. sylvestris

0.2 1982–83 No None 

recorded

35. L. Pokorny Tree 

Farm, Mastadon Road, Talkeetna 

62.2371594N; 

149.9692437W; 188M (Entrance to farm)

Pinus contorta var. latifolia, 

Larix sukaczewii or L. sibirica

0.2 1990 No None

recorded

62.2339857N; 

149.9569300W; 196M

P. sylvestris ~20 1990 No None

Start of major 

plantings; south end of lodgepole pine

62.2329558N;

149.9620689W;179M

P. sylvestris, P. pungens, 

Larix sukaczewii or L. sibirica

~40 1990–

2000

No Severe top 

damage and stem breakage

Moose 80 

North end of 

lodgepole pine

62.2406993N;

149.9620689W;184M

Pinus contorta var. latifolia, 

Larix sukaczewii or L. sibirica

~15 1990–

2000

No Tops of pines 

browsed; larch damaged

MooseHares?

10 pine

40 larch

36. Kingsberry’s Birch 

Creek Ranch, 3-mi Mastadon Road, Talkeetna 

62.2658746N; 

149.9588078W; 206M

P. sylvestris, P. pungens, 

A. balsamea

Pinus contorta var. latifolia

1.5

0.1

1986, 

1989

1987–88

No

Yes

Tops and 

branches browsed

Tops and stems

MooseMoose

75 pine

50 spruce 

and fir

15

Kenai Peninsula:

37. Division of Forestry, 

Kenai-Kodiak area office, Soldotna 

60.4983793N;

151.0117140W;46M

Pinus contorta var. latifolia 0.2 1978–85 Yes None 

documented

38. Division of Forestry, 

Kenai-Kodiak area arboretum and weather station, Soldotna

60.4977675N; 

151.0129182W; 49M

Pinus contorta var. latifolia 0.1 1978–85 Yes Severe top 

damage

Moose 50 

60.4977675N; 

151.0129182W; 49M

L. dahurica, Larix sukaczewii

or L. sibirica, Abies lasiocarpa, Picea abies, Pinus sylvestris, P. aristata Engelm., Thuja plicata Donn ex Don 

0.1 1978–85 No Some damage Moose 25 

39. Power line road 

extending from Tustumena Lake Road

60.2563713N; 

151.2413619W; 77M(At group 3)

60.2543994N; 

151.2479777W; 86M

Pinus contorta var. latifolia—

15 groups of 3 to 20 trees each

Larix sukaczewii

5 (net)

.05 

(2 trees)

~1982~1982

NoNo

Trees stripped 

of bark; stems and branches broken

MooseBear or 

porcupine

None

30

1
55

Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous ainterior and south-central Alaska (continued)Site GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

40. R. Stingley Farm 

(David Newton Boyer Homestead), 3-mile North Fork Road, Anchor Point

59.7972136N; 

151.7689794W; 58M

Pinus contorta var. latifolia 1.5 1977 No None 

recorded

41. Arc Loop Road, 

Soldotna

60.4349124N; 

151.1170936W; 56M

Pinus contorta var. latifolia 0.05 

(3 trees)

1973 Yes None 

recorded

42. Moose Pass power 

line

60.4926732N; 

1493714115W; 180M

Pinus contorta var. latifolia, 

P. sylvestris

0.5 1988 No None 

recorded

60.4940396N; 

149.3715517W; 182M

Larix sukaczewii 0.5 1988 No None 

recorded

43. Dave (Curly) Wynkoop, 

Strawberry Road, Soldotna-Kenai

60.5528488N; 

151.0850293W; 31M

Larix sukaczewii 0.05 

(6 trees)

1975 Yes Tops broken 

and bark stripped

Moose 

and porcupine

50 

Pinus contorta var. latifolia, 

P. sylvestris, Picea, Abies, Tsuga

0.1 (1–5 

trees 

each)

1978–

~1985

No Broken tops 

and branches

Moose 30 

44. Strawberry Road, 

SW of D. Wynkoop, Soldotna-Kenai

60.5509673N; 

151.0860314W; 36M

Pinus contorta var. latifolia 0.1 ~1974–78 Yes Trees forked 

and crooked

Moose 40 

45. Funny River State 

Recreation Area, Soldotna

60.4929988N; 

150.8603450W; 34M 

Pinus contorta var. latifolia 0.05 ~1987 Yes None

46. Dean Glick, Lake 

Street, Soldotna

60.4305789N; 

151.1698003W;66M

Pinus contorta var. latifolia, 

Tsuga mertensiana (Bong.) Carr.

