< Back to BLT Main Site

CHAPTER FOUR: BIOLOGICAL COMMUNITIES

PLANTS
Plant Communities:
The vegetation of Branford (Figure 7; Vegetation) cannot be considered "virgin" to the landscape. Clear-cutting for agriculture earlier in its Colonial history and more recently the landscaping of lawns and parks, the introduction of escaped ornamentals and other introduced species, and the expansion of invasive plants have significantly changed the nature of the vegetation within the entire region. Therefore it is not necessary to discuss natural plant communities. Instead the following discussion will concentrate on existing plant community structure and will not include managed areas within residential or commercial developments.

The plant communities of Branford can be divided into many different habitats based on the presence of dominant plant species. For purpose of discussion the vegetation of the watershed will be divided into three major categories: upland, wetland, and agriculture. The plant lists are not meant to be exhaustive, but, rather, to provide an overview of the more dominant associations. Plant taxonomy is after Gleason (1952), Fernald (1970), Sutton and Sutton (1986) and Niering (1986).

The upland plant communities are divided into the following cover types:
• early-successional field
• late-successional field
• deciduous forest/riparian
• coniferous forest/riparian
• introduced species

Agriculture is separated based on dominant crop and includes:
• herbaceous farm
• tree farm
• grazing pasture

Wetland communities are separated into:
• freshwater non-tidal swamp (with trees)
• freshwater non-tidal marsh (without trees)
• freshwater non-tidal bog (heath shrubs and moss)
• vernal pools and intermittent watercourses
• freshwater tidal marsh
• brackish tidal marsh
• tidal salt marsh
• aquatic and subtidal

Upland Plant Communities
Early-Successional Field - are fields that have recently been abandoned and are dominated by herbaceous plants and low vines (you can generally see over the tops of the plants). Species diversity in these fields is very high and a lot of pioneering species can be found persisting in the community. Grasses tend to dominate these areas and include foxtail (Setaria, spp.), redtop (Agrostis sp.), fescue (Festuca spp.), and a variety of species belonging to the genera Panicum, Poa, Eragrostis and Aristida among others. Non-grass plants commonly found here include dandelions (Taraxacum spp.), clover (Trifolium and Lespedeza), plantains (Plantago spp.), asters, cinquefoil (Potentilla spp.), buttercups (Ranunculus spp.), St. Johnswort (Hypericum spp.), goldenrods, yarrow (Achillea spp.) and smartweeds (Polygonum spp.) among others.

Late-Successional Field - refers to old fields that have been allowed to revert back towards a forested condition. The late-successional field is composed of shrubs, small trees, and herbaceous plants. Trees common to these areas include white and gray birch (Betula papyrifera and populifolia), red cedar (Juniperus virginiana), black cherry (Prunus serotina), choke cherry (Prunus virginiana), and young oaks. Shrubs common to these areas include red stemmed (Cornus stolonifera) and gray (C. racemosa) dogwoods, sumac (Rhus spp.), pussy willow (Salix discolor), alder buckthorn (Rhamnus frangula), and maple leaf viburnum (Viburnum acerifolium). These fields often support large amounts of vines and vine-like plants including poison ivy (Toxicodendron radicans), virginia creeper (Parthenocissus quinquefolia), grape (Vitis spp.), raspberries (Rubus spp.), currant (Ribes spp.), greenbrier (Smilax spp.), morning glories (Ipomoea spp.), and honeysuckle (Lonicera spp.), and a large population of introduced species such as multiflora rose (Rosa multiflora), Chinese wisteria (Wisteria sinensis), oriental bittersweet (Celastrus orbiculata), garlic mustard (Alliaria officinalis) Japanese knotweed (Polygonum cuspatatum) and Japanese honeysuckle (Lonicera japonica). Herbaceous plants are also common in these late successional fields and include ragweed (Ambrosia sp.), goldenrods (Solidago spp.), Queen Anne's Lace (Daucus carota), beggar's ticks (Bidens spp.), asters (Aster spp.), sunflower (Helianthus spp.), thoroughworts (Eupatorium spp.), thistle (Cirsium spp.), loosestrife (Lythrum spp.) and a variety of grasses.

