Baseline Study of Vegetation

at Strawberry Island, Niagara River, NY

Completed by

Robert Lichvar Jonathan Campbell

US Army Engineer Waterways Experiment Station USACE-WES-ER-W

December 16, 1997

PREFACE This report was prepared by Robert Lichvar and Jonathan Campbell, ecologists, Wetlands Branch of the US Army Waterways Experiment Station (WES) This report is the summary of research finding and conclusions based on a New York State Department of Environmental Conservation (NYDEC) sponsored baseline study of terrestrial and aquatic vegetation and mussel communities at Strawberry Island, Niagara River, NY. Wayne McCready of NYDEC and Paul Leuchner of the Buffalo District Corps of Engineers were instrumental in obtaining and financially supporting this study. Permission to release this study was granted by NYDEC. Also, we acknowledge the use of a NYDEC photograph on the cover page. Other supporting personnel involved in this study were James Bissell and Beverly Miller from the Cleveland Science Museum who assisted in vegetation sampling in the aquatic bed and field verification of Irus virginica; Robert Bush and Dale Yocum from WES who assisted in obtaining GPS and field sampling data and developed map layers in a GIS.

-i-

Table of Contents

1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 Descript ion of study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Location and descript ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.4 Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.0 Methods for mapping and vegetat ion survey . . . . . . . . . . . . . . . . . . . . . . . 53.1 Sampling protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2 Sampling protocol of the terrestrial vegetat ion . . . . . . . . . . . . . . . . . 53.3 Sampling protocol of the aquatic vegetat ion . . . . . . . . . . . . . . . . . . 63.4 GPS and GIS support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.5 Stat ist ical analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.0 Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1 Terrestrial community . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.2 Aquatic community . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.0 Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix I . . . Species list of vegetat ion found on Straw berry Island, NY Appendix II . . Summary table of major plant species that compose the vegetat ion

of Straw berry Island (terrestrial and aquatic)Appendix III . . . Means (Std) of environmental variables on Straw berry Island by

plant community

Appendix IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Terrestrial f ield data sheets

Appendix V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aquatic f ield data sheets

Map PocketMap 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Straw berry Island Study AreaMap 2 . . . . . . . . . . . . . . . . . . . . . Straw berry Island Terrestrial Vegetat ionMap 3 . . . . . . . . . . . . . . . . . . . . . . . Straw berry Island Aquatic Plant Bed

-ii-

List of Figures

Figure 1. General locality map of the upper Niagara River and Straw berry Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure 2. Map of Straw berry Island and aquatic w eed bed study area . . . . . . . . 3

Figure 3. TWINSPAN analysis of vegetat ion communit ies of Straw berryIsland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 4. RA analysis of the plant community on Straw berry Island . . . . . . . . . 12

Figure 5. TWINSPAN analysis of aquatic bed surrounding Straw berryIsland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 6. CCA analysis of vegetat ion and environmental variables in aquaticbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

-iii-

List of Tables

Table 1. Summary of variables collected at each sample point . . . . . . . . . . . . . 6

Table 2. Summary of variables collected at each aquatic sample point . . . . . . . . 7

Table 3. Addit ional species reported for Straw berry Island . . . . . . . . . . . . . . . . 9

Table 4. Description of ecological communit ies . . . . . . . . . . . . . . . . . . . . . . . 10

Table 5. Summary of terrestrial communit ies at Straw berry Island . . . . . . . . . 11

-1-

1.0 INTRODUCTION

A baseline study w as done at Strawberry Island and the adjacent NiagaraRiver for vegetat ion and mussels near Tonaw onda, New York. This study w asconducted in response to an interagency request from the New York StateDepartment of Conservation (NYSDEC), US Army Corps of Engineers, BuffaloDistrict (Buffalo District), New York State Department of Transportat ion (NYSDOT),and the w estern New York Walleye Associat ion. The focus of this group is topreserve and manage the natural resources associated w ith the island and toprotect the aquatic bed w hich is used as a spaw ning area for w alleye in the NiagaraRiver.

This inventory provides a baseline record of the exist ing f lora, vegetat ioncommunit ies, both aquatic and terrestrial units, and the mussel populat ions andlocations. These results help support the development of management plans andprovide for a start ing point for other studies undertaken later.

Object ives of the vegetat ion study w ere as follow s:

a. To establish a digital spatial data base using Geographic InformationSystem (GIS) and Global Posit ioning System (GPS) technology.

b. To perform a botanical survey of both the aquatic plant beds andterrestrial habitats.

c. To perform a mussel inventory.

d. To provide guidance for management of human resources.

The follow ing chapters describe the sett ing for and the methods used toinventory the vegetat ion and mussels.

-2-

2.0 DESCRIPTION OF STUDY AREA

2.1 Location and description.

Straw berry Island is one of several islands in the upper Niagara River in ErieCounty, New York. Both Straw berry and Motor islands are found off the southernt ip of Grand Island (Figure 1). Straw berry Island is about 4.3 miles dow nstreamfrom the mouth of Lake Erie. The est imated sizes of these tw o island are 7.62 and5.71 acres respectively. The center of Straw berry Island is found at lat itude78° 55N22.6 and longitude 42° 57N14.8. The aquatic w eed bed associated w ithStraw berry Island loosely forms a triangle from the southern t ip of Straw berryIsland to the north t ip of Motor Island and westw ard to the southern t ip of GrandIsland.

