Disappointing Friday Field Trip

Male red-winged blackbird (Agelaius phoeniceus) in full mating display

Last Friday (April 11) I escorted my graduate landscape restoration students on a field trip to a site I had previously visited but had never used for a class field trip - and was disappointed.  The site was on the expansive campus of an exclusive and very expensive private school.  The campus straddles a large, flood-prone creek.  Years ago, probably before the creek's upper watershed became so heavily suburbanized and covered with impermeable surfaces, the school had built its athletic fields on the creek's flat floodplain. 

But, as the creek began to flood with increasingly frequency, the fields could be used less and less often.  The school finally decided to undertake major capital improvements.  It moved the fields out of the floodplain and replaced the fields with a series of interconnected basins that gather stormwater and hold it until the creek's level falls low enough to accommodate the runoff.  In addition, the basins were naturalized with native plants to create wildlife habitat. 

The school spared no expense in this project (both to build its new first-class athletic fields and to restore the floodplain), so I guess that's why the results were all the more disappointing.    

Parking lot "rain gardens"

Our tour began at the athletic fields parking lot, where runoff from the paved surfaces is channeled to rain gardens where it filters into the soil or, if the soil's infiltration capacity is overwhelmed, is shunted to a detention basin.  Unfortunately, the "rain gardens" consist of thick layers of mulch and a very few forlorn shrubs. 

Up against the wall, rain garden

Next we visited a rain garden adjacent to a retaining wall holding up the football playing field.  Our guide (a faculty member among whose other responsibilities at the school is to manage the new restoration area) explained that the construction activity had left the area completely barren and full of clayey, compacted soil.  So, to create the rain garden, the contractor had excavated five feet of poor soil and replaced it with layers of stone, gravel, and sandy loam to improve infiltration.  Then, the contractor planted shrubs and trees.  Unfortunately, it appeared to my students and me that the rain garden, which should have looked like a shallow depression, was actually slightly mounded above the rest of the landscape.  So much for collecting much runoff.

Overlooking the basins on the floodplain

We finally got to the floodplain, where the athletic fields had been replaced by the interconnected wetland basins.  Our host explained that cattails (Typha spp.), a native but aggressive species, quickly colonized the basins after construction and had completely taken over the shallow wetlands, providing a bit of wetland habitat, but not diverse, high quality habitat.  Our host explained how the students' parents did not want the school to use herbicides to control the cattails, and that she had instead organized volunteer work parties to uproot the cattails.  For a few years, the work parties could keep ahead of the advancing plants, but then the novelty of the project wore off and the volunteers disappeared, hence the rank growth.  In addition, the dreaded and highly invasive Phragmites australis reed had begun to appear in the ponds, too.

Re-excavated wetland basin

Our last stop was a wetland basin that the school uses as for water quality studies.  This basin, like the others, had become overwhelmed by cattails, but the school needed to maintain open water so that the students could conduct water quality monitoring.  Over the winter, the school hired a contractor to excavate the basin and remove the accumulated organic matter and the cattails and reeds.  How long until the cattails reappear (and the contractor returns)?

Because we had a little time before the class was over, we walked up a small drainage to a spring seep on a hillside.  Here, in the wet area below the spring, skunk cabbage had begun to emerge from its winter dormancy.

Skunk cabbage (Symplocarpus foetidus) in a spring seep

Eastern garter snake (Thamnopnis sirtalis sirtalis) on the floodplain among the invasive non-native lesser celandine (Ranunculus divaricata)

I have to ask the students this Friday if they felt that the field trip was worthwhile.