Non-Native Invasive Plants Vs. Native Habitats in Brookline
Welcome to the Conservation Commission’s webpage on native plants and non-native invasive plants. This page addresses the following questions and provides occasional news and updates on non-native invasive plants in Brookline (click blue links below to learn more):
Why is the Conservation Commission concerned about non-native plants?
Why does the Conservation Commission prefer native plants to non-native invasive plants? The Conservation Commission understands that native ecological communities across Brookline are a vital resource for Brookline, both for its residents and for the wildlife that inhabits this area. Certain non-native invasive plants have been disrupting natural areas in Brookline and causing a loss of native biodiversity.
What are native plants? “Native” or “indigenous” plants are defined as those that evolved in our area and in similar habitats and were growing here before the first European contacts with North America. Plants that people call “wild flowers” may be native or non-native plants. For example, Pink Lady Slipper, Canada Mayflower, and Wintergreen are native plants of Massachusetts forests. Certain kinds of violets and asters are native plants, while other kinds of violets and asters found in our woods are non-native.
Native plants can survive and establish new plants without intervention by humans. Some native plants are quite adaptable, and can survive human intervention. Brookline’s natural areas and minimally managed lands provide habitat for remnant populations of these adaptable plants. However, even these plants can be crowded out or extirpated by intense use by humans and their pets or by non-native invasive plants.
Other native plants are more vulnerable to human disruption and habitat changes. Those that rarely set seed and do not multiply rapidly from roots or rhizomes cannot survive multiple disruptions. Native plants that survive only in very specific microhabitats are lost when the microhabitat is disrupted. Plants that are useful or beautiful, such as Pink Lady Slipper, have been dug from the wild and have become rare in most of Brookline’s natural areas.
Why are native plants important to habitats and our local ecosystem? No one knows if there is any kind of native plant that can disappear from local natural areas without precipitating other losses. This is particularly problematic in our area, where farming, residential uses, and urbanization have successively destroyed natural areas, leaving only disconnected fragments of natural habitats.
The term habitat refers to the places that provide all the resources (such as food, shelter, protection, and opportunities for offspring) that individuals need for their entire life cycle. Each species requires specific plants and animals for survival. Those plants and animals require other plants and animals. The whole suite is a tangled web of intertwined habitats, called an ecological community.
These intertwined communities of living things also require specific non-living conditions, such as a certain range of temperature, rainfall, sunlight, and soil type. The combination of non-living conditions and the ecological communities they support are known as an ecosystem.
Groups of plant and animal species that have been living together for millions of years under particular conditions, such as in wetlands in the northeast or grasslands along the coast, have evolved together. The survival of one species may depend on other species in the ecological community, even if it does not directly benefit from those other species.
For example, the larvae of monarch butterflies need to eat milkweed leaves. The chemicals in the milkweed make the adult monarch butterfly irritating to most birds. Most local birds do not eat Monarch butterflies. Viceroy butterflies look like Monarch butterflies, but are quite palatable to birds. Birds that have sampled Monarchs avoid eating Viceroys. If there are few remaining Monarchs in an ecosystem, birds are more likely to eat Viceroys. Though Viceroys have no use for milkweed, they benefit from having milkweed in their ecosystem.
Changing conditions or disruption of the habitat of one or two species of plant or animal may result in a cascade of disruptions and losses of species in a given location, or across an ecosystem, or even globally.
What are non-native invasive plants and how do they cause harm?
Certain plants that have never before been part of our local ecological communities have been causing disruption and harm to native habitats. We refer to these plants as non-native invasives. They are also called invasive exotics or aliens.
The plants that concern ecologists are those that are both non-native and invasive, and that also have the potential to crowd out native plants or disrupt or destroy native ecological communities. Such plants are causing considerable disruption and harm within Brookline and across the world.
Non-native plants evolved in some other place or in a different kind of habitat. They may have spread here from nearby parts of North America, or been brought in from any part of the world, whether by early settlers or by recent gardeners eager for new and exotic plants.
Non-native plants can become invasive—they escape cultivation and spread vigorously into the native landscape. Plants that are native to other parts of the US and are not invasive in their own ecological communities can become invasive and disruptive when they become established in a new setting.
When a non-native invasive plant establishes itself in our natural areas, it can out compete and harm native habitats. It can destroy a network of plants and animals required for food, shelter, or reproduction of an array of species. Loss of even one species can cause a chain reaction of loss in native biodiversity.
