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Sherburne
National Wildlife Refuge consists of 30,700 acres located
in the east central region of the Minnesota, approximately
50 miles northwest of the Minneapolis/St. Paul metropolitan
area.
The
refuge has recorded over 230 species of birds, 58 species
of mammals, and 25 species of reptiles and amphibians. Established
in the mid-1960s, the refuge's primary mission is to represent
a diverse biological community characteristic of the transition
zone between tallgrass prairie and forest. That mission is
being challenged by invasive plants.
The
native grasslands that are historically characteristic of
the area are disappearing. The Siberian elm, a fast-growing
and aggressive tree is choking the life out of the natural
habitat at Sherburne. Introduced into the U.S. in the 1860s,
it is a very hardy elm, surviving in areas with long, cold
winters. (It is now found from Minnesota south to Arkansas
and west to Utah.)
Black
locust also poses a serious threat to native vegetation in
dry and sand prairies, oak savannas and upland forest edges,
outside of its historic North American range in the Southeastern
U.S. It is, therefore, not alien to the U.S., but alien to
the region. Upon introduction to an area, black locust expands
readily into places where their shade reduces competition
from other (sun-loving) plants.
Both
these trees have been foci of the Volunteer Invasives Monitoring
Program, and purple loosestrife, a wetland plant affecting
about half the refuge is another plant to be targeted. (Purple
loosestrife crowds out higher-quality nutrition for wildlife,
making life tough for ducks, marshbirds, muskrats, and other
species depending upon native vegetation for food and housing
material.)
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