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Chapter 5 : Biological Resources
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The Swatara Creek watershed has managed to survive the intense commercial, industrial, and transportation development that the eastern portion of Pennsylvania has succumbed to. The majority of the watershed has historically been and still is used primarily for agricultural purposes (Figure 2-1). Indications of the past still remain along the hillsides, in the form of well-preserved farm complexes built by the German and Scots-Irish settlers of the 18 th century, who set out to clear the land for farming. Prior to this time, this area of Pennsylvania was located within the original Oak-Chestnut Forest Region (Braun, 1950). Along with the clearing of these lands by settlers, this forest region was virtually eliminated during the destruction of the American chestnut (Castanea dentata) by chestnut blight fungus (Endothia parasitica) in the early 1900’s. Although, some populations of American chestnut have been noted in Lebanon County.Currently, the old-growth forests in this area are non-existent and forestland is confined to a few extensive, contiguous areas within the more mountainous terrain typical of the northern portion of the watershed. The existing forest is located within the Appalachian Oak Forest Region or Mixed Oak Forest Region (Bailey, 1980) and is dominated by numerous oak species ( Quercus spp.), along with red maple (Acer rubrum), beech (Fagus grandifolia), and tulip poplar (Liriodendron tulipfera). This forest type occurs on the slopes and tops of mountain ridges as well as in some of the narrower valleys of Dauphin County. Most understory areas are composed of blueberries (Vaccinium sp.), huckleberries (Gaylussacia spp.), and mountain laurel (Kalmia latifolia).Some areas that have remained undisturbed, particularly those located in the southern portion of Dauphin County, contain native vegetation, including native grasses such as little blue stem ( Schizachyrium scoparium), big blue stem (Andropogon spp.) and Indian grass (Sorghastrum nutans), and small trees such as sassafras (Sassafras albidum) and red cedar (Juniperus virginiana) (Nature Conservancy, 1999). Other native small trees, such as red bud (Cercis canadensis) have also been noted within the watershed.Any plant growing where it is not wanted and having objectionable characteristics, such as aggressive growth or noxious properties that cause allergic reactions or poisoning are considered as invasive vegetation (Haber, 1997). The introduction of these invasive species dates back to the earliest arrivals of explorers and settlers to the region. Their ships were carriers of a wide variety of seeds and invasive animals. Seeds were present in hay bales, natural packing materials, and in food products. Even some of the seeds brought for cooking ended up being invasive weed species. Once established, clearing of these lands for logging and agricultural purposes aided in the spread of these invasive species. Photo 5-1: Purple loosestrife (Lythrum salicaria) When invasive species become established in forestlands, prairies, and wetlands, they tend to suffocate out the native vegetation. This then leads to the reduction of the biological diversity of the area, decrease in wildlife habitat of the area, and in some situations, the degradation of water quality and reduction of the recreational value of an area. A good example of this situation is the introduction of the chestnut blight fungus (Endothia parasitica) that so greatly influenced the health and composition of the forests in the watershed. There is a long list of plants considered invasive within the United States and the Swatara Creek watershed including the Japanese honeysuckle ( Lonicera japonica), tree-of-heaven (Ailanthus altissma), garlic mustard (Alliaria officinalis), multiflora rose (Rosa multiflora), tall reed (Phalaris arundicacea), purple loosestrife (Lythrum salicaria), kudzu vine (Pueraria lobata), mile-a-minute weed (Polygonum perfoliatum), and Japanese knotweed (Polygonum cuspidatum). Invasive floating or submerged aquatic vegetation, such as pondweed, (Potamogeton spp.) has also become the dominant plant species in some areas of the watershed.The problem associated with these species is controlling the invasion. This is related to the biology of the species, especially its propagative characteristics. Species that reproduce both sexually by seed and vegetatively by adventitious roots require the traditional mechanical means of controlling such as hand pulling, tilling, cutting, and mowing. Special care needs to be taken with these measures, as there has to be great care in the timing of pulling. This usually works best prior to seed production. It is also important to pull the whole plant including all roots. This can be a very labor-intensive process with large well-established populations. Tilling creates some of the same situations but also ensues the problem of the soil seed bank. Sometimes by tilling the