IMPACT OF MOOSE BROWSING ON FOREST REGENERATION
IN NORTHEAST VERMONT

Haley A. Andreozzi1, Peter J. Pekins1, and Matt L. Langlais2

1Department of Natural Resources and the Environment, University of New Hampshire, Durham, New
Hampshire 03824, USA; 2Department of Forests, Parks & Recreation, St. Johnsbury, VT 05819, USA

ABSTRACT: Moose (Alces alces) play an important role in the ecological and economic resources of
northern New England, a landscape dominated by commercial forests. This study measured the impact
of moose browsing on forest regeneration in Wildlife Management Unit E1 in northeastern Vermont
where moose density was considered high in the 1990–2000s. We surveyed 37 clearcuts categorized
into 4 age classes (3–5, 6–10, 11–15, and 16–20 years old). The stocking rate (stems/plot) of commer-
cial species ranged from 74–76% in the 3–5, 6–10, and 11–15 year age classes, increasing to 86% in
the 16–20 year age class. The proportion of plots containing a commercial tree without severe damage
was above the accepted threshold stocking level of 40–60% in all age classes. The proportion of plots
containing a commercial hardwood stem declined with increasing age class; the opposite occurred with
softwood stems indicating a possible shift from hardwood- to softwood-dominated stands from selec-
tive browsing pressure. Height of 11–20 year old stems was less than in New Hampshire, indicating
that growth was possibly suppressed in Vermont due to higher moose density. Overall, browsing
was not considered a major problem based upon stocking rates. Further study is warranted to evaluate
whether compensatory growth occurs in response to reduced browsing as forests age and/or moose
population density declines.

ALCES VOL. 50: 67–79 (2014)

Key words: Alces alces, browsing, clearcut, damage, moose, New England, regeneration, stocking.

Moose (Alces alces) populations have
experienced a regional increase in northern
New England over the last several decades,
making them an increasingly valuable wild-
life resource. They play an important role
ecologically and economically in Vermont,
with 78% of the state open to regulated
moose hunting and 406 hunting permits
issued statewide in 2011 (VTFW 2008,
2011). With forests also covering 78% of
Vermont's landscape, the state generates
over $1.5 billion annually from forest-based
manufacturing and forest-related recreation
and tourism (NEFA 2007). The majority
of forestland, 4 million acres, is owned
privately or by timber investment manage-
ment organizations; local, state, and fed‐
eral government owns ∼19% (919,440
acres) (NEFA 2007). Forest and wildlife

management aimed at sustainable forest pro-
duction is critical for the long-term stability
of both Vermont's economy and moose
population.

With adult moose weighing 300–600 kg,
substantial browse is required to maintain
such large body size (Bubenik 1997), esti-
mated at daily dry matter intake of 2.8 kg/
moose/day in January (Pruss and Pekins
1992). Moose have the ability to substan-
tially alter plant communities and are cap-
able of damaging woody plants (Renecker
and Schwartz 1997); repeated browsing can
suppress height growth and recruitment of
saplings into the canopy (Risenhoover and
Maass 1987). Moose browsing has the cap-
ability to affect the structure and dynamics
of forest ecosystems over the long-term
(McInnes et al. 1992), which has important

67



implications for the management of forests
where moose populations are regulated.
Moose show preference for forage in clear-
cut and early-successional habitat that is
typical of the commercially managed forests
of the northeast (Thompson et al. 1995, Scar-
pitti et al. 2005). For example, productive
moose habitat in New Hampshire was linked
directly to the early successional forage cre-
ated by commercial forest harvesting and
early-successional browse is a dietary com-
ponent year-round (Scarpitti et al. 2005,
Scarpitti 2006). Clearcuts 5–20 years old
provide suitable early winter habitat, as
regenerating hardwood and softwood species
provide both browse and cover for moose
(Thompson and Stewart 1997). While the
impact of moose browsing on forest regen-
eration has received substantial attention
elsewhere, little attention has been paid to
the potential and actual effects in northern
New England (Pruss and Pekins 1992,
Scarpitti 2006, Bergeron et al. 2011).

In order to manage moose and forest
resources with respect to moose density and
damage to regeneration, it is important to
have extensive ecological knowledge of the
relationships among moose, the ecosystems
they inhabit, the plants they use as forage
(Edenius et al. 2002), and the associated
impacts on forest production such as timber
quality impairment. As moose populations
have increased in northern New England,
land managers have implied that a relation-
ship exists between high population density
and reduced forest regeneration in clearcuts.
On Isle Royale, McInnes et al. (1992) found
that moose browsing affected the structure
and dynamics of forest ecosystems on a
long-term scale; however, in larger land-
scapes such impacts are usually more loca-
lized and often relate to high seasonal density.