Not all non-native plants are invasive and native plants can be invasive without being harmful. When non-native plants do not spread from gardens, they are not considered invasive. A locally native plant plays an integral role in its local ecosystem, even when it grows aggressively. For example, poison ivy provides berries that are edible for birds and rodents, leaves that certain insects eat, and shelter for the many native animals that do not have an allergic reaction to it.
Non-native invasives are not “bad” plants. They are often beautiful and fascinating. They may provide berries that birds love, or nectar that attracts butterflies, yet still cause harm. Many non-native invasives were originally brought here and sold to homeowners because of their attractive qualities.
It is hard to trace how non-native invasive plants are spread. Often the source is plants growing as “weeds” in yards or along roadsides. The seeds may be carried by birds or other animals or by wind or water. They may travel on car tires, on snowplows, or with landscapers.
Even if Brookline could remove all of the non-native invasives from our sanctuaries, non-native invasives would still be able to repopulate themselves from plants growing in our yards, gardens, and roadsides.
Monitoring the health of native habitats is an ongoing need, not only because of the threat from non-native plants but also from continuing threats from development, urbanization and global climate change.
Examples of non-native invasives in Brookline There are very many kinds of non-native invasives in Brookline. The following examples are among the more obvious and easy to find. Photos are courtesy of L. Mehrhoff/IPANE or USDA.
Japanese Knotweed looks quite exotic, with tall stems, huge leaves, and large, feathery-looking white flowers. It grows into a practically impenetrable thicket, especially along roadsides, including Hammond Pond Parkway.
Garlic Mustard was brought to North America by colonists who savored the spicy greens early in spring. It grows knee-high, attracts bees and butterflies, has beautiful white flowers and crowds out almost any other plant—even lawn grass—as it spreads across the spring landscape.
Black Swallow-wort is a relatively recently established non-native invasive that is causing concern in Brookline. This vine, with shiny leaves and seedpods that look like milkweed pods, has been popping up in yards, hedges, and weedy places. Its seeds travel by air. It quickly overspreads an area, and re-sprouts from the roots after it is cut. Worse, where milkweed does not grow, Monarch butterflies may lay their eggs on Black Swallow-wort, but those larvae do not survive to adulthood.
Milkweed Pod (Note: This is a native species, shown for comparison to swallow-wort pods.)
What is the Town of Brookline doing about non-native invasive plants?
Town Invasive Plant Management The Town strives to discourage the growth of non-native invasive plants, while encouraging the growth of native plants. Managing non-native invasive plants includes removal and control of existing species, and monitoring for the appearance of new species and spread of existing species. Every year, Parks Division and contract crews remove non-native invasive plants such as Japanese knotweed, garlic mustard, black swallow-wort, glossy buckthorn and tree of heaven from public open spaces. Control and removal techniques may include pulling, cutting or mowing plants depending on the species and location. Herbicides are used with care when necessary, and are only applied by licensed herbicide applicators. The Parks Division also regularly works with local organizations and volunteers who offer to assist with removal of non-native invasive plants. The Parks Division routinely incorporates native plant species into new plantings and landscaping in Brookline’s parks and open spaces. Certain species that were planted in the past, such as Norway maples and cork trees, are now known to be invasive and are no longer planted. Finally, the Parks Division helps to educate the public about non-native invasive plants through its outreach and educational programs.
Resolution to reduce the proliferation of invasive plant species In the fall of 2008, Town Meeting passed Article 28, Resolution to reduce the proliferation of invasive plant species. Here is the full text of the resolution:
Whereas, there exists certain plant species which are considered invasive because they starve out native species and plant material we work to maintain;
Whereas, these species are on the Massachusetts Prohibited Plant List as of January 2009 and are specifically banned from sale, propagation by the Commonwealth of Massachusetts Department of Agriculture. http://www.mass.gov/agr/;
Whereas, these species growing on private property may create offspring growing in Brookline parks, conservancies, or other public property or private property;
Whereas, these species kill trees and affect the life cycle of desirable wildlife and destroy the health of wetlands;
Whereas, these species are costly to control on public land and these costs will increase over time.
