BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Vaccinium vitis-idaea | Mountain Cranberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Mountain cranberry is a low, creeping, evergreen subshrub that commonly
reaches 2 to 6 inches (5-15 cm) in height [4,90,114].  It typically
grows in dense rhizomatous colonies and frequently forms mats [106].
Stems are slender and trailing [38,114]; stem morhpology has been
examined in detail [76].  The root system is variable [6].  Plants have
a network of fine, shallow, fibrous roots, and may possess a taproot
[32,38].  The dichotomously branched rhizomes possess numerous hairlike
roots [98].  Maximum rooting depths of 2 to 11 inches (5-28 cm) have
been reported [42,100].

The thick, simple, leaves are obovate, oblong, or elliptic [38,90].  The
green leaves turn purplish in fall [38].

Flowers occur on terminal racemes singly or in groups of up to 15 [90].
Floral morphology has been examined in detail [79].  Fruit is a bright
to dark red, globular berry approximately 0.2 to 0.4 inch (6-10 mm) in
diameter [4,55,106,114].  The four-celled berries are acidic to sour or
bitter [6,90,106].  Yellow, short-beaked seeds average 0.04 inch (1 mm)
in length [42,106].


RAUNKIAER LIFE FORM : 
   Chamaephyte
   Geophyte


REGENERATION PROCESSES : 
Mountain cranberry reproduces through seed and by vegetative means [38].

Seed:  In many areas, seedlings first bear fruit at 3 or 4 years of age
[32,63].  However, British studies suggest that few flowers are produced
until plants reach 5 to 10 years of age [88].  Flowers are pollinated by
bumblebees and bee flies (syrphid flies) [38,42].  Plants may be self-
or cross-pollinated, but fruit set is much greater after
cross-pollination [6].  Berries are often produced in abundance.  In
parts of North America, berries average 3 to 15 seeds per berry [43].
Seeds are dispersed by birds and mammals [38].

Germination:  Seed can germinate on bare ground, but only if conditions
are favorable [38].  Fresh seed generally exhibits best germination
[37,38].  Germination declined from an average of 76.5 percent for seed
extracted from fresh fruit and then planted immediately to less than 10
percent for seed stored 12 to 16 months before planting [38].  In
laboratory tests, good germination was reported after stratification at
32 to 41 degrees F (0-5 degrees C) for up to 5 months [42,61].  Seeds
typically germinate within 3 weeks after exposure to temperatures of -7
to -4 degrees F (20-25 degrees C) in light or dark [32,42].  Germination
characteristics of mountain cranberry have been examined in detail
[19,62,63].

Seedling establishment:  Seedlings are rarely observed in the field
[42,62,75,102].  In Estonia, seedlings are generally observed only in
protected areas such as near tree stumps, fallen logs, or stones [71].
Some seedlings do develop in favorable years in parts of Nova Scotia and
Newfoundland [38].

Seedbanking:  Seed of mountain cranberry has been detected in soil
samples [75,106], but seed banking potentials for this species are
unknown.  In black spruce (Picea mariana)-jack pine forests of the
Northwest Territories, seeds of mountain cranberry and bog blueberry
were found in 71 percent of the soil samples tested [50].  Studies near
the Great Slave Lake revealed mountain cranberry and bog blueberry seed
in 65 percent of the cores sampled.  Seed densities averaged 3.3 per
1,000 cc, but only 21 percent were viable.  A second study revealed 4.8
seeds per 1,000 cc, but none of the seeds were viable [38].

Vegetative regeneration:  Vegetative regeneration is of primary
importance in the mountain cranberry [88].  Plants commonly expand
through horizontal rhizomes [88].  Rhizomes may sprout singly or in
groups of 1 or 2 per square meter [42].  Large, older clones may be
separated into numerous daughter clones by disturbances such as frost,
fire, or burrowing mammals [38,88].  Rhizome length, depth, and the
location of shoots on the rhizomes are greatly influenced by soil and
other site characteristics [98].  Rhizome depth is inversely related to
the thickness of soil organic layers [98].  Rhizomes grow well in peat
but can also penetrate to mineral soil.  In Britain, rhizomes are
generally confined to the humus layer [38] and are estimated to average
4 to 8 inches (10-20 cm) deep [88].  Smith [98] reported that rhizome
depth in Alberta varied from 8 to 11 inches (19-28 cm).  He found that
22.1 percent of the shoots were located terminally and 77.9 percent
arose at midrhizome locations.  Rhizome characteristics as related to
various site characteristics have been examined in detail.

