Natural History of the EcoPreserve

Natural History of the EcoPreserve

When walking through the preserve in spring, look along the ground for some of spring ephemerals found in the region. These include Spring Beauty (Claytonia virginica), with small, stunning white and pink blooms, Trout lily (Erythronium americanum), recognized by its mottled green leaves and graceful yellow flowers, mayapple (Podopyllum pendulatum) with its twin umbrella shaped leaves and large white flower, Skunk Cabbage (Symplocarpus foetidus) a plant that grows in wet areas and is capable of thermogenesis (the ability to produce heat above the surrounding ambient temperature and is thus capable of melting snow), and finally ‘Jack-in-the-Pulpit’ (Arisaema triphyllum), is found in moist areas, displaying a distinctive array of three-parted leaves and flowers found in its spadix, covered by a hood (hence the name “Jack-in-the-Pulpit”).

Watersheds are an integral part of all ecosystems due to both their abiotic and biotic interactions with plants and animals that call it home.  Protected by the preserve’s forest cover, the headwater streams that drain from the Preserve provide high quality water to the Raritan River downstream. The two primary streams that have their start in the EcoPreserve  are Buell Brook, which drains directly into the Raritan River after a quick jaunt through Johnson Park. As Buell Brook cuts through the center portion of the preserve, hikers have an elevated view of the brook and can clearly see its meandering nature through shallow cut banks and slick shale facies. Metlars Brook, drains the western side of the preserve.  In the lower reaches of Buell Brook,  black-nosed dace (Rhinichthys atratulus), creek chub (Semotilus atromaculatus) and the elver stage of American eel (Anguilla rostrata) inhabit quiet pools.  Northern two-lined (Eurycea bislineata) and norhtern dusky salamanders (Desmognathus fuscus) inhabit the streams and adjacent riparian zones.

Located within the Piedmont physiographic province of New Jersey, this area is dominated by the Newark Supergroup which is the cluster of formations that make up the Newark Basin, which extends through central and northern New Jersey. Commonly known as New Brunswick shale, this outcrop of red shale most likely is representative of the Passaic Formation, formed during the late Triassic age.

Cultivated from the mid-1700’s, by the early 20th century most of agricultural fields were abandoned by the mid to late 1930’s. Natural ecological succession took over and the agricultural fields were invaded by grasses, wildflowers, shrubs and then trees. Many of the fields were separated by small strips of forest which served as wind breaks or hedgerows. Many of these old hedgerows composed of large Pin Oaks (Quercus palustris), Red Maples (Acer rubrum) and Black Cherry (Prunus serotina) trees are still visible in the forest today. As you walk around the preserve, look for more of these larger “Grandfather” trees denoting the edge of an old field. The abandoned farm fields to the east and west are now mostly populated by Eastern Red Cedar trees (Juniperus virginiana). As time progresses in the forest, early “old-field” pioneer tree species like the cedars will be overtopped and shaded out by larger deciduous trees. Red Oak (Quercus rubra), White Oak (Quercus alba),  Ash (Fraxinus), Beech (Fagus grandifolia) and Hickory (Carya). These tree species now dominate the matue Kilmer Woods forest area in the Northeastern corner of the preserve. Interestingly, old burned stumps of cedar trees can still be found in some areas of Kilmer Woods, probably dating from when this area was a pasture back in the early 1800’s before the present day hardwood forestwas established.


SuperStorm Sandy walloped the Ecopreserve in October 2012. A Number of the largest red, white and black oak trees were toppled.  As the trees were still in leaf, they were carrying a lot of surface area and susceptible to the high winds that accompanied this tropical storm system.  Note that most of the trees were uprooted with the top of the boles falling towards the west-southwest due to the prevailing winds coming from the east-northeast.  The fallen trees have left large light gaps that are allowing understory plants and tree seedlings and saplings to flourish.  However, in most cases, these gaps aren’t large enough and don’t provide enough sunlight for the shade intolerant oak species to regenerate. Over the coming decades we expect that the more shade intolerant oak trees in the canopy will “age out” and be replaced by the more shade tolerant beech, sugar and red maples.


