HomeMy WebLinkAboutSite Invasive Species Management Plan for Six Mile Creek Natural Area - 2005 SITE INVASIVE SPECIES MANAGEMENT PLAN
FOR
SIX-MILE CREEK NATURAL AREA
(ITHACA,NY)
(2005)
WRITTEN BY
SIX-MILE CREEK INVASIVE PLANT ADVISORY COMMITTEE(SCIPAC)
CHARLOTTE ACHARYA, MERIAM DJELIDI,
DANIEL OTIS,AND ANNA STALTER
WITH THE HELP OF:
JACOB BARNEY,TANIA SIEMENS,
KATIE CREEGER,AND LARISSA SMITH
Adapted from the Site Weed Management Plan,TNC's Wildland Invasive Species Program
Table of Contents
1. INTRODUCTION....................................................................................................................3
A. History of the management plan and the need for invasive species control.......3
B. Description and purpose of the site (preserve or managed area)......................4
C. How invasive species interfere with management goals .....................................5
D. Inventory of invasive plant species that interfere with management goals .........8
2. OVERVIEW OF THE INVASIVE SPECIES MANAGEMENT PLAN..............................9
A. General management philosophy...........................................................................9
Prioritized list of species for species-led control...........................................10
Prioritized list of species for site-led control...................................................11
C. Summary of specific actions planned.....................................................................11
D. Sample invasive species management plan implementation schedule.............14
E. Resources necessary to implement invasive species management plan..........20
F. Notes on past invasive species removal................................................................21
3. SPECIFIC INVASIVE SPECIES ACCOUNTS..................................................................22
4. REFERENCES .....................................................................................................................35
5. PICTURES OF NATIVE AND INVASIVE PLANTS...........................................................38
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1. INTRODUCTION
A. History of the management plan and the need for invasive species control
In winter 2005,the Natural Areas Commission(NAC)convened a group to advise them on management practices
for the Six-Mile Creek Natural Area.The NAC was following up on recommendations in the Resource Inventory
and Restoration Plan for the Six-Mile Creek Natural Area produced by Dr.Tom Whitlow and students in his
restoration ecology class at Cornell University.The advisory group,which included members of the Cornell
community and others with expertise in conservation,forest ecology,and invasive plants,came to be called the Six-
Mile Creek Invasive Plant Advisory Committee(SCIPAC).
Dr. Whitlow's restoration plan noted that invasive plants present a serious threat to the natural area: "Unless
something is done about these[invasive] species,the area will quickly become overrun with exotic invasive
plants....it cannot be stressed enough how important it is to implement a long-term invasive weed eradication
program and start controlling these plants now"(p. 72).Accordingly, SCIPAC members expanded on the
invasives work undertaken by the class,choosing 19 species that presented serious threats,mapping their locations
when possible,and developing control plans.
Since 2003,the Friends of Six Mile Creek,a citizens group,has organized volunteer work days,which are largely
devoted to invasive plant removal.As had NAC before them, SCIPAC initially thought that continued,but
increased,volunteer effort would be adequate to prevent the spread of invasive species in the natural area. It
became evident,however,as SCIPAC members gathered information,that the problem was more serious,and that
the solution would require more intensive long-term effort than volunteers alone could provide.
The mission statement of SCIPAC became:To preserve for future generations the ecological integrity and beauty
of the threatened native community of the Six-Mile Creek basin,we will(1)identify and protect populations of
native wildflowers,rare plants,and old growth;(2)control invasive plant species,emphasizing small,nascent
populations that can be eradicated before they spread throughout the basin; and(3)monitor and report on our
progress.
The consequences of invasion
The invasion of natural communities by(primarily)nonnative plants is an insidious problem because it is obvious
only to the informed.When a forest is clear-cut for lumber or bulldozed for development,the changed landscape is
obvious to all.Invasive plants can alter an ecosystem just as thoroughly,but because the process involves one
species replacing another over a relatively long time period, few people notice.
When invasives overrun a native forest,every organism in the ecosystem is affected. The loss of the Six-Mile Creek
Natural Area to invasives would be especially unfortunate because,for the last two hundred years,the site has
provided a refuge for native plant populations and the species that depend on them. The landscape of Tompkins
County was once 99.7 percent forested,but by 1900, 80 percent of this forest had been cut and the land plowed.
Only areas unsuitable for crops or grazing retained vestiges of native ecosystems. The Six-Mile Creek Natural
Area is one of these remnants;although parts of the natural area are heavily invaded,some areas are nearly pristine
and unusually rich in rare species.
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Why combat invasives?
A recent flora of Tompkins County found 2027 plant species growing here;of these, 800—about 40 percent—are
nonnatives,and approximately 10%of those are considered invasive.Many nonnative invasive plants left most of
their specialized pathogens and herbivores behind,giving them a competitive advantage over the native flora.This
competition can lead to local extirpation of native plant species.For the many native plant species found over a
broad swathe of the Northeast, local extirpation does not necessarily mean complete extinction.However, if native
plant communities are not preserved they will eventually be found only in the center of great preserves. Small,
fragmented forests like those surrounding Ithaca may lose native species:the Norway maples may replace sugar
maples;garlic mustard may replace trilliums and other spring ephemerals. Indeed,the edges of these small forests,
including those around Six-Mile Creek,are already saturated with buckthorn,privet,and honeysuckle rather than
native sumac and spicebush.
Few private landowners have the desire,the knowledge,and the labor to address this problem.It is a monumental
task,one that must be carried on in perpetuity,which puts it beyond the reach of an individual person's enthusiasm.
In our view,then,efforts to preserve uninvaded native ecosystems must be overseen by permanent institutions.
The longer we fail to address the invasives problem,the worse it will get. If we don't act,in a century there may be
no place in central New York where one can see an example of the healthy,uninvaded forest ecosystems that once
covered the Northeast. These are worth preserving.for they are part of our biological heritage,the context in which
our communities evolved.
B.Description and purpose of the site(preserve or managed area)
The Six-Mile Creek Natural Area encompasses 1130 contiguous acres of woodlands,meadows,and water
bodies in Tompkins County,New York. It was designated as a natural area by the Common Council of the City of
Ithaca in 1998 to protect the reservoir,which is the source of the city's drinking water,and the surrounding
watershed. The Six-Mile Creek Natural Area is considered to have"significance for ecological and/or recreational
reasons...[and is] best appreciated and maintained in a natural,relatively undisturbed state(rather than as an active
use park)"(Code of the City of Ithaca,NY, Chapter 114).
Several natural communities occur in the Six-Mile Creek Natural Area.Two of these are unique to the region:a
remnant of old-growth hemlock-hardwood forest,and a north- and east-facing slope where no fewer than three
state-listed rare plants are found(pens. comm.F.R.Wesley,D. Werier).In addition,the natural area encompasses
acres of floodplain forest(where the county's largest sycamore tree can be found)and ridge tops covered by
Appalachian oak-hickory forest. The abandoned fields and shrub lands that are common to the central New York
landscape are also extensive in the natural area.
Though it is the intention of SCIPAC to propose management guidelines for the entire 1130 acre natural area,our
current knowledge of invasive species distribution across the whole area precludes a comprehensive plan.
