KUCHLER TYPE DESCRIPTION
Kuchler Type: Conifer bog


PHYSIOGRAPHY : 
Conifer bogs occur in shallow peat-filled basins on slopes, on level
peatlands, or in raised peat.  Bogs are hydrated by acidic,
nutrient-poor water [7,8].  South of the geographic limit of ombrogenous
bogs, conifer bogs are restricted to two types of landscapes:  areas
underlain by sand and gravel mostly in valleys and on the coastal
plains, and areas underlain by glacial till derived from acidic rocks
such as gneiss, schist, sandstone, or granite [7].

The interlaced roots and rhizomes that form the bog surface mat can be
firm enough to walk on even though they are actually floating, hence the
term quaking bog.  Peat can only accumulate where there is sufficient
water to retard decomposition of litter and debris.  This condition can
be met by particular combinations of climate and topography; basins in
cool climates often accumulat peat, but level sites where humidity is
very high can also do so [20].  Bogs modify the local drainage patterns
by retention of water in the layers of peat [8].  Peatlands have an
active upper zone (acrotelm) in which water can circulate freely, and a
lower zone (catotelm) in which water is tightly bound in the intra- and
intercellular spaces.  It has been estimated that less than 1 percent of
all the water that leaves a peatland does so from the lower zone.  Early
hypotheses suggested that peatlands give up water to adjacent areas
during drought, but recent studies show that when the water table drops
during dry periods, water in the lower zone is still retained by the
peatland [20].


CLIMATE : 
In the northern parts of the Great Lakes States, the climate is subhumid
continental.  The summers are short and warm and the winters are long
and cold.  Mean annual precipitation ranges from 20 inches (508 mm) in
northwestern Minnesota to 34 inches (860 mm) in the upper peninsula of
Michigan.  Approximately two-thirds of the precipitation falls as rain
during the warm seasons.  Average January temperatures range from 2
degrees Fahrenheit (-17 deg C) in Minnesota to 16 degrees Fahrenheit
(-10 degrees C) in Michigan.  Average July temperatures are about 67
degrees Fahrenheit (20 deg C) in the northern parts of the Great Lakes
States (northern Minnesota, upper Michigan, and northern Wisconsin) [3].


SOILS : 
Conifer bogs occupy low, wet, minerotrophic to ombrotrophic peat [8].
Bogs are saturated with water for most or all of the year [7].  The open
water adjacent to bogs can be alkaline or acidic, but under and in the
midst of sphagnum mosses the water is always acidic [8].  Sphagnum peats
are acidic, poorly to very poorly drained, and mostly humic gleysols or
terric humisols [10].  Black spruce-Alnus bogs, as defined by Kurmis and
others [23], have slightly higher nutrient levels than black
spruce-Kalmia bogs [23].


VEGETATION : 
Conifer bogs are dominated by pure stands or mixtures of tamarack, black
spruce, and northern white-cedar [21,22].  Vascular plant diversity in
forested bogs is usually low, but the bryophytic and lichen flora may be
relatively diverse [26].  Minerotrophic sites have higher vegetative
diversity than ombrotrophic sites, though they have many species in
common [3].  Black spruce in nutrient-poor bogs usually exhibits
severely stunted growth [21].

Northern white-cedar-dominated types:  Even-aged stands of northern
white-cedar originate in large openings created by wildfire or
clearcutting.  Uneven-aged stands of northern white-cedar develop where
northern white-cedar is successional to black spruce or tamarack, or
where reproduction has occurred in canopy gaps caused by windthrow.
Northern white-cedar invades speckled alder (Alnus rugosa) thickets
following wildfire or changes in water level.  The most common
associates of northern white-cedar on wet sites in the boreal regions of
Canada are balsam fir (Abies balsamea) and tamarack.  Farther south,
associated species on very wet sites include black spruce, tamarack,
black ash (Fraxinus nigra), and red maple [10].