0.05 1989 No None 

47. 2.5 mi Falls Creek 

Road

60.1670571N; 

151.4036339W;94M

Larix sukaczewii, Pinus 

sylvestris

3 1988 No Broken tops 

and forking

Moose 5-10 

48. Seaside Farm, East 

Homer Road

59.6766577N; 

151.4101712W; 28M

Pinus contorta var. latifolia and 

var. contorta, P. sylvestris

 0.1 1978 No None

49. East Hill Road, 

Homer

59.6557901N;

151.5143179W; 79M

Pinus contorta var. latifolia 0.05 ~1977 No None

50. Homer Demonstration 

Forest

59.6621930N;

151.6194564W; 219M

Pinus contorta var. latifolia 0.5 1982 No Bark 

stripping

Moose <5 
56Table 8—Locations and foreign conifers examined for evidence of escape and colonization, and injuries from indigenous a

interior and south-central Alaska (continued)Site GPS Species Acres Date Progeny Injury Animal

Percentage 

of trees 

injured

51. Milepost 54.1, 

Seward Highway

60.7546546N; 

149.4608109W;252M

Pinus contorta var. latifoliaa 0.05 1968 No None

52. Tyonek, Site 82-3 61.0820566N; 

151.4077338W; 121M

Pinus contorta var. latifolia 3 1982 Yes Bark clawing 

and stripping

Bear 5-10 

53. Tyonek, Site 76-3 61.0457344N; 

151.4817521W; 93M

Pinus contorta var. latifolia 0.2 1976 No Bark stripping Bear 20 

54. Cohoe Loop Road, 

G. Hermansen

60.3467272N; 

151.3153560W; uncorrected

Pinus contorta var. latifolia 0.05 

(2 trees)

1969 

est.

Yes Scarred and 

forked

Human 100 
57

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Table 9—Mean age, size, and annual growth of native and nonnative species sampled with <30 trees on 

mainland Alaska

Trees Mean age Mean d.b.h. Mean height

Growth

Species sampled and range and range and range D.b.h. outside bark Height

Years Inches Feet Inches/year Feet/year

Jack pine 12 25 (13–34) 6.0 (2.4– 9.0) 36 (16–48) .273 1.36 

Dahurian larch 3 24 (0) 5.4 (4.0–6.2) 29 (26–31) .255 1.21

Paper birch 18 26 (18–48) 4.9 (2.9–8.4) 40 (25–64) .227 1.63

Balsam fir 8 31 (27–35) 5.9 (4.8–8.3) 38 (31–48) .217 1.24

Aspen 10 23 (18–34) 4.4 (2.0–6.4) 33 (20–47) .216 1.52

Douglas-fir 4 35 (0) 5.8 (4.8–8.0) 30 (27–34) .195 .86

Norway spruce 8 35 (35–36) 5.5 (3.7–8.8) 34 (24–50) .180 .97

Siberian fir 5 35 (0) 4.9 (4.0–6.1) 32 (20–46) .149 .91

Alaska larch 2 34 (0) 5.0 (4.4–5.5) 35 (29–41) .146 1.03

 Average 8 30 5.3 34 .206 1.19

Note: D.b.h. = diameter at breast height.
58Table 10—Spreadsheet summaries of sites and species data