Deciduous forest - can also be further divided into upland and riparian/floodplain forests and is the most dominant upland plant community within the Town. Deciduous forest is generally dominated by combinations of oak (Quercus spp.), maple (Acer spp.), and hickory (Carya spp.) and a variety of co-dominants such as ash (Fraxinus spp.), cherries (Prunus spp.), poplar (Populus spp.), tulip tree (Liriodendron tuliperfera), walnuts (Juglans spp.), sassafras (Sassafras albidum) and birch (Betula spp.). A host of understory plants share the forest floor and include dogwood (Cornus spp.), arrow-wood (Viburnum dentatum), winterberries (Ilex spp.), shadbush (Amelanchia spp.), cherries (Prunus spp.) and laurels (Kalmia spp.).

The upland deciduous forest is dominated by oaks (Quercus spp.) with red oak (Q. rubra) and white oak (Q. alba) accounting for a majority of the oak trees. The next most abundant trees are the hickories and include the shag-bark hickory (Carya ovata), bitternut hickory (C. cordiformis), pignut hickory (C. glabra) and mockernut hickory (C. tomentosa). In many of the younger forested areas, oaks are mixed with birch, red cedar and black cherry. In disturbed habitats, oaks can be found in association with trembling aspen (Populus tremuloides). In the forested areas within the more urbanized zones, oaks can be found mixed with a number of introduced species such as tree of heaven (Ailanthus altissima), European (horse) chestnut (Aesculus hippocastanum) and Norway maple (Acer platanoides). The maples (Acer spp.) are also important trees in the upland forest and include sugar maple (A. saccharum), silver maple (A. saccharinum), and to a lesser extent red maple (A. rubrum).

Throughout the Town, the oaks are found in different associations. The most common association is oak/hickory with red oak being the dominant oak species. Oak and maple are often associates, as are oak/maple/hickory associations. On some ridgetops along the Jurassic fault line, white oak forms associations with hickory and sassafras. At the Supply Ponds, oak/maple associations are common and swamp white oak may be found along the wetter areas.

The riparian/floodplain deciduous forest is dominated by pin oak (Q. palustris) and red maple (A. rubrum). Within this zone, other tree species may include sycamore (Platanus occidentalis), eastern cottonwood (Populus deltoides), willows (Salix spp. including the introduced weeping willow - S. babylonica), black locust (Robinia pseudoacacia), sweetgum (Liquidambar styraciflua), elm (Ulmus americana), swamp white oak (Q. bicolor), and black ash (F. nigra), the latter two also commonly found in swamps.

In a number of locations, power line right-of-ways bisect forested areas. In order to keep the area free of large trees these right-of-ways are cut and planted with various shrub species. Plants common to the right-of-ways include alder, sumac, Russian olive (Elaeagnus angustifolia), poison ivy, pussy willow, morning glory, Japanese honeysuckle, wisteria, goldenrod, deer-tongue panicum (Panicum clandestinum), asters, switchgrass (Panicum virgatum), Queen Anne's Lace, ragweed, raspberries, loosestrife, and reedgrass, among others.

Coniferous forest - are forested areas dominated by Gymnosperms (Coniferophyta) including pines, hemlock, spruce, and fir. Coniferous forest accounts for about 5% of the total forested area and most are the result of plantations. Coniferous forests can be further divided into upland and riparian forests, the latter most important for protecting streams and rivers.