In northern New Hampshire, Bergeron
et al. (2011) evaluated the impact of brows-
ing on the regeneration of commercial tree
species in 3 regions with different moose

population density (0.26–0.83 moose/km2).
While regeneration of commercial trees was
not considered a regional problem at any
density, specific clearcut sites with low
regeneration were found adjacent to tradi-
tional moose wintering areas. It was pre-
dicted that such sites could change from
hardwood to softwood dominance over
time (Bergeron et al. 2011).

By the early 2000s, there was anecdotal
evidence that the moose population in north-
eastern Vermont, specifically wildlife man-
agement unit (WMU) E, was causing
measurable damage to forest regeneration;
moose densities in WMU E were thought to
be well over 1.5 moose/km2 (4 moose/
mile2) (C. Alexander, VTFW wildlife biolo-
gist, pers. comm.). To achieve the desired
population level, hunting permit numbers
were dramatically increased by the Vermont
Department of Fish and Wildlife (VTFW)
from 440 to 833 permits in 2004, when it
was believed moose had approached their
biological carrying capacity (VTFW 2008).
The number of hunting permits rose to
1046 in 2005 and continued to increase
until 2009, when 1223 permits were issued
statewide in an effort to accelerate popula-
tion reductions to protect forest habitat.
By 2008, the population density was
approaching the goal set by the 10-year
moose management plan (0.7 moose/km2

[1.75 moose/mile2]) and the number of
permits was reduced to 765 in 2010 and
405 in 2011. In response, this study was
designed to evaluate the impact of moose
browsing on the regeneration of commer-
cial tree species in WMU E1 in northeast
Vermont by conducting qualitative assess-
ments of damage in clearcuts between
3–20 years of age.

METHODS
Study Area

The study area was located in north‐
east Vermont and encompassed all of

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BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



VTFW WMU E1, covering an area of
682 km2 bordered by New Hampshire and
Quebec (Fig. 1). Elevation ranges from
∼250–1,130 m, and it is dominated by
maple (Acer saccharum, A. pensylvanicum,
A. rubrum) and birch (Betula alleghaniensis,
B. papyrifera) hardwoods, and coniferous
stands of balsam fir (Abies balsamea) and
red spruce (Picea rubens.) While heavily
forested, timber harvesting is common
throughout as the majority of the land is pri-
vately owned and commercially harvested
(NEFA 2007). The 2011 moose density was
estimated at 0.77 moose/km2 (1.96 moose/
mi2) based on a rolling 3-year average of
moose sightings by early winter (November)
deer hunters, and was previously estimated
in 2010 as 0.93 moose/km2 (2.41 moose/
mile2) based on aerial surveys (Millette et al.
2011).

Field Measurements
Regeneration surveys were performed in

June 2012 to measure the impact of moose
browsing on forest regeneration in clear-
cuts 3–20 years old (Leak 2007, Bergeron
et al. 2011). Clear-cuts were separated into
4 age classes (3–5, 6–10, 11–15 and 16–20
years old) in order to assess temporal
changes during both the period of typical
browsing (0–10 years) and at least 10 years
post-browsing (11–20 years). In each age
class, 8–11 clear-cuts were located using aer-
ial photography; each was a minimum of
4.1 ha (10 acres) and a maximum of
16.2 ha (40 acres) in size to reflect the typical
range in size of clear-cuts in the region
(M. Langlais, Vermont Department of For-
ests, Parks & Recreation County Forester,
pers. comm.). In certain cases, clear-cuts
>16.2 ha were used to achieve appropriate
sample sizes within an age class; a section
≤16.2 ha was surveyed.

Small plot surveys (milacre, ∼2.3 m dia-
meter circle) were evenly spaced on equidi-
stant transects throughout each clear-cut
(Fig. 2). In each milacre plot, the dominant
stem (tallest tree) was recorded as a commer-
cial or non-commercial tree species. If the
dominant stem was non-commercial, the
plot was searched for the presence of com-
mercial species; commercial species
included yellow and white birch, sugar and
red maple, American beech (Fagus grandifo-
lia), aspen (Populus spp.), black cherry (Pru-
nus serotina), balsam fir, red and black
spruce (Picea mariana), and tamarack (Larix
laricina). Stem damage was assessed on a
qualitative basis as fork, broom, or crook
(Fig. 3). The height of the damage above or
below breast height (approximately 1.4 m)
was recorded, as well as the number of forks
and crooks, and the severity of crooks based
on angle. Light crooks were those ≤30°,
moderate crooks were those 30–60°, and
severe crooks were those ≥60° from the
dominant stem. The relative height of the

Fig. 1. The location of the study area in Vermont
used to assess the impact of moose browsing
on forest regeneration, 2012. The area included
all of WMU E1 in northeast Vermont.

