INVASIVE ALIEN SPECIES AT ROCKY HILL SCHOOL
2014-2015
Invasive Alien Species at Rocky Hill School
Kyle R. Hess and
Laura A. Meyerson
This material is based upon work supported by the National Science Foundation DEB Awards under Grant No. 1049914 & The University of Rhode Island College of the Environment and Life Sciences Agricultural Experiment Station Project RI00H-332, 311000-6004 In cooperation with Mike Jedry & Rocky Hill School Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Š 2015 Meyerson Laboratory at the University of Rhode Island
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• CHAPTER 1 •
INVASIVE TREES
Trees are perhaps the most surprising plants to invade our native ecosystems. Exotic trees are extremely popular landscape features in parks, along city streets, and in suburban neighborhoods. Many have been planted with little or no impact on native flora and fauna, but some have spread with disastrous consequences.
How to identify:
Ailanthus altissima
1. Leaves are compound, and resemble many native species like sumac (Rhus spp.) and walnut (Juglans spp.). 2. The easiest way to identify this tree is to break off a leaf and tear it--the smell of burnt peanut butter is hard to miss. 3. Ailanthus is a dioceous species and its flowers also exude the rancid peanut butter odor. 4. This species is easily spotted on roadsides or in forests when its flowers bloom in late spring to early summer.
Tree of Heaven Tree of heaven, also known as paradise tree and Chinese sumac, was introduced to the United States in the early 1800’s with the hope that it would colonize landscapes degraded by mining and urban development. Indeed, this hardy species can thrive in various climates, polluted and depleted soils, and can outcompete our most robust native trees. Further, ailanthus is allelopathic, producing chemicals into surrounding soils that inhibit the growth of other plants.
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How to identify:
Acer plantanoides
1. The tree is deceptively
similar to the sugar maple (Acer saccharum), but the leaves are usually wider and have more lobes.
2. An easy way to
identify the Norway maple: break off a leaf and look for the distinctive white sap inside the petiole.
Norway maple Norway maple was introduced from Europe to North America around 1750 for use as an ornamental tree. This tree is a versatile species that can thrive in shade, is drought tolerant, and persists in a wide range of soil types. The Norway maple’s versatility has enabled it to spread rapidly, crowding out native tree species like oak (Quercus spp.) and hickory (Carya spp.) that require more sunlight to thrive. 4
• CHAPTER 2 •
INVASIVE SHRUBS
Shrubs are woody plants that are smaller than trees and have several main stems arising at or near the ground. Many invasive shrubs are introduced through the horticulture industry to meet consumer demand for attractive landscape foliage. Unfortunately, many of these plants escape and displace native species in forest understories, meadows, and roadsides.
Berberis thunbergii
How to identify: 1. Japanese barberry is a deciduous shrub that grows to be 2 to 8Â ft tall. 2. Leaves are tear drop shaped and stems are thorny. 3. Flowers are yellow and usually clustered, but can also be found distributed individually. 4. Small, red, jelly-bean shaped berries mature in summer and last through winter.
Japanese barberry Japanese barberry was first imported to the United States in 1875 and has been a popular ornamental plant since 1910. Numerous cultivars include plants selected for yellow, dark red to violet, or variegated foliage, erect growth (for hedge rows), and dwarf size. Japanese barberry has spread from neighborhood landscapes to forests. In the forest, it is displacing native species and helping other invasive species (invasion meltdown), such as invasive earthworms.
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Buddleja davidii
How to identify: 1. Deciduous shrub grows 6-16 feet tall. 2. Flowers are most often purple but selective breeding has resulted in a wide range of colors including red, yellow, and blue. 3. Leaves are longer than they are wide and have toothed edges. 4. Butterfly bush can often be found inundating a stream bank, roadside, or other disturbed landscapes.
