5.10. SR 12-20-2004 - Laserfiche WebLink

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. If elimination of exotics and prescribed burns over several seasons fails to restore desired diversity, consider plant community restoration through supplemental seeding of cut and burned area. Reconstructed prairies and savannas will require maintenance through infrequent mowing or prescribed burn regimes (burning is preferred over mowing when possible). Plantings should use native seed from local sources. . In general, savannas can be burned less frequently than prairies and droughty sites burned less frequently than mesic or wet sites. Average burn frequency for the dry prairies and savannas in Elk River is approximately five years, with a range of 1-10+ years. In addition, burn frequency should be greater during the first couple of years if control of nonnative species is a management objective. . Seasonal timing can have a profound effect on species composition. Current research information indicates that spring fires, conducted prior to April 15, tend to favor cool season grasses and summer-blooming forbs. Late spring fires (April 15 _ June 1) tend to favor warm season (usually native) grasses and usually negatively effect forbs and tree/shrub species. Summer burns would mimic lightning set fires, and although these did occur, they appear to have been less of an influence on the presettlement landscape than human-set fires. Current information indicates that fall fires (after September 15) are most effective at maintaining a balance between grass and forb species and for controlling brush. . There is also reason to believe, based on historical records that frequent fall burns most closely mimic the presettlement burning pattern used by Native Americans in the tallgrass prairie region of the Upper Midwest. . Mowing can al.so be used on si\es with adequate accessibility and low risk for site disturbance. Mowing somewhat mimics the effect of grazing and can give many of the effects that prescribed burning can. Proper timing and techniques in mowing can be used to maintain a healthy balance between grasses and forbs. . Management of native communities, especially prairie, must also consider effects on the animal populations that are dependent on the community. The influence of management activities (i.e. burning) are not completely understood on animals such as butterflies and other invertebrates. To minimize the potential for devastating impacts on community obligate species and/or fire sensitive species, management should be carried out so as not to influence the entire area upon which these species depend on. An example would be not burning an entire prairie at once; this would leave refugia for the species of concern and allow for potential recolonization of burned areas. City of Elk River, MN - Natural Resouce Inventory Bonestroo Natural Resources. September 2004 58