ALCES VOL. 50 ANDREOZZI ET AL. – BROWSING AND FOREST REGENERATION

69



dominant stem was estimated to the nearest
foot when <3.05 m (10 ft), or as ≥3.05 m.

Data Analysis
Broomed stems and multiple forks

above breast height were considered browse
defects indicative of a severely damaged
tree; otherwise, damage was considered light
or moderate. Trees with lesser damage are

expected to recover during future growth
(Switzenberg et al. 1955, Carvell 1967,
Trimble 1968, Jacobs 1969). Stems with sin-
gle forks above breast height, or multiple
forks either above or below breast height
were considered to have moderate damage.
Stems with a single fork below breast height
or crooks were considered to have light
damage. A fully stocked stand (average den-
sity for undisturbed stand) at 80 years was
assumed if a minimum of 40–60% of plots
(threshold) contained a dominant commer-
cial stem without severe damage (Leak et al.
1987). To evaluate relative height between
age classes and further assess browse impact,
comparisons were made of the proportion of
plots containing a dominant commercial
stem ≥3.05 m height without severe damage,
as vegetation ≥3.05 m was presumed to be
above the typical height of moose browsing
(Bergström and Danell 1986).

Temporal comparisons were made to
assess if younger age classes with high initial
browse pressure recover to fully stocked
stands after 10–15 years. Analysis of var-
iance (ANOVA) and pairwise Tukey's test
were used to look for differences in browse
damage between clear-cuts and age classes.
Analyses were performed with Systat v. 13.
Significance for all tests was assigned a

Fig. 2. Example of the sampling design used to
measure browse damage in clearcuts in north-
east Vermont, summer 2012. Equidistant
transects were established upon which 100–
400, 2.3 m diameter plots were established to
measure the presence of dominant commercial
stems, stem quality, and relative height;
modeled after Bergeron et al. 2011.

Fig. 3. The 3 qualitative browse categories used to describe browsing damage
of dominant stems in milacre sample plots (Bergeron et al. 2011).

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BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



priori at α = 0.05. Results are presented
throughout as ± SE.

RESULTS
A total of 37 clearcuts were surveyed:

11, 8, 8, and 10 in the 3–5, 6–10, 11–15,
and 16–20 year age classes, respectively.
There were 1709, 1291, 1442, and 1585
milacre plots surveyed in the 4 age classes,
respectively. Stocking rate of commercial
trees (stems/plot) was high in all age classes,
and increased with age class (Table 1); it ran-
ged from 74–76% in the 3–5, 6–10, and 11–
15 year age classes, increasing to 86% in the
16–20 year age class. The proportion of
commercial trees with severe damage was
low overall, with <10% damaged severely
in all age classes except in the 16–20 age
class (11%, Table 1).

The proportion of plots containing a
commercial tree without severe damage
was above the defined threshold stocking
level of 40–60% in all age classes (Table 1,
Fig. 4), ranging from 67–68% in the 3–5,
6–10, and 11–15 year age classes, and
increasing to 75% in the 16–20 year class.
The proportion of dominant commercial
trees ≥3.05 m without severe damage
increased with age class with 1, 25, and
39% in the 6–10, 11–15 and 16–20 year
age classes, respectively. The proportion of
plots containing a commercial hardwood
stem declined with age class, averaging 62,
51, 43, and 40% in the 4 age classes, respec-
tively. Conversely, the proportion of plots
containing a commercial dominant softwood
stem increased with age class, averaging 12,
24, 33 and 46% in the 4 age classes, respec-
tively (Fig. 5). The highest stocking rates
(>80%) were restricted to softwood-domi-
nated stands. The majority of plots with a
dominant non-commercial stem also con-
tained commercial stems (70–81% across
age classes).

