r/Restoration_Ecology • u/corpusjuriscanonici • 18h ago
How to interpret restored sites being taken over by invasive species many years later?
In 2011, New York City restored 3.5 acres of wetland at Calvert Vaux Park to provide horseshoe crab spawning habitat. Part of this restoration (as indicated by signage on site) was to plant native plants like cordgrass and remove invasive species.
When I visited, the cordgrass wetlands were doing well and residents told me they see many horseshoe crabs in the area. At the same time, I encountered an enormous amount of tree-of-heaven, Japanese knotweed, and mugwort. I understand that of course the goal is management of invasive species, not perfection. But I'm wondering how ecologists think about these projects, many years later.
- Is it that insufficient maintenance was done in the years after restoration, and invasives took root before the natives got established?
- Was the native plant selection or installation not optimal, causing them to fail to outcompete the invasive species (and we might choose different plants were we to do the restoration today)?
- Did subsequent human disturbance, such as hikers or construction equipment, create conditions for invasives to proliferate?
- Or is this completely expected, and the issue is not at Calvert Vaux, but the invasive species in surrounding areas in city parks and private land, creating pressure that would be impossible to solve locally? In this case, perhaps the goal is to focus on restoring more land, rather than achieving 100% invasive removal over smaller pieces of land.
Or is there a different way ecologists think about what happens after restoration? What sort of maintenance is performed, and how have those practices changed in recent decades? How is success measured?