Populus balsamifera

Salicaceae -- Willow family

    John C. Zasada and Howard M. Phipps

    Balsam poplar (Populus balsamifera) is the northernmost  American hardwood. It grows transcontinentally on upland and  flood plain sites but attains the best development on flood  plains. It is a hardy, fast-growing tree which is generally short  lived, with some trees reaching 200 years. Other names are  balm-of-gilead, bam, tacamahac, cottonwood, or heartleaf balsam  poplar. Many kinds of animals use the twigs for food. The light,  soft wood is used for pulp and construction.

     AK  CO  CT  DE  ID  IL  IN  IA  ME  MD
     MA  MI  MN  MT  NE  NH  NJ  NY  ND  OH
     OR  PA  RI  SD  TN  UT  VT  VA  WV  WI
     WY  AB  BC  LB  MB  NB  NF  NT  NS  ON
     PE  PQ  SK  YT

More info for the term: tree

Balsam poplar occurs mainly in riparian areas of boreal and montane
conifer forests [35].  Its distribution extends from Alaska across most
of Canada to Labrador and Newfoundland [93,101].  In British Columbia it
is restricted to areas east of the Rocky Mountains [8,36].  Balsam
poplar is rare in the northwestern United States, with sketchy records
of its existence in Idaho and Oregon [32].  It occurs sparingly in the
Rocky Mountains of Montana, Wyoming, Utah, and Colorado
[25,26,27,35,36,37,105,106] and extends east through the northern Great
Plains to the Atlantic Coast.  It is found along creekbanks, moist
hillsides, sandhill potholes, and knolls in North and South Dakota [93].
North and east of the Great Plains, balsam poplar forms extensive
floodplain forests [35].  New York [32] and West Virginia [61,101] are
alternately reported as the southern extreme for this tree in the
eastern United States.

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    8  Northern Rocky Mountains
    9  Middle Rocky Mountains
   10  Wyoming Basin
   11  Southern Rocky Mountains
   14  Great Plains
   15  Black Hills Uplift
   16  Upper Missouri Basin and Broken Lands

The range of balsam poplar spans about 110° in longitude (55°  to 165° W.) and 26° in latitude (42° to 68°  N.). It extends across North America along the northern limit of  trees from Newfoundland, Labrador, and Quebec west to Hudson Bay  and northwest to Mackenzie Bay. From northwest Alaska, its range  extends south to southwest Alaska and part of southcentral  Alaska, north and east British Columbia; east to southeast  Saskatchewan, east North Dakota, northeast South Dakota,  Minnesota, Wisconsin, northwest Indiana, Michigan, southern  Ontario, New York, and Maine. It is local in the western  mountains, south to northeast Oregon, Idaho, extreme northern  Utah, central Colorado, extreme northwest Nebraska, and the Black  Hills of South Dakota and Wyoming. It is also scattered in  northern Iowa, northeast Ohio, Pennsylvania, northern West  Virginia, extreme eastern Maryland, and northwestern Connecticut.

   
  -The native range of balsam poplar.

Populus candicans Aiton:
Canada (North America)
United States (North America)
China (Asia)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Populus × gileadensis Rouleau:
Canada (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Populus balsamifera var. subcordata Hyl.:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Populus balsamifera var. balsamifera :
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Populus balsamifera L.:
Canada (North America)
United States (North America)
Ecuador (South America)
Bolivia (South America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Newfoundland, Labrador to northwest Alaska, northeastern British Columbia, east through Alberta, northern portions of the Great Lakes states, northern New England, and locally from Iowa to Connecticut and in the Rocky Mountains. (Fowells 1965)

More info for the term: tree

Balsam poplar is a medium to large native deciduous tree.  Heights of
mature trees range from 30 to 100 feet (9-30 m) and trunk diameters from
4 inches to 2 feet (10-60 cm) [101].  The trunk of balsam poplar is
straight and cylindrical with an open crown of a few stout ascending
branches [63].  The bark is smooth and light gray to grayish brown but
furrows with age [22].

Winter buds are 1 inch long (2.5 cm) with sticky resin and a pungent
balsam odor in the spring [101].  Drooping pistillate and staminate
catkins occur on separate trees.  Leaves are ovate or broadly
lanceolate, 2.25 to 4.5 inches long (6-11 cm) and 1.5 to 3 inches wide
(4-7.5 cm) [101].  Leaves are shiny green above and pale green below
with finely toothed margins [22].

Roots are shallow, especially on wet soil types or shallow permafrost
[36]. 

Trees; crown wide. Branches stout and spreading; branchlets chestnut colored, terete, tomentose. Buds large, very viscid. Leaves of sprouts and mature trees nearly uniformly shaped; petiole terete, 3-5 cm, tomentose; leaf blade broadly ovate-deltoid, 12-16 × ca. 10 cm, abaxially whitish, adaxially dull green, both surfaces pilose, more densely so along veins, base cordate, rarely truncate, margin crenate-serrate, ciliate, apex acuminate. Fruiting catkin to 16 cm; rachis pubescent. Capsule ovoid, glabrous, 2-valved, often sterile, stipitate. Fl. May.

Populus balsamifera Linnaeus var. candicans (Aiton) A. Gray; P. balsamifera var. subcordata Hylander.

More info for the term: tree

Balsam poplar generally occurs on moist sites, such as river
floodplains, stream and lake shores, moist depressions, and swamps, but
will also grow on drier sites [9,22,63,111].  It commonly grows in moist
forests, such as white and black spruce (Picea mariana) forests of the
boreal zone, and is found in the forest-tundra transition zone in Canada
[63,68].  Balsam poplar can be found growing beyond the coniferous tree
line along rivers and on southern slopes having less permafrost than the
surroundings [63,97].

Common associated species of balsam poplar include the following:

Canada and Alaska: white spruce, black spruce, blue spruce (Picea
pungens), lodgepole pine (Pinus contorta), jack pine (P. banksiana),
subalpine fir (Abies lasiocarpa), tamarack (Larix laricina), black
cottonwood, paper birch, aspen, alders (Alnus spp.), willows (Salix
spp.), currant, (Ribes spp.), red-osier dogwood (Cornus sericea), and
prickly rose (Rosa acicularis) [16,19,36,55,56,63,74,77,80,99].

Minnesota:  balsam fir (Abies balsamea), black ash (Fraxinus nigra),
American elm (Ulmus americana), red maple (Acer rubrum), aspen, and
bitter cherry (Prunus emarginata) [14].

Glacial moraines in the northern boreal forest commonly support stands
of balsam poplars.  Permafrost may occur discontinuously in these areas
[66].  Typical soils where balsam poplar is found are those of alluvial
floodplains, including gravel, deep sand, clay loam, silt, and silty
loam [24,36].  Abundant soil moisture is needed, but stagnant brackish
water is intolerable to this tree [36].  Balsam poplar has high nutrient
requirements; it needs a good supply of calcium and magnesium.  It does
not tolerate acidic deep peats and humic soils in which nutrients are
released slowly [36].