Within the Town, the coniferous upland forest community type can be further subdivided into mixed hardwood (deciduous)-coniferous and coniferous forests. The mixed hardwood/coniferous forest includes two major associations: the hemlock/beech mixed association and the white pine/hickory association. The coniferous forest type is typically the result of plantings on abandoned fields. These forests are comprised of stands of white pine (Pinus strobus), and/or Norway spruce (Picea abies), although hemlock may be locally important. Other plantations include European larch (Larix decidua), white spruce (Picea alba), and northern white cedar (Thuja occidentalis). These stands are typically maintained by the selective cutting of hardwoods.

One of the best examples of existing hemlock/beech mixed forest type can be found along the slopes and streams running through North Farms Park located just over the border in North Branford. Judging by the size of some of these hemlocks, portions of this stand are between 75 and 100 years in age. Along with the hemlock and beeches, the canopy also includes black birch (Betula nigra), red oak, tulip tree, red maple, shagbark hickory, mockernut hickory, bitternut hickory, pignut hickory, and some white oak. The understory in this area is a mix of shrubs including sassafras (Sassafras albidum), mountain laurel (Kalmia latifolia), witchhazel (Hamamelis virginiana), dogwood, American hornbeam (Carpinus caroliniana), arrowwood, and saplings such as red maple and black birch. Herbs in the understory include raspberries (Rubus spp.), false Solomon's seal (Smilacina racemosa), Canada mayflower (Maianthemum canadense), wood aster (A. divaricatus), path rush (Juncus tenuis), goldenrod and a variety of ferns including Christmas fern (Polystichum acrostichoides), hayscented fern (Dennstaedtia punctilobula), and lady fern (Athyrium Filix-femina).

The riparian/floodplain mixed coniferous forest is similar in structure to the upland coniferous mixed forest type except for the understory that is dominated by more moisture tolerant species. Along stream banks and wetter areas, other woody species such as sweet pepperbush (Clethra alnifolia), alder (Alnus spp.) and red maple become important and a variety of herbaceous plants such as jewelweed (Impatiens capensis), smartweed (Polygonum spp.), duck potato (Sagittaria latifolia), and skullcap (Scutellaria spp.) can be found growing in slow moving reaches of the stream. The riparian coniferous forest is typically dominated by hemlock, although stands of white pine may also be found along floodplains.

In many areas, hemlock has been dying due to infestation by the wooly adelgid. This pest is severely limiting hemlock and may one day eliminate this plant from the Town except where it is maintained through spraying.

Another mixed coniferous forest type is the white pine/hickory association. The most common hickory is the mockernut hickory, although, bitternut and shagbark hickories can also become important. At the Supply Ponds, red maple also becomes a co-dominant in this association in many areas. The understory also varies between sites and includes American hornbeam, witchhazel, arrow-wood, dogwood, winterberry (Ilex verticillata), and the introduced winged Euonymus (Euonymus alatus).

The coniferous forest community is dominated by white pine associations. Although many of these areas have been maintained (selectively cut, planted), they have become an important upland forest community. The best example of this forest type can be found in pockets surrounding Regional Water Authority land along Lake Saltonstall. In many of these areas the white pine may be mixed with Norway spruce and/or red spruce. Red pine is present in the forest but most of the specimens are relatively young suggesting recent cutting of this species. Frazier fir is also found in the area but these are almost exclusively found planted in Christmas tree plantations (neat rows with regular spacing). In some places the white pine also includes associations with hemlock, although the hemlock tends to favor ravines and lowland areas. The understory in this forest type contains a variety of species including blueberry (Vaccinium spp.), poison ivy, raspberries, asters, Virginia creeper, and Japanese honeysuckle.

Agriculture
Agriculture accounts for approximately 10% of the land-use within the Town. Most of the agricultural fields are devoted to corn and pasture land with orchards locally important. Tree farms are present in the Town and many are used to grow Christmas trees, although red pine and white pine plantations are also evident. Agricultural fields may be further subdivided into tilled (vegetation is periodically removed) and untilled fields (periodically maintained by mowing, when not mowed will form the early successional field). Small farms are spread throughout the Town with a majority of them located north of I-95 and to a lesser extent, along the Guilford line.

