Visitors to Iowa's parks and forests expect a certain... aesthetic accompanying
their adventures. They might be looking for exposed bedrock or rolling Bluffs
but the number one expectation is trees with pervasive green leaves. Iowa may not
have mountains or oceans but our recreational areas are packed with trees,
well... that is they CURRENTLY are packed with trees.
"Right now we are standing at
the northeast part of Backbone Park or a Backbone State Forest lies. We're looking
at some of the larger more mature vines of oriental bittersweet. This is what
happens when it goes unmanaged. it's vined all the way up to the top of
the tree, its shaded out the canopy, there's no lateral branches left in this
tree, they're technically dead. Everything that you look through this forest I would
say about 60-70 percent of these trees are dead or near-dead. As a forest health
program leader I was brought up here a couple years ago and asked "What would I
do with this massive stand of woods?" An answer was simple... but the public won't
like it. I'd clear-cut it.
Asiatic, or oriental, bittersweet is one of the many
invasive plant species that are slowly and surely strangling Iowa's forests.
While each carries its own ecological threat, invasive introductions to Iowa
all sing a common refrain.
Asiatic bittersweet was initially discovered for
its unique vines and beautiful bright red berries, which hobbyist gardeners and
landscape designers began using freely. It wasn't until it was far too late that
the forestry community discovered there are no native predators in the North
American ecosystem, and the plant practically spread like wildfire.
Of the six invasives we'll look at today
each found its way across Iowa through
similar means, and spread far and wide before their threat could be detected. So
we'll start with Asiatic bittersweet.
We see this in the Iowa landscape
throughout most of the state right now. It's very aggressive. The vines can be
easily six inches in diameter. The fruits are carried by birds easily.
The process to control Asiatic Bittersweet
is costly and dangerous. Using a basal bark
herbicide, which is a dangerous mix of chemicals and diesel fuel only,
the treatment is to spray the vine of the invasive plant only as this
measure will likely kill any plant it comes into contact with. On top of the
chemical hazard, this technique adds up costing hundreds of dollars per acre. But
we've tried everything. We tried burning it and anytime that you open up the
forest floor you get more of this oriental bittersweet bittersweet.
We tried sprain in a young area and you can look out throughout this forest and
you'll see these lines everywhere out here. The big key in my opinion is its
very paramount to walk your forest annually. Especially if you can get your
district forester out there and look for this plant. If you see it there
manage it as soon as you find it.
Another invasive that spreads with little effort
is Japanese knot weed. Found primarily around waterways and moist forest floors
similar to asiatic bittersweet, Japanese knot weed grows at an exponential rate,
and it will steal any and all resources from native plants. This is one that we
see on the forests edge. We'll see along the edges of trees,
Usually in disturbed areas. Often along
repairing areas along streams. It could be very very tall. The
problem when you're next to a stream is if you mow it and you break off a piece
and this falls into a wet area this will grow. To fully grasp how bad invasives
can be to a native ecosystem, Japanese knot weed is the perfect illustration.
Once it takes over nothing in our environment can withstand its resource
pressure. If you look at how dense this is, and imagine if you're a tree seedling
trying to grow underneath there, it can't at this point. It's just too shaded out.
Invasive species have been an issue for as long as there have been pioneers
traveling through forests. When the first settlers of Iowa stomped their way
across Iowa's marshy plains, black locust was commonly used to stabilize nitrogen
levels and for fence posts. While sturdy, its an invasive that spreads like a
weed and has tiny barbs that irritate the skin. Similarly, reedcanary grass was
brought in during the late 1800s for pasture and erosion control, and now it
is virtually everywhere due to its seed being carried by the wind to all corners
of the country. In the 20th century, Bush honeysuckle
arrived as an invasive that literally started as an ornamental. Designers would
line houses with the plant or make Christmas wreaths featuring the berries
but once again the bush became so oppressive it was eventually banned for
any use. Its illegal to transport it anywhere in the state of Iowa because
it's so invasive and those berries are still viable no matter where you go. So
that's the last thing we want people to do is think they have a pretty plant and
they're gonna make an ornament out of it and when they're done with the ornament
in the fall they throw in the ditch well, its gonna grow. Of course not all
invasive fights are losing battles. Garlic mustard was once pervasive in
Backbone and in 2005 the DNR secured grant money to test using one of
conservationists most powerful tools in a hope to restore the natural forest
floor. So we started with all the typical techniques to control it. We started it out
with hand pulling it and bagging it up. We started out with spraying it with
glysophate. And then we started out with burning it, and then we notice the
strange phenomenon; burn it burning it work quite well. Another thing that we
found though from the burning is we need to look back in here you'll see the
ferns came back, jack in the pulpit, all the native forbs, and flowers. Everything
came back that we haven't seen in this forest for quite some time because it
was just this carpet of garlic mustard that is now gone. Invasive species are
puzzles; some are easy to figure out others... extraordinarily complicated.
While difficult invasives such as asiatic bittersweet or Japanese knot weed
can be managed, once they get out of control... See straight down the trail a
little bit strangling the tree? ...reining them back in takes time, money, and
intensive labor. Resources the Iowa DNR is always judicious with. Unfortunately,
it could take up all of our time but we have, we have to prioritize. And we don't
have enough time to, to spend 40 hours a week on invasive species, but we have so
many other priorities that we have to attend to to make the park nice and to
attract people, and keep everybody safe.