Tamarack-dominated types:  Associates of tamarack on bogs include
northern white-cedar, balsam fir, black ash, and red maple.  Tamarack
stands often support an understory of black spruce.  [10].  Open stands
of tamarack support tall shrubs including swamp birch (Betula pumila),
willows (Salix spp.), speckled alder, rhodora (Rhododendron canadense),
and red-osier dogwood (Cornus sericea).  Low shrubs include bog Labrador
tea (Ledum groenlandicum), bog-rosemary (Andromeda glaucophylla),
leatherleaf (Chamaedaphne calycalulata), bearberry (Arctostaphylos
uva-ursi), huckleberries (Gaylussacia spp.), sweet gale (Myrica gale),
and blueberries and cranberries (Vaccinium spp.)  [10,21].  Herbs
include sedges (Carex and Cyperus spp.), cottongrasses (Eriophorum
spp.), starry Solomon's seal (Smilacina stellata), marsh cinquefoil
(Potentilla palustris), marsh-marigold (Caltha palustris), and bogbean
(Menyanthes trifoliata) [10].

Black spruce-dominated communities:  Overstories are either pure stands
of black spruce or mixtures with tamarack, paper birch (Betula
papyrifera), and balsam fir (in the boreal regions), or with northern
white-cedar, black ash, and red maple farther south.  The presence of a
shrub layer depends on canopy density.  Very open stands have a
well-developed shrub layer and dense stands tend to have only sparse
shrubs [21].  Reschke [26] described black spruce-tamarack communities
in New York.  The black spruce and/or tamarack cover ranged from less
than 50 to 90 percent.  Open stands had a well-developed shrub layer
which included leatherleaf, bog-laurel (Kalmia polifolia), sheep-laurel
(K.  angustifolia), highbush blueberry (Vaccinium corymbosum), bog
Labrador tea, and mountain-holly (Nemopanthus mucronatus).  The ground
cover typically consisted of sphagnum mosses, threeseeded sedge (Carex
trisperma), cottongrasses, purple pitcherplant (Sarracenia purpurea),
and small cranberry (V. oxycoccus).  Under dense shade, groundlayer
plants included goldthread (Coptis trifolia) and creeping winterberry
(Gaultheria procumbens) [26].  Species occurring in the black
spruce/sphagnum variant of SAF cover type 12 include low sweet blueberry
(V. angustifolium), bog-laurel, cottongrasses, pitcher plants
(Sarracenia spp.), small cranberry, and round-leaved sundew (Drosera
rotundifolia).  Sheep-laurel is usually the dominant shrub in eastern
black spruce bogs from the southern boreal forest southward.
Leatherleaf and locally, bog Labrador tea, are dominant to the west and
north [10].  Another variant, black spruce/speckled alder, is also
common.  These communities are open to well-stocked stands with
well-developed tall shrub and herb layers.

Kurmis and others [23] described the following lowland black spruce
cover types in Minnesota:  black spruce-Alnus and black spruce-Kalmia.
The black spruce-Alnus type is dominated by pure to nearly pure stands
of black spruce.  It has a tall shrub layer that is dominated by
speckled alder and includes bog Labrador tea and creeping winterberry.
The ground layer is dominated by sphagnum mosses.  The black
spruce-Kalmia type is similar to the black spruce-Alnus type.  It
consists of open stands of black spruce over sphagnum mosses and low
shrubs.  Species diversity is low and upland plants are rare.  Speckled
alder may be present but is not extensive [23].

Niemi and others [25] described two community types that appear to be
similar to conifer bog as defined by Kuchler:  semi-open conifer lowland
and mature conifer lowland.  Semi-open conifer lowland consists of a
dense, low-lying heath layer up to 3.3 feet (1 m) high, and a sparse to
moderately dense tree layer up to 19.8 feet (6 m) tall usually composed
of black spruce or tamarack.  The mature conifer lowlands are closed
stands of black spruce, tamarack, or northern white-cedar.  The closed
canopy is up to 66 feet (20 m) high; there is a sparse shrub layer and a
dense herb layer mostly composed of ericaceous shrubs and mosses [25].


