Urban Woodlands are an important part of our local plant communities. Besides all of the environmental benefits that urban trees provide, woodlands provide valuable shelter and homes for much of our urban wildlife. Protection and conversation of our remaining woodland segments are a vital part of mainting the beauty and integrity of our local communities.
Oak Savannas are classified as terrestrial plant communities dominated by grasses, native perennials with scattered oak trees. They are commonly found in zones between prairies and wooodlands. Oak savannas are often called an “oak openings”, which refers to the characeristic of open-grown oak trees. Oak savannas have an upper limit of 50% tree coverage, which leaves a large portion of the savanna to be dominated by grasses and perennials. If the savanna has more than 50% tree coverage, it is classified as a woodland.
Prairies are open grassland communities dominated by grasses and perennials. Prairies generally lack enough rainfall to support trees. Prairies are classified into 3 basic types, which are (1) short / dry, (2) tall / wet and (3) mixed / mesic. Unfortunately, less than 1% of our prairies in Minnesota remain today. An urban prairie of any size can add value to residential landscapes, as well as commercial sites.
Wetlands are a dominant part of Minnesota plant communities. Wetlands are a critical component of water retention and flood management. They also provide food and shelter for numerous animals and birds. Wetlands are generally classified by the type of vegetation on site and the lenght of time that water is present. The wetlands of Minnesota are broken into the following catergories:
Type 1 Seasonly flooded basins are poorly drained, shallow depressions that can have standing water for a short time each year, but is commonly dry for most of the time. The alternating periods of wet and dry conditions can make it difficult for many plant species. Tree species can dominate as much as 50% of seasonaly flooded basin.s
Type 2 Fresh meadows are a transition area between aquatic communities and drier upland communities. Fresh meadows will generally only have standing water after periods of heavy rain, flooding or snow melt.
Type 3 Shallow marshes have soils that are saturated with standing water up to 6 inches for the majority of the year. Shallow marshes are dominated by sedge, bullrush, and cattail species.
Type 4 Deep marshes have standing water between 6 inches and several feet for the majority of the year. Deep marshes will have both emergent and submergent vegetation.
Type 5 Open water wetlands (lakes and ponds) are the “classic wetland” dominated by submergents and emergent vegetation along the shoreline.
Type 6 Shrub swamps are dominated by plant species that are less than 20 feet in height. Two common types of shrub swamps are alder thickets and shrub-carrs. Shrub swamps are commonly dominated by dogwood, willow, alder, and elderberry.
Type 7 Wooded swamps are forested wetlands dominated by conifers and lowland deciduous trees such as black ash, silver maple, red maple, birch and American elm. Coniferous swamps are comprised of cedar and tamarack trees.
Type 8 Bogs are a transitional state between open water and hardwood forest. Bogs are formed over saturated, acid peat soils that are commonly low in nutrients.