The stocking rate of dominant commer-
cial trees was lower (P = 0.02) in the 3–5

year age class than in the 16–20 year age
class, although stocking rate was above the
threshold stocking level in all age classes.
The proportion of dominant commercial
hardwoods was higher (P = 0.014) and the
proportion of dominant commercial soft-
woods lower (P = 0.015) in the 3–5 year
age class than in the 16–20 year age class.
The proportion of plots beyond browse
height (≥3.05 m) and without severe damage
in the 6–10 year age class was lower than the
11–15 year (P = 0.022) and the 16–20 year
age classes (P < 0.001).

At least 3 commercial species accounted
for ≥50% of the species composition within
each age class (Table 2). The majority of
these species were classified with light
to no damage, and the proportion of non-
commercial species declined as age class
increased (Tables 1 and 2). The proportion
of dominant commercial stems classified as
hardwood declined with age class, averaging
83 ± 7.6, 69 ± 8.5, 58 ± 8.5 and 49 ± 7.2% in
the 4 age classes, respectively; the opposite
occurred with the proportion of dominant
commercial stems classified as softwood
that averaged 17 ± 7.6, 31 ± 8.5, 42 ± 8.5,
and 51 ± 7.2%.

Red maple and yellow birch accounted
for 24 and 20% of total species composition
in the 3–5 year age class; no other commer-
cial species accounted for more than 6%. In
the 6–10 year class, red maple, balsam fir,
and yellow birch accounted for the highest
proportion of species composition (14–16%
each) and in the 11–15 year age class, these
3 species accounted for 11–17% each, and
red spruce 11%. Red maple, balsam fir, and
red spruce accounted for the greatest propor-
tion of dominant commercial stems (21–23%
each) in the 16–20 year age class; yellow
birch fell to 6% (Table 2).

DISCUSSION
Overall, the impact of moose browsing

on the regeneration of commercial tree

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71



Table 1. Summary values indicating the stocking of commercial tree species, stocking of commercial trees
with and without severe damage, the proportion of commercial trees ≥3.05 m in height without severe
damage, and the proportion of dominant commercial hardwood and softwood stems in clearcuts in
northeastern Vermont, 2012. Rows with the same letter within columns are not statistically different
(P > 0.05).

Age
Class

Stocking rate
of dominant
commercial
trees (%)1

Stocking rate
of dominant
commercial
trees w/o
severe

damage (%)2

Stocking rate
of dominant
commercial

trees w/ severe
damage (%)3

Proportion of
dominant
commercial
trees w/o

severe damage
and ≥3.05 m

tall (%)

Proportion of
dominant
commercial

hardwoods (%)

Proportion of
dominant
commercial

softwoods (%)

3–5 74a 67 6 N/A 83a 17a

6–10 75ab 68 7 1a 69ab 31ab

11–15 76ab 67 9 25b 58ab 42ab

16–20 86b 75 11 39b 49b 51b

1Proportion of plots containing dominant stems considered to be commercial species
2Proportion of plots containing dominant commercial stems not considered to be severely damaged
3Proportion of plots containing dominant commercial stems considered to be severely damaged

Fig. 4. Stocking guide for main crown canopy of even-aged hardwood and
mixed-wood stands relative to basal area, number of trees per acre, and mean
stand diameter. The A-line is fully stocked, the B-line is suggested residual
stocking (˜60%), and the C-line is minimum stocking (˜40%) (Leak et al. 1987).
The proportion (%) of commercial trees without severe damage are plotted by
age class; stocking is projected to a 4" mean stand diameter.

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BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



species in northeast Vermont was considered
minor. The stocking rate of commercial trees
without severe damage was acceptable in all
age classes based upon the minimum thresh-
old stocking level of 40–60%, and severe
damage from browsing was low in all age
classes with regard to acceptable levels, ran-
ging from 6–11% (Table 1). While damage
was low in all age classes, site-specific
severe browsing can shift species composi-
tion (Edenius et al. 2002). For example,
moose drastically altered localized species
composition on Isle Royale, Michigan where
browsed sites had lower overall tree density
than unbrowsed sites due to decline in bal-
sam fir and mountain ash (Sorbus ameri-
cana) and concurrent increase in white
spruce (Picea glauca) densities (Snyder and
Janke 1976).

The increasing proportion of dominant
softwood stems with age indicates a possible
shift to softwood-dominated stands due to
selective browsing of hardwood species

(Fig. 5). The highest stocking rates (>80%)
were restricted to softwood-dominated
stands, and stands experiencing the highest
levels of damage were stocked predomi-
nantly with hardwood species that had
much higher damage relative to the softwood
species (Table 2); softwood species will
likely dominate these stands as they mature.
The most commercially valuable hardwood
species in the study region are yellow birch
and sugar maple, and they were dominant
species in the youngest 2 age classes, but
accounted for only 6 and 5% of dominant
stems in the 16–20 year class.