Agriculture has had a major impact on the entire region. During the last three hundred years, all habitats have at one time or another been clear-cut and most have been plowed. Farming activities since European settlement have eliminated all virgin forests and have had a major impact on plant community structure in these areas. For instance, American chestnut (Castanea dentata) and hickory were not forest dominants prior to European settlement. Chestnut dominated the regrowth of cut forests between the 1600's and the twentieth century before succumbing to an Asiatic blight during the early 1900's. Once chestnut died off, hickory and oak were able to replace it in the forest canopy. Thus, the oak/hickory association is a relatively new plant grouping in these forests. There is also some evidence that coniferous forests were more prevalent in the Town and have since been replaced by the deciduous forest type. Since these forests are relatively young, trees such as birch and red cedar (left-overs from late succession) are more prevalent then we would expect to see in mature forests. Similarly, the proliferation of vines and vine-like plants is a direct result of repeated forest cuts during the last few centuries that have resulted in opening up the canopy to sufficient light to allow for extensive understory growth. The vast majority of early and late successional fields are also abandoned farm fields. The forests and many of the wetland habitats that we see today are secondary growth habitats with the oldest continuous areas typically being less than 150 years in age.

Wetland
Since wetland areas were hardest to farm without extensive draining and tilling many survived human activities during the last few centuries. This does not suggest that they survived untouched, it just supposes that the area had a better chance of remaining wetland for longer periods of time. Although any one type of wetland may have a long history within the watershed, many of these wetland areas are relatively new to the sites in which they are presently found because the landscape has been altered and the hydrology has been extensively manipulated. Even wetlands that have maintained their place on the landscape for many centuries have also changed significantly through the years (i.e., hydrology, vegetation). The only class of wetlands that have escaped relatively untouched are the tidal salt marshes, although here too, the marshes have been hayed, ditched for mosquito control and diked off to reclaim the land for development or to allow for a road or railroad crossing. Today wetlands are protected by law; however, with continued development and the need to control hydrology (i.e., storm water discharge, increased impervious cover) these habitats are still stressed and are experiencing shifts in plant community structure. Like the upland habitats, wetlands can be separated into divisions based on the dominant vegetation and hydrology. [NOTE: freshwater refers only to the absence of salts, it does not denote water quality]

Non-Tidal
Freshwater swamps - are wetlands that are dominated by trees. Within the Town, the most common swamps are dominated by red maple. Pin oak, swamp white oak, and black ash are also important species and may locally become co-dominants. Shrubs such as sweet pepperbush, alder, American hornbeam, and buttonbush (Cephalanthus occidentalis) are common in the understory. Other species of note include black willow (Salix nigra), highbush blueberry (Vaccinium corymbosum), spicebush (Lindera benzoin), and black birch (B. lenta)). The swamp habitat is wet for most of the year and is characterized by limited herbaceous ground cover.

Freshwater marshes - are wetlands dominated by herbaceous plants. Dominant species include tussock sedge (Carex stricta), jewelweed, cattail (Typha spp.), skunk cabbage (Symplocarpus foetidus), smartweed (Polygonum spp.), canary grass (Phalaris arundinacea), arrow arum (Peltandra virginica), duck potato (Sagittaria latifolia), and a variety of sedges and rushes including those of the genus Scirpus (i.e., S. cyperinus, S. fluviatilis), Cyperus (i.e., C. strigosus), Carex (i.e., C. crinata, C. lurida), Eleocharis (i.e., E. obtusa) and Juncus (i.e., J. effusus). Reedgrass (Phragmites australis) has been spreading recently and now dominates a number of sites. Although this plant is native to Connecticut, it has become an invasive species (a non-native genotype has now been confirmed growing in the area) and now grows in areas historically not typical of the plant. Introduced species such as multiflora rose and Japanese knotweed have acclimated to many of these habitats as well, particularly along the upper borders. Freshwater marshes are characterized by hummocky topography, peaty substrates, and saturated ground water conditions. Although natural to the landscape, many marshes are the result of damming and diversions of river, stream flow, and storm water drainage during the last few hundred years.

