Trempealeau National Wildlife Refuge is a prairie wonderland.
Prairies are a type of grassland, a landscape dominated by herbaceous
plants, especially grasses; trees are either absent or only widely scattered
on the landscape. This prairie was formed after the glaciers melted. Extensive
sand was deposited by glacial meltwaters which formed dunes, ridges, and
swales. It is frequently referred to as a sand prairie. The prairie grasses
that grow here do not form woody tissue or increase in girth. Their stems
are hollow except where the leaves join. Leaves are narrow with parallel
veins and flowers are usually small and inconspicuous. Some grasses such
as big bluestern, indiangrass, and switchgrass can reach heights of eight
or nine feet.
As impressive as the height of the grasses are, the root structure of
prairie plants is even more impressive. Roots reach many feet deep. This
is necessary in sandy soils where water is quickly absorbed and stored
many feet underground. Root systems also store energy which produces new
growth. This helps the plant endure extreme conditions such as a harsh
winter or a fire.
Growth of prairie grass is stimulated with prescribed burning. Spring
fires set back non-native grasses before the latter native grasses begin
to grow. Fire also burns up dead plant debris on the ground allowing the
sun and rain to penetrate the soil. Also, fire releases nutrients that
promote growth and increase seed yields.
The prairie at Trempealeau National Wildlife Refuge is constantly on
the attack from two grassland exotics. These invaders spread quickly,
choking out more desirable grasses and forbs.
One exotic is leafy spurge (Euphorbia esula). This species originated
in Europe and Asia. The plant quickly spread over the sandy soil by sending
out runners from its root system. We are attempting to control leafy spurge
by releasing flea beetles (Apthona) in existing spurge beds. The adult
beetles feed exclusively on the adult spurge plant while the larval stage
mines the plant's root system. Releases were started in 1991, and there
are now enough beetles established that we are able to collect them and
distribute them to new spurge concentrations. The progress is slow but
there is a noticeable decrease in spurge plots where the beetles have
been released.
Another non-native plant that is found extensively on the refuge is black
locust (Robinia pseudoacacia). This tree was planted on the refuge by
the Civilian Conservation Corps in the 1930's to control erosion. It spreads
quickly by suckers that sprout from a vigorous root system. Eliminating
black locust is very labor intensive. Trees must be cut, and the stumps
treated with herbicide. Even after chemical treatment, new suckers may
sprout, requiring additional cutting and chemical application. There are
many stands of black locust on the Refuge. We are only attempting to control
the spread of locust in grassland areas within the perimeter of the wildlife
drive. |