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

Region I. Interior Alaska

17. Georgeson Larix sukaczewii P 35 9.2 30 Open grown; 

Botanical Garden 40 9.5 30

9 1.5 20

41 12.9 30

33 9.3 20

1. T-Field Arboretum Larix sukaczewii P 70.1 9.2 36 Former Unive

66 10.6 36 land—6/4/02

66 8.8 36 dust in bark 

65 8.3 36 Sawfly predator eggs on

defoliated branches

Abies sibirica P 32 4.9 35

20 4 35

31 4.2 35

Larix sukaczewii P 56 7.4 36 A Ural Mount

59 5.7 36

56 7.2 36

64 7.4 36

Pinus contorta P 64 8.4 37 150 20 Older cones (15 yrs.) 1958 Whiteho

var. latifolia on lower crown

61 7.5 37 100 20 

57 11.3 37 450 35 Stem forked several times

52 7.2 37 75 10 Top forked

Pinus contorta P 40 7.6 35 300 <5 Teslin, Yukon 

var. latifolia 49 11.8 35 600 >5

47.5 7.4 35 100 <5

Pinus banksiana P 48 5.4 35 50 0 Cones to 12 yrs.; older Fort Simpson

43 8.3 35 500 5 cones on low branches

47 6.2 35 350 5

45 7.8 35 500 4 Open only on low branches

Pinus contorta P 53 7.2 27 500 4 Carmacks, Yukon-R1, 1974 lodgepol

var. latifolia tallest tree reps 1 and 2

48 8.3 27 500 15 Ethel Lake, Yukon-R1

46 6.5 27 100 50 Jackfish Creek, BC-R1

47 9.9 27 500 10 Cassiar, BC-R1

45 7 27 100 0 Jackfish Creek, BC-R2

44 7.3 27 500 0 Ethel Lake, Yukon-R2

43 7.2 27 500 2 Carmacks, Yukon-R2, 

codominant

43 6.4 27 300 2 Cassiar, BC-R2 
59

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

Pinus banksiana P 46 9 27 500 0 1974 provenan

42 8.4 27 100 0

42 7.6 27 500 4

47 7.5 27 500 4

Picea glauca P 52 6.4 37 21-tree plot; tr

52.5 8.9 37 and planted 

51 7.3 37

46.5 7.3 37

44 5.4 37

Picea glauca P 50.5 36 Adjusted for a

above 51.5 36

50 36

44.5 36

43 36

Picea glauca N 4.89 16 Understory re

4.95 18 pine provena

4.07 14

6.04 16

3.64 17

3.61 17

2.49 17

Picea glauca N 30 4.4 21 Regeneration 

33 5.3 23 provenance t

34 6.6 25

33 6.5 23

Picea abies P 38 3.8 36 Plots of 14 and 

33 4.3 36

50.5 6.1 36

44.5 4.6 36

48 3.9 36

Pinus sylvestris P 58 7 36 Thirty-six tree

54.5 6.7 36 season 1966

48 6.8 36

44 6.4 36
60Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

16. D. Kratzer, Pinus contorta P 21 4.8 17 250 20 Planted in 198

Nenana, Alaska var. latifolia 22 4.9 17 300 50

14 4.5 17 100 30

21 6.1 17 100 20

Pinus contorta P 27 7.6 19 200 15 Planted in 198

var. latifolia 25 7.3 19 300 10

22 4.6 19 100 10

25 7.6 19 300 1

Picea glauca P 16 3.7 19 Planted in 198

17 4.0 19

20 3.8 19

17 4.4 19

Larix sukaczewii P 24 3.9 14 Planted in 198

26 4.4 14

24 5.1 14

20. Chena Hot Pinus contorta P 40 6.8 34 10 0 Transplant be

Springs Road var. latifolia 33 4.1 34 0 surviving tre

36 4.7 34 6 17

31 4.7 34 6 0

Larix laricina N 29 4.4 34

var. alaskensis 41 5.5 34 Estimated age

35 5.0 34

Populus tremuloides N 47 6.4 34

37 6.0 34 Estimated age

38 6.0 34

3. Rosie Creek Pinus contorta P 23 2.9 17 20 95 1985 prov./fam

var. latifolia 22 4.3 17 200 80

23 2.6 17 20 65

24 3.9 17 100 0

25 3.1 17 45 65

Pinus banksiana P 2.4 17 1985 prov./fam

4.2 17 cones were n

Betula papyrifera N 30 4.3 18 Estimated age

25 2.9 18

Populus tremuloides N 34 4.2 18 Estimated age

43 5.2 18
61

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age no. cones cones Tree notes Remarks