Therefore,we have identified three conservation targets,or priority areas.Two of these priority areas,the Second
Bowl-Beech Woods,and the Dry Shale Talus Slopes,are found in the part of the natural area most heavily
damaged by anthropogenic factors,making them the most susceptible to past„and continuing,plant invasion.The
third,the Amphitheater, is an area where the rare sedges, Carex careyana and Carex jamesii, and the critically
rare grass,Poa sylvestris,occur.Furthermore,the Amphitheater is the only site in the natural area where the
aggressive invasive species,Japanese stilt grass(Microstegium vimineum), is known to occur.
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C.How invasive species interfere with management goals
Second Bowl—Beech Woods
The Second Bowl begins approximately one-half mile from the entrance at Upper Giles Street,and is situated
mostly east of the trail.Most closely resembling the maple-basswood rich mesic forest community type,the
overstory is dominated by sugar maple,American basswood,and white ash.The herbaceous understory is highly
diverse,containing an abundance of spring ephemerals.Early spring4owering species such as Trillium,Hepatica,
Bloodroot,and Spring-beauty,among others,attract many visitors to the natural area. The preponderance of
invasives here,however,threatens the survival of this much-loved and ecologically important site.
The Second Bowl is heavily invaded by garlic mustard,particularly along the trail. Garlic mustard also occurs in
dense patches within the forest stand itself. Studies have shown that some forested stands invaded by garlic
mustard have lower herbaceous species cover and/or diversity. Invasive shrubs present in the Second Bowl include
exotic bush honeysuckles,Japanese barberry,and privet. These shrubs may outcompete and displace native herbs
and shrubs. Garlic mustard may also threaten native butterfly populations, including the rare West Virginia White
(Pieris virginiensis).Adults of several species may lay their eggs on garlic mustard rather than the native host
species,Dentaria diphylla,and many or all of these larva may die.
Beech Woods is an old-growth stand of hemlock and northern hardwoods,located just up the trail and contiguous
to the Second Bowl.The flora of Beech Woods is similar to that of the Second Bowl and includes many spring
ephemerals.Beech Woods is less invaded than the Second Bowl;because the site is slightly higher in elevation than
the Second Bowl,and farther from the creek,it is less susceptible to invasion by the water-borne propagules of
invasive species such as garlic mustard. Surveys conducted by SCIPAC in spring 2005,however,have revealed
that the threat to Beech Woods is greater than previously thought. The proximity of Beech Woods to the trail and
to the seriously invaded Second Bowl makes it increasingly susceptible to the same species that are already
ubiquitous in the Second Bowl. For this reason we are treating the two forested stands as one management unit.
Dry Shale Talus Slone
An Appalachian oak-hickory forest community occupies the ridges surrounding the natural area.In at least three
locations,dry shale talus slopes exist below these ridges.These generally south-facing slopes are host to several
remarkable native species,including Carolina vetch(Vicia caroliniana), broadleaf sedge(Carex platyphylla),
yellow pimpernel(Taenidia integerrima),meadow zizia(Zizia aptera), Seneca snakeroot(Polygala senega),
low bindweed(Convolvulus spithamaea),and four-leaf milkweed(Asclepias quadrifolia)(pers. comm. F.R.
Wesley).This community type is most seriously threatened by illegal foot traffic.It is not yet known which invasive
species, if any,are present.
Amphitheater
The Amphitheater,a steep slope rising above the first reservoir under hemlock and northern hardwoods, is located
just south of the 30-foot dam,on the west side of the creek. This area contains the rare sedges, Carex careyana
and Carex jamesii,and the critically rare grass,Poa sylvestris.For the sake of these rare species alone,the
Amphitheater deserves high priority.It is also the only site in the natural area where the highly aggressive invasive
species,Japanese stilt grass(Microstegium vimineum), is currently known to occur. It is critical that this species
not be allowed to spread. Other invasive species reported from a brief survey of the Amphitheater include lesser
celandine,honeysuckle,and garlic mustard.
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Invasive species in present in the Six-Mile Creek Natural Area, but not yet assessed
Scientific name Common Name
Ampelopsis brevipedunculata porcelain berry
Celastrus orbiculatus oriental bittersweet
Chelidonium majus greater celandine
Coronilla varia crown vetch
Dipsacus fullonum fuller's teasel
Euonymus alatus burning bush,winged euonymus
Forsythia sp. forsythia
Hemerocallis sp. daylily
Hesperis matronalis dame's rocket
Iris pseudacorus yellow iris
Verbascum thapsus common mullein
2. OVERVIEW OF THE INVASIVE SPECIES MANAGEMENT PLAN
A. General management philosophy
Although invasive species control is part of the overall site management program,the focus is on preserving the
native species and communities. In addition,management priorities have been established with the objective of
minimizing the total,long-term workload.Thus,the plan encompasses two approaches:a species-based
approach to prevent the establishment of new infestations,and a site-based approach to protect priority areas.
The species-based approach involves the implementation of programs to keep the site free of invasive species
that are present,though not yet well established in the natural area,and that are known to be pests elsewhere in
the region.While their current impact is minimal,if left alone these species will severely impact the natural area
and native plant communities.These are species that can be eradicated from the natural area.
The site-based approach is used for the control or elimination of invasive species that are already well
established on the site. Control priorities will be set,according to the actual and potential detrimental effects the
invasive species have on native species and communities,particularly on our conservation targets:the priority
areas. This means the most valued sites in terms of biodiversity,aesthetics and recreation will be the first to be
protected from further invasion of all invasive plants.
For both approaches, it is recommended that action be taken only when careful consideration indicates that
leaving the invasive species unchecked will result in more damage than controlling the species using available
methods.
An adaptive management strategy is one that uses the lessons from previous seasons of work to mold future
efforts.The various phases of our strategy are:
1. Establish management goals for the site.
2. Identify invasive species interfering with these goals and assign priorities based on their likely
impacts.
3. Determine effective control options.Assess the likely effects on the target and non-target
species and adjust the weed priorities, if necessary.
9
4. Develop and implement the management plan.
5. Monitor and assess the impacts of management actions.
6. Evaluate the effectiveness of methods(measured against the site goals)and use this
information to refine our control priorities,methods,and goals and learn what is practical,
effective,and realistic.
Return to step one...
