14 



NORTH AMERICAN FAUNA 73 



Jack Pine Barrens 



This community exists tliroughout 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 Bur- 

 nett, Pine, and Polk counties. Curtis (1959) considered fire to be an impor- 

 tant 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 trembhng aspen. Sweet fern, 

 New Jersey tea, and blueberry are the most important shrubs of this com- 

 munity. 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, winter- 

 green, 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 locahzed areas of 

 Jack Pine Barrens in northwestern and western Burnett County. 



Pine Plantations 



This artificial community has become an important avian habitat pri- 

 marily in St. Croix and Washington counties. Large hectarages of cropland, 

 hillsides, and Old Field Communities have been converted to Pine Planta- 

 tions. The estabUshment of this community has accomplished three pur- 

 poses: 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 estabhshment, 

 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 Ught, 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*. 



Wetland Communities 



Prairie Wetlands 



Much of central St. Croix, southern Polk, north central Washington, and 

 south central Chisago counties are dotted with smah semipermanent and 

 permanent wetlands. These wetlands occur on glacial outwash associated 



