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messy, they support a high number of plants and animals throughout their <br />decomposition cycle, and are therefore important. <br />• The removal of weedy and /or exotic tree species such as Siberian elm, boxelder, <br />Russian olive, black locust and eastern red cedar is encouraged. Plant higher value <br />native trees and shrubs back into forests following problem species removal. <br />• Oak forest communities are adapted to fires and can often be improved through <br />prescribed burns. Prescribed burns will generally increase diversity of grasses and <br />forbs, encourage oak seedling germination and set back exotic or invasive shrub <br />species. Where oak forest communities occur adjacent to prairie and savanna <br />communities, fires from prescribed burns should be allowed to burn into the oak <br />forest. <br />• Lowland hardwood forest communities should not be burned as frequently as oak <br />forest, savanna, prairies, or some wetlands. <br />• Oak wilt may be of particular concern in several of the parks due to the dominance of <br />oak. Oak wilt is spread during the growing season through damaged parts of oak <br />trees. Canopy openings created by oak wilt can augment invasion by exotic species if <br />not replanted or managed to restore oak woodlands. Oak trees should not be cut, <br />pruned or injured between April 15 and July 1 of each year. Exposed roots injured by <br />construction activities facilitate the spread oak wilt infection. If injury occurs, the <br />wound should be treated with a tree wound dressing within 15 minutes or less to <br />reduce the infection potential. A vibratory plow can be used to sever roots along the <br />edge of any construction area prior to beginning work. This can prevent the transfer <br />of oak wilt fungus between individuals through grafted roots and allow for <br />regeneration at the point of cutting. If vibratory plowing is used, the disturbed ground <br />should be restored to pre -plow contours and planted with an appropriate native seed <br />mix to prevent invasion by nonnative shrubs and weeds. Tree protection zones <br />should be fenced to prevent entry or compaction by construction equipment. Soil and <br />construction materials should not be stored within the tree protection zone, as this can <br />result in contamination of the tree protection zone and /or other construction sites. <br />City of Roseville 33 <br />Parks Natural Resource Management <br />