B. Prioritized list of invasive species:
Prioritized list of s ecies forspecies-led control
Scientific name Common name Priority for threat to Potential Ease of Able to Eradicate(May
all of natural area overall priority control for change if known
this species extent of species
changes)
Microstegium Japanese stilt-grass High High Medium Probably
vimineum
Vincetoxicum pale swallow-wort High High Hard Unknown
rossicum
Phragmites australis common reed High along stream High Hard Probably
Fallopia japonica Japanese knotweed High along stream Med.High Medium Maybe
Ailanthus altissima tree-of-heaven High High Hard Yes
Acer platanoides Norway maple High Medium Medium Probably
Alliaria petiolata garlic mustard Medium Medium Hard No
Ranunculus ficaria lesser celandine Medium Medium Hard No
Rhamnus cathartica common buckthorn Medium Medium Medium Maybe not
&R.ftangula and alder buckthorn
Lonicera spp. exotic bush Medium Medium Medium No
honeysuckles
Vinca minor periwinkle Medium Medium Low Med.Hard Maybe
Berberis thunbergii. Japanese barberry MediunrLow Medium-low Easy Maybe
Artemisia vulgaris mugwort Low Medium Easy Probably
Rosa multiora multiflora rose Low Medium Medium Unknown
Hedera helix English ivy Low Medium Medium Maybe
Centaurea sp. knapweed Low Low Easy Probably
Ligustrum sp. privet Low Low Medium Maybe
Tussilago farfara coltsfoot Low Low Hard Maybe not
Elaeagnus autumn olive unknown Medium Unknown Unknown
umbellata
Lamiastrum yellow unknown Mediuni-Low Med.Hard Unknown
galeobdolon archangel/yellow
deadnettle
i0
Prioritized list of species for site-led control
Scientific name Common Name Priority as judged by Potential priority in
threat to priority sites current priority sites
Alliaria petiolata garlic mustard High High
Microstegium vimineum Japanese stilt-grass High High
Acer platanoides Norway maple Medium High
Vincetoxicum rossicum pale swallow-wort Medium MediunrHigh
Ligustrum sp. privet Med Medium
Berberis thunbergii Japanese barberry Med Medium
Lonicera spp. exotic bush honeysuckles Med Medium
Ailanthus altissima tree-of-heaven Med Medium
Tussilago farfara colt's foot Low Medium
Vinca minor periwinkle Low Medium
Rhamnus cathartica and R. common buckthorn and Medium Unknown
ran ula alder buckthorn
Phragmites australis common reed Low Low
Fallopia japonica Japanese knotweed Low Low
Artemisia vulgaris mugwort Low Low
Centaurea sp. knapweed Low Low
Hedera helix English ivy Low Low
Rosa multijora multiflora rose Low Low
Elaeagnus umbellata autumn olive Unknown Low
Lamiastrum galeobdolon yellow archangel/yellow Unknown Low
deadnettle
Ranunculus ficaria I lesser celandine unknown Low
C. Summary of specific actions planned
All of the species listed in the above tables are known to exist in the Six-Mile Creek Natural Area,but the
extents of their populations are not known.Our current knowledge about the locations of native and invasive
species is derived from a limited number of walks on trails in the Six-Mile Creek Natural Area and consultations
with local naturalists.It is ill-advised to make specific management recommendations without a comprehensive
inventory of the plants found throughout the natural area..Because of this limitation,specific management actions
have not yet been developed.Included herein is an outline of the general steps necessary to manage the invasive
species known to be present and a sample management implementation schedule that demonstrates how the
overall management strategy (as described in section 2A)can be applied.
The first step toward protecting native plant communities and removing the invasive plants in the natural area is to
inventory and map the invasive plant populations and the locally rare or endangered native plants. Because
volunteers lack the time and often the knowledge to conduct a detailed survey we recommend a professional be
hired.The professional will map the extent and abundance of the invasive plant populations and the locations of
any rare or endangered flora. This information will allow the Natural Areas Commission to understand the extent
of the invasive plant populations and allow the NAC to modify, any goals recommended in this plan.
11
Auer the inventory and mapping are completed,we recommend a review of the priority areas,of the prioritized
list of invasive species threatening the priority areas,and a reassessment of the eradicability of the invasive
species populations found within the natural area.Then,within each priority area a"defensible area"should be
delineated. A defensible area is defined as a manageable subunit containing an otherwise healthy native plant
community that contains some invasive plants within it. To be manageable,a defensible area should be small
enough that every year all of the mature invasive plants found within it can be removed and prevented from
reproducing or spreading vegetatively. Defensible areas should have clear boundaries so that control efforts can
be monitored unambiguously. As invasive species are successfully controlled,and the number of individual
invasive plants found within the defensible area decreases overtime,the defensible areas will become larger. if
control efforts are not successful, invasive species found within the area will increase and the"defensible area."
the area in which invasive plants were prevented from reproducing or spreading vegetatively,would become
smaller over tune.
Once the initial inventory and delineation of defensible areas are completed,systematic invasive plant control can
begin.This strategy is clear,but the particular species targeted may change based on the inventory and planning
work described above.
As described above,defensible areas will be created for all of the priority areas,currently identified as Second
Bowl-Beech Woods,the Amphitheater,and the Dry Shale Talus Slopes.Every year inspections should be
conducted to identify and plan the removal of invasive plants found within the defensible areas. Our current
knowledge of species found in and around the Second Bowl-Beech Woods indicates the need to control garlic
mustard, lesser celandine,Norway maple,and the invasive bushes,Japanese barberry,common and smooth
buckthorns,exotic bush honeysuckles,and privet. Our current knowledge of species found in and around the
Amphitheater points to the need to control Japanese stilt-grass, lesser celandine,exotic bush honeysuckles,and
privet.We do not currently know what invasive species are present on the Dry Shale Talus Slopes, so we do not
yet have any recommendations for them.Invasive species control in these three priority areas will be largely
mechanical,such as hand pulling or cutting of flowers and seeds from mature plants.This work is time consuming
and particularly suited for volunteer work parties. In addition,limited herbicide application would be
recommended to control some species,e.g. large Norway maples,tree-of-heaven,and possibly garlic mustard.
Herbicide work would take only a few hours to complete,but must be done by a licensed herbicide applicator.
SCIPAC recommends the hiring of a paid coordinator to manage both the volunteer work parties and the
herbicide applications.
To prevent the establishment of new invasive species it is important that the entire natural area be managed for
invasive species,not just the priority areas.We strongly suggest the development of programs to monitor the
natural area for additional invasive species that have not established themselves in the natural area but are present
around Ithaca.These surveys could be done by paid naturalists or trained volunteers on organized surveying
trips.Passive monitoring,in which rangers and users of the natural areas report the location of new invasive
species populations,could be a first step toward a more comprehensive program.In addition,the initial inventory
of invasive species may identify species whose current populations are small enough to be eradicated,but are
likely to expand rapidly in the natural area.All populations of these species will be targeted for control,whether
or not they occur in a priority area.These efforts will help prevent new invasions from becoming established in
the natural area. We have identified the following species for a species-based approach to control:common
12
reed. Japanese knotweed,Norway maple,Japanese stilt-grass,tree-of-heaven,and pale swallow-wort. This
eradication will require periodic surveys of the natural areas by experts.Any populations identified should be
monitored,documented,and scheduled for removal.Control work for these species would be performed
through mechanical or targeted chemical methods.
We have chosen to focus our resources on populations that can be eliminated or are an immediate threat to a
priority sites. The following plants are not eradicable and are not currently a threat to the priority areas. therefore
they are not currently targeted for removal: autumn olive,coltsfoot.English ivy,knapweed,mugwort,multiflora
rose, periwinkle,and yellow archangel.
The strength of the adaptive management strategy that we recommend is the ability to learn from previous
management experiences. To evaluate the effectiveness of applied methods and learn what is practical,effective,
and realistic,the impacts of all management actions must be monitored and assessed.Therefore,thorough and
accurate records of all management activities must be maintained.For example, for the priority sites.the location
of invasive plant populations before control work begins and the location of the boundaries of the defensible
areas should be recorded.Every time control work is done,notes will also include the following information:the
number of work hours,the location of the work,a brief description of the invasive plants targeted,and an
assessment of the area after work is finished—i.e.was the targeted species completely removed?Is garlic
mustard about to flower?At a minimum,all priority area should be surveyed each fall and notes taken to indicate
if invasive species were prevented from reproducing or spreading vegetatively within the defensible areas.Each
winter,all invasive species control work should be summarized,and each subsequent spring,the summary
compared with the new surveys of emerging plants to determine the success of the previous years' efforts.
