Natural Invaders

The news from Worcester, Massachusetts in recent weeks is grim. The Asian Longhorned Beetle has been found in the city and has in fact been boring into our trees in stealth for several years, starting a process that could destroy New England’s hardwood forests if left unchecked.

Photo courtesy US Dept. of Agriculture

Photo courtesy US Dept. of Agriculture

Hitchhiking its way to central MA in packing material shipped from the Far East, the beetle’s arrival is an unfortunate side effect of a globalized trade system.

In other areas where this beetle has been found in the US (currently only Chicago, New York and New Jersey), the USDA declared a state of emergency and launched major (and costly) eradication campaigns. The end result? Over thirty thousand hardwood (maple, birch, willow, ash, poplar, sycamore and elm) trees were removed from the areas where the beetles were found. Yikes! That list pretty much includes most of the trees around here! Along with the imported Hemlock Wooly Adelgid pest threatening the Hemlock trees that blanket the Worcester Hills, arborphiles in central MA should be worried.

Imagine a New England devoid of spectacular maple foliage? This is not just about pretty trees, though. The extensive hardwood forests of northern New England sustain an economy built upon the timber industry. Autumn foliage brings millions of tourist dollars into our region. New England’s maple syrup industries rely on Sugar Maple trees, which are already at stress due to damage from road salt and road construction (which damages their shallow root systems). Habitat loss from development is already a serious problem for many New England birds, pollinators, plants and other wildlife who rely on trees and woodlands for part of their life cycle.

If that’s not enough to make you want to hug the nearest hardwood, trees in general provide many environmental benefits. Trees absorb carbon dioxide from the atmosphere, helping to mitigate our carbon emissions and improve air quality. They take up moisture through their roots, preventing soil erosion and flooding in urban and residential areas, and filtering pollutants that would otherwise flow through groundwater directly into our waterways. They also provide shade for homes and buildings, reducing energy costs as well as the urban heat effect. In other words, we need our trees!

Natural Selection Gone Bad
Scientists consider alien, or invasive, species to be one of the major threats to our environment. Invasive species such as the Asian Longhorned Beetle, free of the natural controls of their native lands, proliferate at an unnatural rate in their new home, causing rapid changes to the ecology of an area. Invasive plants, in particular, quickly overwhelm local ecosystems, altering natural environmental processes and patterns of ecological succession. Native plants and animals that have evolved together for thousands of years cannot always adapt to such rapid changes in their habitat, and either suffer extensive losses or disappear altogether.

Many argue that invasive species migration is no different than the natural geographic migration of species that has occurred since life began on this planet. However, the
processes of species migration has traditionally occured through natural events such
as floods and fires, or changes in resource availability due to glacial movement, volcanoes
and earthquakes.

Foreign species are nothing new around here, though. Dodging the emotive issue of whether European colonists to the New World were themselves exotic invaders or a natural migratory evolution, foreign plants and animals have been arriving on these shores since colonists first began settling here many centuries ago. Most of them settled happily into their new home without causing chaos. Think Cabbage, Tomatoes, Lilacs, Peonies, Hollyhocks or European Mountain Ash.

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Purple Loosestrife taking over a wetland in Leicester, MA.

Some of them, however, have already dramatically altered our landscape. Purple Loosestrife (pictured above), brought here as a garden plant in the 1800s, has jumped the garden gate and spread into wetlands across the northeast. It may be pretty, but Purple Loosestrife is responsible for degrading millions of acres of wetlands, choking out the native vegetation crucial to many forms of aquatic wildlife and birds. The American Chestnut, once the dominant hardwood tree in New England’s forests, was virtually extinct here by 1940, wiped out by a blight carried by by chestnut trees imported from Asia around 1900. The imported chestnuts carried their own disease strains with them, as well as their own immunity. The native chestnut wasn’t so lucky.

Although the arrival of the Asian Longhorned Beetle was accidental, the sad fact is that many of New England’s invasive plants were deliberately brought here for ornamental or agricultural use. Japanese Honeysuckle, Burning Bush (yes, the one you see on every street corner and strip mall) and Japanese Barberry are all popular landscape plants that have potential to degrade our natural areas.  The state of Massachusetts has recently passed legislation to halt the further distribution of these species, and time will tell if this will stem the tide of habitat destruction. Multiflora Rose was brought here for farmers to use as windbreaks, provide erosion control and to supply wildlife habitat. It is now a ubiquitous pest across New England, forming thorny thickets that are difficult to eradicate. In the old field behind our farm, Asiatic Bittersweet, the popular vine for creating holiday wreaths and decorations, has pulled whole stands of trees right down to the ground under the sheer weight of the vines.

One of my clients lives in Holden only a mile from one of the beetle sightings. She and her husband are understandably very worried about losing the large trees that initially attracted them to their shady, mature area of Holden. As the SWAT team descends upon Worcester, examining every tree within the “infestation zone”, she is waiting anxiously for the news of whether she will lose her trees. A helpless feeling, but there is much that we can do as homeowners to protect our unique New England landscape from further invasions.

Know Thy Weeds
Take some time to learn what is growing in your own backyard. Look at the New England Wild Flower Society’s photo gallery of New England invasive plants. You may be shocked to realize how many of your “wild” plants are actually invasive foreign invaders! The idea of removing them may be daunting, but each plant that you remove (and replace with a suitable non-invasive plant or tree) will reduce the damage that continues to undermine the stability of our environment.

Pictured below, Fringetree (Chianonanthus virginicus) makes a great alternative to Autumn Olive, which is a small tree (native to China, imported here during colonial times) that has escaped cultivation and now runs rampant along roadsides and woodland edges. Fringetree blooms in white clouds in spring, and birds like to dine on its dark berries. It blooms best in moist, fertile soil with at least 3-4 hours of sun.

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A beautiful blooming Fringetree growing in Spencer, MA.

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