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

Some fairly major vegetation changes have taken place over the past 50 years in Millbrook Marsh. The most obvious change has been an increase in shrub cover (Figure 5-9). Aerial photography from 1948, 1961, c1960s, 1974, 1986, and 1994 (Figure 5-10) shows the vegetation changes over the course of 46 years (Brooks et al. 1998). In 1948, both sides of Slab Cabin Run were farmed along the entire length in Millbrook Marsh.

Figure 5-8 Canada Thistle, Cirsium arvense,
in field along Bathgate Spring Run in Millbrook Marsh July 1998.

Figure 5-9 Shrub invasion in Millbrook Marsh, mainly Multiflora Rose, Rosa multiflora
and Japanese Honeysuckle, Lonicera japonica College Township
Building in lower left. July 1998. (Photo by R. Brooks.)

Figure 5-10 Historical aerial photographs of Millbrook Marsh and
vicinity documenting changes in land use and land cover 1948-1994.

The west side of Thompson Run was wooded, with one patch of trees on the east side, and there were trees sporadically along all the streams. All areas within Farm 12, including the wetland area along Bathgate Spring Run, were farmed. The fen seems to have encompassed approximately 2.5 to 3 ha and had not yet been filled in along the southern edge of the marsh. No utility lines crossed the wetland in 1948. The second aerial photograph was taken on April 20, 1961, during near flood state for the wetland and streams, and shows drainage patterns and floodplains clearly. Farming seems to have been reduced on the south side of upper Slab Cabin Run, and the power line is now shown running through the marsh. The fen still shows no impact by filling. The c1960s photograph, though taken during a drier time, shows no great departure from the 1961 photograph. The 1974 photograph proves farming was still occurring along lower Slab Cabin Run, and the farm road crossing in the northeast corner of the site is visible. The fen is no longer intact in entirety. The apparent change is the addition of fill along the southern edge of the marsh, including part of the fen. It appears to have been reduced to cover only about 1 ha adjacent to the emergent wetland vegetation. The woody cover seems to have matured but not increased substantially in area. By 1986, construction of the Mt. Nittany Expressway is visible, and with it, the corresponding farmed area has been eliminated. The filled fen area and some previously farmed sections exhibit an increase in woody cover, and it appears that either fill is graded or farming activities are occurring along lower Slab Cabin Run and the north side of upper Slab Cabin Run. More fill has also been added along the south east edge of the marsh. The 1994 photograph shows the completed Mt. Nittany Expressway, and in this photo the most change in woody cover is evident. Significant increase occurred along lower Slab Cabin Run, the north side of upper Slab Cabin Run, and along Bathgate Spring Run. By 1994, there was also shrub cover seen in the center of the marsh, between Slab Cabin Run and Thompson Run. The original woody cover throughout the marsh had matured as well.

In a 1996 landscape analysis of Millbrook Marsh, the percent cover of 5 habitat types was approximated using a February 1993 aerial photograph (Urban 1996). The 2 wetland areas within Millbrook Marsh, discussed earlier in Chapter 2, were analyzed. Each site was 6 ha. The "natural" site between Slab Cabin Run and Thompson Run was estimated to be 25% woodland, 70% emergent wetland, and 5% scrub-shrub wetland. The 20 year old "restored" wetland, prior farmland located between Slab Cabin Run and Route 322, was 15% woodland, 10% emergent wetland, 70% scrub-shrub wetland, and 5% open grass. A third site, now separated from Millbrook by the Mt. Nittany Expressway, is only 10 years old. It was restored after the highway construction and is 10% woodland, 0% emergent wetland, 20% scrub-shrub wetland, 30% open grass, and 40% teasel. It will be interesting to note whether the scrub-shrub wetland increases, or whether the open grass and teasel areas become invaded with non-native shrub species in another 10 years.

  On to Vegetation Discussion