Feet Inches Years Percent

2. Bonanza Creek Pinus contorta P 19 3.9 15 1985 prov./fam

Experimental Forest var. latifolia 20 4.2 15 trees in buffe

20 3.7 15 2001; cone cr

24 4.7 15

23 3.8 15

25 3.8 15

4. Rosie Creek Pinus contorta P 22 4.5 16 50 60 1986 Universit

var. latifolia 17 3.6 16 3 study; few su

21 4.3 16 50 30

26 3.7 16 25 60

5. Rosie Creek Pinus contorta P 24 4.4 17 60 20 1985 Alaska D

var. latifolia 28 4.7 17 100 20 planting; alt

27.5 4.2 17 100 30

25.5 5.0 17 25 0

Picea glauca P 18 3.0 17 1985 Alaska D

16.5 2.4 17 planting; alte

15 2.2 17 var. latifolia

21. Delta Agricultural Larix sukaczewii/ P 32 5.2 17 Seed orchard 

Experiment Station L. sibirica 31 5.5 17

30 5.3 1730 4.5 17 

33 5.8 17

11. Red Fox Drive, Pinus contorta P 9 1.6 10 University of A

Tok, Alaska var. latifolia 9 1.0 10 1992 stockin

8 1.1 10

10 1.4 10

12 1.9 10

10. Tok Rifle Range Pinus banksiana P 16 3.4 13 1989 species tr

18 3.8 13

Larix sukaczewii/ P 18 3.1 13 1989 species tr

L. sibirica 22 3.6 13

21 3.2 13

Pinus contorta P 17 3.8 13 1989 prov./fam

var. latifolia 17 3.4 13
62Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

18. L. Viereck’s Larix sukaczewii P 70.5 10.6 36

Tree Farm 67.6 11.3 36

70.4 10.2 36

67 9.2 36

60.8 12.4 36

61 8.0 36

68 10.5 36

74 12.7 36

78 14.4 36 Tallest tree evaluated

67 11.7 36

Picea abies P 37 5.8 36

24 3.7 36

27 5.8 36

Abies sibirica P 31.8 6.1 36

46 5.4 36

Pinus sylvestris P 42 12.8 36

42 9.0 36

55. Alaska Tree and Pinus contorta P 37.5 7.4 25 30 0

Garden Center var. latifolia 37 8.5 25 100 5

40 6.5 25 100 5

36 6.5 25 50 20

36.5 6.3 25 50 10

7. Samuels Tree Pinus contorta P 26 6.2 20 300 10 1982 provenan

Farm, Delta var. latifolia 25 6.2 20 200 10

Junction 31 5.9 20 50 50

29 5.7 20 50 5

28 5.8 20 0

Pinus contorta P 25 6.1 18 300 10 1984 species tr

var. latifolia 25 4.8 18 200 10

21 4.0 18 50 50

Pinus contorta P 28 5.4 18 30 10 1984 provenan

var. latifolia 23 4.3 18 50 10

26 4.3 18 10 026 6.0 18 150 50

Larix sukaczewii/ P 27 4.5 18 1984 species tr

L. sibirica 27 4.8 18

29 4.3 18

31 4.7 18

Picea glauca P 14 1.9 18 1984 species tr

13 2.1 18

12 1.8 18

11 2.6 18
63

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

Betula papyrifera N 29 3.7 18

29 3.9 18

26 3.6 18

9.B. Swain’s plantings Pinus contorta P 23 4.3 14 100 2 4.5 mi Tanana 

var. latifolia 20 3.8 14 25 90 in 1988 (estim

20 4.7 14 100 75

21 4.6 14 50 15

Larix sukaczewii/ P 25 4.4 14 Trees climbed 

L. sibirica 28 4.5 14 cone collecti

28 5.2 14

26 5.3 14

23 4.6 14

8. Brann’s Tree Farm Pinus contorta P 21 3.9 18 0 1984 prov./fam

var. latifolia 18 3.7 18 30 50 (glacial outw

20 4.2 18 50 10

16 3.3 18 20 95

Larix sukaczewii/ P 23 4.9 18 1984 species tr

L. sibirica 20.5 4.2 18

Pinus banksiana P 16 3.5 18 75 10 1984 species tr

dominant tre

22. Alaska Division Pinus sylvestris P 66 9.4 48 3700 Airport W

of Forestry 59 7.5 48

Compound 59 8.4 48

61 7.6 48

Betula papyrifera N 56 7.4 48

58 6.7 48

60 5.6 48

64 7.8 48

62.5 8.4 48

Larix sukaczewii/ P 62 10.8 48

L. sibirica 60 11.6 48

61.5 18.8 48 Largest d.b.h. measured

59 13.4 48

58.5 12.5 48

6. Rosie Creek, site 2 Pinus contorta P 27 3.8 18 15 50 1985 “G” Spur 

var. latifolia 24.5 3.2 18 12 20 container lod

29 4.3 18 58 20

24.5 3.7 18 100 30

28 4.4 18 150 15
64Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

Betula papyrifera N 30.5 3.1 18 Some coppice 

33.5 4 18

32 4.1 18

35 5.6 18

Picea glauca P 19 2.8 18 Spruce and lo

18.5 2.5 18 (8 ft between 

16.5 2.6 18

20 2.5 18

6. Rosie Creek, site 1 Pinus contorta P 31 4.8 18 180 20 1985 “G” spur 

var. latifolia 28 4.5 18 9 0 superior to 1

34 4 18 50 8

34 4.1 18 80 20

Picea glauca P 18.5 2.4 18

17 2.3 18

22 2.6 18

19 2.3 18

Betula papyrifera N 41 4.3 18 Some trees ap

34.5 4.4 18 1983 Rosie C

31.5 4.5 18

37.5 4.3 18

Region II. Mat-Su Valley

34. Alaska Division of Pinus contorta P 20 5 20 20 50 Former Eagle 

Forestry Nursery var. latifolia 1992 estimat

survivors am

open birch a

Pinus sylvestris P An estimated 

birch and sp

24. G. Holmberg Larix sukaczewii/ P 24 5 11 A 1991 plantin

Tree Farm L. sibirica 27 4.7 11 Wasilla

24 3.8 11

27 3 1127 3.8 11

25. G. Holmberg Larix sukaczewii/ P 75 16.5 50 Surviving tree

Tree Farm L. sibirica 70 13.2 50 overstory in 19

65 9.1 50

26. G. Holmberg Larix sukaczewii/ P 34 5.4 11 A 1991 plantin

Tree Farm L. sibirica 32 4.8 11 Wasilla

29 4.8 11
65

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

27. Houston City Pinus sylvestris P 21 5.9 15 Site was grade

Educational Park 20 5.2 15 soils are grav

17 4.9 15

Larix sukaczewii/ P 20 3.3 15 An estimated 

L. sibirica 21 3.9 15 subsoil in ~1

20 3.5 15

21 3.6 15

Pinus contorta P 14 3 14 100 40 A typical dom

var. latifolia no other tree

in ~1988

Pinus banksiana P Fourteen tree

equivalent to 

28. Division of Pinus contorta P 24 4.5 15 200 70 Recently relea

Forestry’s Houston var. latifolia 24 3.4 15 20 25

Demonstration Forest

Pinus sylvestris P 18 3.3 15 Planting date 

18 3.7 15 planted with 

18 3.5 15 released from 

29. Wasilla Veterinary Larix sukaczewii P 42 10.3 14 Seed source: J

Clinic, Parks Highway 40 8.1 14 planted as 1-

42 8.1 14

40 8.9 14

23. Mat-Su College Larix sukaczewii P 42 6.7 17 Planted as 1-1 

Arboretum 36 5.5 17

35 6.6 17

33 6.4 17

Pinus contorta P 25 4.9 17 Cone product

var. latifolia 25 5.7 17

27 6.0 17

30. Thom’s Point Pinus sylvestris P 23 5.6 16 Dense (6 × 6 f

Mackenzie Farm 25 5.7 16

33 5.8 16

31. Trytten’s Pinus contorta P 12 2.5 10 To buffer farm 

hedge row var. latifolia Point; trees o

Pinus sylvestris P 12 2.5 10Larix sukaczewii P 18 2.5 10
66Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