WILDLIFE : 
None of the animal species that occur in conifer bogs occur there
exclusively, but several bird species reach their highest densities in
conifer bogs:  spruce grouse (Dendragapus canadensis), yellow-bellied
flycatcher (Empidonax flaviventris), palm warbler (Dendroica palmarum),
Connecticut warbler (Oporonis agilis), northern waterthrush (Seiurus
noveboracensis), and Lincoln's sparrow (Melospiza lincolnii) [4,9].

Birds inhabiting or frequenting conifer bogs include olive-sided
flycatcher (Contopus borealis), Nashville warbler (Vermivora
ruficapilla), rusty blackbird (Euphagus carolinus), three-toed
woodpecker (Picoides tridactylus), black-backed woodpecker (P.
arcticus), gray jay (Perisoreus canadensis), golden-crowned kinglet
(Regulus satrapa), ruby-crowned kinglet (R. calendula), tree swallow
(Tachycineta bicolor), boreal chickadee (Parus hudsonicus), hermit
thrush (Catharus guttatus), Swainson's thrush (C. ustulatus), solitary
vireo (Vireo solitarius), red-eyed vireo (V. olivaceus), black-and-white
warbler (Mniotilta varia), Cape May warbler (Dendroica tigrina),
yellow-rumped warbler (D. coronata), Blackburnian warbler (D. fusca),
bay-breasted warbler (D. castanea), common yellowthroat (Geothlypis
trichas), evening grosbeak (Coccothrastes vespertinus), dark-eyed junco
(Junco hyemalis), chipping sparrow (Spizella passerina), white-throated
sparrow (Zonotrichia albicollis), and swamp sparrow (Melospiza
georgiana) [7,8,9,25,26].  Birds occurring in the Lost River Peatland of
northern Minnesota include sharp-tailed grouse (Tympanuchus
phasianellus), ruffed grouse (Bonasa umbellus), spruce grouse, and
common raven (Corvus corax) in addition to many of the abovementioned
species [2].

On bogs dominated by tamarack, birds that use shrubby habitats are
present.  Great gray owl (Strix nebulosa) use tamarack bogs as a major
portion of their habitat.  In northern white-cedar stands, there may be
high densities of northern parula (Parula americana) and black-throated
green warblers (Dendroica negrescens) [9].

Mammals:  Most of the large mammals occurring in the northeastern United
States move across peatlands but do not spend much time in them.  Moose
(Alces alces), white-tailed deer (Odocoileus virginiana), and black bear
(Ursus americana) use peatlands more than other large mammals do.  Moose
make extensive use of aquatic habitats during the summer [7].  The
timber wolf (Canis lupus) occurs in northern Michigan and uses conifer
bogs in winter [2].  The woodland caribou (Rangifer tarandus caribou) is
extant in Canada and sometimes uses conifer bogs [2].
  
Other bog-using mammals include common porcupine (Erethizon dorsatum)
[21], southern bog lemming (Synaptopmys cooperi), and northern bog
lemming (S. borealis).  Lemmings are more closely associated with
sphagnum than with peatlands per se and also occupy more upland
habitats.  Other rodents common in bogs include masked shrew (Sorex
cinereus), water shrew (S. palustris), smokey shrew (S. fumeus), pygmy
shrew (S. hoyi), meadow jumping mouse (Zapus hudsonius), white-footed
mouse (Peromyscus leucopus), and southern red-backed vole (Clethrionomys
gapperi) [7].
  
Herpetofauna:  Few amphibians or reptiles can be considered peatland
species even though many are found in peatlands.  Low pH, low
temperatures, and saturated substrates make bogs unsuitable habitat for
some species but favorable for others.  Amphibian species occurring in
bogs include wood frog (Rana sylvatica), green frog (R.  clamitans),
northern leopard frog (R. pipiens), blue-spotted salamander (Ambystoma
laterale) [7], and four-toed salamander (Hemidactylium scutatum) [26].
Reptiles include eastern garter snake (Thamnophis sirtalis), bog turtle
(Clemmys muhlenbergii), and spotted turtle (C.  guttata) [7].