Freshwater Shrub/Scrub Wetlands/Bog - are wetlands dominated by woody shrubs. Although these wetlands are less common in the watershed, a few examples do exist within Town, most notably along Quarry Road. In these habitats, swamp azalea (Rhododendron viscosum), alder, buttonbush, dogwood, spicebush, steeplebush (Spirea tomentosa), and sweet pepper bush can be found. Bogs in Town are few and far between. They differ from the shrub/scrub wetland by having shrubs interspersed with sphagnum moss, and various associations with tussock sedge, sensitive fern (Onoclea sensibilis), and jewelweed. Some examples can still be found in the Pisgah/Queach Brook subwatershed along the utility right-of-way around the Supply Ponds.

Vernal Pools/Intermittent Watercourses - are wetland areas that dry out for a portion of the year. Although not dominated by any one vegetation type, they are important breeding habitats for amphibians. Vernal pools are wet in the spring and are common in red maple forests (not necessarily swamps). These may vary in size, although most are typically a few square yards in area. Typically, these pools are limited in vegetation and are small depressions where leaves may accumulate. During much of the year, they are drained and not very obvious. A recent inventory of vernal pools for the Town's Conservation and Environment Commission found 55 pools scattered on public and quasi-public property (private land was not surveyed) throughout the town (Dr. N. Proctor, Survey of Branford Vernal Pools, Report to the Conservation and Environment Commission, May 31, 2002). Information on each pool is on file with the commission.

Intermittent watercourses are those that have a defined channel and exhibit some form of surface flow such as alluvial sediments (sands and muds carried by water) or wrack (plant debris or floatables that come to rest in tree branches or rocks). Water flows occur during storm events and support a variety of plants including sedges, jewelweed, and cattail. Although many of these watercourses are located in wooded areas, there are many that are grass-covered and incorporated into lawns and fields.

Aquatic - refer to areas that are under water for most of the time. In freshwater aquatic habitats, vegetation may include waterweed (Potamogetan spp.), water marigold (Megalodonta beckii), duckweed (Lemna minor), arrow arum, duck potato, and water lily, among others.

Tidal Wetlands
Freshwater tidal marshes - are tidally influenced wetlands that are inundated in freshwater and dominated by herbaceous plants. Because dams and road culverts block the path of water, most of this type wetland is limited to small bands along the upper-most reaches of the Branford River (near I-95) and some of the smaller tributaries such as Queach Brook. The vegetation here is dominated by jewelweed, cattail, arrow-arum, a variety of sedges and reedgrass. Water lily (Nymphaea odorata), and duck potato can also be found in the wetter areas.

Brackish marshes - are tidal marshes that are inundated with tidal waters with a salinity of less than 18 ppt. The dominant plants in these marshes include reedgrass, saltwater cord grass, salt hay, blackgrass and a variety of sedges (Scirpus robustus, Scirpus maritimus and Scirpus olneyi). Aster and goldenrod may also be important locally. These marshes are prevalent between the freshwater and salt marshes in the lower river/harbor and small tributaries. The best example of this type marsh can be found between the Branford High School and Route 1 and along the lower reaches of Queach Brook.

Today brackish marshes are also prevalent where roads have bisected a coastal marsh and have restricted tidal flows. This restriction in flow reduces saltwater inputs and eventually, with enough rain, the soils in these systems become diluted. The change from salt water to brackish conditions leads to a change in the plant community as well. Many of these areas are now supporting monocultures of reedgrass (e.g., upper Mill Creek). Attesting to the changes in tidal hydrology, many of the marshes still contain pockets of salt marsh plants such as salt hay and spikegrass (Sybil Creek above Route 146) and a variety of transition zone species such as salt marsh bulrush (Scirpus robustus), goosefoot (Atriplex patula), dock (Rumex spp.), and saltmarsh fleabane (Pluchea purpureascens).

