The Arboretum at Penn State


Hartley Wood Restoration

Thickets of privet and honeysuckle overwhelming the understory of the woodlot

Thickets of privet and honeysuckle overwhelming the understory of the woodlot

The Hartley Wood is a 43-acre tract of forest owned in part by the University and in part by the Borough of State College as a portion of Sunset Park. Approximately 30 acres of the Hartley Wood are occupied by a remnant of original, pre-settlement forest. In the stand are several white oaks that exceed 300 years of age and several hundred trees over 150 years. This parcel was part of a much larger tract purchased by James Hartley in 1784. Much of the surrounding land later became the property of Centre Furnace, and its constituent forest was harvested for charcoal. Our old-growth remnant owes its survival to its earlier purchase, and retention, by Hartley.

In 1907, the land was purchased by H. Walton Mitchell, a prosperous judge from Pittsburgh who served on the Penn State board of trustees. Mitchell eventually built a house on his property (the current Schreyer House). The University’s portion of the land, including the house, was purchased from the Mitchell family in 1989.

Dendrochronological research by Samuel Grinstead1 reveals a distinct cohort of trees originating in the stand between 1837 and about 1850, when we believe selective cutting occurred for the first time in the Hartley Wood. Almost all of the trees that survive from this cohort of regeneration are white oaks. After about 1900, oak recruitment virtually stopped and other species began to appear. Red maple, black cherry, and other trees that have entered the stand since about 1910 are “shade tolerators.” The last century also saw the influx of a large number of non-native species dispersing from the nearby neighborhood of College Heights beginning as early as the 19-teens. Shade-tolerators and, of course, exotic species would have been uncommon or absent in the pre-settlement forest purchased by James Hartley. Research by Penn State faculty members and others shows that frequent, light disturbance (primarily fire) favored oak species on sites similar to that of Hartley Wood. One of the goals of the Arboretum is to attempt to return the Hartley Wood to a semblance of its pre-settlement state.

1Grinstead, S.C. 2007. A Restoration Management Plan for the Hartley Wood in The Arboretum at Penn State. Master of Forest Resources Paper, The Pennsylvania State University. 211 pp.

Native Prairie Restoration

Making progress removing nonnative shrubs

Making progress removing nonnative shrubs

In winter 2011, we began recreation of a dry limestone prairie on a five-acre parcel within the Arboretum grounds. The site, once overgrown with invasive shrubs, is now well-stocked with newly-seeded grasses and forbs native to Centre County. While limestone prairies were never common in central Pennsylvania, their existence was noted as long ago as the 1770s, and some remnant parcels persist to this day. While we do not know whether an extensive prairie once existed on the current restoration site, small patches of prairie plant species in the area provide evidence that reconstruction could be both suitable and successful. By recreating this rare but native plant community, we hope to contribute to the ecological diversity of the local landscape and restore some of the region’s natural heritage.

Water Conservation

The Dr. James J. and Lynn D. Ramage Marsh Meadow was designed to represent a grassy wetland. Despite its name, however, the Marsh Meadow is not usually marshy or even wet, although once or twice a year it contains standing water for brief periods. The true purpose of this landscape feature is to protect a critical area for the infiltration and cleansing of storm water runoff and, ultimately, replenishment of the underground aquifers from which the University and community draw their water. The plantings in the Marsh Meadow were designed to minimize disturbance to the soil because a healthy and intact soil profile is critical to this process.

The low area occupied by the Marsh Meadow is part of a shallow natural drainage way that originally continued very gradually downhill and eventually ended in Big Hollow. Changes to the landscape caused by campus expansion and construction now obstruct the natural flow of this drainage.

Because the water that flows into the Marsh Meadow can no longer flow out, it must infiltrate the soil or evaporate. Increased storm water runoff into this basin, coupled with its inability to flow out, have substantially increased the amount of water filtering through the soil and limestone bedrock. Sinkholes have formed as soil is flushed into existing voids within the bedrock. The vegetation of the simple but beautiful Marsh Meadow conceals a critical ecological function – collecting and purifying storm water and recharging subsurface aquifers in a landscape that has been heavily modified. The Marsh Meadow protects an important storm water catchment while serving a prominent aesthetic role in the design of the Arboretum and gardens.