Invasive plants and trees have been on the radar of naturalists, environmentalists and gardeners for quite some time, and efforts to inform the public of this important topic are ongoing. Local experts are helping to not only raise awareness, but also assist local homeowners to create their own native plant gardens.
WHAT, EXACTLY, ARE INVASIVE PLANTS?
“Invasive plants are those which are nonnative to an area and are known to cause harm to the environment, economy, or human health,” said Amy Jewitt, invasive species coordinator, Western Pennsylvania Conservancy. “Once introduced into a new environment, invasive plants tend to grow quickly and aggressively, outcompeting desirable native species.”
In the past, invasive plants have often been introduced to an area for their ornamental value and enjoyment in landscapes and gardens, but over time, they can become harmful in their new environments.
“In their natural range, plants are limited by factors that keep them in balance with the rest of nature. These factors include pests, herbivores or diseases,” Jewitt explained. “When introduced into an area where these limitations are absent, however, some species can become invasive.”
That is when these plants can wreak havoc on the biodiverse plant and wildlife communities that have evolved in a region over time, she added.
The dangers of invasive plants include reducing food and habitat sources for wildlife, bird, insect, spider and bee populations; creating soil erosion; preventing native seeds from germinating; and even affecting human health by causing hay fever and other allergies. And that’s just to name a few!
Many invasive plants are drawing particular attention because of how rapidly they are spreading. Jewitt said homeowners and gardeners should be aware of Japanese barberry (Berberis thunbergii) and Callery pear (Pyrus calleryana), both recently added to the Pennsylvania Noxious Weed List.
According to terms established by the Controlled Plant and Noxious Weed Committee (CP&NWC) in conjunction with the Pennsylvania Department of Agriculture, these plants are banned from being distributed, cultivated or propagated in the Commonwealth. Due to their current use in the nursery trade, however, enforcement of this ban for both species will be phased in over two years to allow time for nurseries to eliminate them from their stock, find nonharmful alternatives, and develop seedless, sterile varieties.
Garlic mustard (Alliaria petiolate) is another invasive plant that has been taking over gardens and open spaces for many years now, according to Rachel Handel, communications director, Audubon Society of Western Pennsylvania. “The plant’s seeds can remain viable in the ground for nearly 10 years, so it can be very difficult to eradicate,” she said.
Another plant that also has caused concern in this region is Japanese Knotweed (Reynoutria japonica). “This fast-growing and fast-spreading plant quickly chokes out almost any plant around it,” Handel said.
Eradicating invasive plants isn’t always easy, but efforts should still be made to stop or slow their spread when feasible. Many local parks and environmental organizations have hosted efforts to remove invasive plants, especially knotweed. And home gardeners should follow suit.
“You can pull them out and bag them in a trash bag—then put that bag into the garbage. Don’t place the pulled plants into community green recycling bins because that simply spreads the seeds,” Handel said.
Management guidelines for many common invasive species found in home landscapes is available through Penn State Extension. Jewitt cautioned that it is very important to pull out the whole plant, including all of the roots or the plant will simply come back. “Not all species can feasibly be hand-removed and sometimes multiyear efforts are needed, not just a one and done,” Jewitt said.
The advantages of planting and maintaining native plants are numerous. Just as invasive plants harm wildlife and birds, native plants—those that occur naturally in a region—provide them with food and shelter.
“They serve as the ecological basis upon which life depends and are needed by both wildlife and humans,” Jewitt said. “For example, butterflies and other insects rely on native plants for nectar and other food resources, and humans rely on the presence of pollinating insects for agricultural crops to grow and produce our food.”
Other benefits of native plants include their low maintenance once established; adding beauty and shade to gardens and lawns; conservation of precious water resources and aid in combatting climate change.
“By choosing native plants for your landscaping, you are not only helping wildlife but you are creating a healthier place for yourself, your family, and your community,” Jewitt said.
Resources for Identifying Invasive Plants
It is important to be able to identify invasive and native plants, and fortunately there are numerous resources to help.
For example, the Audubon Society of Western Pennsylvania has a list of native plants on its website, www.aswp.org. “There are pictures of each plant and descriptions of the type of environment where the plant will do well,” said Communications Director Rachel Handel.
In addition to eradicating invasive plants, gardeners and homeowners can plant more native plants on their own property. Handel said that Audubon’s native plant nursery, located at Beechwood Farms Nature Reserve, has many plants available starting in May. “There are also native plant experts on hand who can help people choose the right plants for their yards,” she said.