32. Mackenzie Creek Pinus contorta P 23 4.9 20 Few cones, not assessed 1983 Bureau o

Airstrip Road var. latifolia 25 4.2 20 planting in b

19 3.2 20 logging; a we

22 4.5 20 <20 1 

33. Gonder Homestead, Pinus sylvestris P 46 9.9 39 1963 garden p

Big Lake, Alaska 49 9.9 39

50 9.6 39

47 10.3 39

Pinus sylvestris P 40 14.5 39 1964 transplan

40 13.2 39

40 11.2 39

50 14.1 39

Abies balsamea P 39 5.8 35 1968 planting 

31 4.8 35 east of home

48 8.3 35

38 6.2 35

Abies balsamea P 39.5 6.4 27 “Back-40” plo

35 5.1 27 about 1975

37.5 5.4 27

35 5.4 27

Picea abies P 39 6.8 35 Estimated 196

29 4.6 35 ridge; intra-s

36 4.3 35 are severe

31 4.5 35

50 8.8 35

Pseudotsuga P 28 5.3 35 Estimated 196

menziesii 34 8.0 35 ridge; severe 

27 5.3 35 competition; 

32 4.8 35

Pinus contorta P 20 4.7 16 400 0 Estimated 198

var. latifolia 25 4.4 16 150 20 slope of east 

23 4.4 16 50 20

Pinus contorta P 30 11.5 25 600 10 Estimated 197

var. latifolia 27 9.3 25 1000 60 Yukon seed 

27 9.3 25 400 10 with large bu
67

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

36. Kingsberry Tree Pinus contorta P 20 3.3 15 5 40 Estimated 500 

Farm, Talkeetna var. latifolia 21 3.4 15 40 25

19 3.3 15 25 20

Pinus sylvestris P 17.5 4.2 17 Estimated 200 

18.5 3.7 17

18.5 3.2 17

35. Pokorny Tree Farm, Pinus contorta P 22 3.8 12 10 0 A large tree fa

Mastadon Road, var. latifolia 24 4.6 12 5 20 initiated in 1

Talkeetna 20 3.3 12 0

23.5 4.6 12 30 0

22.5 3.2 12 0

Pinus sylvestris P 15 4.3 12 Moose killed Larix sukaczewii/ P 23 5.2 12 Trees were me

L. sibirica 18.5 4.8 12

28 4 12

Region III. Kenai Peninsula–Cook Inlet

37. Division of Pinus contorta P 36 10.5 24 450 50 Forty-two tree

Forestry Kenai- var. latifolia 34 8.2 24 450 10

Kodiak Area Office 34.5 8.1 24 450 5

41. Arc Loop Road, Pinus contorta P 36 11.3 29 500 50 Sandy loam so

Soldotna var. latifolia 32 9.3 29 400 50 transplantin

37 11 29 500 25

44. Strawberry Road, Pinus contorta P 39 7.3 24 100 60 Planted in a m

Soldotna var. latifolia 34 8.9 24 400 70

31 6.7 24 200 40

32 5.5 24 50 10

21 7 24 200 20

43. Wynkoop Larix sukaczewii/ P 45 12.4 26 Planted in a ga

L. sibirica

46. Lake Street, Pinus contorta P 15 3.7 13 0 A back-yard p

Soldotna var. latifolia 15 3.1 13 30 90

12 2.1 13 5 100

11 1.7 13 0

14 3 13 7 86
68Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

38. Division of Forestry Larix sukaczewii/ P 35 6.2 24 Small planting 

Kenai-Kodiak Area L. sibirica 34 6.5 24

Arboretum

Larix dahurica P 30 6.2 24

26 5.9 24

31 4.0 24

Pinus sylvestris P 18 2 24

26 2 24

22 2 24

39. Tustumena power Larix sukaczewii/ P 29 6.1 24 Species plante

line L. sibirica 24 5 24

Pinus contorta P 27.5 6.8 19 75 25 Groups 1 and 

var. latifolia 19 5.3 19 20 10

31 6.8 19 100 10

27 7.7 19 200 20

32 7.5 19

Pinus contorta P 28 7.2 24 300 70 Groups 9 and 

var. latifolia 31 7 24 100 20

30 8 24 400 30

42. Moose Pass Pinus contorta P 12 2 13 1 0 Old burn; seve

var. latifolia 200 seedling

Larix sukaczewii/ P 12 1 13 Typical dominant tree 10 survivors o

L. sibirica

47. Falls Creek Road Larix sukaczewii/ P 16 2.8 14 Estimated 500 

L. sibirica 19 3.3 14 beetle salvag

18.5 3.1 14 into the und

20.5 3.6 14

19.5 3.5 14

Pinus sylvestris P 12 2 14 Average dominant ~200 survivor

Scots pine

48. Kelcher Pinus contorta P 33 12.6 25 50 0 Stock from an 

Seaside Farm var. latifolia and 32 10.2 25 20 0 Kachemak B

var. contorta 30 12 25 not counted

27 14.4 25 100

49. East Hill Road, Pinus contorta P 20 13.9 25 20 Roadside open grown Wildlings tran

Homer var. latifolia 25 11.6 25 20 Highway, Yu
69

Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

50. Homer Pinus contorta P 6 0.9 20 0 Planted on an 

Demonstration var. latifolia 5.5 0.6 20 0 understory

Forest 6.5 0.8 20 0

51. Milepost 54.1, Pinus contorta P 52 7.6 36 0 Rooted from a 

Seward Highway var. latifolia — 5.8 36 0 Severely malformed birch-spruce 

— 3.9 36 0 Severely malformed

52. Tyonek, 2000 Pinus contorta P 32 6.9 20 400 30 Division of Fo

Road Northwest var. latifolia 37 7.9 20 200 spacing in 19

27 8.5 20 200

32 7.8 20 200

39 8 20 100

52. Tyonek, 1000 Pinus contorta P 23 5.5 27 300 10 Division of Fo

Road West var. latifolia 25 6.9 27 100 5 of ~35 surviv

30 5.2 27 100 40 the late 1980

28 5.3 27

40. Stingley North Pinus contorta P 18.6 4.1 25 25 50 North Fork A

Fork Ranch var. latifolia 22.2 4.7 25 25 50 planted unde

22 5.1 25 25 50 6 ft spacing; 