Climates in which balsam poplars grow range from arctic to temperate
but most commonly are boreal.  Average temperatures in British Columbia
boreal forests are below 26 degrees F (-3 degrees C) in the coolest
month and around 50 degrees F (10 degrees C) in the warmest month [36].
Mean annual precipitation is 177 inches (452 cm); about one-third is in
the form of snow [65].

Elevational ranges for balsam poplar are reported as follows:

                        feet          meters      reference

Alaska               0 -  3500        0 - 1067     [101]
British Columbia     0 -  5400        0 - 1650     [36]
Colorado          6000 - 12000     1800 - 3700     [24]
Wyoming           3500 -  9000     1067 - 2740     [24]
Montana                   5500            1675     [24]
Utah                      4300            1310     [24]

More info for the term: tundra

Balsam poplar is a seral species that occurs primarily in ecotones
between boreal forest and tundra or prairie, and along streams and
rivers.  It is most common in white spruce (Picea glauca) forests of
Canada but can extend beyond the conifer treeline in western Canada and
Alaska [63].  Classifications including balsam poplar as a dominant
component in community types (cts), plant associations (pas), or
ecosystem associations (eas) are listed below.

Area                  Classification            Authority

Alaska                general veg. pas          Viereck 1989
                      general veg. cts          Viereck and Dyrness 1980
                      postfire forest cts       Foote 1983

British Columbia      general veg. eas          Pojar & others 1984
Alberta               general veg. cts          Dirschl & others 1974
wc Alberta            forest cts                Corns 1983   
Ontario               forst eas                 Jones & others 1983
Canada                general veg. pas          Roi 1967
                         boreal forests

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: cover

   Eastern Forest Cover Types:
     1  Jack pine
     5  Balsam fir
    38  Tamarack
    16  Aspen
    33  Red spruce - balsam fir
    37  Northern white cedar
    39  Black ash - American elm - red maple
  
   Western Forest Cover Types:
   201  White spruce
   202  White spruce - paper birch
   203  Balsam poplar
   251  White spruce - aspen
   252  Paper birch
   253  Black spruce - white spruce
   206  Engelmann spruce - subalpine fir
   217  Aspen
   222  Black cottonwood - willow
   235  Cottonwood - willow

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

   K012  Douglas-fir forest
   K015  Western spruce - fir forest
   K016  Eastern ponderosa forest
   K017  Black Hills pine forest
   K018  Pine - Douglas-fir forest
   K063  Foothills prairie
   K064  Grama - needlegrass - wheatgrass
   K066  Wheatgrass - needlegrass
   K067  Wheatgrass - bluestem - needlegrass
   K074  Bluestem prairie
   K081  Oak savanna
   K093  Great Lakes spruce - fir forest
   K094  Conifer bog
   K096  Northeastern spruce - fir forest
   K098  Northern floodplain forest

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES17  Elm - ash - cottonwood
   FRES19  Aspen - birch
   FRES20  Douglas-fir
   FRES21  Ponderosa pine
   FRES23  Fir - spruce
   FRES28  Western hardwoods
   FRES38  Plains grasslands
   FRES39  Prairie

Most of the range of balsam poplar has a continental climate, but  some is in the maritime zone and the transition between these two  broad regions. Average temperature ranges from -30° to -4°  C (- 22° to 25° F) in January and from 12° to 24°  C (53° to 75° F) in July. The lowest temperatures range  from -18° to -62° C (-10° to -79° F); the  highest from 30° to 44° C (85° to 110° F).  Annual precipitation is lowest in central Alaska (15 to 30 cm; 6  to 12 in) in the Yukon-Tanana drainage. The highest  precipitation, 140 cm (55 in), occurs in the Maritime Provinces  of eastern Canada. Distribution of precipitation varies  throughout the range, but prolonged summer droughts are uncommon.  Annual snowfall is lowest in interior Alaska (100 to 200 cm; 40  to 80 in) and highest in Newfoundland (400 cm; 160 in). Maximum  summer daylength varies from 16 to 24 hours. Minimum daylength in  winter drops to zero above the Arctic Circle. The frost-free  period varies from 75 to 160 days. The longest growing seasons  are in the southern part of the range and the shortest in the  north, but growing seasons can be 120 days in parts of Alaska.

Comments: Climatic conditions vary throughout the ranges, but are often characterized by low seasonal temperature provided by high altitudes or northern latitudes, and short growing seasons. P. balsamifera most frequently grows in moist soils of various textures including subirrigated sandy and gravelly soils, calcareous clay loams, or silt loams. It grows at elevations from sea level to about 5,500 feet (1,676 m). It is usually found in cool lowlands such as alluvial bottoms, sandbars, stream banks, lake shores and swamps. It grows in pure stands or in the following forest types: aspen, balsam fir-paper birch, white spruce-balsam fir-paper birch, black ash-American elm-red maple, aspen-birch, white spruce-aspen, and black cottonwood-willow (Fowells 1965).

Planted. Xinjiang [Asia, Europe, North America, but native range uncertain, probably of hybrid origin]

Foodplant / pathogen
Xanthomonas populi infects and damages cracked, cream slime oozing shoot (one year old) of Populus candicans 'Aurora'
Other: major host/prey

Foodplant / saprobe
fruitbody of Exidia thuretiana is saprobic on dead, fallen wood of Populus candicans
Other: minor host/prey

In Great Britain and/or Ireland:
Foodplant / spot causer
mostly hypophyllous, in small groups, rarely epiphyllous and singular uredium of Melampsora laricis-populina causes spots on live leaf of Populus candicans
Remarks: season: 7-10

In Great Britain and/or Ireland:
Foodplant / spot causer
loosely gregarious pycnidium of Phyllosticta coelomycetous anamorph of Phyllosticta populi-nigrae causes spots on dead, fallen leaf of Populus balsamifera ssp balsamifera
Remarks: season: 8

Foodplant / saprobe
immersed, in groups of 5 to 12 perithecium of Valsa sordida is saprobic on dead branch of Populus balsamifera
Remarks: season: 2-4

Balsam poplar occurs in the following forest cover types (13):  Balsam Poplar (Society of American Foresters Type 203), White  Spruce-Aspen (Type 251), White Spruce (Types 107 and 201), Jack  Pine (Type 1), Aspen (Type 16), Red Spruce-Balsam Fir (Type 33),  Northern White-Cedar (Type 37), Black Ash-American Elm-Red Maple  (Type 39).

