St. Croix WMD |
Grassland Management
Many species of wildlife require grassland habitats, and in our district nearly 95% of the native prairie habitat has been lost to the plow and development. Grasslands provide shelter for birds, mammals, reptiles, and insects. Species like meadowlark, short-eared owls, upland sandpipers, bobolinks and other songbirds require large tracts of grasslands to make their homes. All species of ground nesting birds like waterfowl, pheasants, and songbirds need grasslands to build and conceal their nests.
The native prairie species in the tallgrass and mixed height prairies vary in size from side oats grama that is about one foot tall to prairie cordgrass and big bluestem which can reach seven feet tall. These plants develop root systems that are sometimes twice as long as the plants are tall. Because of this dense root system, these plants form sod that has a tremendous capacity to absorb runoff and rain water. These plants can take up chemicals and nutrients that are carried into the grassland by run-off thus filtering the water that flows through a tract of grassland.
Grassland Restoration and Management
When a new tract of land is acquired, it has generally been farmed. The District restores the wetlands on the
new property and then seeds the uplands back to local ecotype native prairie species. The native seeds that are
planted were all collected locally. These seeds are adapted to local growing conditions and represent a
portion of the plant species found in Western Wisconsin. A typical planted prairie on a Waterfowl Production
Area may have over 50 forb species and five grass species. The seed is planting using a broadcast seeder
and cultipacker.
A diverse seed mixture is important because the grasses and flowers provide food for many species of insects. Grassland birds feed on the insects found in the prairie. A grassland tract with a diverse species composition can support more wildlife than a less diverse planting. Plant species diversity also provides variability in the grassland structure. Some wildlife species need dense grasses overhead and passageways near the ground; others like shorter open areas in grassland. Plant diversity provides better cover, nesting habitat and food for a larger variety of wildlife species.
|
||
Following planting, these restoration sites may undergo intensive mowing or prescribed fire to stimulate the growth of desirable native species and reduce the growth of unwanted trees, shrubs and invasive species. It may take two to five years for the planted native prairie to become established. Fire is typically used in the third or fifth years after seeding to stimulate the growth of native plants. Although the prescribed fire may impact nesting birds, the long term value of maintaining these areas as prairie outweighs the short term impact. Once a seeding is established, it is difficult for weeds to invade these native prairie stands.
Cool Season Grass Transition to Native Fields
The District is actively changing fields from monotypic stands of exotic cool season grasses, typically former
CRP contract plantings, to planted stands of local ecotype native grasses and forbs. The planting of native grasses
and forbs on these sites is designed to provide structural (height-density) and species diversity to benefit
breeding grassland dependent birds. Removal of trees and woody vegetation also makes the grassland patches more
attractive to grassland nesting birds. An increase in block size also provides better habitat for many species
of grassland dependent birds. Numerous studies have shown that trees and shrubs should be removed from within
and around grassland patches to decrease nest predation and brood parasitism. Patches for restoration of grassland
habitat should also be as large as possible to decrease contact with edge predators.
Several techniques are used to transition fields from exotic cool season grasses to native species with the underlying realization that we cannot recreate a pure native plant species stand. Due to many outside influences such as past farming history, agricultural chemical use, erosion, invasive species and landscape level influences by humans, we will have to live with a certain number of invasive or exotic species in the grasslands we manage in the District. Total elimination of these species is not practical.
Depending on site conditions, transition techniques include three year cropping rotation and various combinations of tree removal, chemical treatment, prescribed fire, cover crops and overseeding. Factors such as the presence of tree stumps, the availability of farmers to crop areas, soil types, erosion potential and existing species on the site are considered in deciding how best to restore and manage the site. Optimal management conditions will be reached when prescribed fire is the primary tool used to manage and maintain grassland.