22.1 4.5 25 25 50 2002; only 2 

were filled

45. Funny River Pinus contorta P 26 6.2 15 400 1

Recreation Site, var. latifolia 23 5.3 15 200 5Soldotna 23 4.3 15 10 100

54. Hermansen, Pinus contorta P 31 12.6 33 Transplanted 

Homestead, var. latifolia 26 13 33 Highway; ma

Cohoe Loop Road (not assessed

Region IV. Copper River Valley

12. Tazlina Pinus contorta P 24 4.5 18 20 25 Planted in 198

Experimental var. latifolia 23 4 18 0 injuries; con

Planting 21.5 4.5 18 42 25

24 4 18 50 80

Picea glauca P 20 4.1 18 Planted in 198

19 3.5 18

20 3.7 18

22 5 18
70Table 10—Spreadsheet summaries of sites and species data (continued)

Estimated Open

Site Species Statusa Height D.b.h. Age No. cones cones Tree notes Remarks

Feet Inches Years Percent

13. Luebke Planting Pinus contorta P 17 3.6 16 10 0 Seedling source: Copperville, 1

var. latifolia 16 2 16 30 20 Alaska State Nursery

20.5 4.7 18 100 20 Seedling source: 

Alaska State Nursery

20.5 4.3 18 3 0 Seed source: Alaska 

Highway before 

Whitehorse

14. Zerbinos Planting Pinus contorta P 9 1.7 15 0 Rose Avenue, 

var. latifolia 14 2.3 15 20 90 after gravel e

16 2.3 15 0 subsoils; ~ 10 

13 2.9 15 30 20 

12 2.7 15 50 20

15 2.6 15 15 100

15. Old Edgerton Pinus contorta P 17.5 3.4 18 Planted in 198

Highway Provenance var. latifolia 18.5 3.3 18 commercial 

Experiment 17.5 3.2 18

18.5 3.7 18

21.5 4.1 18

Populus N 24 3 18 From coppice 

tremuloides 22 2.2 18

20 2 18

27 3.8 18

aP = Planted; N = Natural regeneration.
71

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

Regeneration Data and Notes Summarized from Spreadsheets

Region I. Interior Alaska—

1. T-field Arboretum: 

 (1) Larix sukaczewii, Raivola strain—06/04/02:

 No. of offspring: 175 (Additional holes where 3 trees were removed)

 Two trees were found on east side of plot. All others were observed on 

 the north side 

 Mean height: 64 cm; StDev: 82.6 cm; Range: 8 to 390 cm 

 Mean age: 8 years; StDev: 3.4 years; Range: 3 to 17 years

 Offspring stocking (density): 850/acre (810 seedlings/acre within 25 ft 

 of seed parents) 

 (2) Larix sukaczewii, Ural Mountain provenance—06/05/02:

 No. of offspring: 3 (25 ft northwest of Ural Mountain plot. Offspring could be

 from either the Ural Mountain or Raivola plot)

 Mean height: 132 cm; StDev: 163.6 cm; Range: 22 to 320 cm

 Mean age: 9 years; StDev: 3 years; Range: 5 to 12 years

 (3) Pinus contorta var. latifolia, 1958 Whitehorse provenance:

 No. of offspring: 6 (On east side of plot. Two additional progeny removed 

 from Arboretum)

 Mean height: 233 cm; StDev: 307 cm; Range: 51 to 853 cm

 Mean age: 11 years; StDev: 4.6 years; Range: 6 to 19 years

 (The 6-year-old and 70-cm-tall seedling is east of the jack pine (JP) plot and is

 probably a JP or JP X LP hybrid; the 19-year-old seedling is 175 ft east of the

 Whitehorse provenance, and may have been planted)

 (4) Teslin, Yukon Pinus contorta var. latifolia provenance—06/05/02:

 No regeneration with the possible exception of a 105-cm-tall, 12-year-old

 progeny that was observed under the crown and 4 ft west of the Teslin

 provenance. 

 (5) Pinus banksiana, Fort Simpson, NWT provenance:

 No Regeneration with exception of the 6-year-old jack pine or jack pine 

 hybrid offspring described under (3) above. The seedling is ~20 ft from its

 likely seed parents. 

 (6) Pinus contorta var. latifolia, 1974 provenance study, rep 1 and 2: No regeneration.

 (7) Pinus banksiana, 1974 provenance study, Petitot River, BC: No regeneration.

 (8) For native Picea glauca regeneration outside and inside (understory) the 1974

 Pinus contorta var. latifolia provenance trial and estimated age (years), see 

 Table 10.