    In eastern North America, balsam poplar is found mainly in mixed  stands where other species dominate. In Saskatchewan, it is a  component of the following forest types: Aspen-hazelnut (Populus  tremuloides/Corylus cornuta), white spruce (Picea glauca)-feathermoss,  aspen-sarsaparilla (Aralia nudicaulis)/twinflower  (Linnaea borealis), white spruce/aspen-bunchberry (Cornus  canadensis)/bishops cap (Mitella nuda), black spruce  (Picea mariana)feathermoss, and white  spruce-horsetail (Equisetum spp.) (31). Balsam poplar is  uncommon in boreal white spruce forests east of about 75°  longitude and is not present in black spruce stands east of 85 to  86° longitude. It grows with white spruce east of 75°  longitude, however (45). Other associated trees are balsam fir  (Abies balsamea), paper birch (Betula papyrifera),  black ash (Fraxinus nigra), American elm (Ulmus  americana), red maple (Acer rubrum), tamarack  (Larix laricina), and northern white-cedar (Thuja  canadensis).

    In western and northern parts of the range, balsam poplar is  associated with balsam/alpine fir (Abies lasiocarpa),  aspen, paper birch, white spruce, and black spruce on upland  sites. It reaches its most widespread development on the river  flood plains. On these sites, it occurs in pure stands and is  associated with mountain alder (Alnus incana) and various  willows (e.g., Salix alaxensis, S. interior) during  early stand development and white spruce in later stages when it  finally disappears from these sites (53,57).

    Low shrubs associated with balsam poplar include redosier dogwood  (Cornus stolonifera), bunchberry, mountain maple (Acer  spicatum), bearberry honeysuckle (Lonicera involucrata),  beaked hazel, American cranberry bush (Viburnum  trilobum), highbush cranberry (V edule), red  raspberry (Rubus idaeus var. canadensis and strigosus),  prickly rose (Rosa acicularis), mountain cranberry  (Vaccinium vitis-idaea), devil's club (Oplopanax  horridum), and red currant (Ribes triste).

    Some associated herbaceous plants are horsetails (Equisetum  arvense, E. pratense), bluejoint reedgrass (Calamagrostis  canadensis), bedstraws (Galium boreale, G. triflorum),  fireweed (Epilobium angustifolium), panicle bluebells  (Mertensia paniculata), red baneberry (Actaea rubra),  alpine pyrola (Pyrola asarifolia), claspleaf  twistedstalk (Streptopus amplexifolius), wild  sarsaparilla, butterbur (Petasites spp.), and bishops  cap.

    In mixed stands, various feathermosses (e.g., Hylocomium  splendens, Pleurozium schreberi) and lichens may be  associated with balsam poplar. In Alaska, two mosses, Eurhynchium  pulchellum and Mnium cuspidatum, have been reported  in flood plain stands (53). Moss and lichen cover is generally  low in these stands.

Known Pests: CRYPTORHYNCHUS LAPATHI

Susceptibility of balsam poplar to fire  is determined by characteristics of individual trees and stands.  Thickness of bark increases with age, giving increased resistance  to fire; however, the bark of mature trees tends to be deeply  fissured, and the protection afforded the cambium is less than if  a continuous sheath surrounded it. Mature trees can withstand  mild and perhaps moderately intense fires. Balsam poplar supports  crown fires only under the severest burning conditions (41).

    Fire fuels differ in the various vegetation types where balsam  poplar occurs. Pure stands of balsam poplar support fires of less  intensity than those in mixed conifer-hardwood stands, and tree  survival is greater. Early successional stands containing only  hardwoods are less likely to burn intensely than later  successional stages or mixed balsam poplar-conifer stands (41).  Balsam poplar produces root suckers after fire, and burned sites  can be colonized by seed reproduction when mineral soil seedbeds  are created.

    As rivers create sites for establishment of balsam poplar, they  also destroy sites with established stands. This process can be  gradual as the river slowly undermines its bank at the rate of a  few feet per year, or the erosion can be dramatic. It is not  uncommon to see river channels change by 30 to 60 m (100 to 200  ft) in several years. These channel changes can destroy  significant areas of established poplar stands.

    Moose, deer, elk, and other animals browse on balsam poplar stem  material but eat little foliage (3). Stems as large as 5 cm (2  in) d.b.h. may be broken by moose and the tops browsed. Where  browsing occurs for only 1 or 2 years, however, form is not  adversely affected because subapical buds rapidly replace damaged  terminals. Simulated browsing of 9 to 14-year-old poplars  resulted in increased twig biomass, indicating that only under  the severest, repeated browsing is it adversely affected (16).

    Resin of balsam poplar appears to repel snowshoe hares, and foliar  buds have higher resin contents than internodes. As a result,  hares may eat internodes of twigs and stems but not the buds  (3,38). High terpene and phenolic resin content are sufficient to  reduce cellulose digestion, making balsam poplar less palatable  to animals (43).

    Girdling by hares or rodents can kill saplings or small trees  above the girdle, but dormant buds from below the girdle usually  form a new stem. Ruffed grouse may feed on staminate buds in the  winter.

    Beaver frequently cut balsam poplar growing along watercourses;  usually, sprouts are not produced or, if they are, they either  die or are browsed and subsequently die. On small streams, ponds  created by beaver dams can kill poplars growing in or adjacent to  ponded areas.

    The poplar and willow wood borer (Cryptorhynchus lapathi),  bronze poplar borer (Agrilus liargus), and the poplar  borer (Saperda calcarata) are among the most damaging  insects. They girdle or badly weaken trees larger than 2.5 cm (1  in) in diameter by tunneling in the main stem and limbs (9).

    The forest tent caterpillar (Malacosoma disstria), satin  moth (Sti1pnotia salicis), gray willow leaf beetle (Pyrrhalta  decora decora), and aspen leaf beetle (Chrysomela  crotchi) feed on balsam poplar foliage, but the species is  not their principal host (1). The highly resinous buds and leaves  of balsam poplar may render them relatively less palatable than  the principal tree hosts (3).

    In mature trees, the most common decay-causing fungal species is  Phellinus tremulae with Pholiota destruens, Corticium  expallens, and Bjerkandra adusta also being  important. A canker caused by Neofabraea populi has been  observed on balsam poplar in Ontario less than 3 cm (1.2 in) in  diameter (22,23). The occurrence of decay varies with site  conditions and among clones, with the latter appearing to be the  most important cause of resistance (23). Infection by Rhytidiella  moroformis causes a roughening of the normally smooth bark  and the formation of deep furrows. Melampsora spp.  cause a leaf rust and Linospora spp., a leaf blight  (22). Venturia populina causes a leaf and twig blight and  can stunt the main stem.

    Septoria musiva and S. populicola cause a leaf  spot and canker on balsam poplar seedlings. Septoria musiva  was reported to cause the highest percentage of canker and leaf  spot in southern Manitoba. Septoria incidence on native  poplars within their range is negligible (61).

    Frost damage occurs to trees of all ages in exposed stands  established after bums and logging, in nursery stooling beds, and  in plantations of hybrid poplar (60). Entire twigs may be shed.  Distortion from frost damage occurs adjacent to cankers, and  dieback results in burl formation, bud proliferation, sucker  production, and uneven development of bark, leaf, and sapwood  (60).

