A Natural History of Millbrook Marsh,
A Wetland In An Urbanizing Setting

Description

Millbrook Marsh comprises approximately 36 ha that includes riparian zone, palustrine scrub-shrub and emergent wetland, calcareous fen, upland borders composed of early successional brush and forest, and about 5 ha of pasture and farmland with interspersed woody hedgerows (Figure 2-1). Parts of the wetland include 11 ha in private ownership. The pasture, farmland, and 20 ha of wetland make up the Millbrook Marsh Nature Center.

Millbrook Marsh is bordered on two of four sides by urban development along Routes 322 and 26 (Map 1, Map 3). Puddintown Road borders the site along the western and northern boundaries, with an upland buffer consisting of residential areas and farmland. Springs emerge from the adjacent private farmland behind the residences. Two small spring fed streams flow into the Millbrook Marsh Nature Center site at the northwest corner and then merge. This stream flow, known here as Bathgate Spring Run (Figure 2-2), travels through a field and an emergent wetland area at the bend in Puddintown Road, finally joining with Thompson Run just above its confluence with Slab Cabin Run. This section seems to be one of the least affected at this time by the surrounding urban development which is influencing much of the rest of Millbrook Marsh.

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Figure 2-1 Millbrook Marsh and Farm 12, Puddintown Rd. on left, Rte. 322 at top. July 16, 1997.  (Photo by R. Brooks.)

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Figure 2-2 Bathgate Spring Run. Early spring, 1997. (Photo by K. Tamminga.)

Across the road from the Farm 12 building complex, along the western edge, is one commercial site, a small dairy distribution facility,. A well established residential neighborhood known as Bathgate is across Puddintown Road. Over the hill from the private farm to the northwest of Millbrook Marsh is a stormwater detention pond designed to hold the stormwater runoff from the University land, particularly from the Beaver Stadium parking areas and construction sites adjacent to the Bryce Jordan Center.

The southern boundary includes a small single family residential area behind the commercial development on Route 26 (Figure 2-3). Along Route 26, known locally as East College Avenue, are small businesses, restaurants, a convenience store, gas station, hotel, and the College Township Building. Parts of the marsh have been covered with fill to enable some of the development, including the residential section between the commercial development and the wetland as well as the College Township building. There are both commercial and residential developments on the other side of East College Avenue, including a car dealership and a building supply company. At times of flooding or heavy precipitation, the runoff from these sites and others has a significant impact upon Millbrook Marsh (Figure 2-4). This area on East College Avenue frequently becomes inundated with stormwater (Map 2, Map 4).

The remaining side, the eastern border of the site, is bounded by a paved bikeway and footpath leading from the northeast corner of Millbrook Marsh under the Route 322 overpass to the southeast corner. At lower elevations the path follows Slab Cabin Run. Downstream of Millbrook Marsh it continues along Puddintown Road to Spring Creek Park. The path also serves as a connection to and beyond Slab Cabin Run Park, on the south side of East College Avenue, with one of the few remnant stands of old growth trees in the area. For some reason this small area of native Oak/Sugar Maple/Basswood was not cut during the Juniata iron era. The trees, averaging 24 m high or more, are estimated to be between 150 and 300 years old (PennDOT 1981). Beyond the path is Route 322, a 4-lane highway, and just beyond that is the developing Clover Highlands neighborhood, including both residential and some commercial development, primarily office buildings.

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Figure 2-3 Millbrook Marsh from southeast corner.
East College Ave. on bottom, Rte 322 on right. July 1997. (Photo by R. Brooks.)

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Figure 2-4 Thompson Run at Puddintown Rd. and East College Ave.
1997. (Photo by R. Brooks.)

There are various levels of disturbance in Millbrook Marsh, ranging from minimal to severe, and a range of time elapsed since disturbance. One area that has had minimal impact contains mostly palustrine emergent wetland and is approximately 6 ha (15 ac) in area (Figure 2-5). This portion of the marsh is bounded by Slab Cabin Run on the east, Thompson Run on the west, and a treeline north of the housing development along Route 26 to the south (Urban 1996). It is dominated by cattails (Typha spp), sedges (Carex spp.), and rushes (Scirpus spp.).

Adjoining the central emergent wetland area is the calcareous fen. The approximately 1 ha area within Millbrook Marsh represents a sizable example of a calcareous fen in Pennsylvania, one of the rarest types of ecological communities found in Centre County (Stack et al. 1991). It is dominated by sedges and supported by a steady flow of groundwater filtering through the limestone bedrock, with numerous small springs emitting water along the southern edge of the fen. At this edge there is a distinct boundary between fen and upland vegetation. It is probable that the fen boundary is also the terminus of added fill (see Chapter 4). It is also possible that part of the fen has been

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Figure 2-5 Palustrine Emergent Wetland between Thompson Run and
Slab Cabin Run. July 1998.

covered, but persists nonetheless (PennDOT 1981). Interpretation of historical photographs indicates that possibly only two thirds of the original fen exists at this time (see Chapter 5). The spring water flows northward, supporting the fen vegetation. It progressively fades to become indistinguishable from the remainder of the emergent wetland, and as such, there is no clearly visible boundary between the fen and the emergent wetland on the northern edge. In a study of calcareous fens in Pennsylvania (Western Pennsylvania Conservancy 1995), the fen in Millbrook Marsh was classified as part very wet open fen, part wet open fen, and part wet shrub fen. As many as 10 species of special concern have been reported for the site, although not all have been reconfirmed within the past 10 years. Additional rare species are believed to exist and could be revealed by further study.

An area with greater disturbance occurs within the boundaries of Slab Cabin Run to the west and the paved path and Route 322 to the east. It is approximately 6 ha in size and was a cattle pasture in 1971. It seems that it was abandoned and allowed to revert to its current condition, consisting mostly of shrub species such as alder (Alnus spp.), willows, (Salix spp.), and dogwoods (Cornus spp.) intermixed with several large elm (Ulmus spp.), and black willow (Salix nigra) trees, as well as grasses and grasslike species (Carex spp. and Scirpus spp.) (Urban 1996).

Thompson Run enters the site at the southwest corner and converges with Slab Cabin Run in the middle of the marsh. Population increases in the State College region and continued development are causing increases in stormwater input into Thompson Run. This has resulted in scouring of the creek bed, causing increased siltation further downstream in Thompson and Slab Cabin Runs. Water velocity increases due to the scouring, which in turn results in more scouring. Turbidity is also increased, especially during storm events. Due to these factors, fish populations have decreased, and some fish species are also no longer spawning in this area of Thompson Run, as they were as recent as 5 years ago (N. Deno, pers. comm.). According to local fishermen, fish populations may have gradually decreased in Slab Cabin Run also over the past 10 years .

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