Conversely, the commercial softwood
species, balsam fir and red spruce, were
minimal in the youngest age classes, but
accounted for a large proportion of the domi-
nant stems (21% each) in the 16–20 year
class. Red maple, a less valuable commercial
species, was the most common deciduous
tree species in all age classes ranging from
13–24% of dominant stems (Table 2). A

Fig. 5. Proportion (%) of plots containing either dominant commercial
hardwood or softwood stems by age class in nothereastern Vermont, 2012.

ALCES VOL. 50 ANDREOZZI ET AL. – BROWSING AND FOREST REGENERATION

73



Table 2. Species composition (%) and browse damage category of dominant stems by age class in clearcuts
in northeastern Vermont, 2012.

Age
Class Species Severe Damage Moderate Damage Light Damage No Damage Total

3–5 American beech 0 0 2 1 3
Aspen spp. 0 0 3 0 3

Balsam fir 1 0 2 3 6

Black cherry 1 0 0 0 1

Red maple 0 0 15 8 24

Red spruce 0 0 1 3 5

Sugar maple 0 0 4 2 6

Tamarack 0 0 0 1 2

White ash 0 0 0 0 1

White birch 1 0 1 1 3

Yellow birch 1 0 13 5 20

Non commercial NA NA NA NA 26

6–10 American beech 0 0 2 1 3
Aspen spp. 0 0 1 0 2

Balsam fir 1 1 4 9 15

Red maple 1 1 12 3 16

Red spruce 0 0 0 9 9

Sugar maple 0 0 8 2 10

White ash 1 0 0 0 1

White birch 2 0 2 0 4

Yellow birch 1 0 11 3 14

Non commercial NA NA NA NA 25

11–15 American beech 1 0 1 0 3
Aspen spp. 0 0 3 2 6

Balsam fir 2 1 7 7 17

Black spruce 0 0 0 1 1

Red maple 3 2 8 0 13

Red spruce 0 0 1 9 11

Sugar maple 1 0 3 0 4

White birch 4 1 4 0 9

Yellow birch 2 0 8 1 11

Non commercial NA NA NA NA 24

16–20 American beech 1 1 3 2 6
Aspen spp. 0 0 0 1 1

Balsam fir 2 0 5 14 21

Black spruce 0 0 0 1 1

Red maple 7 1 14 1 23

Table 2 continued . . . .

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BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



similar trend occurred in New Hampshire
(Bergeron et al. 2011) where the proportion
of dominant commercial hardwood stems
also declined with age class. Heavy brows-
ing pressure could potentially accelerate suc-
cessional development by arresting or
retarding the height development of pre-
ferred browse species in the region (McInnes
et al. 1992, Davidson 1993). While previous
site compositions are unknown, it is possible
a shift from hardwood to softwood domi-
nated stands may be the natural successional
trend for these sites. Although harvest records
were unavailable for most sites, it appeared
that many were originally mixed wood
stands.

The proportion of dominant commercial
trees ≥3.05 m (beyond browse height) with-
out severe damage increased with age class,
peaking at 39% at 16–20 years (Table 1).
These stems are expected to recover from
any moderate or light damage during future
growth without browsing. In contrast, aver-
age values in adjacent northern New Hamp-
shire were 36, 60, and 71% in the 3 older
age classes, suggesting that growth was
more suppressed in Vermont. Intense brows-
ing in areas of high moose density can arrest
or retard growth of preferred browse species
(Bergerud and Manuel 1968, Angelstam et al.
2000). A study with exclosures on Isle Roy-
ale, Michigan indicated that repeated brows-
ing by moose retarded vertical growth of
palatable species such as aspen and paper

birch, and prevented stems from growing
beyond browsing height resulting in a more
open canopy (Risenhoover and Maass
1987). Although heavy browsing of the
same species in successive years can result
in hedgy growth and lower height potential
(Peek et al. 1976, Peek 1997), such stems
can compensate if browsing declines or if
removed in successive years; for example,
after release of a dominant stem in forked
stems (Jacobs 1969) and the straightening
of crooked stems with secondary growth
over time (Switzenberg et al. 1955, Trimble
1968). A clipping study on Isle Royale indi-
cated that the site-dependent survival and
growth of balsam fir were related to suppres-
sion brought about by severe browsing in
previous years (McLaren 1996). Accurate
prediction of damage is complicated by this
dynamic process that is likely influenced by
local site conditions, and seasonal moose
density and site fidelity.