More info for the terms: natural, shrubs

Prescribed burning for wildlife:  Fire-induced poplar and willow
sprouting can increase forage for moose [67].  Beaver also benefit from
an increased supply of poplar sprouts following fire [83].  Repeatedly
burning white spruce forests and balsam poplar stands can convert large
areas into grasslands used by elk and Stone's sheep [90].  Cyclic burns
(every 10 years) are needed to maintain sedge (Carex spp.) grasslands
which would otherwise be taken over by shrubs and deciduous trees,
including balsam poplar; sedges are the main food item for bison in
northern latitudes [15].  Wood Buffalo National Park, a large bison
preserve in Canada, is characterized by extensive areas of white spruce
and mixed hardwoods, and extensive sedge meadows.  Natural fire cycles
here have been estimated to be 50 years [40].

Fire control has had little or no impact in most of the far northern
boreal forest and natural lightning-caused FIRE REGIMES prevail [40].
Estimated fire intervals of white spruce stands vary from 80 years on
morainic uplands to 300 years in floodplain stands [40].  Closed white
spruce forests of interior Alaska tend to have either high intensity
crown fires or severe surface fires which kill and regenerate entire
stands [40].  Balsam poplar present in white spruce stands will recover
rapidly after fire [78].  White spruce replacement may be retarded with
cyclic fires [63].

Balsam poplar easily colonizes large burn areas due to seed dispersal
distances and its ability to regenerate vegetatively.  White spruce may
be more successful at reestablishing small burns [96].

More info for the term: prescribed fire

Hamilton's Research Papers (Hamilton 2006a, Hamilton 2006b)provide
information on prescribed fire and postfire response of plant
community species, including balsam poplar, that was not available when
this species review was originally written.

More info for the terms: cover, frequency, hardwood

Balsam poplar is stimulated to produce root suckers within several weeks
following fire [36,38].  Active recovery is likely to begin 1 year after
fire; balsam poplar increased in cover and frequency after 1 year on a
severely burned site in Alberta [53]:

                 cover   frequency
     prefire      .4 %       5 %
     postfire    3.2 %      33 %

Most balsam poplar suckering occurred in the second season after a
spring burn in a 15-year-old stand in Alberta, and after 5 years poplar
density was greater on burned areas than before the fire [4].

Two years after logging and broadcast slash burning in a floodplain
white spruce area, white spruce seedlings were outnumbered and
overtopped by hardwood seedlings, including balsam poplar [28].  Soil
temperatures on these sites were doubled, which encourages vegetative
expansion by balsam poplar [36,86].

See black cottonwood for further information on sprouting response of
balsam and other cottonwoods.

More info for the term: top-kill

Severe fires kill balsam poplars [53]; however, underground parts
survive in moist soils [111].  Moderate fires may top-kill some trees;
light fires usually do not harm mature balsam poplars [53].  Young trees
may be top-killed because of their thin bark [16].  Repeated burning may
permanently exclude balsam poplars [16].

More info for the term: root crown

   survivor species; on-site surviving root crown or caudex
   off-site colonizer; seed carried by wind; postfire years 1 and 2

More info for the term: tree

Balsam poplar is considered one of the tree species most well adapted to
fire in the northern boreal forest [36].  Its ability to produce sprouts
from roots, stumps, and buried branches enables it to quickly recover
after fire [74].  The bark of older balsam poplars can be up to 4 inches
(10 cm) thick at the base, affording fire protection [32].

More info on this topic.

More info for the terms: root sucker, succession

Balsam poplar is a pioneer species which invades disturbed wet sites by
seeding or suckering [22].  It is among the fastest growing trees in
temperate latitudes [22,101].  Rapid early growth allows it to establish
and dominate for up to 100 years; it has lived up to 200 years in Alaska
[36,75] but is considered more short-lived in southern areas.

Balsam poplar is highly flood tolerant [36] and is able to form
adventitious roots within a few days of a flood [58].  It showed no
noticeable injury from 2 months of flooding in several different areas
of Minnesota [1].  Balsam poplar is a seral species, eventually shaded
out by other hardwoods or by conifers [14,22].  In Minnesota it is
commonly found in transition zones between prairie and conifer forest
[14], and it is found in the transition zone between boreal forest and
tundra in far northern latitudes [63].

Balsam poplar occurs on both dry and wet sites, with different factors
controlling succession on these different sites.  Dry sites such as
south slopes or coarse alluvium supporting balsam poplar are affected to
a great degree by fire [75,96,97].  Fire is a major factor controlling
succession in northern montane boreal forests [78].  Repeated wildfires
have led to the development of balsam poplar- and aspen-dominated stands
within white spruce forests [78] and retards white spruce replacement
[63].  Fire will stimulate balsam poplar to root sucker and increase in
density where it is present in any succcessional stage [36].  This tree
has an explosive recovery rate after even severe fires [53].

Fire is uncommon [40,77] and plays no apparent role in succession of
alluvial floodplain sites in boreal forests [75].  Flood or other soil
disturbances allow colonization by willows, alders, and balsam poplars,
with balsam poplar eventually overtopping the other species and
dominating for up to 100 years [10,76,99].  Eventually white spruce
overtops the poplar and matures as an even-aged white spruce forest.
Conversion from balsam poplar to white spruce usually occurs within 120
to 150 years unless an inadequate white spruce seed source exists or
severe flooding recurs [97].  These white spruce stands eventually
become uneven-aged and permafrost may develop due to a lack of sunlight
penetrating through to the soil.  Permafrost development will lead to
replacement by black spruce and tamarack.  Balsam poplar is occasionally
reported to occur in black spruce forests [17,48,49] but does not
persist.

More info for the terms: formation, mesic, tree

Balsam poplar reproduces both sexually and vegetatively.

Seed production and dispersal:  Balsam poplar flower production begins
at about 8 years of age, with a good seed crop produced every year [36].
Most seeds are wind dispersed and fall within 650 feet (200 m) of the
parent tree [36].  Seeds remain viable for 2 to 4 weeks [57,63] but will
germinate immediately following arrival on a suitable seedbed of
exposed, moist mineral soil [57].  A 98 to 100 percent germination rate
was obtained in 2 to 3 days at temperatures ranging from 41 to 77
degrees F (5-25 degrees C) in a greenhouse study [110].  Seedlings
require 1 month of abundant moisture to survive [36].

Vegetative reproduction:  Balsam poplar is capable of regenerating from
root suckers, stump sprouts, stem sprouts, and buried branches [36,57].
Root suckering is thought to be primarily a means of expansion rather
than a means of recovery following clearcutting or fire [57].  Once
established on more mesic sites, balsam poplar will expand onto drier,
sandier sites adjacent to river floodplains through vegetative expansion
[57].  Most root suckers grow from roots about 0.4 inches (1 cm) in
diameter within the top 0.8 inches (2 cm) of soil [36].  Suckering is
most common when the organic layer has been removed, exposing mineral
soil [36].  Root suckering activity may increase when soil is disturbed
or when the overstory is removed, thus allowing warmer soil temperatures
[36].  Balsam poplar suckers are larger than those of eastern and
narrowleaf cottonwood and are more vigorous than aspen suckers [88].

