Wednesday, September 1, 2021

Invasive Species: the saga continues

 by Beth Sullivan

Multi-flora rose offers some protection
for nesters and berries for food, but can
take over a field in no time.
Over the last years I have written about invasive species, plant, animal and insect.  It is a challenge to actually define the term as there are many species that have been brought to our habitats that are not truly native or were not here before European contact.   Many species of animals have been domesticated such as cows, sheep, horses, pets. Most don’t become an invasive problem but could, like feral cats. Some species, like the Eastern Cottontail, have been introduced  purposefully and now have taken over a niche that was occupied by their native relative the New England Cottontail.  They have become naturalized, a nuisance, but not many people would refer to them as invasive.

Invasive insects have become a bigger problem. As products from foreign countries come to our shores, they contain plant material or insects and their eggs associated with the wood or packing material.  Once these insects are released into a new environment, they do not have native predators to control them.  Often, they find sources of abundant food and appropriate habitat.   Then they go to town, unimpeded and often leave a path of destruction. We have witnessed this most recently with gypsy moths, hemlock woolly adelgid, emerald ash borer, Asian long-horned beetles and now spotted lanternfly.  As climate warms, many of these pests are not affected by winter temperatures anymore, so they survive. In most cases there are few, if any, natural insect controls. I don’t think many of our native birds are fully adapted to eat invasive insects, but we know cuckoos eat gypsy moths and woodpeckers will go into wood for various beetle larvae.   As a result of invasive insects, we are losing our hemlocks, ash trees and many of our oak trees.

Porcelain berry, a beauty of a beast
that will cover and smother entire
trees and walls.

Invasive plants form another real threat.  People have been intrigued by plants and their uses, probably forever!  Moving plants around for food, medicine and decoration is an ongoing activity.  Centuries ago, people, and plants, didn’t move quite as far or as quickly as they can now.   Settlers introduced grasses for their livestock that have become integrated into farm fields. Food plants were introduced to give us all greater variety.  But most of these kinds of plants have “better manners”.  Most don’t spread widely or aggressively.  In the last century, ecologists have noted new plants becoming monocultures in some areas, taking over habitats, killing native species with various methods, and ultimately enticing native wildlife to make use of them and spread their seeds far and wide.   Some of these plants are beautiful,  and the uninformed are also responsible for their spread.  Some plants were deemed useful in landscaping and no one really knew how aggressively they would spread beyond their intended use.

Oriental bittersweet twist 
their way up and then 
strangle the supporting tree.
So, here we are, as stewards for Avalonia, hoping to maintain habitats that are appropriate for all kinds of wildlife and reflect, as closely as possible, native species in their natural habitats. Sadly, as we look closely and learn more, it is hard to see the native forest…for all the invasive trees and shrubs and vines in the way!  There are several places where I feel the landscape would be completely barren, if we were able to remove all the invasive plants.  On some preserves, we have worked tirelessly to remove invasive shrubs such as multiflora rose and autumn olive and bush honeysuckle. However the minute the area is opened to sun, new invasives take their place.  We got bittersweet, reed canary grass and porcelain berry. When those were tackled, swallowwort, bindweed and stilt grass have began their destructive march.

A habitat overrun by invasives may offer some minimal shelter for wildlife, but the food value is often very poor. In some cases, nothing eats an invasive plant. In the worst case, our native and endangered Monarchs are fooled into laying their eggs on black swallowwort but when the caterpillars emerge, they cannot eat that plant, and they die.

Stilt grass has taken over the banks
of the Pequotsepos Brook and will 
spread downstream.

Stilt grass is relatively new here. However, in the more southern/mid Atlantic states, the grass has spread so rapidly, and destructively, that it carpets entire forests and parks, preventing any native plants, flowers, or tree seedlings, from germinating.  The seeds originally came in packing material that protected Japanese ceramics.  It is now wreaking havoc in our area. 

Avalonia stewards are determined to learn the best way to control this grass, and other invasive species. We are conducting workshops, and compiling data/fact sheets for our stewards to use. These, we hope will soon be available on our website.   Right now, Japanese stilt grass is being tracked into preserves by hikers and bikers.  It has spread along the roadsides and vehicles carry seeds to parking lots and other preserves. Landscape equipment can carry and spread seed.  This is the time to identify it and begin to wage war.   As an annual grass, it relies on self-seeding, so removal now, before the seeds are set, is imperative. It is easy to pull.  If seeds are present, already, it should be bagged and not put into compost.   It can even be “weedwhacked”  down close to the ground at this time of year, to inhibit the seeds. The plants will die.  But sadly, seeds from previous years are already in the seed bank and can last up to five years.  Too bad we didn’t start, didn’t know, years ago!

There is a lot to learn. Identification is the first step.  Then learning about the best ways to manage or treat infestations will take time and thought.  We, as an organization are working on finding the right balance. 

This is a great resource:   Good luck in your own home areas.

Connecticut Invasive Plant Working Group:

If you find swallowwort, at least remove the 
pods to prevent seeding. 

Autumn Olive berries make great jam, but there
are just too many of them!

Stilt grass is not too hard to identify,
once you know it.

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