Butterfly bush Butterfly bush has only recently been recognized as an invasive species in many states. This attractive, lilac-like bush is native to China and was imported to the United States around 1900. Butterfly bush is so-called because its nectar-rich flowers attract butterflies in droves. Unfortunately, most butterfly species rely on specific larval host plants and cannot use the butterfly bush. As is the case with most exotic species, native wildlife is better served by choosing native species for garden plantings. Butterfly diversity could be at great risk if butterfly bush continues to colonize North America at the expense of native host species. 7
How to identify:
Elaeagnus umbellata
1. Oval shaped leaves are green on top and silver underneath. 2. Clusters of pale yellow flowers bloom in spring. 3. Throughout the summer and fall, its plentiful red berries with silver flecks easily distinguish autumn olive from other shrubs--also, they’re delicious!
Autumn olive Autumn Olive is a large shrub that can reach 20 feet in height and 30 feet in width. Best known for the fruit from which it gets its name, Autumn olive was brought to the United States from Asia in 1830 to be planted for wildlife food and to revegetate degraded land. Autumn olive is capable of nitrogenfixation via a symbiotic relationship with bacteria. This conversion of atmospheric nitrogen to forms that can be stored in the soil contribute to the plants ability to outcompete native species. 8
Rosa rugosa
How to identify: 1. Prickly-stemmed, shrub grows 3 to 7 feet tall. 2. Wrinkled (or rugose), shiny, dark green leaves are pinnate and compound. 3. Flowers are small (2.5 to 4 inches) and pink, purple or white. 4. Easiest to identify by its fruit, or hips, which are edible.
Beach rose Beach rose, also known as Japanese rose, is a shrub that has become a common site on beaches and in gardens on the east coast of the United States. No one knows for sure when this species was introduced from its native range in east Asia to North America. It has, however, been here for so long that many New Englanders believe this is a native species. Beach rose colonizes beaches and dunes forming dense thickets that exclude native plants. It spreads vigorously
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• CHAPTER 3 •
INVASIVE VINES Like many invasive species, vines were introduced to the United States from Europe and Asia due to their aesthetic appeal and heartiness. Vigorous growth and seed dispersal, shade tolerance, and a coiling growth habit make invasive vines a dire threat to native ecosystems.
How to identify
Celastrus orbiculatus
1. Mature vines are often seen coiled around trees. 2. Leaves are oval to almost round. 3. The best way to distinguish invasive from native bittersweet is to look at the berries -Oriental bittersweet berries occur in the leaf axils while American bittersweet berries are only found at the end of stems.
Bittersweet “The vine that ate the north!� Oriental bittersweet is a tenacious invader that has inflicted substantial harm on native plant communities in the northeastern United States. Bittersweet coils around native trees, strangling and eventually toppling them. This ornamental vine is still misguidedly maintained in gardens and prized for its use in wreaths. Traditionally, American bittersweet (Celastrus scandens) was used for wreath making and would be a far better option to prevent further spread of the invasive species. 11
How to identify:
Wisteria sinensis
1. Leaves are green and pinnately compound. 2. Differentiate native Wisteria from the invasive species by its flowers. Native wisteria’s inflorescence is compact; almost round. Chinese wisteria blooms are long and loose.
Wisteria Native to China, Wisteria is a woody legume that was brought to the United States between 1830 and 1860. Wisteria is still prized for its showy racemes of flowers and has escaped cultivation throughout the United States with negative affects on native species. Wisteria vines will aggressively climb structures such as houses and trees causing damage and even collapse. Other species of wisteria include W. floribunda from Japan and W. frutescens and W. macrostachya which are native to North America. Recent studies found that the Japanese and Chinese species have hybridized, likely increasing the potential for this plant to invade native ecosystems (hybrid vigor). 12
Hedera helix
How to identify: 1. Leaves are dark green and and palmate, however, there can be considerable variation in leaf shape. 2. If exposed to full sun, ivy will flower and bear fruit. Flowers are small and green or white. Fruit are small black berries. 3. English ivy is typically found growing on buildings or blanketing the ground.
English ivy English ivy was brought from Europe to North America as an ornamental by colonists and persists in its popularity even today. This plant has become a common site on the sides of brick buildings and as ground cover in urban and suburban landscapes. Once it escapes cultivation, this extremely shade tolerant plant can consume a forest understory excluding native plant species. Additionally, English ivy provides no value to native wildlife, yet its berries are eagerly consumed by the invasive, European starling.