Cut stumps produce sprouts from callus tissue and from dormant buds
[36].  Branches must be well buried to produce aerial shoots [36].  Stem
sprouting effectively aids recovery after destructive flooding in which
the main stem is broken or bent over [57].  Plant fragments washed
downstream may be a means of colonization for balsam poplar [57].  In
such cases sprouts can form on either root or shoot segments, leading to
the formation of new roots and establishment of a new plant.

Stands of balsam poplar are often polyclonal, with several genotypes and
their sprouts making up a stand [41].

More info on this topic.

More info for the terms: geophyte, phanerophyte

   Undisturbed State:  Phanerophyte (mesophanerophyte)
   Burned or Clipped State:  Cryptophyte (geophyte)

More info for the term: tree

Tree

Balsam poplar shows all the  characteristics of an early successional species: that is, low  shade tolerance, rapid juvenile growth, prolific seed production,  relatively short life span, good self-pruning, and replacement by  more tolerant associates. It is most accurately classed as very  intolerant of shade.

    In primary succession on river flood plains, balsam poplar is an  early invader and is associated with various willows and alder  for about 20 years after formation (53). It appears to assume  dominance as a result of greater stature and relative growth rate  than willow and alder, which precede it in succession, and white  spruce, which follows it (58,59). It may have an allelopathic  effect on alder germination and germinant development, but these  effects have not been substantiated under field conditions  (27,58,59). Balsam poplar bud extracts inhibit nitrification  under laboratory conditions, indicating the potential for  nitrogen conservation within poplar stands and an effect on  forest development and succession (49). It is the dominant  species for about 50 years. White spruce gradually replaces  balsam poplar, and by age 100 to 150 years, the poplar is a minor  component of the stand. Deviations from this general pattern  include the Yukon and Susitna Rivers where poplar stands more  than 200 years old occur, and white spruce is a minor species  present mainly in the understory.

    Balsam poplar can be important in secondary succession on bums and  cutovers or primary succession on lakeshores and sites severely  disturbed by mining and construction. Asexual and sexual  reproduction are important in burned and cutover areas, but only  sexual reproduction is important on severely disturbed sites.  Balsam poplar can reproduce asexually under stand conditions, but  the suckers are short lived.

On flood plains, the balsam poplar root  system is multilayered, owing to the deposition of new soil by  periodic flooding. Although early root development is downward,  subsequent development progresses upward as root development  occurs on the buried stem. In one instance, major new root  development occurred at least six times as the initial root  system and 2 in (6.6 ft) of the main bole were buried by silt   deposition during a 30- to 40-year period (40). Root development  on the buried stem of seedlings occurs within several weeks of  burial and appears to be associated with the presence of  preformed root primordia (8,34).

    Expansion of the root system and subsequent sucker production can  play an important role in clone development and colonization of a  site after the seedling ortet becomes established. Extension of  lateral roots 1 to 3 cm (0.4 to 1.2 in) in diameter has been  observed to be at least 14 m (46 ft) in 15-year-old clones.  Expansion of the root system ranged between 0.5 and 8.0 m (1.6  and 26 ft) in a 15-year-old clone; maximum rate of expansion  occurred between 5 and 9 years (33). Root system expansion  determined from clone size and age appears to be lower at  treeline than at lower elevations where clones of about the same  size occur but are 6 to 10 times older (6,33,35.).

    On sites without active soil deposition, formation of the root  system is predominantly downward and lateral. Depth of rooting is  restricted on the relatively wet sites where balsam poplar is  commonly found. Lateral root spread on upland sites is at least 8  to 12 in (26 to 39 ft).

PESTS AND DISEASE: Populus spp. have many natural enemies. The poplar and willow borer, Cryptorhynchus lapathi, is the most serious insect pest of balsam poplar and causes considerable mortality of saplings (Fowells 1965). The forest tent caterpillar, Malacosoma disstria, will only feed on the foliage of P. balsamifera when other Populus spp. (P. tremuloides and P. grandidentata) found in the same area have been completely destroyed (Fowells 1965).

Moderate browsing by mammals such as deer causes little permanent damage to suckers. Mice, voles, and rabbits can girdle suckers, and beaver frequently cut larger trees.

More info on this topic.

Balsam poplar flowers bloom and seeds disperse before leaves completely
emerge [36,101].  Bloom and seed dispersal dates in several geographic
areas are as follows:

                         flowers bloom    seeds disperse

Alaska [57,101]           May-June          June        

British Columbia [36]     April-June        May-June    

CO, MT, ND [24]           April-May

Lake States, Maine &      April-May         May-July
  Nebraska [32]

Balsam poplar is one of the most  versatile members of the Salicaceae in its potential for  vegetative reproduction. New stems originating from intact or  broken roots, preformed or adventitious buds on stumps or at the  base of trees, and buried stems or branches have been observed in  primary or secondary succession on flood plain and upland sites  (33,66,69).

    In Alaska, segments of stems and branches broken and buried during  autumn logging contribute to regeneration. This buried material  was from 2 to 6 cm (0.8 to 2.4 in) in diameter and 10 to 200 cm  (4 to 79 in) long (69).

    Dormant hardwood stem cuttings, as old as 10 to 15 years and  probably older, will produce roots and new shoots. Older cuttings  frequently take longer to root than younger cuttings. The distal  portion of the current year's growth may root more poorly than  the basal part of the current growth and 2-year-old wood. In a  rooting study conducted with material from Ontario, cuttings  collected after December had a higher percentage of rooting, more  roots per cutting, and a higher percentage of cuttings with bud  activity than those collected before December. Age of the parent  tree had no effect on number of roots produced or bud activity  (8). Clonal differences are a major source of variation in  rooting percentage and the number of primary roots produced by  dormant cuttings (15). Rooting potential for hardwood cuttings  ranges from 75 to 100 percent (8,24); rooting of softwood  cuttings ranges from 23 to 63 percent, depending on treatment  (24).

    Unrooted stem sections have been used with varying success in  regeneration of field sites. In one study in Alaska, survival  after 3 years ranged from 15 to 82 percent. Highest survival was  observed on gravel substrates, least on silt and sand soils.  Third-year height was greatest on silt and sand-1.2 m (3.9 ft)  (28). In a prescribed bum, survival after 5 years was generally  low; microsites burned to mineral soil supported the best growth.  Relatively deep organic layers, whether burned or unburned,  provide a poor environment for the establishment of unrooted stem  cuttings (65,66).

