Laura Greenleaf, our Invasive Plant Guru, shared some information about a recent project:

The James River Park System’s sections are as distinctly unique as the neighborhoods that surround them, their varied geography and natural communities contributing to how visitors enjoy them. Some are hangouts, ideal river access for kayakers and rafters, or the perfect place to let young children roam. More than any other Park unit, the Buttermilk Trail is a place to be in motion—mountain bikers, hikers, walkers, and runners vie in single-file for the narrow span of winding trail that rises and falls along Riverside Drive from 21st Street and the Boulevard (or Nickel) Bridge.

But if you slow down along the Buttermilk, you will find something much more than a point A to point B athletic challenge: “You feel like you’re walking through a real forest,” notes Anne Wright, retired Affiliate Faculty in VCU’s Center for Environmental Studies, creator of the Science in the Park program, and member of the JRPS Invasive Plant Task Force. Beech and oak trees dominate the hillsides, leaf litter decomposes into a nutrient- and oxygen-rich humus layer of soil, and groundwater ‘seeps’ percolate from fissures in the Petersburg Granite underlying this Mesic Mixed Hardwood Forest. All of this is possible because of a concerted effort to remove English ivy (Hedera helix).

English Ivy Removal

Ivy removal in action

Since 2014 Wright—along with students and volunteers—has been pulling English ivy vines from the forest floor along a section of the Buttermilk Trail west of the 42nd Street parking lot. It began with a Science in the Park project to measure annual tree growth and calculate the carbon intake of trees of different species and sizes in a one-fifth of an acre test plot. Wright recognized that the English ivy invading the area did not belong there and posed a threat to the woodland, but she came to understand the full extent of ecological harm that ivy causes from the ground up:

  • English ivy groundcover changes soil composition and chemistry, depleting it of the nutrients native plants need to thrive and producing allelopathic chemicals capable of suppressing germination of seeds of other plants.
  • Ivy infestations also alter hydrology—how water moves through a natural system. Those thick expanses of vines hog groundwater and precipitation, drying out the soil and depriving trees and other indigenous vegetation of water.
  • Carpets of impenetrable invasive vines also block sunlight and create a physical barrier to the growth of other plants.
  • English ivy’s goal is to climb a vertical surface (trees) and send out aerial roots that ultimately flower, fruit, and produce seed that become more ivy plants. Along the way they clasp the tree’s trunk in a woven mass of vines that can grow to several inches in diameter and create heavy curtains hanging from the tree’s branches; the combined weight burdens an already stressed or weakened tree and increases the likelihood it will come down in wind, snow, or ice.
  • Like all invasive plant infestations, English ivy diminishes the diversity of indigenous plants on which our native wildlife depends, and it further degrades habitat through changes in ‘community structure’; for instance, dense ivy mats prevent the regeneration of forest understory that supports songbirds and block the accumulating layers of leaf litter that shelter box turtles through the winter.

If this is not persuasion enough to get rid of English ivy consider this: “English ivy makes ideal conditions for harboring mosquitoes,” Wright reports. The vines trap moisture, particularly against a tree’s trunk, and this fosters mosquito breeding.

Clover Hill students at work

Clover Hill students attack a hillside

After initiating removal work with students from Open High School and Clover Hill High School, Wright created and taught the course “Invasive Species Management in an Urban Park” for two and a half years while making the Buttermilk work an Invasive Plant Task Force project focus area with public volunteer opportunities. The area cleared of ivy now verges on more than three acres. Wright ensures removal of all ivy debris—freshly pulled vines can re-root if they make contact with soil.

In a few months, spring wildflowers including trout lily and two species of toothwort will peep above the crust of leaf litter, unrestrained by the tangled cover of ivy and nourished by those leaves shredded and consumed into soil by microorganisms and insects. Groundwater from seeps flows more strongly than it did prior to removal of the carpets of ivy. And the American beech, oak, hickory, American holly, pawpaw and other trees will remain free of the invasive vine cover overtaking too much of our Park’s canopy.

Bird's Eye View of Buttermilk Trail

A panorama view of the Buttermilk Trail

The ivy along Buttermilk Trail—and everywhere else in the James River Park System—originated in neighborhood yards. If you have decided to remove English ivy from your yard, Wright recommends working soon after rain or snowmelt because damp soil makes it easier to pull up a vine in its entirety, buying you more time before having to pull up new ivy seedlings. Monitor the area carefully for what plants emerge; it is not unusual for different invasive species, particularly Japanese stiltgrass, to take advantage of an area cleared of other invasive plants. If you have trees covered in ivy, follow these guidelines and remember, you will need to follow up with monitoring and repeating removal as necessary.

To volunteer with invasive removal at Buttermilk Trail or elsewhere in the James River Park System, visit the park calendar.

And for a more homeowner-centric perspective on why and how to vanquish English ivy, check out Why I Hate English Ivy.

Laura Greenleaf is a Certified Virginia Master Naturalist (since 2010), a founding member of the James River Park System Invasive Plant Task Force (2015), and the park’s  Co-Coordinator for Invasive Species Management.