Salt marshes - are marsh systems dominated by tidal hydrology and regularly inundated with full strength seawater (Long Island Sound is typically about 25 ppt). These marshes are dominated by grass including saltwater cordgrass (Spartina alterniflora), salt hay (Spartina patens), spikegrass (Distichlis spicata), blackgrass (Juncus gerardii), and a variety of non-grass plants such as seaside goldenrod (Solidago sempervirens), salt marsh aster (Aster tenuifolius), sea lavender (Limonium nashii), and glassworts (Salicornia spp.).

The transition zone between freshwater and saltwater is very diverse and includes the natural habitat for reedgrass. In this upper border transition zone, it is also common to find rose (Rosa rugosa and Rosa multifora), poison ivy, marsh elder (Iva frutescens), marsh mallow (Hibsicus palustris), waterhemp (Achnida cannabina), goosefoot, bulrush and fleabane.

Subtidal - refer to areas that are under water for most of the time. The subtidal zones are located in the lower reaches of the harbor and historically included widgeon grass (Ruppia sp.) and possibly eelgrass (Zostera sp.), although the latter is subject to debate (a disease has killed much of this species within this century and records are not clear as to the distribution of this species prior to this century). The subtidal zone also includes green algae (Enteromorpha intestinalis), knotted wrack (Ascoplyllum nodosum), rockweed (Fucus vesiculosus) and sea lettuce (Ulva lactuca).

ANIMALS
Animal Communities:
Animal communities are more difficult to define than plant communities because the animals are able to move around. Instead, it is often easier to divide the animals based on the phylum (major subdivision) to which they belong (insect, arthropods, amphibians, reptiles, birds, mammals).

During the last few centuries, animal populations have changed dramatically in the Town in response to changes in land-use. Clearcutting during the 1700's changed the nature of the animal community from woodland species to open field species. Additionally, many animals have been introduced to the habitat either intentionally (i.e., pigeons) or by accident (i.e., Norway rats). In other cases, competition for food and protection of livestock led to the elimination of certain species. For example, bears and coyotes were pushed out of the area by the 1800's. Although both species are making a comeback in Connecticut, coyotes have come back to the Town while bears are still north of Town. Other animals that were probably more prevalent in the past include beavers, otters, and muskrats.

Urbanization has also had an impact on animal communities throughout the watershed. European starlings, house sparrows, rats, mice, skunks, squirrels and raccoons have all adapted well to the urban environment and, at present, dominate many habitats within Town. Urbanization has also led to an increase in feral cat populations.

Although data are limited, there are some inferences that can be made about the impacts of recent residential development within the Branford River watershed. A survey of reptiles in Branford during the late 1940's found 10 of the 15 species of snake and 8 of the 10 species of turtles known to exist in Connecticut were found at both Ward's Millpond and the Supply Ponds (Finneran 1948). This included the northern ring-neck snake (Diadophis punctatus), eastern hog-nose snake (Heterodon platyrhinos), northern black racer (Coluber constrictor), eastern garter snake (Thamnophis sirtalis), black rat snake (Elaphe obsoleta), eastern milk snake (Lampropeltis triangulum), northern water snake (Nerodia sipedon), northern brown snake (Storeria dekayi), eastern ribbon snake (Thamnophis sauritis) and northern copperhead snake (Agkistrodon contortrix mokeson), and stinkpot turtle (Sternotherus odoratus), common snapping turtle (Chelydra serpentina), spotted turtle (Clemmys guttata), wood turtle (Clemmys insculpta), northern diamondback terrapin (Malaclemys terrapin), painted turtle (Chrysemys picta), eastern box turtle (Terrapene carolina) and Emys blandingii. A survey conducted at these sites during the 1990's found that only the northern ring-neck snake, northern black racer, eastern garter snake, eastern milk snake, and northern water snake and common snapping turtle, spotted turtle, wood turtle, and eastern painted turtle could be confirmed living in the area. That means that snake diversity (number of species within the watershed) has declined 50% and turtles over 35% in the last fifty years. More telling signs include changes in population of each species. For example, the northern brown snake, copperhead snake, the stinkpot turtle and the eastern box turtle were common during the 1940 survey and are now listed as species of special concern. A more complete list of animal species found in Branford is found in Appendix I.

