Forty-three employees of Air Products and Chemicals, Inc. in Allentown participated in a Day of Caring at Lehigh Gap Nature Center last week. They helped with several major projects, including weeding the Habitat Gardens, trimming brush along the LNE Trail, and monitoring the forbs planted inside and outside of the deer exclosures in the grassland. But the bulk of the work done on this day was the removal of birch trees from the grassland area of the refuge.
LGNC's re-vegetation strategy at Lehigh Gap included the use of prairie grasses to return a functioning ecosystem to the refuge area that was barren because of the high levels of zinc, cadmium, and lead in the soil. These grasses do not take up appreciable quantities of the metals and therefore sequester them in the soil as required by the Environmental Protection Agency.
The grasses have proven very successful at both colonizing the barren, rocky, contaminated slopes, and in keeping the metals in the soil and out of the food chain. As each year's growth dies and decays, an organic layer is building on top of the contaminated subsoil and organisms are thriving in the relatively metal-free zone.
But natural succession has begun, and pioneering gray birch trees are rapidly taking over much of the grassland. Gray birch is a native species and its appearance marks the beginning of succession toward a forest, so normally, this would be welcome news. However, succession rarely leads to an oak dominated forest today because of heavy grazing pressure by deer. More importantly, the birches take up the metals, which become concentrated in the leaves in potentially harmful concentrations. These metals move into the food chain when the leaves are eaten by insects, and return to the surface of the soil when the leaves fall from the trees, depositing more metals in the newly formed organic layer than does grass litter.
As a result, EPA is concerned about the risk the birches pose, and LGNC officials are seeking ways to manage the grassland in a way that excludes the birch and arrests succession. Grassland is in very short supply in the East and the species it supports are increasingly rare in the region. In addition, there is potential for transplanting a population of Regal Fritillary butterflies to the refuge if we can maintain healthy grassland with plenty of nectar plants and violets, the larval food plants of the Regal.
One way to manage the grassland is with prescribed fire. A test burn is now scheduled for next spring. Meanwhile, the birches are shading out the grasses and we are in danger of losing the grasses if the birches are not controlled. Enter the Air Products work crew.
Last Friday, forty-three Air Products workers arrived at the Osprey House for their Day of Caring. After a brief introduction to the restoration work by LGNC Director Dan Kunkle, Dr. Jen Lansing, ecological consultant for the Superfund process, led a safety briefing for the volunteers. The volunteers were then divided into groups, with an LGNC intern assigned to work with each group. The workers carpooled to the staging area on the mountain and the teams began their day's work.
Most of the teams were engaged in cutting birch trees and dragging them to one of several paths in the grassland area where they worked. The cut trees were stacked along the trails for easy access. The dead trees will be chipped and transported to another area of the Superfund site for disposal.
Six of the workers teamed up with LGNC's Corey Husic to help with the monitoring of the forbs, which were planted in 2009. That planting was part of an effort to enhance the quality of the grassland by introducing flowering plants to provide nectar and pollen for bees, butterflies, and other pollinators, and to provide seed for birds and mammals. The group was able to perform the monitoring work on four of the six test plots.
While on the mountain, the workers were treated to various wildlife sightings. Blue Grosbeaks, which nest in our grassland, were on their territory singing. The monitoring group had to leave an area when a Common Nighthawk began a distraction display that indicated it had a nest nearby. A fawn was surprised by the group and flushed from its hiding place in the grassland. The entire crowd was treated to the sight of an adult Bald Eagle flying overhead.
Scott Snyder, one of LGNC's workers on the site, commented that it would have taken the interns three weeks to accomplish what this group did in one day. Kunkle thanked them, complimenting their work ethic, and also saluted Air Products for supporting this day of caring by allowing workers to volunteer for LGNC while being paid their regular salary.