Wetlands restoration at Morris Arboretum …
first three years investment paying off

by Judy Goldschmidt

Think of the Morris Arboretum of the University of Pennsylvania and areas such as the Rose Garden, the Fernery or a grove of metasequoias immediately comes to mind. Successful, specialized and visible efforts like these are easily discerned. But when visiting the arboretum, you might overlook a particular three acres that is being restored to its more natural state. This is the Paper Mill Run wetlands section of the arboretum, the area you drive by on your right after you enter from Northwestern Avenue.

Wealthy siblings John and Lydia Morris established their summer estate on sweeping, hilly grounds in the mid 1800s. At the same time, John also built and maintained a farm that bordered the Wissahickon Creek, through which the Paper Mill Run naturally flows. This area is a natural limestone flood plain, where excess water from storms would flow and drain through the porous ground. So that the land would be drier and more suitable for farming purposes, John installed an underground system of clay pipes to redirect waters from the natural spring system. After acquiring land along the Montgomery County side of Northwestern Avenue, Morris moved his farm there. This had been the status for many years.

Now, thanks to a major renovation program under the supervision of Morris Arboretum, this flood plain and the stream bank have been carefully and thoughtfully converted back into a natural wetlands area, to the delight of such species as bird-watching humans, frogs, turtles, wood ducks, cattails and more.

The planning began years ago, when the project was envisioned as part of a major Arboretum long-term strategy. Implementation of the stream bank restoration began in 1998; however, the wetlands restoration was not possible until funding was obtained to hire a dedicated staffperson to oversee it. Chestnut Hill residents Ron and Roberta Berg — ardent advocates of the Wissahickon Valley and of Morris Arboretum — provided a three-year grant for this purpose. Pam Morris (no known relation to John and Lydia), a biologist and specialist in water management, was hired. Pam was already familiar with the area, having worked on the stream bank project as an intern through the Delaware Riverkeeper Network.

“We started from scratch,” she said, “and approached it like a recipe. What elements could we bring into this situation that would make things happen quickly and create a balanced, sustainable ecological system?” Just some of the factors that had to be considered included: removal of the underground clay pipe system, overpopulation of certain animals, invasion of non-native plants, figuring out the best gradations and slopes for natural water flow while creating a handicapped accessible pathway around the pond, selection of the best plants for the renewed habitat and the planting of vegetation at varied stages of growth.

What is there to show for the first three years? Anyone who has taken time to stroll through this area will be pleasantly surprised. Witness a great blue heron in the water, a frog jumping, a glimpse of the red-bellied woodpecker. Notice the return of pink milkweed and verbena, plus the less desirable cattails. The restoration work may not be as obvious as high season in the Rose Garden. But don’t let appearances fool: much hard work and planning has gone into getting the area to its present condition.

According to Pam, “Three years is just a start. My time was spent planning, organizing, building and stabilizing. When we cleared the area, it was a vast field of brown mud. It took one year of dedicated effort just to seed and plant. Now I can turn my attention to stabilization and maintenance, making sure that future growth sustains the ecological balance.”

In dealing with the challenges of such work, it can be staggering to consider the ecological impact — how one plant or animal’s presence can affect the rest. For example, take the earthworm. When one is gardening, the appearance of our wiggly friends can be taken as a sign of soil health. But what happens when there is an imbalance — too many of the critters? That is one issue Pam has had to confront.

“As we removed the soil, we found these incredible masses of worms in each shovel full. They ate and excreted so much that the top soil was composed primarily of worm castings and not the more beneficial humus (decomposed plant material).” As a result, the dirt is “too loose,” she explained. “This creates air pockets in the soil, which kills tree roots and loosens trees, causing them potentially fatal damage.”

The overabundance of worms is not a problem Pam expects to “solve.” Although she is aware of experimental efforts underway by other organizations, her approach is “to try to do our best … when we plant, we remove the top layers to get to the dirt.”

An overabundance of mosquitoes is also a problem. So the restoration of the pond included the addition of fish as well as deep holes within for fish to overwinter. The fish keep the mosquitoes in check by eating their larvae. Bird boxes were installed in the pond, and birds that are naturally attracted to wetlands have returned. They help restore the ecological balance by eating the mosquitoes and other insects that have hatched. As a result, tests conducted regularly by the Philadelphia Water Department have given the Arboretum’s wetlands high marks for mosquito control.

Too many deer also stress the wetlands and surrounding areas by eating away at vegetation. Pam works to maintain a balance by fencing areas and by planting things outside the fenced areas that deer like to eat. She calls them “sacrifice plants” – extra plantings of a species that will help save others. She also plants lots of shrubby dogwoods because they are hardy and more likely to survive the deer nibblings.

According to Pam, “This wetland restoration serves as a demonstration of the ideal management practices within the Wissahickon watershed, while reaffirming the arboretum’s commitment to both education and ecological land management.”

Pam is passionate about her work and hopes that visitors will stop by and appreciate the transformation. “The more the public is aware of this project and interested in it, the more likely it is that Morris Arboretum will obtain the resources for me to continue,” she said. And that would be a win-win situation for all the species impacted!