2. Offspring of a Larix sukaczewii/L. sibirica seed orchard at the Delta 

 Agriculture Experimental Farm: 

 Average stocking under 10 seed parents was 289 ± 193 offspring per acre.

 At the edge of an open meadow 33 ft (10 m) east of the seed orchard stocking 

 was 40 offspring per acre (100/ha). 

3. Georgeson Botanical Garden:

 More than 126 offspring of Larix sukaczewii/L. sibirica were counted on mineral

 soil and in the grass within 80 to 90 ft of four, 20- and 30-year-old seed parents.

 The offspring ranged from a few inches to 3.9 ft (120 cm) tall and 3 to 5 years old.

 Average Larix sukaczewii/L. sibirica stocking, age and height were 2,400 offspring

 per acre (5,928/ha), 4.2 ± 0.8 years, and 30 ± 11 in (75 ± 29 cm) tall, respectively.

 With few exceptions, the offspring were repeatedly mowed.
72

GENERAL TECHNICAL REPORT PNW-GTR-664

4. Pinus contorta var. latifolia regeneration at Kratzer’s Tree Farm, Nenana:

 (1) 1984–85 Pinus contorta var. latifolia plantings produced five 3 year-old 

 offspring on exposed mineral soil.

 Seedling height averaged 12 in (32.5 cm). Native Picea glauca seedlings on the 

 same site averaged 17.5 in (44.5 cm) tall at 4 and 5 (ave. 4.25) years old.

 (2) Ninety-six trees per acre from 1983 Pinus contorta var. latifolia plantings 

 produced 230 1- to 6-year-old offspring/acre on cultivated loess soils, 

 including 130 offspring lifted for transplanting. Picea glauca also planted in 

 1983 produced 4,856 1- to 5-year-old offspring per acre. The offspring grew 

 to a mean height of nearly 2 in (4.25 cm) at 1 to 5 (ave. 2.5) years of age.

5. Brann’s 1984 Pinus contorta var. latifolia provenance/family trial, Delta:

 One 4-year-old, 8-inch (20 cm)-tall offspring was noted. 

6. Viereck’s Tree Farm, Red Fox Drive, Fairbanks:

 (1) Ten 36-year-old Larix sukaczewii produced 1,110 surviving offspring per acre.

 Tops were mowed and 20 were lifted for transplanting. Other noteworthy 

 statistics:

 Including transplants, stocking was 1,450 offspring/acre (3,582/ha) within

 40 ft of the seed parents.

 The most distant offspring was 250 ft from the nearest seed parent. It was

 40 ft tall, 3.7 inches in d.b.h., and ~15 years old.

 The largest offspring was transplanted in 1984 from the 1981 seed crop. 

 It was 45 ft tall and 6 inches in d.b.h.

 (2) Two 36-year-old Abies sibirica produced three, 4-year-old offspring that 

 were 36 ft from their parents.

7. Near’s 1975 Pinus contorta var. latifolia planting, 1566 LaRue Drive, Fairbanks: 

 One 5-year-old offspring that was 30 in (77 cm) tall regenerated 30 ft from the 

 nearest possible seed parent. No other offspring were found.

8. At the former BLM Office, 3700 Airport Way, Fairbanks: Ten Larix sukaczewii

 offspring were observed in 8 m2 of garden area at the base of the largest tree. 

 Offspring totaled 5,060 per acre (12,498/ha), 3 to 4 years from seed. The seed-

 lings were distributed as far as 4 chains (260 ft) from their seed parents.

Region II. Matanuska-Susitna Valley—

1. Regeneration from the Gonder plantings, Big Lake:

 (1) The survivors of ~100 Abies balsamea trees planted in the “Back 40” 

 (planting 1) in 1975 produced 4- to 7-year-old offspring <100 ft from their 

 seed parents. The stocking estimated from six, 1-m2 plots was 30,300 

 ± 10,462 offspring per acre.

 (2) Stocking of Abies balsamea offspring from a 1968 planting 2 on “Wood 

 Road or Trail” was 2,428 ± 5,429 seedlings per acre. The offspring were 

 found on mineral soil less than 50 ft from their seed parents.

 (3) Pinus sylvestris stocking from a 1964 roadside to Homestead transplanting:

 Offspring per acre (per ha) in the understory estimated from six 1-m2 plots:

 Pinus sylvestris 37,700 (93,119)

 Betula papyrifera 28,193 (69,637)

 Both species 65,893 (162,756)
73

Field Survey of Growth and Colonization of Nonnative Trees on Mainland Alaska

 Estimated offspring per acre (per ha) from eight, 1-m2 plots in a mowed field

 that extended 164 ft to undisturbed woodlands:

 Pinus sylvestris 5,657 (14,017)

 (4) Pinus contorta var. latifolia stocking within 33 and 16 ft of seed parents 

 in a mowed field at the new (1977) garden site:

 Offspring 11,113/acre (27,500/ha) within 33 feet (10 m), and 

 16,150/acre (39,890/ha) within 16 ft (5 m) of their 

 seed parents. 

 (5) Pinus sylvestris regeneration at the old (1963) garden site: 

 Seedlings per acre (per ha) on about 800 ft2:

 Pinus sylvestris 500 (1,235) offspring were up to 8 ft tall and 

 12 years old.