    Stem cuttings (hardwood and softwood or greenwood cuttings) have  been the major means of stand establishment for the  short-rotation intensive culture of balsam poplar and hybrid  poplars in Wisconsin, Ontario, and other areas (20). Hardwood  cuttings are grown in clonal orchards, harvested, stored, and  planted either rooted or unrooted. Clones that are difficult to  root may survive better if they are regenerated from rooted  cuttings. Greenwood cuttings provide a means of rapidly  increasing the number of desirable clones, but they must be  rooted before planting (20).

    In the greenhouse, root cuttings of balsam poplar clones from Utah  produced surface suckers from suppressed buds and end suckers  from the cambium at the cut end (46). Root cuttings also  produce new lateral roots from the same origins as suckers.  Alaskan clones respond similarly (69).

    Production of suckers after disturbance of the parent tree varies;  the response is generally less than that of aspen which suckers  prolifically. In Alaska, stocking after 3 years ranged from 4 to  61 percent; densities were 1 to 2 plants/m² (3 to 8/milacre)  in harvested balsam poplar stands. Suckers made up about 80  percent of the stocking in the summer- and winter-logged areas  but only 27 percent in a fall-harvested area. Production was on  intact and broken roots within the upper 2 cm (0.8 in) of the  surface soil. Average diameter of roots producing suckers was 1  cm (0.4 in) (69). In a 40- to 50-year-old stand on the  Tanana River in interior Alaska, stocking was 83 percent and  density 2 trees/m² (8/milacre) (25). In  Saskatchewan, sucker regeneration was observed on dry, moist, and  wet regimes. Stocking was 12 percent in the aspen-hazelnut type;  5 percent in the white spruce-aspen-bunchberry type; 5 percent in  the white spruce/feathermoss type; and 7 percent in the  aspen/sarsaparilla/twinflower type (31).

    Density of suckers is greatest on sites where the organic layers  are disturbed. Organic layers are effective insulators and may  limit sprouting by controlling soil temperature, particularly in  high latitude forests (69).

    Production of suckers may be important in the invasion and  establishment of balsam poplar on disturbed sites and in primary  succession. Expansion has been observed on flood plains from  established stands to areas that did not have poplar (40).  Colonization by clonal expansion is believed to be more  important on dry sites where the probability of seedling  establishment is low (33). The area covered by individual  clones on productive forest sites is not well documented; one  15-year-old clone consisted of 27 ramets and covered an area of  350 m² (3,700 ft²) (33).

    The extent of clonal development is best documented at elevational  and latitudinal treeline sites where seedling establishment is  limited and development of stands through vegetative growth is  the main means of colonization and maintenance of the species  (6,35). Scattered groves of balsam poplar in the Brooks and  Alaska Ranges of Alaska were found to be individual clones.  Representative clones covered from 100 to 200 m² (1,060 to  2,110 ft²) and contained from 90 to 150 ramets. Clones with  the oldest ramets (114 years old) were found on the Brooks Range  sites. Ramets did not occur in areas with dense shrub cover (35).

    New shoots also form on stumps from suppressed buds and  adventitious buds developed from undifferentiated inner bark.  Most originate in the inner bark at the top of the stump.  Sprouting response varies with genotype and declines as tree age  increases. It may be high (50 to 100/stump) initially, but  production and survival of sprouts vary with season and logging  method. The percentage of stumps with sprouts declines over a 2-  to 5-year period (69).

    Balsam poplar stump sprouts may be of little potential value in  replacement of trees in mature stands after disturbance  because of the fragile connection between sprout and stump. In  intensively cultured stands grown on short rotations, coppicing  is used to replace the new crop after harvest of the original  stand established from stem cuttings. Individual cuttings may  produce 10 to 20 sprouts I year after harvesting; 4 to 8 sprouts  will survive after 2 years (20).

    The growth potential of balsam poplar vegetative reproduction is  greater than that of early seedling growth. Average height of  balsam poplar was about 1 m (3.2 ft) after 3 years; height of  dominants was 2.5 to 3.0 m (8.1 to 9.8 ft). The age of suckers at  breast height (1.5 m or 4.9 ft) varies with site quality and the  degree and type of disturbance (21,25).

    The most detailed data available for growth of vegetative  reproduction comes from stands of a P. balsamifera x tristis  hybrid established from stem cuttings. After harvest of the  original stands, coppice stands are managed for several  rotations. Mean annual increment (stem plus branchwood) is 21 to  25 t/ha (9.5 to 11.0 tons/acre), depending on stand age and  rotation length (11). Other studies with this hybrid have shown  that 1- and 2-year-old coppice stands are taller and more  productive than stands of similar age established from stem  cuttings. Architecturally, the stands are different in that each  individual in coppice stands has 10 to 20 stems at age 1 and 4 to  8 stems at age 2. Stands from stem cuttings usually contain one  stem per individual at this age (20).

    Internode length on young vegetative regeneration is usually  greatest in the lower part of the annual shoot. Buds are longest  in the central part of the shoot, and the terminal bud is equal  to the largest nodal bud. First-order branches are smallest at  the base of the previous year's growth and longest near the top.  Angle of divergence of first-order branches is 30° to 40°  (37).

The seed does not exhibit dormancy,  and germination occurs over a wide range of temperatures (5°  to 35° C; 41° to 95° F) provided moisture is  adequate (63). Germination can occur under water, and even mild  water deficits reduce germination (33). Germination is reduced by  exposure to the concentrations of salt that commonly occur as  crusts on river flood plains (33). In a comparison of germination  on different types of naturally occurring substrates, balsam  poplar germinated over a wider range of substrate moisture  content on sand-algal crusts than on silt, sand, or silt-salt  crust substrates (33). Complete germination occurs in the dark  and over a range of overstory conditions (59). Burial of seed up  to several millimeters does not prevent germination but reduces  it.

    Germination is epigeal and can occur after the seed has separated  from the silky hair or in association with the hairs. Under ideal  conditions, germination is rapid, and cotyledons can be expanded  in 18 to 24 hours (33,64). The rate of germination declines below  15° to 20° C (59° to 68° F) (64). A  conspicuous ring of fine hairs is formed at the root-hypocotyl  junction. These hairs anchor the seedling to the substrate until  the radicle provides a more substantial foothold. Moist mineral  soil surfaces are the best seedbeds. Seeds germinate on moist  organic seedbeds, but seedling survival is poor, and most  seedlings die soon after germination (6,59,67).

    Seedling development depends on photosynthesis soon after  germination. After the first growing season, hypocotyl length  varies from 2 to 5 mm (0.08 to 0.20 in) under Alaska conditions.  Tricotyledonous seedlings do occur, but they are rare. Albinism  can be as high as 5 percent in some seed lots in Alaska. Leaf  production begins with the development of two leaves separated by  0 to 4 mm (0 to 0.16 in); the first leaf is I to 3 min (0.04 to  0.12 in) above the cotyledons. Subsequent leaf production and  internode development vary by microsite and with seedling  density, with maximum production of 11 leaves under field  conditions in Alaska. The third and fourth internodes are the  longest (25).