Ideally,a small report would be written each spring detailing gains and losses,and would include a work
schedule for the current year.
13
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E. Resources necessary to implement invasive species management plan
As this plan shows, SCIPAC made many recommendations for control of specific invasive plants. Our most
important conclusion is that the current level of management by devoted volunteers is not adequate to the task we
face. Our recommendation is to establish the infrastructure and funding to maintain, in perpetuity,a Natural Areas
Steward to monitor the health of our natural areas and coordinate efforts to restore them and address problems as
they arise.
Since city finances are tight and government funding may be inconsistent,we thought the wisest course would be to
seek startup funding from private sources. In several months of sporadic searching,we located three possible
sources of grant funds:the Park Foundation,the National Fish and Wildlife Foundation's Pulling Together initiative,
and(in the near future)state programs that will increasingly fund invasives work.To apply for such grants,we must
be able to demonstrate:
1.That we represent the interests of the citizens and government of Ithaca,as shown through government
willingness to help administer the program and provide a level of in-kind matching support necessary to
receive many grants;
2. That we have specific,realistic goals based on shared values and sound scientific evidence; and
3. That a reliable,permanent organization will accept responsibility for managing any funds we receive.
In the long run, it may be wise to establish a Natural Areas Foundation(or some legally analogous group)that could
accept donations;perhaps the members of the NAC could serve as the board of directors.
We should emphasize that some of our recommendations must be regarded as provisional.Although the members of
SCIPAC have devoted many hundreds of hours to assessing the natural area and producing this report,it is far
beyond the capacities of even the most devoted volunteers to thoroughly survey an area of more than 1000 acres
and develop definitive plans and priorities for managing the area To begin formulating a well-documented set of
management plans,a far more extensive survey by experts in invasive and endangered native plant populations is
necessary.The estimated cost for this survey would be about$4500.
The Natural Areas Steward Position:
The responsibilities of the Natural Areas Steward will vary with the funding available.They will also vary with time
and whether the responsibilities extend to all the city's natural areas or just to Six-Mile.A possible breakdown of
responsibilities:
•50%grant-writing and other fund-raising.This may seem high,but every other task depends on funds.A program
that peters out in a few years has failed.Although the nature of the management the natural areas requires
may change over time,the need for management is no more likely to disappear than the need for street
repairs,garbage collection,or reliable electricity.In addition to seeking grants,donations may be solicited
directly,in cash and in kind,from local businesses and individuals.
•30%soliciting and coordinating volunteers and working to control invasives in the field.There exists in Ithaca a
huge array of potential volunteers, such as scout troops,high school groups,fraternity and sorority groups,
20
senior citizen organizations,Cornell and Ithaca.College conservation groups,church groups,and summer
youth employment programs.
•10%networking.Attending meetings and collaborating with groups addressing similar problems,such as the
Native Plant Society,Bernd Blossey's Ecology and Management of Invasive Plants group,the Finger Lakes
Land Trust,the Cayuga Watershed Network,the Nature Conservancy,Cornell and Ithaca College
conservation groups, state and national invasives groups,and town and city government groups.
•5%education and outreach.Leading tours, setting up collaborations with school groups,giving presentations,
perhaps creating a monthly newsletter.The possibility of an exhibit on the history of Six-Mile Creek at the
History Center has already been broached with the center's director,Matt Braun.
•5%supplies.A GPS unit,tools,possibly an on-site storage shed,printing costs,computer access,refreshments
for volunteers.
It is important to recall that Six-Mile Creek is only one of four Ithaca.natural areas.The others are Fall Creek,the
Fuertes Bird Sanctuary at Stewart Park, and the Southwest natural area. The latter two currently receive no
maintenance whatsoever.We recommend that we explicitly define our goals for these areas and then seek
the resources to meet them,rather than permitting passive neglect to determine how these areas evolve.An
ecosystem worth defining as a protected natural area is worth managing,and these areas too should fall under the
responsibility of the natural areas steward.
F.Notes on past invasive species removal
Scientific name Common Name Notes on control performed on this species in the past
Acer platanoides Norway maple It has been mapped by Daniel Otis.
Alliaria petiolata garlic mustard Has been hand pulled at Giles Street entrances,in first flood plain forest,and
toward the Second Bowl.In 2005 we hand pulled the plants at the Second
Bowl.
Berberis thunbergii Japanese barberry A few have been pulled from the Second Bowl.
Fallopia japonica Japanese knotweed In 2004 stem injection of herbicide was performed by Jacob Barney in the first
floodplain forest However,many plants were uprooted and washed
downstream during the high water of the spring of 2005,and some of these
have rerooted.
Lonicera spp. exotic bush In 2005 individuals were pulled from the Second Bowl-Beech Woods.In 2004
honeysuckles many individuals were removed from the Second Bowl;in 2005 we noticed
the improved open s ace,but also some small plants that are there.
Microstegium Japanese stilt-grass David Werier organized a group from the Native Plant Society to hand pull
vimineum this grass during the fall of 2004 and 2005.
21
3. SPECIFIC INVASIVE SPECIES ACCOUNTS
Scientific name:Acer platanoides Common name: Norway maple
A.PRIORITY: Short-term—moderate,but long-term—high. This is a"rapid response"species:when it is
found anywhere in the natural area it should be removed as soon as possible.
B. DESCRIPTION
Norway maples are particularly easy to spot in the first two weeks of November,when most native trees have
lost their leaves but many Norway maples are still bright yellow.With practice,Norway maples are easy to spot
during summer,too,when their dense canopies make a dark impression against a background of natives.
Norway maple is native to continental Europe,except for the extreme north,the extreme west,and Great Britain.
In more southerly areas it is found mainly in mountains.A tall tree,it reaches a maximum height of<30 m and has
a maximum lifespan approaching 400 years.Because they are very tolerant of urban conditions,Norway maples
have been widely planted in cities throughout the northeastern US.In recent decades they have been observed to
form feral colonies around many communities.
C. CURRENT DISTRIBUTION ON THE SITE
Locations of Norway maples can be described in general terms in several areas along Six-Mile Creek.The sites
examined are conveniently divided into two general regions.(1)On the flood plains and adjacent slopes on the
north side of Six-Mile Creek, both above and below the Giles Street dam,and between the Giles Dam and the
30-foot dam approximately 1 km upstream.(2)Along the South Hill recreation way.
1. Six-Mile Creek.After turning right from Rt. 79 onto Giles Street, Giles curves to the right at the entrance to
the access road and heads downhill.Dozens of Norway maples grow along the length of the access road—
generally young trees just reaching the canopy and not yet seeding prodigiously. These trees,when more mature,
will be a constant source of seeding into the slopes and flood plains of Six-Mile Creek.
On Giles Street itself,as one heads downhill from the trail entrance,there are several aged trees growing on
the left and seeding into the adjacent forest.These trees may be the source of most of the Norway maples in the
First Bowl.