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• CHAPTER 4 •
INVASIVE GRASSES Grasses are a seemingly innocuous family of plants that are enjoyed (and obsessed over) by golfers, homeowners, and landscapers alike.
Some species of grass are grown with few consequences for native species, yet others exhibit characteristics that make them aggressive invaders of native ecosystems.
How to identify:
Phragmites australis
1. Phragmites grows in
wet soils found in marshes, rivers, ponds and even roadside ditches. 2. Stem is broad, round,
and hollow with lanceolate leaves. 3. Flowers develop in
panicles at the top of the stem. 4. In autumn, plants
turn golden brown and remain standing throughout winter.
Common reed The common reed, often referred to by its genus, Phragmites, is one of the world’s most invasive wetland plants. The word Phragmites is derived from the Greek phragma, meaning fence. Living up to its name, this perennial grass grows in extremely dense stands and can reach 15 feet tall. Phragmites is unique amongst invasive species in that it has both exotic and native genotypes. The exotic strains were introduced to North America from Europe and have transformed once diverse wetland ecosystems into dense monocultures. 15
Holocus lanatus
How to identify: 1. Tufted grass grows 1 to 3 feet tall. 2. Leaves and stems are pubescent (hence the name, “velvet� grass). 3. Inflorescence is a pink or purple panicle that can grow to 6 inches in length.
Velvet grass A native to Eurasia, velvet grass is now a common invader throughout North America. This perennial grass is believed to have been brought to the western United States as forage for livestock in the 1600’s. Like most invasive species, velvet grass is a robust plant that is tolerant of a wide range of environmental conditions. Its long growing season, prolific seed production, and allelopathy make velvet grass a potent competitor with native species.
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• CHAPTER 5 •
INVASIVE HERBS Herbs are soft-stemmed (as opposed to woody) plants that die back to the soil level in winter. They can be perennial, biennial, or annual. Many of the herbaceous plants that have become common in North American were imported from Europe and Asia for use as food seasonings and for traditional medicine. Many of these useful plants have escaped cultivation and invaded native landscapes.
How to identify:
Verbascum thapsus
1. Large, rosette of soft, lanceolate leaves develop in the first year. 2. Develops tall, 3 to 6 foot inflorescence with yellow flowers in the second year.
Common mullein This European import is now extremely abundant throughout North America. Distinguished by its soft leaves (often referred to as “lambs ear�) and tall, forked inflorescence, mullein is a dramatic feature in disturbed landscapes. Flowers die in autumn but stems often remain standing throughout winter. Mullein has become so ubiquitous in the United States that many assume this plant is a native, possibly confusing it with other yellow flowering plants like goldenrod (Salidago spp.) species.
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How to identify:
• Daucus carota •
1. Plant can reach 1 foot tall. 2. Leaves are pinnate, and slightly pubescent. 3. Flowers white and umbellate. 4. Often found in abandoned agricultural fields and along roadsides.
Queen Anne’s Lace This Eurasian native has spread vigorously throughout North America filling open fields and excluding native species. Sometimes referred to as “wild carrot” due to its hard, conical shaped taproot, Queen Anne’s lace is actually an ancestor of the domestic carrot. This plant is often found in abandoned agricultural land and other early successional fields.
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• CHAPTER 6 •
MARINE INVADERS
Plant and animal species have always been mobile, dispersing to new habitat in search of resources or by being blown off course by severe weather events. Before humans invented ways to sail and fly around the globe, organisms were quite limited in their ability to cross oceans. Today, plants and animals are circulated worldwide both intentionally and unintentionally, sometimes posing a significant threat to their new homes.
Carcinus maenas
How to identify: 1. Found on shore or in shallow water. 2. Color ranges from green to orange or red. 3. Carapace is wider than it is long. 4. Look for 5 toothed edges on each side of the eyes (as opposed to 3 edges on the Asian shore crab).
