Protecting Rare Species from Exotic Invaders
By Zachary Simek
This past summer I worked with the Adirondack Park Invasive Plant Program’s (APIPP) Terrestrial Rapid Response Team and partners from the New York State Department of Environmental Conservation (DEC), Department of Transportation (DOT), Olympic Regional Development Authority (ORDA), and Adirondack Park Agency (APA) on a unique invasive plant control project along the Whiteface Memorial Highway in Wilmington.
In late-August, I received a report from Steve Young, Chief Botanist for the New York Natural Heritage Program, noting a significant increase in the number of invasive plants growing along the Highway. Steve volunteers to survey the alpine plant community of Whiteface Mountain each year. This field season, populations of sweet-clover, knapweed, common mullein, and several other invasive plants were booming at levels much higher than ever before. Steve also confirmed the presence of multiple invasive plants that had previously never been identified on the mountain.
On August 18th I met on-site with Steve and partners from each cooperating agency to assess the situation. We surveyed the roadside and witnessed terrestrial invasive plants beginning to dominate the area along the highways’ shoulder. In many instances, the plants were so tall and dense that they were beginning to fall into and block the shoulder of the roadway. However, what Steve showed us next concerned me most. Over ten rare, threatened, or endangered native plant species – such as alpine goldenrod (Solidago leiocarpa) and snowline wintergreen (Pyrola minor) – grow in very close proximity to the highway. In some instances, they occur immediately adjacent to the paved surface; occupying the same habitat that is now being overtaken by invasives.
Invasive plants are spread in many ways– sometimes through natural transport by wind, water, and wildlife, but more often through human related activities. A total reconstruction of the entire 5 mile scenic highway, that stretches to just shy of the summit of Whiteface Mountain, was completed in 2015; just one year before the sudden influx of invaders. It turns out that the unwanted invaders were inadvertently introduced by these construction activities – most likely through contaminated fill used for the project. Unfortunately, this is not an uncommon occurrence, and many of the infestations that I survey and APIPP manages across the Adirondack region have resulted from road maintenance and construction activities like this.
After witnessing this explosion of invasives firsthand, and their proximity to the mountain’s rare plant communities, it was apparent that management actions needed to be taken. In most instances, I consider these species to be a low priority in comparison to the other invasive threats that I deal with every day. However, the situation along the Whiteface Memorial Highway forced me to make an exception. Never before had my invasive plant control work been so directly linked to the preservation of already imperiled, rare native species.
Management occurred over three days in the weeks following our meeting. No time was wasted as many of the invaders were already beginning to set seed. ORDA assisted by mowing mature plants along the lower section of the highway, where protected species were unlikely to occur. Properly timed mowing can eliminate an invasive plant’s ability to produce and release seed, thereby minimizing the number of individuals that sprout the following growing season. Along the upper section of the highway, I worked with APIPP’s Terrestrial Response Team and a DOT crew member to hand pull all mature plants. We exercised caution to ensure no protected species were removed or disturbed by our management actions. Over three days, we filled sixty-nine 42-gallon contractor bags with invasive plant material.
However, while pulling plants, one of the response team members made another unfortunate discovery. Growing out of several stone water bars recently constructed along the shoulder were numerous patches of Japanese knotweed (Reynoutria japonica). Unlike the other invaders we documented, Japanese knotweed is highly invasive and listed as one of APIPP’s target species. With a rapid growth rate and multiple spread mechanisms, it is capable of causing serious environmental and economic impacts in a short period of time. Furthermore, its extensive root system makes it nearly impossible to eradicate through hand pulling or other manual control options. Thankfully, the patches were still small and are slotted to be treated with herbicide next season once the appropriate permits have been obtained.
While this story will hopefully end as a successful example of early detection and rapid response, much thanks to Steve, it does raise a more important question. How can we address road construction and maintenance activities as one of the leading vectors of spread for terrestrial invasive plants throughout the Adirondack PRISM and New York State? APIPP is actively working with DOT & DPW crews to raise awareness of best management practices that will prevent the spread of invasive plants along the roadway, but much faster and broader adoption of these practices is needed. These BMP’s will not only protect the integrity of our natural ecosystems, but improve traffic safety, and reduce road maintenance costs for DOT and DPW’s; reducing the likelihood of having to deal with long-term invasive species impacts. Together we can help preserve the integrity of the Adirondack landscape by ensuring that the only exotics traveling along our roads have four wheels.
If your highway department is interested in learning more about invasive plant best management practices, please contact us to learn about training opportunities.