Along the driveway to the Giles parking lot are mature, seeding Norway maples to the left and right.There
are also trees growing on the slope to the northeast of the parking lot,and at the top of this slope.
As one walks up the main trail from the parking lot and approaches the mound before the sharp left turn,
there are several massive Norway maples growing to the left of the trail,and one to the right just as one
approaches the left turn.
The First Bowl itself is home to perhaps 20 mature Norway maples,mostly concentrated in the northeast
corner not far from the point where the small tributary stream enters the bowl.
In the Second Bowl are at least two Norway maples.At the upper end of the trail approximately 1 km from
the parking lot,the path ascends a steep slope that leads to a point above the first dam.Approximately 200 in
downstream from this slope,growing on a gravel bar in the stream itself,is a multi-trunked Norway.About 200
in farther downstream from this tree is another,more substantial seasonal island,and a Norway maple grows on
the north,downstream side of this island.
22
On the flood plains downstream from the Giles Street dam are a number of enormous Norway maples,
which in some locations appear to be outcompeting sycamores.
2.Adjacent to the South Hill Recreation Way,on both the uphill(south)and downhill(north)sides,are dozens
of mature, seeding Norway maples, including some enormous old trees. Whether one enters from the Crescent
or the Juniper entrances,Norway maples are very common.
D. DAMAGE AND THREATS
Norway maples are now on the New York State list of the top 20 invasive plants. One of the few nonnative
species adapted to survive in the shade beneath a full-canopy forest,they use light,water,and nutrients very
efficiently,and may offer direct competition to such shade-adapted native trees as sugar maple, beech,and
hemlock.Unlike most native species,they produce seed every year.They cast a dense shade,and their roots
tend to saturate soil to the extent that few plants will grow beneath them. These factors, in combination with their
having left most of their specialized herbivores and diseases behind,may permit them to become permanent,
dominant elements of northeastern forest ecosystems,occupying space that would otherwise be filled by native
species,and perhaps discouraging the growth of spring ephemerals and other natives.
Scientific name:Ailanthus altissima Common name: tree-of-heaven
A.PRIORITY High throughout the entire natural area.This is a"rapid response"species:when it is found
anywhere in the natural area it should be removed as soon as possible.
B. DESCRIPTION
A native of China,tree-of-heaven is a fast-growing tree with alternate compound leaves.It reaches heights of 60'
or more and produces numerous suckers(fast-growing new shoots) from its roots.Of loose,open habit, it is
generally dioecious,with male and female flowers on separate trees,but some trees have flowers of both sexes.
Some find the fragrance of the female flowers unpleasant.Dirr calls it"the most adaptable and pollution tolerant
tree available;withstands the soot,grime and pollution of cities better than other species."This is the tree about
which A Tree Grows in Brooklyn was written.Dirr notes that in the United States it has no serious natural pests
or diseases.It is well established in many locations around Ithaca.
C. CURRENT DISTRIBUTION ON THE SITE
Many tree-of-heavens are established near the Giles St.parking lot,particularly on the right slope as one
descends the driveway to the parking lot. Some of these trees are seeding heavily over the water, increasing the
likelihood that they will become a problem downstream. Several years ago a tree established on the island to the
right at the first sharp left turn on the path from the parking lot. This tree grew about 8 feet in height per year for
the last 3-1 years.The main trunk was destroyed in the floods of the spring of 2005,but at least three trunks
have grown from the roots. There are other trees within seeding reach of the flood plain, including several along
the South Hill recreation way and one on the north bank below the 30-foot dam. Since seed may be transported
by water,trees may establish in areas subject to spring flooding.
23
D. DAMAGE AND THREATS
Tree-of-heaven is a very fast-growing, suckering tree. Female trees can produce enormous quantities of seed
that disperse to great distances.It has naturalized over much of the United States.
Once established,roots can travel at least 100 feet from the parent tree, sending up stout, fast-growing suckers
along the way.Although it doesn't readily establish in deep shade,"mother"stems growing in sun may send roots
into shaded areas,and should a gap occur in the vicinity, suckers from these roots are well suited to become
dominant canopy trees by their rapid growth and,presumably,by"support"from the mother tree.They are
known to be allelopathic, so they have long-term damaging effects on the germination and establishment of other
species, including native trees, shrubs,and herbaceous plants. Once established,they are difficult to eradicate
without herbicides.
Scientific name:Alliaria petiolata Common name: garlic mustard
A. PRIORITY:Medium. This species will be controlled if it is in a priority area.
B. DESCRIPTION
Garlic mustard is a biennial herb with stalked,triangular to heart-shaped,coarsely toothed leaves.First-year
plants appear as a rosette of green leaves close to the ground.Rosettes develop into mature flowering plants the
following spring.Flowering plants of garlic mustard reach from 2 to 3 1/2 feet in height and produce buttonlike
clusters of small white flowers,each with four petals in the shape of a cross. Seeds remain viable for 5 years or
more. Seeds are transported to new areas by animals and by flooding.
C. CURRENT DISTRIBUTION ON THE SITE
Garlic mustard is densely distributed around the Giles Street parking and continues upstream through much of the
Second Bowl.It is also very dense at the upper Giles Street entrance.Garlic mustard is also abundant upstream
of the dam. The species is less abundant in some parts of the Second Bowl-Beach Woods and on the southern
hillside of the natural area.This species is also abundant in properties surrounding the natural area
D. DAMAGE AND THREATS
Once introduced to an area,garlic mustard out competes native plants by aggressively monopolizing light,
moisture,nutrients,soil, and space.Many native wildflowers that complete their life cycles in the spring(e.g.,
spring beauty,wild ginger,bloodroot,Dutchman's breeches,hepatica,toothworts, and trilliums)occur in the
same habitat as garlic mustard. Wildlife species that depend on these early plants for their foliage,pollen,nectar,
fruits,seeds,and roots are deprived of these essential food sources when garlic mustard replaces them. Humans
are also deprived of the vibrant display of beautiful spring wildflowers.
24
Scientific name:Artemisia vulgaris Common name: mugwort
A. PRIORITY: Medium,but no populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION
Mugwort is a rhizomatous perennial herb native to Eurasia and introduced to North America via ship ballast and
for cultivation.Once introduced to a site,local spread is primarily via vegetative propagules,but vast amounts of
viable seed are produced.Upon establishment,native species are displaced within the canopy.
C. CURRENT DISTRIBUTION ON THE SITE
Currently,mugwort occupies a small area(3m x lm)just past the kiosk at the Giles Street entrance,with a small
satellite population along the rip-rap near the bench in the `meadow.' Several small populations are established
uphill on Giles Street,possibly contributing seed to the Six-Mile Creek Natural Area.
D. DAMAGE AND THREATS
Currently,the area occupied by mugwort has caused little damage to the natural area,but the potential exists for
complete displacement of native species within mugwort stands.Mugwort is not very shade tolerant and would
be unlikely to colonize the forest understory,but could threaten native species on the fringe of the focus areas.
Scientific name:Berberis thunbergii Common name: Japanese barberry
A.PRIORITY: Medium.This species will be controlled if it is in a priority area.