European green crab The European green crab has been established in New England marine ecosystems for almost 200 years. This shore crab species has significantly altered the assemblage of shore-dwelling fauna, feeding on a variety of native mollusks, crustaceans, and even fish fry. Interestingly, green crab populations have declined significantly in recent years and studies suggest that another of New England’s invasive crabs, the Asian shore crab may be the cause.
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How to identify
Hemigrapsus sanguineus
1. Square shaped carapace. 2. Prominent banding on appendages. 3. Color varies from brown to orange or red, but can also be green. 4. Look for 3 toothed edges on each side of the eyes (as opposed to the 5 edges found on the European green crab).
Asian shore crab Native to the east coast of Asia, the Asian shore crab is now a dominant invader of marine ecosystems on the Atlantic Coasts of the United States (from Maine to North Carolina) and Europe (from Germany to France). The high fecundity, superior competitive ability, and formidable predation on other crab species make the Asian shore crab a serious threat to native species. This crab has proven to be so robust, that it is implicated in the decline in another invasive crab, the European green crab, whose abundant populations have been a fixture on the New England coast for generations.
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Codium fragile
How to identify: 1. Often found attached to piers, rocks, or other structures--can also be found freefloating. 2. Green, extensively branched, and spongy. 3. Grows up to 3 feet in length.
Dead man’s fingers Often referred to by its genus, Codium, this green alga was introduced from East Asia as a stowaway in ballast water in the 1950‘s. It has since spread throughout coastal ecosystems from Canada to South Carolina. Codium is a long-lived, prolific, and herbivore-resistant species that is now established throughout Narragansett Bay. This invasion poses a serious threat to native species as well as to local recreation and commercial activities. Codium is notoriously caught up in the props of boat motors, fishing nets, and can engulf shellfish beds.
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• CHAPTER 7 •
INVASIVE PATHOGENS Pathogens are undeniably the most insidious group of invasive alien species. Being microorganisms, these small, often singlecelled viruses, bacteria, fungi, and protists cannot be easily identified by the naked eye. Invasive pathogens pose a significant threat to the health of native plants and animals--including humans.
How to identify:
Ophiostoma ulmi & Ophiostoma novo-ulmi fungi
1. Elm leaves first wilt and then turn yellow. 2. Branches develop dark (brown or black) streaks. 3. The two insect vectors of the disease are very small. It is easiest to identify their presence by finding the tunnels (called “galleries�) they create.
Dutch elm disease Dutch elm disease was introduced to the United States from Europe in the 1930‘s via diseased elm logs. This disease ravaged American elm species (Ulmus spp.) throughout North America and continues to devastate them today. Two beetles play a key role in spreading Dutch elm disease, the European elm bark beetle (Scolytus multistriatus) and the native elm bark beetle (Hylurgopinus rufipes). These insects tunnel through the bark of elms to lay eggs. If the tree is infected with O. ulmi or O. novo-ulmo, the newly emerged offspring will carry the fungus from these tunnels to other trees. Researchers have worked for many years to develop disease-resistant strains of elm to replace this once abundant species. 25
Legend Asian shore crab Autum olive Butterfly bush Common mullin English ivy European green crab Japanese barberry Norway maple Oriental bittersweet Tree of heaven Phragmites Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community
0
375
750
1,500 Feet
´
GPS coordinates of invasive alien species at Rocky Hill School. Collected by University of Rhode Island students on 14 October 2014.
