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<br />Some of the Tamarack swamps within the city tend to be fragmented by <br />fences/differing past land use, disturbed by excavation or ditching, and have invasive <br />~ . <br />species such as cattails (Typha spp.), reed canary grass (Pha/aris arundinacea), and <br />purple loosestrife (Lythrum sallearia) present. However there are also some Tamarack <br />communities that appear to be of good or very good quality, particularly in the north <br />half of the city. Despite this, City of Elk River lies within the southwestern range of this <br />plant community within Minnesota, and therefore, these remnants are somewhat rare <br />and unique to the region. <br /> <br />Tamarack swamp is present throughout the deciduous forest-woodland and conifer- <br />hardwood forest zones of Minnesota. It occurs on minerotrophic muck and shallow <br />peat along rivers and in shallow lake basins, and on nutrient-poor, mildly-acidic to <br />acidic peat in ice-block basins or large peatland systems. Tamarack is either the only <br />canopy specie-s or is mixed with black spruce, paper birch, yellow birch, white pine, <br />black ash, American elm, or red maple. The sedge Carex strieta is common under <br />relatively open stands of tamarack; cyperus-like sedge (Carex pseudo-eyperus) and <br />black chokeberry (Aronia melanocarpa) are often present on tear-drop islands in large <br />peatland complexes. <br /> <br />In the absence of catastrophic disturbances, tamarack swamps may succeed shrub <br />swamps, rich fens, poor fens, and possibly hardwood swamp forests. Fire, flooding, <br />and insect infestations (e.g., larch sawfly) often reverse this succession. Wind throw, <br />disease, and selective cutting of tamaracks in dense stands help maintain tamarack <br />cover by creating gaps in the canopy in which the very shade-intolerant tamarack <br />seedlings and saplings are able to grow. <br /> <br />Tamarack swamp differs from mixed hardwood swamp in part by having at least 50% <br />of its canopy cover formed by tamarack. Tamarack swamp differs from bog <br />communities in the pH of its surface waters and by having minerotrophic species that <br />do not occur in true bogs [such as bog birch (Betula pumi/a), several sedge species <br />(Carex leptalea, C. paupercula, C. tenuiflora), swamp loosestrife (Lysimaehia <br />thyrsiflora), marsh cinquefoil (Potentilla palustris), willow (Salix pedieellaris), and <br />northern white cedar (Thuja oeeidentalis)]. <br /> <br />Lowland Hardwood Forest (MLCCS Code 32220 1417 Total Acres) <br />A total of 44 lowland hardwood forests were documented within the city. Lowland <br />hardwood forest is a wet-mesic forest that is present throughout Minnesota It is <br /> <br />City of Elk River, MN - Natural Resouce Inventory <br />Bonestroo Natural Resources, September 2004 <br /> <br />21 <br />