soil, the seeds can be brought to the surface and germinate. Animals can also be considered as invasive species. In recent years, two invasive mussels, the zebra mussel ( Dreissena polymorpha) and the Asiatic clam (Corbicula fluminea), have created numerous problems in Pennsylvania waterways. These mussels have been introduced through the ballast of ships and have quickly spread. Neither of these species has become established within the watershed; although, the zebra mussel has been identified in the Susquehanna River Drainage. Being rapid reproducers, these animals have the potential to clog water intake pipes and reduce nutrient levels in water bodies that native species need to survive. Suggested methods of control for these species include screening off water pipes and releasing small amounts of chlorine or bromine to kill juvenile individuals.Chemical means of control bring their own concerns with polluting waterways, killing other desired species, and the potential harm to the user. Biological controls can be used to control the main mass of the population. A biological control works by using the plant’s natural enemies against it. Recently, the loosestrife beetle has been released within the Hershey property to try to control purple loosestrife. Therefore, it has been suggested that the best solution for the control of invasive species is an integrated pest management strategy. This includes a combination of several methods including mechanical, chemical, and biological controls. Mechanical and chemical efforts should be focused around the edge of the population to prevent further spreading but thorough and extensive care should be taken with these methods. Related to the vegetation of the area, wildlife species present within the watershed are common for the habitats of the area. Oak, maple, and beech all provide food sources for black bears, beavers, foxes, raccoons, squirrels, chipmunks, mice, and white-tailed deer (Martin, Zim, and Nelson, 1951). Numerous birds, both game and non-game species, also utilize these resources. Table 5-1 summarizes wildlife species located within the watershed. A listing of avian species located within the watershed can be located in Appendix F. Although not conducted directly within the Swatara Creek watershed, the Forest Bioblitz ’99 was organized adjacent to the northwest portion of the watershed in a 10 square mile area of State Game Lands 211 in the Stony Creek watershed. A group of individuals including agency personnel recorded 1,250 species of plants and animals within this area. It was estimated that 414 plant species, 146 beetle species, 106 moth species, 90 bird species, 50 moss and liverwort species, and 36 lichen species were identified. Counts for mammals were too large to estimate but did include the sighting of a black bear ( Ursus americanus) and a pygmy shrew (Sorex hoyi thompsoni).Further discussions of fauna and assessments of fish and macroinvertebrate species are presented in the Water Resources section of this report. Recently, a new cooperative trout nursery was started within the watershed in Pine Grove Township, Schuylkill County. This was a joint effort by sportsmen’s clubs, businesses, and individuals to provide fish for stocking Swatara Creek. Two thousand brook trout (Salvelinus fontinalis), 1,300 rainbow trout (Salmo gairdneri), and 100 golden rainbow trout (Salmo gairdneri sp.) fingerlings were initially released in the hatchery. It is estimated that by stocking time next year these trout should grow to 13 to 14 inches and weigh over a pound. There are also cooperative nurseries on Indiantown Run and Bachman Run in Lebanon County and on Spring Creek in Derry Township. The nursery located on Indiantowm Run raises 4,000 brook trout, 2,000 rainbow trout, and 2,000 brown trout. The facility on Bachman Run raises 4,000 brook trout, 1,000 rainbow trout, and 400 brown trout (Salmo trutta) every year. This hatchery also provides 400 brook trout for a children’s fishing derby in Derry Township, Dauphin County. The nursery on Spring Creek raises 5,500 brook trout and 500 brown trout for release. All of these fish are released into waters open to the public for fishing.
The following waters are stocked with trout by PFBC and/or the local cooperative nerseries: Mill Creek and Little Swatara Creek in Berks County; Manada Creek in Dauphin County; Trout Run, Quittapahilla Creek, Bachman Run, and Snitz Creek in Lebanon County; and Upper Little and Lower Little Swatara Creeks in Schuylkill County. There was also verified trout reproduction in Mill Creek in Schuykill County, Indiantown Run in Lebanon County, and Manada Creek in Dauphin County. In a 1999 survey of Trout Run (in Lebanon County), conducted by the PFBC, an American Eel ( Anguilla rostrata) was collected from the stream. The last survey of this stream, prior to 1999 was conducted 22 years ago and identified no American Eels. Table 5-2 summarizes the macroinvertebrates historically collected within the Swatara Creek watershed.
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