The trailing or creeping stems of mountain cranberry also root at the
nodes [38,114].  This mode of regeneration may be important on some
harsh, subarctic sites [38].


SITE CHARACTERISTICS : 
Mountain cranberry is widely distributed in northern temperate forests
and in many arctic and alpine communities [38,60,114].  It commonly
grows on exposed sites, such as windswept crags, bare headlands, rocky
ledges, scree, sea cliffs, hilly rocky barrens, and mountain summits
[21,38,81,88,91].  At the southern edge of its range, mountain cranberry
occurs primarily in bogs, but in the north it grows on both wet and dry
sites [38].  Mountain cranberry occurs on high moors, heath barrens,
sand dunes, and in peatlands, forest swamps, and bogs [38,41,114].  In
mature forests, plants often grow on top of decaying tree stumps [42].

Climate:  Mountain cranberry grows under a variety of climatic regimes.
In much of Canada, it occurs in areas characterized by short cool
summers and long cold winters [38].  In black spruce-white spruce-jack
pine forests of northern Canada, its distribution may be correlated with
arctic air masses.  However, in harsh rockfield and tussock communities
of the far North, it may be related to the influence of moist Pacific
air masses [38,60].  In taiga communities of Alaska, winters are long
and cold, but summers are short and hot [110].  Mean annual
precipitation is 8 inches (21 cm), and average annual temperature is 20
degrees F (-6.7 degrees C) [84].  In parts of the Northwest Territories,
annual precipitation averages 12 inches (30.4 cm) [68].

Soils:  Mountain cranberry grows on shallow, poorly developed mineral
soil as well as on drained peat [51,88].  Soils are often of low
fertility and have little calcium but may be high in decaying organics
[42,101].  Mountain cranberry commonly grows on acidic sandy loams or
loamy clays [42,57].  Holloway and others [45] reported poorest
vegetative growth on sandy soils.  Soil pH ranges from 2.7 to 8.2, but
best growth has been reported at 4.0 to 4.9 [38,42,49].  Soils are often
characterized by low base saturation and low lime content [45].  Soils
may be derived from a variety of parent materials, including sandstone,
gneiss, granite, and glacial outwash sands and gravel [38].

Elevation:  In New England, mountain cranberry is generally restricted
to higher mountains [55].  In the Northwest Territories, plants often
occur at lower elevations (to 4,950 feet [1,500 m]) [38].  Generalized
elevational ranges by geographic location are as follows:

Location         Elevation                          Authority

Adirondacks      up to 5,300 ft (1,615 m)           Keeler 1969
e Canada         sea level to 4,250 ft (0-1,290 m)  Hall and Shay 1981
AB               to 7,400 ft (2,250 m)              Hall and Shay 1981
Yukon            6,900 to 7,900 ft (2,100-2,400 m)  Hall and Shay 1981


SUCCESSIONAL STATUS : 
Mountain cranberry is noted for its wide ecological amplitude [69].  It
is not generally considered a pioneer species but does occur in early
seral stages in some communities [38,65].  Mountain cranberry persists
indefinitely, unless shaded out by conifers, and assumes a climax role
in various rockfield communities of the far North [38].

Mountain cranberry commonly invades tundra bog communities dominated by
species such as alpine sweetgrass (Hierochloe alpina), lichens
(Alectoria ochroleuca, A. nitidula), and woodrush (Luzula confusa) from
adjacent summit rockfields.  Mountain cranberry also invades senescent
cottongrass tussock communities and areas of frost activity after the
establishment of initial pioneers.  However, on some sites, seral mat
communities made up of mountain cranberry, crowberry, and lichens
eventually give rise to white spruce stands.  In barrens of
Newfoundland, mountain cranberry grows as a seral species which is
displaced by black spruce and balsam fir [38].  It also occurs in some
early seral communities dominated by paper birch [65].