 Picea glauca 2,500 (6,175) offspring were up 12 ft tall and 

 14 years old.

 Both species 3,000 (7,410)

2. Pinus contorta var. latifolia stocking on mineral (cultivated) silt loam soil

 within 19 ft (6 m) of 15-year-old parents at Kingsberry’s Tree Farm, Talkeetna: 

 Seedlings/acre (per ha): 661 (1,500). No seedlings were observed beyond 

 19 ft (6 m) of the seed parents.

3. Regeneration in the Houston Educational Park:

 (1) Larix sukaczewii/ L. sibirica stocking of 5-in seedlings on exposed gravel 

 to within 75 ft (23 m) of their 15-year-old parents: 

 Seedlings/acre (per ha): 28,327 (69,968). No seedlings were observed beyond

 75 ft (23 m) of the seed parents.

 (2) Pinus contorta var. latifolia regeneration on gravel soils within 10 ft (3 m) of 

 14-year-old seed parents:

 Seedlings/acre (per ha): 16,150 (39,890). Only one 5-in seedling was observed 

 beyond 25 ft (7.5 m) of the seed parents.

 (3) Pinus banksiana or possibly Pinus contorta var. latifolia seedlings were

 observed under one of fourteen 14-year-old Pinus banksiana trees. Five

 seedlings were counted under one tree.

 (4) No cones or regeneration were observed for seven 15-year-old Pinus 

 sylvestris trees.

Region III. Kenai Peninsula–Cook Inlet—

1. Division of Forestry, Kenai-Kodiak Area Office: Regeneration under Pinus

 contorta var. latifolia, and on a road bank 6.6 ft (2 m) from the crowns of the

 Pinus contorta var. latifolia plantings:

 Trees per acre (ha) from 22, 1-m2 plots each under Pinus contorta var. latifolia

 crowns and on a road bank:

 Under Two meters

 crowns from crowns Average 

Pinus contorta var. latifolia 2,024 (5,000) 4,626 (11,428) 3,325 (8,213)

Picea xlutzii 368 (909) 2,506 (6,190) 1,437 (3,549)

Betula papyrifera var. kenaica 184 (454) 578 (1,428) 381 (941)

All species 2,576 (6,363) 7,711 (19,047) 5,144 (12,706)
74

GENERAL TECHNICAL REPORT PNW-GTR-664

2. Regeneration estimated from three, 1-m2 plots on sandy loam soils within 

 100 ft south of the Arc Loop Road Pinus contorta var. latifolia planting in 

 ~1972 (29 years):

 Seedlings per acre (ha)

Pinus contorta var. latifolia 1,348 (3,330)

Picea xlutzii: 6,744 (16,658)

Betula papyrifera var. kenaica 37,770 (93,292)

Populus tremuloides 4,046 (9,994)

Populus balsamifera 5,395 (13,326)

All species 55,303 (136,600)

 Six pine seedlings to 22 inches (55 cm) tall on disturbed road bank, 

 north side of plantings. 

 No regeneration on grass under the pine parents.

 Thirty pine seedlings lifted for transplanting on south side of 

 the plantings.

3. Wynkoop’s L. sukaczewii/L. sibirica on Strawberry Road, Kenai Alaska:

 Eight seedlings/m2 or 32,000 per acre (79,040/ha) were counted in a garden site

 under the seed parent. No seedlings were observed on exposed sandy (roadside) 

 soils beyond 70 ft (21 m) of the seed parent.

4. Pinus contorta var. latifolia regeneration in an open meadow south of Wynkoop’s

 L. sukaczewii/L. sibirica and west of Strawberry Road, Kenai Alaska:

Seedlings per acre Seedlings per acre

(ha) 131 ft (41 m) (ha) 40 ft (12 m) 

from nearest P. from nearest P. 

contorta seed parent contorta seed parent

Pinus contorta var. latifolia 100 (247) 800 (1,976)

Picea xlutzii 3,000 (7,410) 7,000 (17,290)

Betula papyrifera var. kenaica 500 (1,235) 0

Populus tremuloides 100(247) 200 (494)

Populus balsamifera 500 (1,235) 800 (1,976)

All species 4,200 (10,374) 8,800 (21,736)

 Over the entire meadow, an estimated 120 Pinus contorta var. latifolia

 offspring per acre (296/ha) were observed within 131 ft (41 m) of the 

 nearest seed parents.

5. Division of Forestry’s Kenai-Kodiak Area Office Weather Station, 

 Soldotna Alaska: 

 One 37-in-tall (95-cm-tall) Pinus contorta var. latifolia seedling from the 1995

 seed year was found one chain from the nearest seed parent. Seven Pinus

 contorta var. latifolia seedlings were observed overall. Two were found in a 4-in

 moss layer in an open (thinned) Picea mariana understory.

6. Pinus contorta var. latifolia seedlings in the 82-3 planting on three acres, Tyonek:

 Four 12- to 26-in (30- to 65-cm) tall seedlings, 4 to 6 years from seed were 

 observed in moss and herbaceous vegetation.

7. Pinus contorta var. latifolia regeneration at the Funny River Campground, 

 Soldotna:

 One 3-year-old, 4-in (10-cm) tall seedling was found at the base of a 15-year-old

 seed parent.
Pacific Northwest Research Station

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