A Crowd of Ferns
(From the Nokomis Interpretive Trail Guide)
"Look around...you are amid a crowd of Hay-scented Ferns (Dennstaedtia
punctilobula). They are so thick that nothing else is able to
grow on the forest floor. How does such a small plant dominate a
large area?
By chemical interations, [also known as an
allelopathic effect]!, the ferns prevent other species, even the
mighty oaks, from growing here. The ferns are apparently immune to
their own poisons, perhaps because they spread mostly by underground
shoots.
Crush a frond in your hands to learn how this fern got its name!
Lacking flowers, ferns reproduce by spores found in cases on the underside
of the frond. The size and shape of the Hay-scented Fern's spore
cups (at the margin of the underside) make it an easy species to
recognize."
Is That All She Wrote?
That is what we are trying to find
out. It is true that the Hay-scented Fern has an allelopathic
effect; however, how can an indigenous species become problematic in its
native habitat? The problem is that Hay-scented Ferns become densely
established shortly after a disturbance occurs, allowing sunlight to
reach the forest floor. Once the Hay-scented fern becomes
established, very few, if any, tree seedlings grow, making it nearly
impossible to establish a residual forest after management activities
occur.
The aftermath of a tornado that skipped through Keystone College's campus in 1998 caused
several trees to fall, creating an opening in the forest canopy on this
trail. In late summer of 2001 this was made into a demonstration site that will serve
to answer a two variable question.
The question is; do
deer have an impact on the success of the Hay-scented Fern and the
lack of success of tree seedlings? The variables are the
effects of deer in an area
with established Hay-scented Ferns and an area without them.
As you can see, a small section of the ferns has been fenced to keep
deer from accessing any vegetation. A portion of the fenced in
area and a small section outside the fence received a herbicidal
treatment to eliminate the established fern.
What will happen next? Will
there be any differences between the fenced in area and the accessible
area, or between the treated area and the non-treated area? Do deer
selectively feed on tree seedlings, leaving the Hay-scented Fern to
successfully populate an area, or is this fern's success truly attributed
to its allelopathic properties? Frequent this site to see if you are
able to answer these questions.