B. DESCRIPTION
Japanese barberry is a dense spiny shrub that grows 2-8 ft in height.The small oval leaves are green,blue-green,
or purplish.Pale yellow flowers are present from April to May. The showy,oblong red berries persist through
the winter months.This species should not be confused with the only native species of barberry,Berberis
canadensis.
C. CURRENT DISTRIBUTION ON THE SITE
Populations are frequent but not dense.It occurs in forested areas throughout the natural area, including the
priority site of-Beech woods.European barberry is also present,though it is usually restricted to low pH rocky
cliffs(Pers. comm.F.R. Wesley).
D. DAMAGE AND THREATS
Japanese barberry can form dense stands in numerous habitats from full shade to full sun.This species has been
shown to alter the pH of soils and disturb the microbial ecology of soils,making it less habitable for native
species. Once Japanese barberry becomes established,native plants are displaced and shaded out. The spiny
growth habit of the plant also disturbs and reduces habitat for animals.Animals also avoid the thorny bush,
preferring to feed on native plants,giving Japanese barberry an even greater competitive edge.
25
Scientific name: Centaurea sp. Common name: knapweed
A. PRIORITY:Medium,but no populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION
Knapweed species are some of the worst invaders in the Midwest and prairie states,completely displacing
native species.Knapweeds are biennials or short-lived herbaceous perennials producing seeds that are viable up
to eight years in the soil. It forms mounds of tattered-looking leaves and produces purple flowers.
C. CURRENT DISTRIBUTION ON THE SITE
Knapweed is well-established on the island to the right at the first left turn on the trail from the parking lot,and
probably along the shore and on islands upstream as well. Knapweed does not easily tolerate shade,but
knapweed could become well-established on the shoreline and on islands in Six-Mile Creek.
D. DAMAGE AND THREATS
If uncontrolled it could become a persistent aggressive weed on rocky shorelines and islands and in the meadow
area near the parking lot..
Scientific Name: Eleaegnus umbellata Common Name: autumn olive
A. PRIORITY: Medium, but no populations have been found in priority sites so not yet target for removal.
B.DESCRIPTION
This is a substantial shrub or small tree with simple,alternate leaves,bright green on top, silvery below,and the
shrub as a whole has a silvery appearance. Stems may bear spines.The small white flowers,borne in late spring,
are fragrant. The fruit is small,round,silvery red.
C. CURRENT DISTRIBUTION ON THE SITE
Autumn olive is found in the open fields north of second reservoir and downslope of those fields,and also along
the trail near parking lot(Pers. comm. F.R. Wesley). There is at least one substantial colony,including fruiting
plants,alongside the Recreation Way on South Hill.
D. DAMAGE AND THREATS
Autumn olive is not well-established in the high-priority sections of the natural area,but since the species is
growing in large groves in several nearby areas and is known to be a serious problem in many locations, it should
be carefully monitored.In the long term,the goal should be to remove all plants from the natural area.
26
Scientific name: Fallopia japonica Common name: Japanese knotweed
A. PRIORITY: High throughout the natural area. This is a"rapid response"species:if it is found anywhere in
the natural area it should be removed as soon as possible.
B. DESCRIPTION
Japanese knotweed(Fallopia japonica)was introduced from Asia for ornamental purposes and is now
invading stream habitat in North America and Europe. Its hollow,bamboo-like stems grow rapidly,up to 4 m
tall,and form dense thickets along streams,shading native vegetation and blocking access to streams.Japanese
knotweed's enormous roots can extend 3m deep and are nearly impossible to remove. Its invasion along streams
is aided by downstream transport of plant material during floods,depositing roots and seeds in ideal places for
knotweed growth: sunny and moist stream banks.
B. CURRENT DISTRIBUTION ON THE SITE
An incipient population has established on the island to the right at the first sharp left turn on the main path from
the Giles parking lot;this is probably derived from roots washed downstream during the floods of spring 2005.
A large colony of several hundred square meters in area exists on the floodplain below the Giles Street dam.
D. DAMAGE AND THREATS
Japanese knotweed can outcompete native vegetation along stream banks,diminishing the ecosystem service
and function of riparian vegetation.It is capable of completely monopolizing streamside habitat,especially in full
sun.
u
Locations of Japanese knotweed in 6 Mlle Creek
i I
27
Scientific name:Hedera helix Common name: English ivy
A. PRIORITY:Low:This species will be controlled if it is in a priority area or climbing up desired trees.
B. DESCRIPTION
English ivy is a trailing or climbing vine native to Europe.Leaves are typically dark green,alternate,and simple.
English ivy grows easily in many types of soil,and in light from full sun to complete shade.Roots form when stem
nodes contact moist soil, leading to the formation of a dense mat of vegetation.Ivy roots are vigorous
resprouters. The plant sprawls across the ground and when it hits any upright object it climbs,reaching the tops
of mature conifers of 300 feet.The fiuiting stage typically occurs on climbing plants,but may also occur on
prostrate patches of sufficient age,especially in full sunlight. Flowers are produced in the fall and fiuits mature in
the spring. If it produces fiuit,English Ivy can be spread great distances by birds.
C. CURRENT DISTRIBUTION ON THE SITE
A few small patches are known to exist in the natural area,but not in any of the high-priority areas.
D. DAMAGE AND THREATS
English ivy forms a dense mat of vegetation and prevents native plants from growing under it It can also kill trees
when it gets into their canopy. It is very invasive in more temperate climates,but even in Ithaca it can bury native
groundcover and topple and kill mature trees.
Scientific name: Lamiastrum galeobdolon
Common name: yellow archangel/yellow deadnettle
A.PRIORITY: Medium, but no populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION:
Yellow archangel is perennial,and spreads by runners, seeds,and broken-off stems.Runnering can produce
large stands and makes populations difficult to eradicate.Its variegated leaves are difficult to spot in dappled
light. Yellow flowers are easier to spot in mid-May.
C.CURRENT DISTRIBUTION ON THE SITE:
One well-established population of yellow archangel is located on heavily disturbed banks of tributary streams
along the north edge of the First Bowl.
D. DAMAGE AND THREATS:
Currently minimal because the species is not found in areas of highest density and diversity of native wildflowers.
Potential for spread,however,is high if this small population is not controlled. Yellow archangel spreads easily
by runners and can establish populations in full shade.Known populations should be controlled.
Scientific name:Ligustrum sp. Common name: privet
28
A. PRIORITY: Medium.This species will be controlled if it is in a priority area
B. DESCRIPTION
Privets have escaped the garden and are invading forest edges and the interior shading out native species. Privet
is a shrub reaching 30 ft in height,with multiple stems at the base,with abundant white flowers producing dark
purple to black fruits. Once established privet is difficult to eradicate.
C. CURRENT DISTRIBUTION ON THE SITE
Privet is found almost everywhere in Six-Mile Creek Natural Area,particularly in areas in full or part sun,but it
is also able to flourish and produce fruit in shady habitats.It is established in at least one of the priority areas,and
perhaps all three of the priority areas.
D.DAMAGE AND THREATS
Privet is competing for space and light with natives,thereby reducing native diversity where it exists.If privet is
allowed to expand further into the priority areas,we can expect significant reductions in the native fort and shrub
layer.