A few local nurseries are starting to include more native plants in their own inventories. “It’s exciting to see native plants being sold in more locations—it really shows that people and businesses are seeing the value of including these plants in their backyards,” said Handel. “When choosing a place to buy plants, be sure that the plants are grown responsibly and without pesticides that can impact birds and wildlife that utilize them.”
Amy Jewitt, invasive species coordinator, Western Pennsylvania Conservancy, recommended two online tools that allow members of the public to quickly and easily learn which plants are native to their area simply by entering their zip codes: the Audubon’s native plants database at https://www.audubon.org/native-plants and the National Wildlife Federation’s native plant finder at https://www.nwf.org/NativePlantFinder.
“It’s important for landowners to understand which plant species are native to Pennsylvania, or in some cases, which areas of the state they are native to since some species may only be native to parts of Pennsylvania,” said Jewitt.
She also recommends the Pennsylvania Department of Conservation and Natural Resources (DCNR) Landscaping with Native Plants brochure available at http://elibrary.dcnr.pa.gov/GetDocument?docId=1743796&DocName=Landscaping%20with%20Native%20Plants.pdf.
“This is a fantastic resource that lists plants native to Pennsylvania and provides details on plants’ preferred site conditions, i.e., sunny moist, shady, dry, etc.” said Jewitt. “This easy-to-read brochure highlights a plethora of species that landowners can select from for planting.
“Additionally, the PA DCNR provides online access to several native garden templates for use by landowners that take the guesswork out of how to design their home and garden landscapes,” she added. The Native Garden template is available at https://www.dcnr.pa.gov/Conservation/WildPlants/LandscapingwithNativePlants/NativeGardenTemplates/Pages/default.aspx.
Jewitt also provided the following additional resources:
The Western PA Conservancy provides multiple resources on their website related to invasive plants and their native garden alternatives available in Green Isn’t Always Good.
There is also a webinar recording on the topic: https://www.youtube.com/watch?v=AKKYEXdTHFg.
Penn State Extension has several invasive plant fact sheets: https://extension.psu.edu/announcing-new-invasive-plant-fact-sheets-series.
The PA DCNR offers almost 100 invasive plant fact sheets at https://www.dcnr.pa.gov/Conservation/WildPlants/InvasivePlants/InvasivePlantFactSheets/Pages/default.aspx.
The PA iMap invasives program offers a tracked species list highlighting 400 plus invasives found in PA: https://www.paimapinvasives.org/tracked-species
Pennsylvania Sea Grant has an online field guide, PA’s Field Guide to Aquatic Invasive Species, at http://seagrant.psu.edu/sites/default/files/AIS%20Field%20Guide_1.pdf.
Adding Native Plants To Your Backyard
With the rise in awareness about the advantages of native plants, the Latodami Nature Center, North Park, and the Northern Area Environmental Council (NAEC) have formed a partnership to help local landowners grow their own native gardens.
“The Lawn to Nature Program basically provides everything in a little kit to create a native plant garden. It gives the uninitiated everything they need,” said North Park Assistant Naturalist Ken Knapp.
The idea was generated from webinars featuring Doug Tallamy, an ecologist, professor and author. “His theory is that we can help fix what is wrong with nature by helping to convert land back to native plants, said Knapp. “Since 83 percent of land is privately owned, we can’t fix everything through public lands, and Tallamy believes that it’s a misnomer that this work must be done by the professionals.”
Following Tallamy’s advice and information from his books, including Nature’s Best Hope, the naturalists partnered with NAEC to create the program.
“NAEC already have a native seedling and plant sale, so we are running the program parallel to the sale,” Knapp said.
For $20, landowners receive native seeds to plant a 100-square foot area; the choice of a native tree or shrub; written and video instructions, and stickers and a tote bag in which to carry everything. The first 50 kits will also receive a 20 percent coupon to Acadia Natives, a nursery specializing in native plants located in Washington, PA.
“They can also add on other seeds and seedlings from the NAEC sale if they want to expand,” Knapp said. Gardeners can select either a sunny or part-shade seed mix to grow in a variety of places, and choose between a red oak tree seedling or chokeberry shrub seedling. Kits and additional plants may be ordered through the end of March at www.naecwpa.org/orderlawntonature.
Orders will be available for pickup at the Latodami Nature Center barn on Sat., April 30.
“Sometimes we feel hopeless, like we can’t make a difference, but this is a way to create a habitat in our own private space,” Knapp said, “Tallamy calls it a home-grown national park.”