By Danielle Bongiovanni, LRWP 2025 Science Communication Intern

Without the hard work of volunteers and support from the borough of Highland Park, the Highland Park Native Plant Sanctuary (HPNPS) could not exist. Maintaining the HPNPS requires the endless mitigation of anthropogenic threats ranging from litter to voracious deer, but the ecosystem services and recreational opportunities are worth the work. On March 23, HPNPS leaders invited members of the Lower Raritan Watershed Partnership to tour the sanctuary and discover its ecological wonders.

The HPNPS is almost entirely managed by three long-term volunteers: Susan Edmunds, Andy Warren, and Vicky Kulikow. Kulikow is the main force behind the HPNPS website. Edmunds handles logistical issues such as pursuing sources of funding and collaboration. As the lead volunteer steward, Warren’s responsibilities include replacing invasive species with native counterparts, maintaining trails, cleaning up trash, and leading volunteers.

“We aren’t really an organization so much as several people who stepped up when there was a need,” Edmunds said.

The greatest time of need emerged in 2023 when Mary Denver, who held a leadership role with the HPNPS since the early 2000s, passed. As principal volunteer stewards, Denver and her daughter, Belinda Beetham, were known to work in the sanctuary nearly every day. A banner at the entrance dedicates the three-acre property as the “Mary Denver Native Plant Sanctuary,” and Edmunds is collaborating with the Borough and the Native Plant Society of New Jersey to install a larger memorial in the near future.

Meanwhile, there is always other work to be done. Progress is perpetually threatened by deer and invasive species. Unfortunately, solutions for one often enable the other.

Warren pointed out a recently-planted red twig dogwood (Cornus sericea) surrounded by a tree cage as an example. New Jersey’s overabundant white-tailed deer population devours native plants faster than they can regrow. The cage ensures the sapling grows beyond snacking height and is not killed or damaged by deer rubbing their antlers against its bark. Warren described how the protection comes at the cost of providing “scaffolding for honeysuckle and English ivy (Hedera helix)” that must be regularly removed, lest they strangle the sapling.

Removal alone is not enough, invasive species will return if space is available. Establishing populations of native plants strong enough to crowd them out and hinder their regrowth is difficult due to how much and how quickly deer eat them.

Warren has embraced a strategy of habitat succession planting. He mulches grassy expanses and scatters seeds collected from the area. The resulting “mosaic” of native species deters deer by hiding their favorite snacks. “It demonstrates how having these little diverse pockets helps protect plants that might not be able to grow if you only plant one,” Warren said.

Coupled with aggressive invasive species removal, this strategy has produced visible results. Warren recounted how a large area near the environmental education center was once impenetrable due to Japanese knotweed (Reynoutria japonica) and honeysuckle bush (Ionicera maackii). Volunteer efforts made it accessible for public recreation. Warren said, “I love walking through in the summer and watching the native bees and flies swarming around germander (Teucrium canadense) flowers where there was once nothing but honeysuckle.”

Successfully established natives thus far include snakeroots (Ageratina altissima), asters (Eurybia spp.), and goldenrods (Solidago spp.). A recent grant enabled the HPNPS to obtain more plants, including nodding onion (Allium cernuum), little bluestem (Schizachyrium scoparium), and rattlesnake master (Eryngium yuccifolium).

Funding to obtain plants and volunteer labor to install them are essential for the HPNPS to succeed. Perhaps unexpectedly, the latter can be the greater challenge. Most volunteers require training before they can help effectively, and the frequency at which volunteers are replaced means a lot of time and effort are dedicated to getting new faces up to speed. The HPNPS would benefit greatly from more pledges of long-term involvement. Volunteer opportunities include environmental stewardship, writing articles, and taking photos for the website.

“It’s really about finding people’s interests and abilities and working with them individually on that,” Warren said.

Raising awareness of how the sanctuary not only provides free public recreation, but also uplifts the health of the Raritan River, may encourage more people to join the HPNPS.

“They are cheek by jowl. The edge of the sanctuary is the river and vice versa,” Edmunds said. “Over the years we’re trying more and more to create a real soil there.”

A “real soil” depends on the strong root systems of native plants. By restoring the riparian ecosystem, the HPNPS helps more rainwater absorb into the ground instead of washing dirt and trash into the river and making it flood. Minimizing stormwater runoff reduces the amount of pollution in the Raritan River and the likelihood of flooding, benefitting all Highland Park residents.

Getting involved with the HPNPS is as easy as emailing highlandparknativeplants@gmail.com or attending an event. Warren will lead a “Walk-and-Talk Tour” on Saturday, May 10 at noon and is excited to welcome new faces into the fold.

Danielle Bongiovanni is a lifelong New Jersey resident who graduated with a B.S. in environmental science from Ramapo College in 2024. She is passionate about local journalism, ecosystem restoration, and her dog, Banjo.