In studies assessing browse damage in
both southern and northern New England,
time since harvest was negatively correlated
with foraging intensity (Faison et al. 2010,
Bergeron et al. 2011) which may allow com-
pensatory growth by desirable hardwood
species beyond the 16–20 year age class.
However, an increasing dominance of soft-
wood species coupled with suppressed
growth of hardwood species indicates a pos-
sible shift in species composition in WMU
E1. Several studies have indicated change

Table 2 continued

Age
Class Species Severe Damage Moderate Damage Light Damage No Damage Total

Red spruce 0 0 1 20 21

Sugar maple 0 0 4 1 5

White birch 1 0 1 0 1

Yellow birch 3 0 3 0 6

Non commercial NA NA NA NA 14

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75



in forest composition due to heavy moose
browsing. In Finland, Heikkila et al. (2003)
measured reduced height of preferred browse
species resulting in the release of conifers
from competition. On Isle Royale, moose
prevented aspen, birch, and balsam fir from
growing into the canopy, with little impact
to spruce, resulting in a forest with fewer
trees in the canopy, a well-developed unders-
tory of shrubs and herbs, and an increase in
spruce biomass (McInnes et al. 1992). Simi-
larly, selective pressure resulted in rapid
occupation of spruce (Picea spp.) as the
dominant species in study stands in Russia
(Abaturov and Smirnov 2002). A similar
trend is possibly occuring in northeast Ver-
mont where coniferous species account for
>50% of total species composition in the
16–20 year age class (Table 2). A reduction
in moose density, as implemented in the
study area, may also reduce future browsing
pressure and provide for the release of pre-
ferred hardwood species. A population
reduction in Newfoundland in the early
1960s resulted in dramatic decline in the pro-
portion of white birch and balsam fir stems
browsed in 6–11 and 12–17 year old stands
(Bergerud et al. 1968).

High-density moose populations have
the potential to damage preferred forage spe-
cies (Peek 1997), but the negative impacts of
over-browsing can be minimized if moose
density is kept at low-moderate levels
(Brandner et al. 1990). In Russia, a density
of 0.3–0.5 moose/km2 retarded growth of
preferred forage species such as aspen,
whereas normal stand development occurred
at 0.2–0.3 moose/km2 (Abaturov and Smir-
nov 1992). In Sweden, simulated densities
of 0.8–1.5 moose/km2 did not impact winter
browse availability; impact was predicted at
>2.0 moose/km2 (Persson et al. 2005).

Both northern Vermont and New Hamp-
shire are classified as a combination of
spruce-fir, northern hardwood, and mixed
forest types (DeGraaf and Yamasaki 2001),

and presumably measurable differences in
forest regeneration reflect different moose
density. Bergeron et al. (2011) found a direct
correlation between browse damage and
moose density in northern New Hampshire;
the region with highest density had most
damage. Densities in northeast Vermont
were estimated at 1.2–1.8 moose/km2 in
1999–2009 and were probably higher than
those in the highest density region of New
Hampshire estimated at 0.8–1.5 moose/km2
for the same time period (C. Alexander,
pers. comm., K. Rines, NHFG wildlife biol-
ogist, pers. comm.).

In both states significant differences were
found in the stocking rate of dominant com-
mercial trees, and the proportion of both
dominant hardwood and softwood commer-
cial tree species between the youngest and
oldest age classes. However, the temporal
comparisons among age classes indicate that
sites with high initial browse pressure are
often released from that pressure and recover
to commercially valuable stands. In both Ver-
mont and New Hampshire, stocking rate
increased and damage declined over time
with relative differences seemingly influ-
enced by local moose density. Compensatory
growth in the region was measurable in the
16–20 year age class, but likely begins earlier
when stems grow beyond browsing height.
However, heavy browsing pressure on pre-
ferred tree species may result in lower stand
height as measured in Vermont and a possible
shift in forest composition to coniferous spe-
cies. Further assessment is warranted to best
evaluate the extent of compensatory tree
growth in response to reduction in browsing
due to forest aging and/or moose population
density.