    The height and dry weight of first-year seedlings are affected by  density (25,39). Seedlings grown in a greenhouse from an Ontario  seed source ranged from 5 to 32 cm (2 to 12.5 in) in height and  11 to 220 mg (0.17 to 3.4 gr) per plant as density decreased from  about 59,000 to 323 seedlings/m² (39). Seedlings grown under  normal environmental conditions in interior Alaska ranged from 2  to 6 cm (0.8 to 2.4 in) tall at sowing densities ranging from  73,400 to 1 seeds/m² (6,820 to 0.1/ft²). First-year  shoot growth was proleptic with no branch formation unless the  apex was damaged. Dry weight of leaves and stems ranged from 20  to 520 mg (0.3 to 8.0 gr) (25). Average root length varied from 9  to 13 cm (3.5 to 5.1 in).

    On flood plain sites, height growth of planted seedlings in early  successional stages was twice that in later stages. Growth  appeared to be controlled by nitrogen availability in some stages  of succession and a combination of light, water, and nutrient  availability in other stages. In greenhouse studies, balsam  poplar seedling biomass was greater on soils from alder stands  than on those from earlier successional stages, suggesting that  poplar benefits from nitrogen fixation. The growth of seedlings  on early successional soils increased significantly when they  were fertilized, but growth on alder soils was not affected by  fertilization (58). Natural seedlings were found only in the  early successional stages, and growth rate was similar in each of  these stages.

Seeds are tan and small  (0.3 mg or 0.005 gr); they do not have an endosperm at maturity.  Dispersal begins in May and June throughout most of the range,  but dissemination can occur through the last week of July in  northernmost stands (33,59). Dispersal of seeds lasts for at  least 2 weeks. Viable seeds are found on trees 4 to 6 weeks after  the start of dispersal in some years. Relatively warm, dry  weather causes rapid dispersal. Each small seed is attached to a  tuft of long, silky hair ideally suited for long distance  dispersal by the wind. Under warm, dry conditions, seeds are  frequently carried upward by convection currents. Large  quantities of seeds fall within the stand, however, and large  numbers of short-lived germinants can be found on suitable  substrates in mature stands (59). On flood plain sites, large   quantities of seeds land in water and may be carried long  distances by rivers. Seeds sink rapidly, however, when detached  from the silky hairs.

    Although most balsam poplar seeds die within several weeks of  dispersal, some remain viable for 4 to 5 weeks. Duration of  viability is dependent on temperature and moisture; cooler, drier  conditions prolong viability. Viability can be maintained at 90  percent or greater for at least 3 years when seed is stored in  airtight containers at -10° C (14° F) (4,63,65).

Balsam poplar generally reaches  flowering age between 8 and 10 years. It produces large seed  crops almost every year, but significant annual variation in  production can occur by individual stands and trees (47,59).  Flowering in this dioecious species occurs before leaf flush, in  April and May throughout most of the range, but not until June or  July at northern limits and upper elevations.

    The regional ratio of male to female clones was found to be 1:1 on  treeline sites in northern Quebec. Female clones occurred on  sites with a relatively milder climate or those that were more  fertile and mesic; male clones were more common on inland sites  with drier soil conditions. Most stands were made up of more than  one clone; however, monoclonal stands usually contained a male  clone, and polyclonal stands usually had only female clones.  Stand density and area were greater in male than in female clones  (6).

    Flower clusters (catkins) are 5 to 9 cm (2 to 3.5 in) with many  small flowers about 3 mm (0.12 in) long. Male flowers have 20 to  30 reddish stamens. Mature female catkins are 10 to 15 cm (4 to 6  in) long. Capsules are a lustrous green during development but  turn dull green at time of dispersal. Male flowers are shed  promptly and decay; female catkins are shed shortly after  dispersal is completed but remain identifiable for the remainder  of the summer (2,56).

-Large balsam poplar throughout much of  the range may be 90 to 180 cm (35 to 71 in) in diameter and 23 to  30 in (75 to 100 ft) in height (44). In the northern part of the  range, this species is frequently the largest tree in 80- to  100-year-old stands. Beyond this age, conifers, which eventually  replace balsam poplar, usually attain greater heights but not  necessarily larger diameters.

    The form or branching pattern of young trees is excurrent, with a  clearly defined main bole and conical crown. In the 80- to  100-year-old age class, trees tend to have a more rounded crown,  however, and the central stem gives rise to a more deliquescent  or decurrent growth habit. On good sites the excurrent growth  habit is present to at least 40 to 50 years. On poorer sites, the  decurrent growth habit may occur earlier. The branching system is  composed of long and short shoots; short shoots produce most of  the leaves. Long shoots account for height growth and lateral  branch extension.

    Balsam poplar vegetative buds exhibit unconditional dormancy in  the fall and early winter. A brief chilling period removes this  dormancy, however, and by early February, buds are largely in a  state of imposed dormancy with active growth commencing as soon  as the temperature is high enough (14).

    Specific gravity of balsam poplar wood ranges from 0.326 to 0.346  and differs among sites. Within individual trees, specific  gravity varies from 0.318 to 0.429 and is greatest at the top of  the tree. Fiber length ranges from 1.02 mm (0.04 in) at breast  height to 0.78 mm (0.03 in) at a bole position of 75 percent of  total height. Sapwood pH averages 5.40 and heartwood 8.12. No  significant differences were found among male and female clones  in pH or wood and bark extractives. Lignin content of wood was  higher in the sapwood than in the heartwood; bark lignin content  was three times greater than that of the wood (32,48).

    Balsam poplar stands are generally even-aged, with some variation.  On upland sites in Saskatchewan, the greatest age span is about  17 years, but most stands have an age range of 5 years or less  (10). Age spans are 20 to 25 years or less in young stands and 50  to 60 years in 155- to 165-year-old stands occupying flood plain  sites in northeast British Columbia (40).

    The greatest age spans have been observed in the poplar groves  characteristic of treeline stands. Clones in Alaska treeline  stands have ramets ranging in age from I to more than 100 years  old. New suckers tend to be produced at the periphery of the  clone (35).

    Stand density varies with stand history. The density of stems  larger than 2.5 cm (1 in) varies from 8700/ha (3,250/acre) in  25-year-old stands to 225/ha (91/acre) in 200-year-old stands  (53). In southern portions of the species' range, stand density  is not well documented but is probably lower than in northern  areas because balsam poplar does not normally occur in large pure  stands. In Wisconsin, balsam poplar made up less than 2 percent  of the total stand volume in the types where it was present (for  example, balsam fir-white spruce, aspen, and tamarack) (12). In  mixed-wood sections, balsam poplar makes up 7 percent of the  total volume and annual growth (31), but this percentage varies  with site type and drainage (table 1).