Scientific name: Lonicera tatarica, L. X bella and others
Common name: bush honeysuckle
A. PRIORITY: Medium. This species will be controlled if it is in a priority area.
B. DESCRIPTION
Honeysuckles are upright deciduous shrubs,6-15 feet in height. The leaves have short stalks and are opposite and
egg-shaped, and 1-2.5 inches in length. Older stems are often hollow. Creamy white to pink flowers are borne in
pairs at leaf axils. Honeysuckles flower in early to late spring. Flowering is variable for each species and cultivar.
The fruits are many-seeded berries,red to orange. Seeds are widely dispersed by birds;vegetative sprouting also
occurs.
There are many nonnative species in North America, some of which are invasive in the Six-Mile Creek area. The
Plant Conservation Alliance lists six species and cultivars that are invasive in North America.
C. CURRENT DISTRIBUTION ON THE SITE
Honeysuckle populations are extensive in the Six-Mile Creek flood plain. Populations are encroaching and
numerous in wooded sites, including Beech Woods.
D. DAMAGE AND THREATS
Honeysuckles form a dense layer that crowds and shades out native plants species and deplete soil moisture and
nutrients. Invasive species compete with native honeysuckles for pollinators. Invasive honeysuckles' fruits are a
lower priority for migrating birds than those of native honeysuckles.
29
Scientific name:Microstegium vimineum Common name: Japanese stilt-grass
A. PRIORITY High. This is a"rapid response"species: if it is found anywhere in the natural area it should be
removed as soon as possible.
B. DESCRIPTION
Japanese stilt-grass is an annual grass with a sprawling growth habit. Leaves are pale green, lance-shaped, 1-3
inches long,asymmetrical,with a distinctive shiny mid-rib. Flowers appear in late summer(August-September)with
fruit maturing soon after. The plant's ability to root at stem nodes that touch the ground allow it to colonize areas
rapidly. Seeds are also easily spread by water. The species is native to Japan Korea, China, Malaysia, and India.
C. CURRENT DISTRIBUTION ON THE SITE
Japanese stilt-grass occurs in the amphitheatre area of Six-Mile Creek. This is the only known population of this
species in Tompkins County.
D. DAMAGE AND THREATS
Japanese stilt-grass is a very aggressive annual with easily spread seeds. Once established,Japanese stit-grass
can spread rapidly through an area and overtake native habitat within 3 to 5 years. Each plant can produce 100 to
1000 seeds per year. The seeds remain viable for 3-5 years and are easily spread by water and foot traffic.
Scientific name:Phragmites australis Common name: common reed
A. PRIORITY: High. This is a"rapid response"species: if it is found anywhere in the natural area it should be
removed as soon as possible.
B. DESCRIPTION
Common reed is a rhizomatous perennial grass that forms very dense monospecific stands.Primarily a threat to
riparian and tidal marshes,common reed quickly displaces the native vegetation creating dense lawns of old
shoots.Common reed stands accrete sediment due to their dense rhizome and shoot system,altering the
hydrology of the water body. The genus Phragmites is native to North America,but the native species has been
displaced by a European species.They can be phenotypically distinguished from each other.This weed is very
difficult to control and should be dealt with when populations are small.
C. CURRENT DISTRIBUTION ON THE SITE
A single identified Phragmites stand exists just outside the bounds of the natural area near the settling pools on
Giles Street. We have yet to determine if this is the invasive or native genotype.
D.DAMAGE AND THREATS
Upon introduction by either seed or rhizome figment,common reed will rapidly spread and displace any
existing vegetation.
30
Scientific name: Ranunculus ficaria Common name: lesser celandine
A.PRIORITY: Medium. This species will be controlled if it is in a priority area.
B. DESCRIPTION:
Lesser celandine is a perennial,shade-tolerant,summer-dormant plant with glossy,cordate leaves and shiny
yellow flowers.It does not produce great numbers of seeds but spreads exponentially through tubers(easily
water-home)that form in the leaf axils.
C: CURRENT DISTRIBUTION ON THE SITE:
Limited to high-disturbance areas:
1) Scattered locations along banks of smaller streams along the north edge of the First Bowl.These streams
join shortly after entering the bowl and flow into Six-Mile Creek at the parking area.
2) Along the south shore above the thirty-foot dam,with a large population near the inlet.Lesser celandine
populations could exist elsewhere; the north shore has not been surveyed.
D. DAMAGE AND THREATS:
As a very vigorous spring ephemeral,lesser celandine outcompetes native spring-flowering wildflowers through
crowding,shading,and monopolizing resources.Damage is currently minimal because the species has not
appeared in areas with highest density and diversity of native wildflowers,although it may be damaging marsh
marigolds on the south shore above the thirty-foot dam. Threat:quite high due to its mobility(carried by flood
waters)and rapid spread.
Scientific Names: Rhamnus cathartica and R.frangula
Common Names: common buckthorn and alder buckthorn
A. PRIORITY: Medium. This species will be controlled if it is in a priority area.
B. DESCRIPTION
Common buckthorn,named for the thorns on the end of its twigs,is a deciduous shrub than can reach the size of
a small tree.2-6 meters tall. Its leaves are mostly alternate and are from 3-6 cm long.Its clustered greenish
flowers appear in May and June,followed by drupes(berrylike faits),which ripen in August and September.
Fruits tend to remain on the shrub throughout the winter and are readily dispersed by birds.Dried fruits of this
species can float for up to six days,which is especially significant in understanding common buckthorn's spread
in the Six-Mile Creek Natural Area.Common buckthorn is deciduous and drops its leaves late in the autumn.
The species name cathartica refers to its medicinal value as a purgative. Common buckthorn grows well in well-
drained sandy or clay sites,and can often be found on woodland edges.This species is introduced from Europe
and Asia,and is classified as a noxious weed in several northeastern states.Planting common buckthorn is
prohibited in Connecticut and New Hampshire.
Alder buckthorn can reach up to 7 meters in height.Twigs are grayish or brown and sometimes covered with
fine hairs.Its leaves are alternate,elliptic,and 3.5-6.5 cm in length.Alder buckthom's greenish flowers appear in
31
May and June, followed by purplish black drupes in July and August.The fruits drop to the ground soon after
ripening,to be eaten by birds and mice.Fresh fruits can float for 14 days before sinking.This species grows in
wetter and more acidic soils than common buckthorn,but can be found in all soil types.Alder buckthorn is native
to Europe and Asia,and is considered naturalized in New York and New Jersey.
Both these Rhamnus species were probably introduced to North America before 1800.They did not become
widespread,however,until they became commonly used for hedgerows and roadsides. They can now be found
in pastures,roadsides, fence rows,and ravines throughout North America.In general,buckthorns easily form
dense thickets with canopies that spread until they touch the canopies of other shrubs.
C. CURRENT DISTRIBUTION ON SITE:
Many plants can be found along the path leading upstream from the Giles Street parking lot,and sporadically all
the way to the 30-foot dam.They are also very common along the South Hill recreation way.They often occur
in dense tangles with honeysuckle and privet,as one sees on both sides of the path leading from the parking lot.
D. DAMAGE AND THREATS
This species' ability to form dense thickets with thick canopies means it can shade out native vegetation.