ACKNOWLEDGEMENTS
We are grateful to the numerous com-

mercial and private landowners for their
cooperation and providing access to their
property including, but not limited to, Silvio

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BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



O. Conte National Fish and Wildlife Refuge,
Plum Creek, Heartwood Forestland Fund,
and Devost Leasing. We thank D. Bergeron,
C. Alexander (VTFW moose biologist), and
K. Rines (NHFG moose biologist) for
providing useful data. We are also thankful
to T. Millette, H. Stabins, W. Leak, and
M. Yamasaki for providing knowledge and
guidance throughout the project, and to
J. Trudeau, N. Fortin, and J. Comeau for
assistance in the field.

REFERENCES

ABATUROV, B. D., and K. A. SMIRNOV. 1992.
Formation of stands on clearings in for-
ests with different moose population den-
sity. Bulletin Moskovskava Obshestva
Isputatelij Prirodi Otdelenie Biologii 97:
3–12.

———, and ———. 2002. Effects of moose
population density on development of
forest stands in central European Russia.
Alces Supplement 2: 1–5.

ANGELSTAM, P., P. E. WIKBERG, P. DANILOV, W.
E. FABER, and K. NYGREN. 2000. Effects
of moose density on timber quality and
biodiversity restoration in Sweden, Fin-
land, and Russian Karelia. Alces 36:
133–145.

BERGERON, D. H., P. J. PEKINS, H. F. JONES, and
W. B. LEAK. 2011. Moose browsing and
forest regeneration: a case study in north-
ern New Hampshire. Alces 47: 39–51.

BERGERUD, A. T., and F. MANUEL. 1968.
Moose damage to balsam fir-white birch
forests in central Newfoundland. The
Journal of Wildlife Management 32:
729–746.

———, ———, and H.WHALEN. 1968. The
harvest reduction of a moose population
in Newfoundland. The Journal of Wild-
life Management 32: 722–728.

BERGSTRÖM, R., and K. DANELL. 1986. Moose
winter feeding in relation to morphology
and chemistry of six tree species. Alces
22: 91–112.

BRANDNER, T. A., R. O. PETERSON, and K. L.
RISENHOOVER. 1990. Balsam fir on Isle

Royale: Effects of moose herbivory and
population density. Ecology 71:
155–164.

BUBENIK, A. B. 1997. Behavior. Pages 173-
222 in A. W. Franzmann and C. C.
Schwartz, editors. Ecology and Manage-
ment of the North American Moose.
Smithsonian Institute Press, Washington,
D.C., USA.

CARVELL, K. L. 1967. The response of
understory oak seedlings to release after
partial cutting. West Virginia University
Agricultural Experiment Station, Bulle-
tin 553. Morgantown, West Virgi-
nia, USA.

DAVIDSON, D. W. 1993. The effects of herbiv-
ory and granivory on terrestrial plant suc-
cession. Oikos: 23–35.

DEGRAAF, R. M., and M. YAMASAKI. 2001.
New England Wildlife: Habitat, Natural
History, and Distribution. University
Press of New England, Hanover, New
Hampshire, USA.

EDENIUS, L., M. BERGMAN, G. ERICSSON, and
K. DANELL. 2002. The role of moose as
a disturbance factor in managed boreal
forests. Silva Fennica 36: 57–67.

FAISON, E. K., G. MOTZKIN, D. R. FOSTER, and
J. E. MCDONALD. 2010. Moose foraging
in the temperate forests of southern New
England. Northeastern Naturalist 17:
1–18.

HEIKKILA, R., P. HOKKANEN, M. KOOIMAN, N.
AYGUNEY, and C. BASSOULET. 2003. The
impact of moose browsing on tree species
composition in Finland. Alces 39:
203–213.

JACOBS, R. D. 1969. Growth and development
of deer-browsed sugar maple seedlings.
Journal of Forestry 67: 870–874.

LEAK, W. B. 2007. Accuracy of regeneration
surveys in New England northern hard-
woods. Northern Journal of Applied For-
estry 24: 227–229.

———, D. S. SOLOMON, and P. S. DEBALD.
1987. Silvicultural guide for northern
hardwood types in the Northeast
(revised). Research Paper NE-603. U.S.

ALCES VOL. 50 ANDREOZZI ET AL. – BROWSING AND FOREST REGENERATION

77



Department of Agriculture, Forest Ser-
vie, Northeastern Forest Experiment Sta-
tion, Broomall, Pennsylvania, USA.

MCINNES, P. F., R. J. NAIMAN, J. PASTOR, and
Y. COHEN. 1992. Effects of moose brows-
ing on vegetation and litter of the boreal
forest, Isle Royale, Michigan, USA.
Ecology 73: 2059–2075.