The EcoPreserve represents a large “island” of forest amidst a sea of suburbia and offers both foraging and breeding habitat for Neotropical migrant songbirds. While many warblers and other songbirds are stopping in the forest to refuel as the move farther north to breed, several species nest in the EcoPreserve. In general, warblers are small colorful birds with vibrant songs, short and thin bills, and “flitty” behavior. Once one learns specific songbird species’ behaviors and microhabitats, identification of these beautiful birds becomes easier. For instance, several warblers in the same area will feed in different vertical stratums of trees: look out for Yellow-rumped warblers higher in the tree tops while Black-and-White Warblers will remain closer to the ground and spiral up the trees. During the early summer months, the mating or alarm calls of wood thrush and rufous-sided towhees can be heard by the observant listener. Tree swallows and house wrens nest in the various nest boxes located in and along the edges of the Preserve


An exotic species is one that is non-native to an area and introduced, usually through some form of human intervention (both intentionally and unintentionally). Some exotic species can become “invasive” in that they become established and grow in population such they interrupt the natural functioning of an ecosystem by impacting native plants and animals. Not all introduced, exotic species become “invasive.”  Invasive species can be plants, animals, or micro-organisms. Given the right circumstances, invasive species can place a tremendous burden on natural resources, threaten native biodiversity, cause harm to the human health or the economy. For example, an invasive plant may out-compete for space or habitat with the native plant community of the area. Due to the lack of a natural predator, parasite or disease to keep its population in check, an exotic insect may become a major pest. Invasive species can place a tremendous burden on natural resources and are considered to be a great threat to global biodiversity, second only to outright habitat destruction. New invasive species are always emerging.

As in many natural areas across the state, a number of exotic species have become established in the EcoPreserve. Some of these species are considered invasive, in that outcompete or cause harm to native plants, and are the subject of active control efforts.  For example, Chinese Bush Clover (Lespedeza cuneata) crowds out native grasses and wildflower in the meadows along the edge and the interior of the EcoPreserve and is periodically sprayed with herbicide. As a form of biological control of the invasive Mile-a-Minute vine (Persicaria perfoliata), the NJ Beneficial Insects Lab introduced a weevil (Rhinocominus latipes) to feed on the plant. Other plants are so ubiquitous ,or conversely so difficult to detect, that they are difficult to control.  For example, Japanese stilt grass (Microstegium vimineum) is found throughout the EcoPreserve understory and would require extensive spraying of herbicide to control. Emerald ash borer, Agrilus planipennis, is an exotic beetle has killed millions of ash trees across North America as well as in the EcoPreserve but is often difficult to detect until it is too late. Other exotic species have become “naturalized”. For instance, while wineberries (Rubus phoenicolasius) can dominate canopy gaps in the forest displacing native plants, many people and park/refuge managers tolerate them, if not accept them as part of the ”new normal”.

Need more information?

The New Jersey List of Invasive Species

NJ Invasive Species Strike Team

If you are a visitor to the preserve, there is a pretty good chance that you will encounter the native white-tailed deer in some way. Whether it is seeing their footprints or seeing them, they are one of the most prominent wildlife species in the preserve. Aside from tracks, you may also see a ‘deer trail’, which is a path through the brush, grass, etc. that has been worn due to the passage of one of the animals. There are many of these in the preserve, and it is not difficult to find them, as these narrow and often slight passages can head off of the main trails. Deer are herbivores that selectively browse on plant species, potentially causing changes in composition within plant communities. Although deer herbivory is a naturally occurring phenomenon, the overabundance of deer can have serious deleterious effects on plant communities by reducing the species richness and abundance, which can lead to dominance of invasive species.