Which species will work best to replace ash trees along the estuary’s banks?

  • student researcher measures tree
  • student researcher sprays trees
  • student researchers plant trees
  • Shon Schooler and team of student researchers on a boat in St. Louis River Estuary
  • Seven smiling research students from UW-Superior
  • Research volunteers learn about planting trees
  • Shon Schooler driving research boat with 3 smiling research volunteers


Agrilus planipennis, commonly known as the emerald ash borer (EAB), is an invasive species from Asia that has been wreaking havoc on North America’s ash trees since the 1990s. EAB infestations eventually kill off more than 99 percent of an area’s ash tree population, and EABs have been spreading across the continent from Michigan since their initial discovery there in 2002.

EABs were first discovered in Superior in 2013. With no way to ensure the control of their spread locally, we’re preparing for the ash population to die off within the Lake Superior Reserve in the coming years.

The expected die-off could affect much more than the local ash population within the Reserve, as ash trees are a significant part of the estuary’s shoreline tree population. As such, they play a critical role in maintaining the integrity of the shoreline and riverbanks and reduce erosion into the estuary. If the ash population dies off without new species already growing in its place, riverbanks could quickly begin eroding away, destroying habitat and negatively affecting water quality throughout the estuary.

We’re proactively approaching this problem by preparing the estuary riverbanks within the Reserve for the loss of ash trees—and we’re doing so in a scientifically rigorous way. With the assistance of volunteers, we’ve planted over 800 saplings of various tree species in locations around the Reserve, and we’re monitoring their growth to determine which species will be best suitable for replacing ash as it dies off. We’re also assessing the best methods for ensuring healthy growth of the replacement species.

We already have preliminary data, and we’re looking forward to assisting other agencies and local governments by identifying the best practices for replacing ash trees in ecologically sensitive riverbank habitats.