Black spruce:  Mountain cranberry is important in stable climax black
spruce communities but also dominates many seral stages [34,65,80].
Stands are initially colonized by bryophytes and herbaceous species such
as fireweed and willow [7,27].  Mountain cranberry generally reaches
stable levels within 25 years after fire or other disturbances [38].
However, maximum cover and frequency were attained at 144 years in
certain black spruce/mountain cranberry communities [38].  In black
spruce stands in interior Alaska, mountain cranberry is present within 5
to 30 years after disturbance and persists for many years.  It is common
in stands 200 years old or older and represents the most abundant low
shrub in tree-dominated stages [34].  In black spruce stands of the
Northwest Territories, mountain cranberry remains abundant in 200- to
300-year-old stands despite the decline of most vascular plants [7].
Chapin and others [14] reported that mountain cranberry becomes more
prominent as succession progresses from immature black spruce to muskeg.

White spruce:  Mountain cranberry occurs in many climax white spruce
forests on uplands of interior Alaska [65].  It is present during the
moss-herb stage which occurs 1 to 5 years after fire [27,34].  Mountain
cranberry peaks and declines after the dense tree stage, which occurs
from 15 to 40-46 years or longer after fire, but remains present in
later stages [34].  Dyrness and others [27] reported that in interior
Alaska, mountain cranberry was common in 150-year-old white spruce
stands.

Jack pine:  In jack pine-lichen woodlands of the northern Canada,
mountain cranberry is an early colonizer on recently burned sites [13].
It persists after "the cessation of major successional changes" at 25 to
45 years [13] and remains common in stands up to 280 years of age [38].

Tundra communities:  In sedge-tussock tundra and shrub tundra
communities of Alaska's Seward Peninsula, bryophytes initially
reestablished burned sites.  Bryophytes often reach maximum cover within
2 to 4 years after fire, but the recovery of shrubs such as mountain
cranberry is often much slower.  In shrub-tundra communities, mountain
cranberry may not recover to preburn levels even by 5 to 6 years after
fire or other disturbance [84,85].


SEASONAL DEVELOPMENT : 
In Alaska, vegetative buds began growth during the first week of June
and underwent rapid elongation throughout June.  The growth rate of
terminal vegetative buds decreased by July 1.  Leaf expansion began
during the last week of May and the first week of June; all leaves had
expanded within 1 month [42].  Karlsson [52] observed that old leaves
became photosynthetically active approximately 2 weeks after bud break.
Near Mt. Washington, New Hampshire, and in parts of Nova Scotia,
vegetative growth began in late June [38,42].  In Britain and perhaps
elsewhere, leaf expansion can begin as early as March, although it
usually occurs from mid-May to mid-June.  Shoot growth generally ends in
mid-July.  Leaves may persist for up to 3 years.  However, some old
leaves may be shed by August of the second year [38].  Plants become
dormant by fall [42].

Flowers develop from buds initiated the previous year [101].  In
interior Alaska, reproductive bud growth begins in mid-May [42].  In
parts of Britain, two periods of flowering (spring and summer) have been
observed at certain low-elevation sites [88].  Flowering may last 9 to
18 days [57] or as long as 19 to 27 days.  Fruit ripens approximately 78
to 84 days after full bloom [42].

Phenological development may be related to the timing of snowmelt [38].
In interior Alaska, plants were in maximum full bloom approximately 6
weeks after snowmelt and exhibited first visible signs of growth 2 weeks
after snowmelt.  Unusually cool temperatures can delay phenological
development.  Roots and rhizomes undergo two periods of active growth
annually in early spring and fall [42].

Related categories for Species: Vaccinium vitis-idaea | Mountain Cranberry