RARE AND ENDANGERED SPECIES
Due to the importance of rare and endangered species, the State maintains a list of species and their habitats. Species are listed according to county (Appendix II: Rare and Endangered Species) and areas of special concern are mapped and noted by Town (Figure 8: Areas of Special Concern). To prevent collection of these species, site-specific information is not made public. If you are located in one of the areas of special concern and interested in obtaining potential rare or endangered species lists for your parcel of land, you must contact the CTDEP directly for the information.

INTRODUCED/INVASIVE SPECIES
Introduced and invasive species have become important in the plant and animal communities in Town. Their distribution varies throughout Town and they are typically found both in managed environments (i.e., road sides) and in many natural areas. Although most of these species were brought here to either help contain erosion or used for ornamental purposes (e.g., weeping willow, Russian olive (Elaeagnus angustifolia), Mute Swans), some were introduced by accident (e.g., garlic mustard, Japanese knotweed). Of the plants that were brought here for erosion control, the most dominant ones include olive (Elaeagnus umbellata), and multiflora rose. One of the best examples of olive/rose communities can be seen at the old Cosgrove gravel pit off Tabor Drive. Landscape plants that have escaped and became common on the landscape include winged Euonymus, Japanese honeysuckle, and purple loosestrife (you can still find many of these species being sold in nurseries around Town).

Invasive species are those that have a native form that have recently experienced a significant change in their distribution patterns. The best example of an invasive is reedgrass (Phragmites australis). A native form of the plant has been here for thousands of years, but an introduced variant from Europe has recently displaced much of the native form and is now dominating many habitats. Although many of the introduced and invasive plants are mixed in other communities, they can become dominants on the landscape and may pose additional threats to native plant species in the future. A more complete list of introduced and invasive species is found in Appendix III.

The most prominent introduced animals species are the European starling, Norway rat and Mute Swans. Starling populations have grown considerably over the last decade and Mute Swans have become pest species in many of our ponds and watercourses (their territorial behavior is quite often a problem to smaller native waterfowl in the area). A recent introduction of the Monk Parrot (escaped pet species) has added color and noise to the environment. There are a number of imported insect populations that have become important through the years. The wooly adelgid and the Asian long-horned beetle are two examples. The adelgid is currently decimating hemlock trees in the region and the introduction of the long-horned beetle, which attacks a number of coniferous species, is of great concern. Other introduced species that pose a risk to the environment include Pfisteria, a water-born parasite that is killing coastal fish populations and zebra mussels, a freshwater mollusk that is capable of causing extensive fouling in engines and power plants. Recent introductions of viruses (West Nile virus) have also been of great concern. Some introductions are more difficult to assess. For example, the Asian Lady Beetle is an introduced insect that may have some positive impact on the plant communities by eating aphids. Assessing any introduced or invasive species is problematic because of our prejudices of what may be beneficial or cute to look at.

Some of the introduced species have become so common that we consider them as naturalized species. Species such as multiflora rose, weeping willows and pigeons are considered by many to be very natural to the environment. However, even though they have become part of the landscape, it is still important that we realize that they still have an impact on the native species that have evolved here. Other organisms such as dogs, cats and cattle are so domesticated that we no longer consider them introductions to the landscape; however, when you consider the time and energy put into these species (i.e., aisles of food in the supermarket, pasture land), they have impacts on the landscape that generally out-weigh the impacts of many other introduced organisms.