The Invasives Strike Force (ISF) crew, as part of the Trail Conference Conservation Corps and funded through the Lower Hudson PRISM, is a conservation-based crew devoted to eradicate, contain and prevent the establishment of emerging terrestrial invasive species within the Lower Hudson Valley in order to protect our high-value habitat through the use of skilled labor within the region.
Table of Contents
Invasives Strike Force
by Zachary Keenan and Layla El-Rifai, Invasive Strike Force Crew Leader
Key Accomplishments:
- Managed 15,138 invasive plants and searched 273 acres!
- Targeted the Tier 2 invasive species Sticky sage, Japanese tree lilac, Pale swallowwort, silver vine
- Targeted tier 3 invasive species Border privet, Amur honeysuckle, Japanese Spiraea, toringo crabapple, Chinese silver grass, Black swallowwort, Japanese angelica tree
- Targeted tier 4 invasive species Winged burning bush, Japanese barberry, Oriental bittersweet, Autumn olive, Common buckthorn, Common reed grass, tree-of-heaven, Chinese wisteria, Japanese stiltgrass
Conservation has been at the forefront of our minds this month! The nvasives Strike Force shifted perspective when visiting the Great Swamp in Wingdale NY. When we go to most sites, the ISF will usually have a species we are targeting our treatment at. At the Great Swamp however, we are looking to protect habitat for our conservation target species. The New England cottontail is considered endangered in Maine and New Hampshire and is Vulnerable in this section of our jurisdiction. With a love for these adorable fuzzy friends in our minds, we performed habitat maintenance in an area where the cottontails are known to be around. This consisted of removal of overcrowding barberry and autumn olive and the making of brush piles around the site to preserve shrub like habitat that the cottontails like to use as shelter from predators. The Great Swamp is following this treatment up by transplanting native shrub species found in the local area, allowing the diverse native vegetation already present to thrive a bit more! It was super rewarding work to see the progress of everything as we went, and the group had a great time getting to know the Friends of the Great Swamp.
The work environment is faster than ever! During August, members of the ISF got to spend a day working with the Conservation Dogs program to see what a day in the life of a dog is like. These lovable dogs zoom through the woods and work based on the scent unique to a target plant they’ve been trained on, helping them sniff out plants that are more scattered. If these loose stray plants are ignored, they could go to seed and set treatment of the area back. The ISF members practiced their juggling by pulling any plants found, recording data about the site where they search, and map making of areas searched and treated. The more we worked with the dogs the more we can see that they excel in places where there are few plants but are too big to be searched for by a group of people doing fireline sweeps. The mobility the dogs provide is a fantastic help when we are trying to make sure we nabbed every last plant!
Towards the latter end of the month, the ISF took to the road and went on our camping overnight trip over in Ward Pound Ridge. While there, we visited unique habitat areas found there, consisting of sandy soil that remains moist for long periods. This habitat is a prime candidate for Crotalaria sagittalis or rattlebox. This plant comes up to about ankle height and is considered critically imperiled in New York State Conservation Status Rank (S1). The site was relatively welcoming to rattlebox with its large opening and coarse soils and a healthy population of about 100+ plants were found. Encroaching on that site however was the common reed or phragmites. The ISF helped Ward Pound Ridge staff and volunteers manage the phragmites infestation and relieve the pressure on our conservation target.
Key Accomplishments:
- Managed 15,050 invasive plants
- Targeted tier 2 emerging invasive species: Scotch broom (28 sites), sticky sage (8 sites), Japanese tree lilac, castor aralia and sapphireberry
July!
- Japanese angelica trees in sterling with trail crew :o so lit we managed 935
- Then dover for sticky sage and some for Scotch broom
- Lh prism meeting?
- Vassar for many species like castor aralia, Japanese tree lilac, sapphireberry, and linden viburnum.
- Dover again for sticky sage
This month’s projects started off with a bang! The Invasive Strike Force loves helping the other crews at the trail conference whenever we can to get some joint projects going. It helps us widen the experience we get from this program by providing us with different perspectives and ways of looking at the land around us. The NYNJTC Trail Crew was looking to build trail on a section of forest that had an infestation of Japanese angelica tree, an aggressive resprouter. In order to treat the angelica tree, the trail crew cut the trees down to a stump while the ISF followed behind treating the stumps with a small, controlled amount of herbicide following the cut-stump method.