    Table 1- Density and volume of balsam poplar in  Saskatchewan by site type and drainage (adapted from 23)      Site type and drainage  Density  Volume          trees/ha  trees/acre  Pct of  stand  m²/ha  ft²/acre  Pct of  stand    Whitespruce- feathermoss,
  well drained  17  7  3  11  157  5    White spruce/  aspen-bunchberry,
  well drained  86  35  7  14  200  7    Aspen-hazelnut,
  well drained  91  37  12  22  314  10    Jack pine-feather-moss/
  club moss, moderately well drained  7  3  1  2  26  1    White spruce- feathermoss,  moderately well drained  44  18  6  25  357  8           

    Total balsam poplar biomass estimates in Alaska range from 75 t/ha  (33 tons/acre) in the Yukon River drainage to 180 t/ha (80  tons/acre) on the Tanana River flood plain for 60-year-old stands  (29,68). In Alberta, aboveground dry weight for trees 16 to 65  years old varied from 0.45 to 251 kg (0.99 to 553 lb); 33 to 71  percent of this weight was in the main stem (30).

    Forest survey reports for Alaska indicate that, in unmanaged  stands, balsam poplar (or the hybrid with P trichocarpa) has a  mean annual increment of from 4 to 6 m³/ha (57 to 86 ft³/acre)  in the Susitna Valley. Site indices (base age 100 years) in  British Columbia range from 6 to 12 ft (low) to 34 to 42 ft  (good) (21).

Balsam poplar is in the section Tacamahaca of the genus Populus  (24). Two varieties have been identified: the typical variety  Populus balsamifera var. balsamifera and P balsamifera  var. subcordata, found in eastern Canada (2).

    Balsam poplar and black cottonwood (Populus trichocarpa) have  hybridized and produced mixed populations. Because of this  intermixing, black cottonwood has been suggested as a subspecies  (i.e., Populus balsamifera subsp. trichocarpa) (2,37).  Where balsam poplar and black cottonwood overlap, hybrids with a  range of characters intermediate to those of the two species are  found. An index using capsule shape, capsule pubescence, and  carpel number has been developed (2,55). Other hybrids have been  reported between balsam poplar and P alba, P. laurifolia, P  nigra, R simonii, P. sauveolens, P. tremula, and P tristis  (7,37,69).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 14
Specimens with Barcodes: 23
Species With Barcodes: 1

More info for the term: natural

The South Dakota Natural Heritage Program lists balsam poplar as
uncommon in the state [114].

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: T5 - Secure

Reasons: Element found throughout Canada and northern United States in riparian areas, streambanks, potholes, and floodplains; abundance unknown, but characterized as "extensive." (Harris 1990)

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Global Short Term Trend: Increase of 10 to >25%

Comments: Aspen invasion of grasslands especially at the prairie-forest border has increased primarily because of fire suppression (Buell 1959, Maini 1960, Blake 1963). Aspen groves that were present in the prairie just prior to that time often were of small, brush-like trees instead of tall specimens. Increased wetland drainage probably also has encouraged aspen invasion (Buell 1960)

Undisturbed aspen clones expand into adjacent prairie when light, moisture and soil conditions are appropriate especially for vegetative growth (Maini 1966b). Vigorous root suckers emerge in the prairie at the periphery of a clone, where other woody plants also frequently invade the prairie. As these suckers grow, and crowns coalesce, aspen shades out desirable grassland species.

Rate of invasion is related to disturbance, clone phenotype, slope, wind, moisture, drainage, soil texture and climate.

Aspen persists in prairie regions because of its preference for full sun and its vigorous vegetative reproduction and clonal growth that is well-adapted to top removal (fire, cutting, browsing) and drought.

More info for the term: tree

Balsam poplar is an important stabilizer of riverbanks and river islands
[36]; it also provides habitat for a wide variety of wildlife species.
For these reasons balsam poplar growing in stream corridors should not
be logged extensively [69]. See black cottonwood for further information
on the effects of watercourse damming and stream diversion on balsam and
other cottonwoods.

Mechanical logging places balsam poplar at a competitive advantage over
spruce by creating microsites for seedling establishment [11].  Exposure
of mineral soil favors balsam poplar seed germination [36].  Cutting
mature balsam poplars results in sprouting from callus tissue and
dormant buds [36].  Stump sprouting is most pronounced on winter logged
areas.  Improper harvesting can cause poplars to be suppressed, with
shrubs dominating the clearings [46].  Trees cut in the summer have few
surviving sprouts after four years [36].  Decay is a limiting factor in
balsam poplar utilization [94], but with proper management practices, it
could become a very important crop tree in Canada [94].

Balsam poplar has an allelopathic effect on green alder (Alnus viridis
spp. crispa) [36].
 
Balsam poplar can be controlled by 2,4-D + piclorum [103], glyphosate,
and hexazinone [36], and has an intermediate reaction to 2,4-D and
2,4,5-T [73].  This tree is very sensitive to sulfur dioxide fumigation
caused by landfill fires [44].  In an area less than 10 acres (4 ha)
away from one such fire, many balsam poplars were killed.

Diseases and insect pests of balsam poplar have been discussed by
several authors [21,32].

Natural stands are generally described as underutilized, but its  use is increasing as hardwood utilization increases in the  mixed-wood section of the boreal forest. Although the wood can be  used for a variety of products (for example, pulp, veneer, core  stock, boxes, crates, brackets), species such as aspen and  cottonwood are preferred. Waferboard with excellent mechanical  qualities can be produced from balsam poplar; however, special  procedures are needed to efficiently waferize the wood (17,42).  In northern areas, balsam poplar is used for structural lumber  and milled house logs when other species are not available.

    Balsam poplar hybrids have a potential for a variety of uses.  Populus balsamifera x R deltoides (Populus x jackii) are  used as windbreak and shelterwood plantings in the northern  plains region. Other balsam poplar hybrids are being tested in  short rotation, intensive culture plantations. When properly  cultivated, irrigated, and fertilized, these hybrids yield about  three or four times as much biomass as native aspen in northern  Wisconsin. The resulting pulpwood is of acceptable quality. The  foliage and small woody component can be converted to an animal  feed supplement (26,70).

    Balsam poplar and its hybrids are used or have potential value in  urban forestry and soil stabilization projects, particularly in  the northern portion of the range and in the plains area of  western Canada where the number of indigenous species available  for these purposes is limited. In urban situations, however,  balsam poplar has several undesirable traits. The branches of  older trees tend to be brittle, female trees produce large  amounts of residue from the spent catkins, and relatively rapid  root suckering can result in unwanted colonization of lawns,  sidewalks, and roadways.

    Anyone that has ever walked into a poplar stand in the spring at  bud break is impressed with the fragrance in the air. This  fragrance comes from the volatile compounds in the buds and other  parts of the tree. These compounds have been identified and may  have useful biological and esthetic properties (38). Various  extracts from the winter buds of poplar were recognized by native  peoples as having therapeutic value. For example, a salve or  ointment (balm of Gilead) made by heating the winter buds in oil  was used to relieve congestion (52). In recent years, the bark  has been collected and carved into figures that are sold in gift  shops.