MCLAREN, B. E. 1996. Plant-specific
response to herbivory: simulated brows-
ing of suppressed balsam fir on Isle Roy-
ale. Ecology 77: 228–235.

MILLETTE, T. L., D. SLAYMAKER, E. MARCANO,
C. ALEXANDER, and L. RICHARDSON. 2011.
AIMS-Thermal - A thermal and high
resolution color camera system inte-
grated with GIS for aerial moose and
deer census in northeastern Vermont.
Alces 47: 27–37.

NORTH EAST STATE FORESTERS ASSOCIA-
TION (NEFA). 2007. The economic
importance and wood flows from Ver-
mont's forests. North East State Foresters
Association, Concord, New Hamp-
shire, USA.

PEEK, J. M. 1997. Habitat relationships.
Pages 351–375 in A. W. Franzmann and
C. C. Schwartz, editors. Ecology and
Management of the North American
Moose. Smithsonian Institute Press,
Washington, D.C., USA.

———, D. L. URICH, and R. J. MACKIE. 1976.
Moose habitat selection and relationships
to forest management in northeastern
Minnesota. Wildlife Monographs 48:
3–65.

PERSSON, I. L., K. DANELL, and R. BERGSTRÖM.
2005. Different moose densities and
accompanied changes in tree morphol-
ogy and browse production. Ecological
Applications 15: 1296–1305.

PRUSS, M. T., and P. J. PEKINS. 1992. Effects of
moose foraging on browse availability in
New Hampshire deer yards. Alces 28:
123–136.

RENECKER, L. A., and C. C. SCHWARTZ.
1997. Food habits and feeding behavior.
Pages 403–439 in A. W. Franzmann and

C. C. Schwartz, editors. Ecology and
Management of the North American
Moose. Smithsonian Institute Press,
Washington, D.C., USA.

RISENHOOVER, K. L., and S. A. MAASS. 1987.
The influence of moose on the composi-
tion and structure of Isle Royale forests.
Canadian Journal of Forest Research 17:
357–364.

SCARPITTI, D. 2006. Seasonal home range,
habitat use, and neonatal habitat charac-
teristics of cow moose in northern New
Hampshire. University of New Hamp-
shire, Durham, New Hampshire, USA.

———, C. HABECK, A. R. MUSANTE, and P. J.
PEKINS. 2005. Integrating habitat use and
population dynamics of moose in north-
ern New Hampshire. Alces 41: 25–35.

SNYDER, J. D., and R. A. JANKE. 1976. Impact
of moose browsing on boreal-type forests
of Isle Royale National Park. American
Midland Naturalist 95: 79–92.

SWITZENBERG, D. F., T. C. NELSON, and B. C.
JENKINS. 1955. Effect of deer browsing
on quality of hardwood timber in
northern Michigan. Forest Science 1:
61–67.

THOMPSON, I. D., and R. W. STEWART. 1997.
Management of moose habitat. Pages
377-401 in A. W. Franzmann and C. C.
Schwartz, editors. Ecology and Manage-
ment of the North American Moose.
Smithsonian Institute Press, Washington,
D.C., USA.

THOMPSON, M. E., J. R. GILBERT, G. J.
MATULA Jr., and K. I. MORRIS. 1995.
Seasonal habitat use by moose on mana-
ged forest lands in Maine. Alces 31:
233–245.

TRIMBLE, G. R. 1968. Form recovery by
understory sugar maple under uneven-
aged management. U.S. Department of
Agriculture, Forest Service Research
Note NE-89. Northeastern Forest Experi-
ment Station, Broomall, Pennsylvania,
USA.

VERMONT FISH AND WILDLIFE DEPARTMENT
(VTFW). 2008. Big Game Management

78

BROWSING AND FOREST REGENERATION – ANDREOZZI ET AL. ALCES VOL. 50



Plan 2010-2020: Creating a Road Map
for the Future. Pages 40-52. Vermont
Fish and Wildlife Department, Water-
bury, Vermont, USA.

———. 2011. 2011 Vermont Willdife Har-
vest Report - Moose. Vermont Fish and
Wildlife Department, Waterbury, Ver-
mont, USA.

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	IMPACT OF MOOSE BROWSING ON FOREST REGENERATION IN NORTHEAST VERMONT
	METHODS
	Study Area
	Field Measurements
	Data Analysis

	RESULTS
	DISCUSSION
	ACKNOWLEDGEMENTS
	REFERENCES