Dover, Dover, and even more Dover! Dover was absolutely popping this month. The ISF returns to Dover to continue our treatment that began in June. The Appalachian trail section of the infestation was completed last month but the surrounding properties still have their own seed bank reservoirs to power through. During this month, we tackled several huge properties totaling 140 acres searched and 28.58 acres treated in this month alone! Denser areas of the overall infestation were handled using a foliar spray to cover large patches with ease. More sparce parts of the infestation can be handled with manual removal by pulling up the sage plant and any stolons (specialized roots that shoot out from the plant horizontally to sprout new clones of the plant). As treatment around this section of Dover continues, we see fewer and fewer plants each year, showing just how much of an impact the work we do creates! More sites are being treated manually this year than ever before because the infestations have become less dense and more manageable thanks to the ongoing work of the ISF.
Scotch broom has met its match this month! While the bulk of the ISF was tackling the sticky sage infestation, a couple of us would continue the work treating scotch broom. Crew members Emily Anderson, Avani Tripathi, and Nicholas Eubank have completely treated all remaining locations on our radar in Harriman State Park. In July, 28 sites were visited by the small satellite group covering 28 acres! These plants never even stood a chance. It will be important to continue monitoring of these sites in future years for any seedlings sprouting out of the seed bank in the soil, but almost no scotch broom plants will go to seed this year in Harriman State Park!!
Working with other professionals in the field is always a treat. Vassar college has a group of interns who put in tremendous amounts of work to prepare for us to do herbicidal control on emergent invasive plants in the area. Special thanks go to Lauren Pachelo and Chiara Castaneda for the phenomenal work they put in each day we were working at Vassar between helping us navigate the labyrinth of one-way roads to treating the invasives side by side with us.
Vassar college had several plants they were looking to treat such as a white poplar species that began hybridizing with local aspens, an invasive that just popped up on our radar last year known as Japanese tree lilac, and some follow up treatment on different sapphire berry and castor aralia sites. About 6 Japanese tree lilac were planted on the campus arboretum and tagged. Since they were planted, the infestation has festered and unfortunately flourished. By the end of treatment, 1,603 trees were treated in an area of 1,329 square feet (about half an acre) via the cut stump or the hack and squirt method showing how out of control these plants can get when left to their own devices.
Key Accomplishments:
- Managed 3,572 invasive plants
- Targeted Tier 2 emerging invasives Scotch broom, giant hogweed, and sticky sage as well as widespread invasives for education and outreach during volunteer workdays
- Targeted Tier 3 invasive chocolate vine
- Managed the only sticky sage population in the Lower Hudson Valley treating 1,475 plants and surveying 17.83 acres of land
This month, the ISF is finally rounding out our training and the progress is amazing to see! A mere month ago, plant ID was a skill we were just learning to get the hang of. Now, the ISF has worked in Croton Point Park searching and treating 3 different species at once! Some of the plants like paper mulberry had variable leaf shapes really testing the crew’s plant ID skills the invasive Chinese bushclover, a meadow invader, was managed to prevent it from spreading to a nearby meadow undergoing restoration for bird habitat. On top of all these, the ISF worked on managing sycamore maple seedlings amidst a field of other look-alike species like Norway maple and the native red maple.
New invasive species are always popping up on our radar. In 2022, five leafed aralia was present at one of our sites on the Lenoir property we had been treating. This aralia was very mature and had taken over the hillside along a stair way in the Lenoir trail and began to encroach on the popular hiking spot. In order to manage it, we filed for a FIFRA 2(ee) form letting us use herbicide on our target species to ensure proper treatment. After a hard day's work though, the results were wonderful! Removal of this emergent invasive helped clear the way for lovely native plants nearby and freeing up the space around the property’s pathway.
Towering at almost 15 ft tall, giant hogweed poses a terrible threat to not only the ecosystem but the crew’s personal safety if proper PPE isn't taken seriously. This fiendish plant possesses photophytotoxic chemicals which block your skin’s ability to block UV rays. Over a week, the ISF donned full body Tyvek suits and gloves that reach up to their elbows to protect themselves from the zesty sap hogweed. Our hogweed project has been such a success on a long-term scale. Only 13 sites currently require annual scouting out of the 22 sites in our area still due to our due diligence. One site along a river corridor has been our biggest this year with a whopping 682 hogweed plants found. This is a delightful number to see when compared to last year’s ~1,100 plants and the year before’s ~7,000 plants found. It is positively thrilling to see progress like this with a plant as devious and conniving as giant hogweed.