Common buckthom is shade tolerant and poses a danger to our native shade-loving spring annuals.Both
common and alder buckthorn seeds can survive flooding and can be transported to new sites by water,and may
establish themselves on the edges of Six-Mile Creek and other wet areas.
Scientific name: Rosa multiflora Common name: multiflora Rose
A. PRIORITY:Low.No populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION
Multiflora rose is a 7'-10' shrub with spines,compound leaves with 7-9 toothed leaflets,and pyramidal clusters
of small, fragrant,white flowers appearing in May and June. Its drooping branches,which can root at their tips,
allow the multiflora rose to easily form thickets.In late summer and fall,it bears red-orange fruits.Birds eat the
faits,then regurgitate or deposit the seeds in droppings. Seeds"planted" in this way germinate at a higher rate
than seeds not eaten by birds.A single,medium-sized multiflora rose can produce 500,000 seeds per year.
Multiflora rose also reproduces from root sprouts and horizontal underground stems,or rhizomes.Multiflora rose
tolerates a wide variety of soils.This shrub is native to Japan,Korea,and China.It is a noxious weed in at least
ten U.S. states,persisting in more than 45 million acres in the eastem U.S.Planting multiflora rose is illegal in
some areas.Luckily,it does have some natural enemies,ranging from insects to mildews to fungus.
C. CURRENT DISTRIBUTION ON SITE
There are several multiflora rose near the Giles Street parking lot, including a massive tangle surrounding the first
sycamore to the left as one follows the upstream path from the parking lot.
32
D. DAMAGE AND THREATS
Thick populations of multiflora rose lower land values for forestry and recreation,This shrub forms thorny,
impenetrable thickets through vegetative propagation.Its dense thickets crowd out native vegetation.Entire
pastures have been covered with this noxious weed.Because this plant seems to favor disturbed ground,
especially previously plowed sites,multiflora rose can take over other disturbed areas such as pastures,hedges,
power line corridors,and roadsides.Multiflora rose is capable of establishing huge seeds banks that can continue
to sprout new plants for at least twenty years after the removal of the mother plant.
"Plain old Charlie Dream,"an Indiana state forester and botanist,strongly opposed landscaping of cemeteries
with multiflora rose in 1948.He wrote,"When Gabriel sounds his horn,I am afraid some will be stranded and
not be able to get thru the roses."
Scientific name: Tussilago farfara Common name: coltsfoot
A.PRIORITY: Medium,but no populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION
Introduced from Europe,coltsfoot is a perennial,reproducing by rhizomes and by seed.Plants apparently of two
types:(1)more or less leafless stems bearing flower heads in early spring(March to June),and(2)very short
stems bearing large leaves in summer.In its flowering stage,coltsfoot can be distinguished from dandelion by its
purplish bracts on the flowering stem.After flowering,the vegetative plant can be distinguished from young plants
of burdock by its perennial rhizome system and its broadly heart-shaped,palmately veined leaves.
Coltsfoot is successful in colonizing disturbed environments because seedlings and juveniles can tolerate a wide
range of conditions.The species has high adaptability to many habitat types,and fast growth,development,and
spread of individuals.
C. CURRENT DISTRIBUTION ON THE SITE
A survey for coltsfoot has not been completed,but it has been observed along the emergency access road off
Giles,in dense colonies in the First Bowl,and sporadically at the margins of woods adjoining the shores of the
stream.
D. DAMAGE AND THREATS
Coltsfoot is highly invasive due to its rapid growth and tolerance to disturbed and intact habitats(forests,fields,
disturbed and waste places and along roads,rivers, lakes,ravines and drainage ditches in urban and rural areas)
and can crowd native species.While it is not currently present in the Second Bowl or amphitheatre,there is high
potential for its spread to both these areas of high priority.Rhizomes or seeds originating from populations along
the access road could be transported by water or by animals.
33
Scientific Name: Vinca minor Common Name: periwinkle
A. PRIORITY: Medium, but no populations have been found in priority sites so not yet target for removal.
B. DESCRIPTION
Periwinkle is a short evergreen perennial vine with blue-purple flowers.The plant grows in partial sun to full
shade and is native to Europe and Western Asia.Populations spread downstream easily.
C. CURRENT DISTRIBUTION ON THE SITE
Periwinkle can be found in the parking area near Mulholland Wildflower Preserve and on the rich floodplains on
both sides of stream. (Pers. comm.F.R. Wesley)
D.DAMAGE AND THREATS
Once established in an area, Vinca forms a dense carpet, spreading vegetatively to the exclusion of all other
herbaceous plants.As it grows well in dense shade, it is a particular threat to native spring ephemerals.Its
colonies expand in size each year. Colonies near the Giles parking lot currently cover hundreds of square meters.
Scientific name: Vincetoxicum rossicum
Common name: pale swallow-wort
A.PRIORITY: High due to rapid spread and colonization of undisturbed areas. This is a"rapid response"
species: if it is found anywhere in the natural area it should be removed as soon as possible.
B. DESCRIPTION
Pale swallov-wort is an herbaceous perennial vine in the milkweed family.Plants can easily reach more than 2 m,
especially in shaded areas. The small, five-pointed flowers are light pink to maroon.Fruits are borne in pods that
split open to release tufted seeds that are easily wind-dispersed over long distances.
C. CURRENT DISTRIBUTION ON THE SITE
In 2004,a dense population of pale swallow-wort was found in a small area adjacent to the parking lot,near the
creek. This is the only known population of pale swallow-wort in the Six-Mile Creek Natural Area.This
population currently does not threaten the high-priority,sensitive areas.
D. DAMAGE and THREATS
Swallow-worts form dense monospecific stands in fields and forest understories.They shade out small
herbaceous plants and climb over trees and larger brush.In highly sensitive areas owned by the Nature
Conservancy in Jefferson Co.,NY,these plants have damaged habitats of 57 rare species of flora and fauna.
These species are highly aggressive,spread rapidly,and have been shown to alter soil ecology to favor their
long-term establishment.
34
4. REFERENCES
Amrine,J. W. Jr. Multiflora rose. In R. Van Driesche,B. Blossey,M.Hoddle, S. Lyon,and R.Reardon(Eds.),
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35
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http://www.ipcnys.org/
Kloeppel,B. D.,and M.D.Abrams. (1995).Ecophysiological attributes of the native Acer saccharum and the
exotic Acer platanoides in urban oak forests in Pennsylvania,USA. Tree Physiology, 15, 739-746.
Martin,P.H. (1999).Norway maple(Acer platanoides)invasion of a natural forest stand:the pattern of
colonization and understory consequences.Biological Invasions, 1(213), 215-222.
Namura,O.A.(1993).Expansion of Tussilago farfara L. in disturbed environments: Successful colonization and the
properties of individuals.Acta-Societatis-Botanicorum-Poloniae, 62(1-2), 91-99.
Porter,A.(1994).Implications of introduced garlic mustard(Alliaria petiolata)in the habitat of Pieris virginiensis
(Pieridae).Journal of the Lepidopterist's Society 48:171-172.
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httpJ/plants.usda.gov/cgi bin/topics.cgi?earl=plant_profile.cgi&symbol=RHCA3
36
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http://plants.usda.gov/cgi bin/topics.cgi?earl=plant_profile.cgi&symbol=RHCA3
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37
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