Therefore Be It Resolved, that the Selectmen of the Town of Brookline acknowledge that there is a need to control invasive species in the Town and that proliferation of invasive species on private property can have a direct effect on the number of such plants on public land and the cost of controlling them, and resolve to provide information to citizens on the Town Website and actively encourage through other appropriate media available to them the removal of invasive species from private land, and they encourage the continued training of Town workers in the recognition of and proper handling of invasive species.
Therefore, Be It Further Resolved, that the Town Meeting Members of the Town of Brookline have voted in favor of this invasive species resolution.
Or act on anything relative thereto.
Additional Public Education In addition to the information provided by the Conservation Commission on this website, the Parks and Open Space Division has created a Guide to Invasive Species in Brookline, which includes profiles for additional non-native invasive plant species currently in Brookline, or potential invasives. Descriptions and control methods are listed, but it is recommended that individuals and organizations research the most current control methods before attempting to remove non-native invasives. Certain control methods such as herbicides, burning and biological control may not be advisable or feasible, depending on the extent and location of the invasive plants. Click here to view the Guide to Invasive Species in Brookline.
What can property owners do to protect native plants and control non-native invasives?
Property owners in Brookline can address this problem by avoiding plants that have been found to be non-native invasives here, by protecting native plants, planting native plants, and by controlling or removing non-native invasives from their property.
Avoid plants that are on the Massachusetts Prohibited Plant List A first step in limiting non-native invasives is to be sure that you do not plant them. The Massachusetts Department of Agricultural Resources has banned the importation, propagation, and sale of certain non-native invasive plants that have been found to be disruptive in Massachusetts. The Prohibited Plant List was developed in collaboration with the Massachusetts Invasive Plant Advisory Group (MIPAG).
Check the list of prohibited plants before choosing new plants. Do not buy those plants from out-of-state nurseries. Do not transplant them from other areas, nor accept them from friends and neighbors.
This list, and any list of non-native invasive species, cannot be considered all-inclusive, and may be updated. Keep informed through the links included here.
Protect native plants A simple and satisfying way to protect native plants is to identify any native plants that are already growing on your own property. Places where the soil has not been recently dug or disturbed are likely spots-- such as in a wooded area or under long-established shrubs. Check in old, minimally tended perennial beds and along fences or little used parts of your property. It is best to leave these plants in their places, protecting them from disruption. After you learn more about the species and its preferred conditions, you might try to maintain or improve those conditions.
Plant locally native plants Planting native plants—especially those that would have been growing in the Brookline area before modern life disrupted their habitat—is a great way to appreciate and protect them.
In choosing native plants, choose responsibly propagated plants from native plant nurseries. Responsibly propagated native plants are grown from plants already being grown in nurseries—through seeds, cuttings, or divisions. Do not use plants that have been dug from the wild. Plants that are locally native to eastern Massachusetts are the ones that are most valuable to grow in Brookline.
A mowed lawn is not a native habitat. The fertilizers, herbicides, and watering systems that people use on their lawns are specifically designed to help non-native grasses out compete everything else. Removing a section of lawn and replacing it with native grasses or a garden of native plants adds interest to the property while enhancing environmental values.
Control non-native plants at home Property owners who wish to limit the spread of non-native invasives can work to identify all the plants on their property, making special effort to identify native plants as well as those plants listed in the Massachusetts Prohibited Plant List. Many native plants closely resemble non-native invasives, and it would be a shame to inadvertently destroy the native species.
The Brookline Division of Parks and Open Space website includes a guide to certain non-native invasives that are prevalent in town. Learn to recognize them.
Though the Town may occasionally use herbicides to handle extensive colonies of non-native invasives, this is a technique of last resort. Herbicides should only be applied by a licensed applicator.
The best approach for homeowners are the techniques that are least disruptive, including monitoring and hand-cutting or hand-pulling non-native invasives. Established non-native invasive plants can be difficult to eradicate, but ongoing efforts to limit and control them can have good results.
Methods for controlling or removing invasive non-native plants are dependent on each species’ biology, including the timing of its growth and seed setting. Before attempting to control non-natives learn about each plant.
The easiest way to limit the self-seeding of non-native invasives is to cut off and dispose of all the flower heads before the seeds ever ripen. Seedlings can be pulled like weeds.
Many non-native invasives spread vigorously by roots, runners, or even by small sections of stems that root themselves after having been cut and left on the ground. For such plants, mowing may make matters worse. Some can be readily uprooted; others may require more persistence. Once removed or controlled, ongoing monitoring is necessary.