ECOLOGICAL RELATIONSHIPS : 
There are two primary paths of bog development:  lake-fill and
paludification [17].

Lake-fill Bogs:  Bogs develop in lakes where vegetation bordering the
lake begins to encroach into the area of open water.  Gates [11]
suggested that, in northern lower Michigan, the type of vegetation
occupying the shore of a lake determines the fate of the area.
Soft-stem bulrush (Scirpus validus) and Olney threesquare (S.
americanus) are more likely to be followed by marshes or wooded swamps
than by bogs.  A bog develops if woollyfruit sedge (Carex lasiocarpa) is
present.  This sedge forms rhizomes that grow out into the water and
develop into a floating mat [8,11].  Sphagnum mosses and ericaceous
shrubs invade the sedge mat and further increase organic material
deposition and soil formation, eventually making contact with the actual
lake bottom.  Bogbean and sweet gale are often pioneers on sphagnum
mats.  Leatherleaf and other species such as bog Labrador tea follow.
Eventually, when the substrate is firm, trees colonize the shrub
community; tamarack is usually the first species to establish [9].  The
limit to bog formation is reached where vegetative evapotranspiration
rates are higher than the bog water-holding capacity.  This can lead
succession to more mesic types and the establishment of birches (Betula
spp.) and aspens (Populus spp.).  The removal of trees adjacent to bogs
lowers the evapotranspiration capacity of the site and may lead to bog
expansion (see section on paludification below) [8].

Lake-fill bogs have vegetation zones corresponding to successional
stages.  Tree growth is most dense around the outer edges.  Shrubs form
a ring along the interior edge of the trees.  In the center sphagnum and
other mosses and sedges form dense mats.  There may be areas of open
water.  This type of bog may remain relatively stable for long periods,
may be replaced by upland forest [21], or may invade upland forest areas
and convert them to peatlands (paludification).  Tamarack and black
spruce are usually the first trees to colonize the sedge mat in
lake-fill bogs [31].

Paludification:  Paludification is the creation of a peatland by the
drowning or submergence of upland habitats.  Local paludification may
result from altered drainage (i.e., a beaver dam) or the lateral
expansion of raised peatlands.  Regional paludification, a widespread
expansion of peatlands through the elevation of the water table, can be
caused by regional or global climate change [17].  With a rise in the
water table, roots of upland plants are suffocated and peat begins to
accumulate.  Peat retains water and impedes drainage, increasing the
rate of peat build up and allowing peatland to expand [20].

Trees initially colonize open bogs by seed, but tree cover increases in
conifer bogs largely due to layering.  Tree survival and growth depend
on root growth in the upper layers of peat.  New roots form from the
trunks of black spruce, northern white-cedar, and tamarack, extending
into the uppermost and best oxygenated layers of peat.  The original
base of the tree trunk may be buried several feet beneath the surface.
Tree growth is usually very slow, particularly on ombrotrophic sites.
Trees only 3 to 4 inches (7.6-10 cm) d.b.h. may be as old as 150 years [4].

Tamarack is a pioneer tree species, especially on burned organic soils
and on open (treeless), unburned bogs.  It is intolerant of shade and is
usually replaced by black spruce [10].  Occasional high water levels
will kill tamarack [19].

Black spruce stands form an edaphic climax in boreal and subarctic
ecosystems [10], and black spruce is dominant on nutrient-poor peatlands
where competition is low [31].  In central Quebec black spruce stands
over 200 years old show poor growth, have limited reproduction, and tend
to have dense shrub layers in canopy gaps.  Dead trees are only
partially replaced by layering.  These stands are rejuvenated by fire:
Black spruce is often a postfire pioneer on peatlands, and therefore the
type is maintained by fire disturbance [6,31].  Further discussion is in
FIRE ECOLOGY AND MANAGEMENT.

Related categories for Kuchler Type: Conifer bog