Lat 41.65639 41.65639 41.65639 41.65639 41.65639 41.65639 41.65809 41.65628 41.65686 41.65800 41.65619 41.65800 41.65800 41.65700 41.65667 41.65679 41.65677 41.65676 41.65678 41.65679 41.65639 41.65639 41.65800 41.65844 41.65886 41.65639 41.65891 41.65716 41.65900 41.65800
Long -71.41778 -71.41778 -71.41778 -71.41778 -71.41778 -71.41778 -71.42094 -71.42278 -71.41962 -71.42000 -71.42274 -71.42100 -71.42100 -71.42100 -71.41917 -71.41276 -71.41263 -71.41264 -71.41261 -71.41255 -71.41778 -71.41778 -71.42100 -71.42093 -71.42484 -71.41917 -71.41895 -71.42089 -71.42100 -71.42100
Species Asian shore crab Asian shore crab Asian shore crab Asian shore crab Asian shore crab Asian shore crab Autum olive Autum olive Autum olive Autum olive Butterfly bush Butterfly bush Butterfly bush English ivy European green crab European green crab European green crab European green crab European green crab European green crab European green crab European green crab Japanese barberry Japanese barberry Japanese barberry Common mullin Norway maple Norway maple Norway maple Norway maple
Lat 41.65800 41.65682 41.65870 41.65848 41.65841 41.65863 41.65875 41.65680 41.65701 41.65724 41.65856 41.65900 41.65682 41.65842 41.65810 41.65870 41.65886 41.65848 41.65841 41.65852 41.65927 41.65871 41.65800 41.65810 41.65852 41.65927
Long -71.42000 -71.42298 -71.42483 -71.42186 -71.42196 -71.41893 -71.41894 -71.42127 -71.41952 -71.41924 -71.41856 -71.42100 -71.42298 -71.30524 -71.41799 -71.42483 -71.42484 -71.42186 -71.42196 -71.42190 -71.42221 -71.41895 -71.42100 -71.41799 -71.42190 -71.42221
Species Norway maple Norway maple Norway maple Norway maple Norway maple Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Oriental bittersweet Tree of heaven Tree of heaven Tree of heaven Tree of heaven Tree of heaven
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Photo Credits Arrowhead Enterprises LLC, http://www.arrowheadlandscaping.com/wp-content/gallery/diciduous/butterfly-bush-black-knight.jpg: page 7 Barker, E. John (2011). Canadian Tree Tours. http://canadiantreetours.org/species-pages/Norway_maple.html: page 4 Burger, M.K. (2015). Summer Phragmites Stand: page 15 Calow, Graham (2007). Nature Spot. http://www.naturespot.org.uk/species/yorkshire-fog: page 16 Chandler, Monika (2013). Minnesota Department of Agriculture. Northwest Michigan Invasive Species Network. http://habitatmatters.org/2013/12/on-the-lookout-for-oriental-bittersweet-celastrus-orbiculatus/: page 11 Coggon, Anna (2011). Redbook Garden Design. http://www.redbookgardendesign.co.uk/blog/?p=320: page 12 Cook, Will (2007). Carolina Nature. http://www.carolinanature.com/trees/acpl.html: page 4 deVisser, Miranda (2013). Fisheries and Oceans Canada. Canadian Aquaculture R&D Review 2013. http://www.dfo-mpo.gc.ca/science/environmental-environnement/aquaculture/rd2013/rdshellfish-other-eng.html : page 20 Fewless, Gary (2011). The Trees of Inly. https://sites.google.com/site/inlytrees/home/autumn-olive: page 8 Martinez, Julie (2006). Scientific Illustrator, St. Paul, MN http://na.fs.fed.us/spfo/pubs/howtos/ht_ded/ht_ded.htm#symptomsNijboer, Ronnie, page 25 RN Beetle Galleries: Wych elm (Ulmus glabra). page 25 Rhode Island Marine & Estuarine Invasive Species Site (2010). page 21, 22, 23 Kohn, A. J. (1969). "Between Pacific Tides. Edward F. Ricketts and Jack Calvin. Fourth Edition, Revised by Joel W. Hedgpeth. Stanford University Press, Stanford, Calif., Xvi 624 Pp., Illus. $10." Science 164.3880: 687. page 21 Science 2.0 (2011) What we can learn from the West Nile virus epidemic. http://www.science20.com/anthrophysis/what_we_can_learn_west_nile_virus_epidemic-84085: page 24 Southbury Land Trust, http://southburylandtrust.org/stewardship/invasive-plant-control/japanese-barberry/: page 6 Southern Nevada Water Authority, http://www.snwa.com/apps/plant/detail.cfml?type=86&id=15129: page 12 Washington State University. School of Biological Sciences (2015). Information about amphibian disease. http://sbs.wsu.edu/facilities/amphibian-disease-diagnostic-laboratory/information-about-amphibian-disease.html: page 24
All additional photos by K.R. Hess (2015)