Being a native plant doesn’t mean that the plant cannot also
be invasive. I consider a native plant
to be invasive if it becomes established in a desired ecosystem and has the
ability to replace the existing plant complex with something else. The invasive designation is based on
management goals. This means that a
single species can be both a desirable native plant and an invasive plant
depending upon where it is found at Blue Jay Barrens. A good example of this is the Fragrant Sumac,
Rhus aromatica, shown here invading a tall grass prairie, but growing a hundred
yards away as a desirable native understory shrub.
This process of ecosystem replacement is called succession
and is a natural and perpetually occurring event. Grassland is taken over by brush – Brush
gives way trees – Trees grow into forest. If the process was never disrupted, all we
would have is forest. The idea of
ecosystem management is to inject intentional disruptions that hold succession
at a particular stage.
The Fragrant Sumac forms a dense stand of branches that
eventually eliminates the tall grasses and prairie forbs. The branches of the sprawling shrub can be
overtopped by the tall grass, so the incursion is often hard to detect until
the sumac is well established and expanding its territory.
I find a lot of value in Fragrant Sumac when it grows in a
field edge or shaded understory situation.
These buds will develop into early spring flowers that are visited by a
wide variety of butterflies, moths, flies and beetles. In my management activities, I try to leave
plenty of these shrubs in a condition to bloom.
When a patch of Fragrant Sumac gets out of control in the
prairie, I work to reduce its vigor or eliminate it entirely. This clump of sumac was mowed and will be
sprayed in the spring.
There’s very little left in the way of prairie vegetation at
the heart of the sumac infestation. The
green grasses are bluegrass and fescue, both of which are non-native and
undesirable in the prairie. I’ll
eliminate the grass along with the sumac.
Deciding what must go and what can stay is one of the hardest jobs of
ecosystem management. When you get to
the point of actually eliminating a species, you just hope that your decision
to take that action was correct.
Is that a nice, healthy Formica exsectoides mound in the background? Careful to mow around. :~)
ReplyDeleteHi James. You're right about the mound ID. I'm always careful not to damage the mounds. I once confined a guest to my front porch because he kicked a mound after I had told him to leave it alone.
ReplyDelete