7. PRSR 04-11-2007 - Laserfiche WebLink

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about 9,000 years ago, pines began to decline, and prairie expanded into the region, along with elm and oak forests. The climate remained in this warm period until about 7,000 years ago, when midgrass prairie reached its maximum extent in Minnesota, and covered the southwest half of the state. Prairie, oak woodlands and brushlands, and oak savanna, consisting of scattered trees with aprairie-like ground cover, dominated the Region until about 4,000 years ago, when the climate gradually became cooler and moister. Oak thickets spread, and oak woodlands came to dominate some upland areas, interspersed with tall grass and wet prairies. White pines also migrated to just northeast of Sherburne County as the climate cooled. About 300 years ago, the climate became especially moist and cool, and fires became less frequent. As a result, extensive forests of elm, sugar maple, and basswood (known as the Big Woods) developed in eastern Minnesota. After this, the major patterns of vegetation in the area at the time of European settlement were then in place. Historic Influence of Humans on the Landscape Ideas about the history of Native Americans and their influence on the local landscape are still evolving. Native Americans have probably inhabited and hunted in the area for over 10,000 years. While their impacts were not as great as those of European settlers, Native Americans used a wide variety of plants and animals for food, and altered vegetation patterns for cultivation and by setting fire to broad expanses of landscape. Native Americans (and European fur traders) used fire to hunt game; create desired habitat; clear the landscape for travel, communication and defense; and obtain firewood. While some fires in the region would have occurred naturally, the activities of Native Americans undoubtedly accounted for the vast majority of fires. Prairies, savannas, and oak forests are fire-dependent plant communities, and would most likely not have been present in the Twin Cities Area at the time of European settlement without these fires. At the time of settlement, around 1850, the landscape of the study area supported a rich variety of plant communities including various types of wetlands in low areas and oak and aspen woodlands, brushlands and prairies on drier uplands. As the township developed after the mid-1800s, more intense human activities began to change the landscape and natural communities. In Scott County today, approximately 90-95 percent of the native landscape has been substantially impacted by human activities. Examples of changes since European settlement include the following: Roads and the railroads began to fragment forests and other communities. Agriculture affected hydrology by draining wetlands and altering creeks. Vegetation was altered through clearing, plowing, cessation of regular fires, and grazing. These effects are evident in the reduction of native vegetation diversity in meadow and forest understory and substitution of communities of low diversity Top of the World Park Addition Natural Area Management Plan 2