Lighthouse Park Preservation Society

Invasive Species

When English ivy, Hedera helix, escapes from landscaped plantings it often establishes and spreads in shaded forested lands or natural areas. There it can impact all three zones, the forest floor, the shrub layer and the canopy.

Scotch broom's biological impact is broad. Besides outcompeting native plants like the Nootka rose and Hardhack for sun and space, its conversion of atmospheric nitrogen into other nitrogen-containing compounds changes the chemistry of the soil. This reduces the success of native wildflowers recolonization and supports the growth of other non-native plants such as blackberries and various introduced grasses.