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Birds of the St. Croix River Valley: Minnesota and Wisconsin

Coniferous Communities

Upland Coniferous Forest

Before settlement of the Valley most of the Central Plain and Northern Highland was covered with Upland Coniferous Forest. Logging activities during the late 1800's and early 1900's altered much of this habitat; very few stands of pure Upland Coniferous Forest still exist. Probably the best representative stands occur in and near St. Croix State Park in Pine County and Lucius Woods State Park in Douglas County. In most instances this habitat occurs as small relicts intermixed with several Upland Deciduous Forest species. This habitat type is included because of its past dominance and existing relict stands.

Principal tree species associated with Upland Coniferous Forest are white pine and red pine. Important invaders include white birch, trembling aspen, red maple, sugar maple, black cherry, hazelnut, and ironwood. Prevalent ground layer vegetation includes wood anemone, wild sarsaparilla, big-leaf aster, Pennsylvania sedge, blue bead lily, bunchberry, wintergreen, ground pine, Canada mayflower, partridge berry, starflower, Indian pipe, and dwarf ginseng.

Important breeding bird species of the Upland Coniferous Forest include sharp-shinned hawk, pileated woodpecker, hairy woodpecker, eastern wood pewee, blue jay, common raven, black-capped chickadee, red-breasted nuthatch, hermit thrush, black-and-white warbler, yellow-rumped warbler, pine warbler*, Blackburnian warbler*, ovenbird, purple finch, pine siskin, dark-eyed junco, and chipping sparrow.

Lowland Coniferous Forest

This habitat type occurs in numerous locations north of the Tension Zone. The frequency of the Lowland Coniferous Forest is high but is limited in extent, occurring primarily in three distinct topographic settings: river floodplains, ancient lake beds, and kettles associated with kettle and knob topography in morainal areas. Soils of this habitat are usually acidic and are composed of wet, decaying vegetation that in many instances gives the ground a spongy texture. This habitat type is similar in several respects to the original Boreal Forest. Because most of that habitat type has been destroyed or greatly altered, vegetative characteristics and breeding bird use of the two have been combined.

Principal tree species of the Lowland Coniferous Forest include white spruce, white cedar, balsam fir, yellow birch, black ash, and green ash. Tamarack, American elm, and occasionally red maple, are also important components of this habitat. Shrub layers are usually poorly developed in Lowland Coniferous Forest; green ash and mountain holly are usually the prevalent shrub species. Important species of the ground layer include blue bead lily, bunchberry, creeping snowberry, wintergreen, Labrador tea, Canada mayflower, false Solomon's seal, starflower, blueberry, wild cranberry, round-leaf sundew, downy yellow violet, and sphagnum moss.

Principal breeding birds of this community include pileated woodpecker, yellow-bellied flycatcher, olive-sided flycatcher*, black-capped chickadee, red-breasted nuthatch*, winter wren*, hermit thrush, veery, solitary vireo, black-and-white warbler*, Nashville warbler, northern parula*, magnolia warbler*, yellow-rumped warbler*, ovenbird, northern waterthrush, common yellowthroat, brown-headed cowbird, purple finch*, pine siskin, chipping sparrow, white-throated sparrow, and song sparrow.

Black Spruce-Tamarack Bog

Although not as extensive in distribution as other coniferous or deciduous habitats, bogs are important to a large variety of breeding birds. This community exists primarily north of the Tension Zone and becomes frequent in the Northern Highland. Scattered relict bogs also occur in northern St. Croix and Washington counties. Bogs are formed in ancient lake basins or in outwash associated with morainal deposits. Bog soils are poorly developed and are usually highly acidic, owing in part to anaerobic decomposition of vegetation and temperature.

Black spruce and tamarack are the two most important tree species in this community. Mountain holly and bog birch are the main shrub layer species. Ground-layer vegetation in these bogs is perhaps the characteristic that separates this community from all others. Usually, the most important family is Ericaceae (e.g., leatherleaf, Labrador tea). Herbaceous vegetation in bogs usually contains several carnivorous plants including pitcher plant and round-leaf sundew. Prevalent vegetation includes Labrador tea, leatherleaf, bog rosemary, bog laurel, wild cranberry, buckbean, sphagnum moss, cottongrass, awned sedge, brown sedge, and bluejoint grass.

Principal breeding bird species include olive-sided flycatcher, black-capped chickadee, red-breasted nuthatch, winter wren, veery, black-and-white warbler, Nashville warbler*, yellow warbler, yellow-rumped warbler, common yellowthroat, red-winged blackbird, brown-headed cowbird, purple finch, pine siskin, American goldfinch, chipping sparrow, white-throated sparrow, swamp sparrow, and song sparrow.

Jack Pine Barrens

This community exists throughout the northern portions of the Central Plain and Northern Highland. Extensive stands of Jack Pine Barrens occur on sandy soils associated with the bed of Glacial Lake Grantsburg in Burnett, Pine, and Polk counties. Curtis (1959) considered fire to be an important agent in the origin of Jack Pine Barrens. Soils are primarily sandy and stabilized by various grasses.

Principal tree species of Jack Pine Barrens include jack pine, red pine, Hill's oak, bur oak, large-toothed aspen, and trembling aspen. Sweet fern, New Jersey tea, and blueberry are the most important shrubs of this community. In many areas, blueberry becomes dominant over other shrubs and among the ground layer. Important ground-layer vegetation includes Canada bluegrass, Kentucky bluegrass, pearly everlasting, yarrow, bracken fern, dogbane, big-leaf aster, flowering spurge, whorled loosestrife, wintergreen, and bearberry.

Important breeding birds associated with Jack Pine Barrens are mourning dove, common flicker, blue jay, house wren, American robin, hermit thrush, yellow-rumped warbler, Nashville warbler, ovenbird, northern oriole, brown-headed cowbird, indigo bunting, rufous-sided towhee, chipping sparrow*, clay-colored sparrow, and field sparrow. Recent surveys indicate that the Connecticut warbler is a fairly common breeding species in localized areas of Jack Pine Barrens in northwestern and western Burnett County.

Pine Plantations

This artificial community has become an important avian habitat primarily in St. Croix and Washington counties. Large hectarages of cropland, hillsides, and Old Field Communities have been converted to Pine Plantations. The establishment of this community has accomplished three purposes: soil stabilization, ornamental plantings, and commercial Christmas tree production.

Pine Plantations are primarily monotypic stands of red pine and scotch pine. Occasional stands also include white pine. Size of these plantations usually range from 2 to 20 ha. During the early stages of establishment, ground-layer vegetation retains the character of the original habitat and can consist of Kentucky bluegrass, quackgrass, ragweed, bindweed, Virginia strawberry, and flowering spurge. Continued tree growth, low light, and increased soil acidity results in an almost complete lack of ground-layer vegetation development.

Principal breeding bird species include mourning dove*, blue jay, common crow, house wren, brown thrasher, American robin*, common grackle*, brown-headed cowbird, and chipping sparrow*.

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