Take care when disposing of non-native invasives Proper disposal of non-native plants parts is important, as some can re-root from small cut sections. Seeds may ripen even after a plant is cut, and the seeds may be so small that you do not notice them.
To contain the spread of flowers and seeds, fasten black plastic bags over the plants before uprooting them. Bag up all plant parts, cutting off the roots for good measure. Leave all the plant parts in securely fastened plastic bags or in tightly fastened barrels long enough for them to decompose. When thoroughly dried and decomposed, put the dead material out with your yard waste, in town-approved paper yard waste bags or labeled waste barrels. Remember to remove the black plastic bags first.
Because Brookline is a dense urban area, disposal of invasive plant parts is challenging. Burning is not allowed here, and home composting at high enough heats followed by deep burial is generally not practicable here. Yard waste is not allowed in the regular trash barrels. Unfortunately, the yard waste that we put out in paper bags could escape in transit. It is important to be sure that invasive plants that you have removed are completely incapable of life before putting them out as yard waste.
Monitor for the re-appearance of non-native invasives After working to remove non-native invasives, it is important to keep monitoring the spot where they grew. Bare spots invite invasives. Planting locally native plants that you can readily identify can make it easier to monitor the spot.
* Japanese Knotweed Removal and Restoration in Olmsted Park
The Conservation Commission approved a project that restored the native streambank and wetland plant communities in an area of Olmsted Park near Ward’s Pond, by Pond Ave. and Chestnut Ave. The project area covers 1.33 acres in both Brookline and Boston. This area had been infested with non-native invasive Japanese knotweed. Japanese knotweed spreads quickly and crowds out native plant species, creating a thick near-monoculture that provides little benefit to wildlife or the rest of the ecosystem. The Emerald Necklace Conservancy, a local non-profit organization, initiated this project and worked with a consultant to appropriately treat and remove the Japanese knotweed, to significantly decrease or eradicate the knotweed. Revegetation with appropriate native species was undertaken by the Emerald Necklace Conservancy. Replanting also enhances the reemergence of those native species that are found in the project area. The overall goal for the site was to enhance both biological diversity and wildlife habitat values. The project began in the fall of 2011 and is continuing for several seasons, during which time the Emerald Necklace Conservancy will continue to monitor and maintain the site.
Mile-a-minute weed, or Asiatic tearthumb, is an herbaceous, annual, trailing vine that has been found in many states on the east coast of the United States, including several communities in Massachusetts. Mile-a-minute weed has not been found in Brookline at this point, but is a significant concern for the town. This invasive plant has light green colored leaves that are each shaped like a triangle as well as circular basal leaves, and the stems and undersides of leaf blades are armed with recurved barbs. Mile-a-minute weed grows very rapidly, covering shrubs and other vegetation and eventually killing these plants and reducing native plant species in natural areas. It can also be problematic for nurseries and horticulture crops. In addition to its extreme growth rate, this invasive plant has seeds that last for many years and are very persistent. Mile-a-minute weed has little to no benefit to the environment here. Please keep an eye out for mile-a-minute weed in Brookline and your community. Early detection and removal of non-native invasives is one of the best ways to prevent their establishment in this area.
Mile-A-Minute Weed Foliage Photo courtesty of Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
* Lily Leaf Beetle Alert
The lily leaf beetle (Lilioceris lilii) is a non-native invasive insect that destroys native, as well as Asiatic, lilies. The beetle primarily feeds on lilies and Fritillaria and also feeds on a number of other plants, but only lays eggs and develops on lilies and Fritillaria. The lily leaf beetle is native to Europe and was accidentally introduced through imported ornamental lily bulbs. The beetle is now found in Massachusetts and throughout New England, and is a major pest causing significant damage to native lilies. Adult beetles are bright red with black head, legs, antennae, and underside, and are ~1/2 inch in length. Both adults and larvae will feed on foliage, with the larvae causing the most damage. Lily leaf beetles are active throughout the growing season. To learn more about the lily leaf beetle and how to control and manage this beetle on your property, click the following links: UMass Extension Lily Leaf Beetle Fact Sheet or URI Lily Leaf Beetle Fact Sheet.
Lily Leaf Beetle Photo courtesty of University of Rhode Island