Giant hogweed is only one of the long-term projects that the ISF is tackling. The ISF began working along the Appalachian Trail this month. We in the ISF prioritize treatment of emergent invasive species, and sticky sage is only found in 3 places in New York. Our goal is to take out all sticky sage along the Appalachian trail to prevent the spread of it down the high traffic trail. Last year, the ISF finally encompassed the outer borders of the infestation and treated 71 acres of land making this no small feat. This week begins the first of our 4 weeks spent in Dover and we are faced with big shoes to fill. Treating sage after sage, the ISF has been chugging along tirelessly and in our first week we were able to treat nearly the entire section of the Appalachian Trail that passes through the infestation. With this completed, our July focus will be set on the properties surrounding the Appalachian Trail.
After finishing this high priority project, the ISF had the chance to return to work on Scotch broom in Bear Mountain State Park. At this point in the season, the plants are beginning to set fruit, so it is extremely important to manage them, as their seeds can stay viable for up to 30 years. In just one day, the crew managed over 830 Scotch broom plants! These plants were full of immature fruit, so the ISF bagged up any fruiting plants to be solarized making sure the seeds were no longer viable for growth.
June has brought us to the tip of the iceberg for our big projects. With the strong start to the season, we had last month and the amazing successes with each of our big projects, the ISF has really been killing it out there! Looking ahead to July, we plan to continue work on sticky sage and Scotch broom while also hopping over to Vassar college to aid their fight against the invasives. Stay tuned for more on all the antics the ISF has been getting up to next month!
Key Accomplishments:
- Managed 8,837 invasive plants
- Targeted the Tier 2 invasive species Scotch broom
- Targeted Tier 3 invasive Japanese spirea to prevent spread into areas with the conservation targets cattail sedge (Carex typhina) and creeping bushclover (Lespedeza repens)
- Targeted Tier 4 Japanese barberry
Turning Over a New Leaf
Although the paths we took that brought us here are numerous and unique, the ISF crew finds themselves together on the trail with a common goal of tackling invasives. Making a difference in the ecosystem is no small or easy task. Through rigorous training, the ISF has been studying a wide array of management practices, plant identification, and how to safely use/mix herbicide. Education is a critical component of responsible stewardship and helps us make informed decisions about the work we do and where to put our priorities. With the training in our head, pick mattocks in our hands, and passion in our heart, the ISF begins their field work.
Reveling at the opportunity to put their training to the test, the ISF began their ongoing Scotch broom project. Scotch broom is an emergent invasive plant in New York whose seeds can stay dormant and viable in the soil for up to 30 years making it a prime target for the ISF. Between removing dense stands of Scotch broom from the hillsides of Bear Mountain and pulling up hundreds of densely packed seedlings from Harriman State Park sites, the crew was finally able to get their hands dirty with field work!
Working on a regional basis requires us to prioritize emergent invasives most of the time so that we have manageable goals of regional eradication. However, when it comes to protecting various rare, threatened, or endangered species (r/t/e) the ISF will treat more widespread invasives that are overcrowding the area around our conservation target. On our trip to Arnika this was just the case. Cattail sedge and creeping bushclover were on our list to protect so we continued on work removing the woody spiraea shrubs encroaching on them.
It warms our heart to see parks and landowners incorporating sustainable land stewarding into their mission. After seeing the work put in by Lewisboro Land Trust into invasive removal on top of striving for accessibility and wellness, the ISF decided it was time to lend a hand. We really put the herbicide skills we learned to the test! Deciding which herbicide application method to use based on plant density helped minimize the amount of herbicide needed. Overall, 1518 barberry bushes were treated using the cut-stump and foliar methods and many more were removed physically with the help of the Lewisboro staff.
And we’re only just getting started too. Learning is a process, but we’ve finally been able to take action helping the ecosystems we visit. With a whole season ahead of us, I can hardly wait to see the work we do unfold.
