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Prairie and savanna management should consider the following actions, as appropriate for each <br />site: <br />• Remove exotic species with appropriate methods. Cutting and herbicide treatment <br />are often most appropriate for tree and shrub species such as black locust, sumac, and <br />buckthorn. Repeated herbicide treatments or biological controls may be needed for <br />other exotic species such as leafy spurge and reed canary grass. <br />• Remedy disturbance problems where possible, by closing trails where erosion is <br />occurring, or reduce /rotate grazing to maintain plant populations. <br />• Use prescribed burns to control cool season grasses and other exotics, remove <br />accumulated plant litter, encourage recruitment of prairie plants from the seedbed, <br />and to maintain the health of the prairie for the long term. Burns may be scheduled <br />annually at first, and reduced to every three to four years, depending on amount of <br />litter available to successfully support a burn. Vary the burn regime over the long- <br />term to include both fall and spring burns. Burn only a portion of any given prairie to <br />conserve insect diversity. <br />• If elimination of exotics and prescribed burns over several seasons fails to restore <br />desired diversity, consider plant community restoration through supplemental seeding <br />of cut and burned area. Reconstructed prairies and savannas will require maintenance <br />through infrequent mowing or prescribed burn regimes (burning is preferred over <br />mowing when possible). Plantings should use native seed from local sources. <br />• In general, savannas can be burned less frequently than prairies and droughty sites <br />burned less frequently than mesic or wet sites. Average burn frequency for the dry <br />prairies and savannas in Roseville is approximately 2 -5 years. The burn frequency <br />should be greater during the first ten to twenty years if control of trees and brush is a <br />management objective. <br />• Seasonal timing can have a profound effect on species composition. Current research <br />information indicates that spring fires, conducted prior to April 15, tend to favor cool <br />season grasses and summer - blooming forbs. Late spring fires (April 15 —June 1) <br />tend to favor warm season (usually native) grasses and usually negatively effect forbs <br />and tree /shrub species. Summer burns would mimic lightning set fires, and although <br />City of Roseville 29 <br />Parks Natural Resource Management <br />