Figure 1. General locality map of the upper Niagara River and Straw berry Island

The current size and shape of Straw berry Island (Figure 2) have beeninfluenced by human act ivity. Original surveys of the island size in 1824 w ereestimated to be about 100 acres. During the excavation of the Erie Canal,excavated materials w ere deposited at the island and its size w as increased toabout 200 acres. Then betw een 1914 and 1940' s the island was dredged forgravel and its size w as reduced to about 60 acres. Dredging of the islandcontinued into the 1950' s. This last episode of dredging at the north end of theisland created the u-shape f igure that exists today (Sw eeney 1997). The contourrelief on the island is minimal. Along the south and w est sides there is an elevatedridge about 5-10 feet high. The remainder of the island is mostly level to gentlysloping.

-3-

Figure 2. Map of Straw berry Island and aquatic w eed bed study area

2.2 Geology

The study area is w ithin the Erie-Ontario lake plains province (Fenneman1938). This region is relat ively f lat in the immediate area surrounding the island. The geology of Straw berry Island is rew orked sediments and gravel deposits fromLake Erie dating back to the Pleistocene (Kindle and Taylor, 1913). The localstrat igraphy consists of Ordovician and Upper Devonian dolomites, limestones,si l t st o n es, an d shal es, m an t l ed by a t h i n l ay er of gl ac i al an d al l u v i al dep o si t s. Inadjacent reaches of the Niagara River near the Black Rock Lock, it w as found thatt h es e u n c o n s o l i d at ed d ep o s i t s w er e i n t h e Fal k i r k m em b er o f t h e Ber t l e group.

-4-

2.3 Soils

The soils of Straw berry Island are mapped as either beaches or Haplaquolls. Most of Straw berry Island is mapped as Haplaquolls in the USDA, Soil Survey ofErie County, New York (1968). Haplaquolls are soils that are very poorly drainedand ponded w ith shallow w ater most of the year. These soils are formed inlacustrine, outw ash, glacial t ill, and alluvial and organic deposits. The Haplaquollson Straw berry Island are generally f looded w ith 5 to 10 inches of w ater. Thesesilty to sandy organically enriched soils are mott led in the surface layer and w erefound to be mostly gray on the island.

The remainder of Straw berry Island is mapped as beaches. The soils in thisgroup are deposit ional materials from both Lake Erie and the Niagara River. Thetextures of these soils range from sandy to gravelly. These deposited materialslack developed soil horizons and vary in texture throughout a soil prof ile.

2.4 Climate

Erie County is in the Ontario Plain and Finger Lake Region of the LandResource Regions and Major Land Resource Areas of the United States (USDA1981). In this region the average annual precipitat ion is 37 inches. Precipitat ion isevenly distributed throughout the year. Half the annual precipitat ion occurs assnow fall in the w inter. The average w inter temperature is 26 degrees F and thesummer average is 68 degrees F.

-5-

3.0 METHODS FOR MAPPING AND VEGETATION SURVEY

3.1 Sampling Protocol

The vegetat ion survey of Straw berry Island is composed of tw o separatestudies. These are 1) the terrestrial vegetat ion of Straw berry Island and 2) theaquatic w eed bed associated w ith the island in the Niagara River. The goal of eachstudy w as to develop a baseline of the exist ing vegetat ion condit ions that occur inthese tw o locations. Two separate teams sampled the aquatic bed and theterrestrial vegetat ion during July 1997. A total of 52 sites, 21 terrestrial and 32aquatic, w ere sampled on Straw berry Island and in the aquatic plant bed. Oneaquatic and six terrestrial vegetat ion communit ies w ere sampled and mapped. Fourof the 6 terrestrial vegetat ion communit ies corresponded w ith descript ions of“ ecological communit ies” described by Reschke (1990). The sampling protocol foreach study is presented below .

3.2 Sampling Protocol of the Terrestrial Vegetation

Vegetat ion communit ies w ere mapped in the f ield using GPS equipment. Plant community level interpretat ions and labels w ere based on the EcologicalCommunit ies of New York State (Reschke 1990). Based on preliminary f ieldinvestigat ions, each community w as identif ied and the boundaries mapped usingGPS equipment.

Vegetat ion structure and composit ion w ere assessed quantitat ively w ithineach community. Each community w as sampled to a sampling adequacy of (p >80) or until a minimum of 5 samples per type in most cases. Percent cover ofindividual species in a vegetat ion type w as est imated to the nearest percentagepoint. For trace species, cover values w ere est imated below 1 percent. All speciesoccurring in the sample quadrat w ere recorded, percent cover est imated, and aspecies list assembled. Quadrat size for trees, shrubs and herbaceous species w asa 10 x 10m. All sampling stat ions w ere photographed. Most species w ereidentif ied in the f ield, and taxonomic nomenclature follow s Kartesz 1994. Unknow n species w ere identif ied later at the Cleveland Museum of Science. Native and alien species w ere categorized by using the Flora of the Niagara FrontierRegion (Zander and Pierce, 1979).

At each sample point, collect ion of other data included 7 addit ionalenvironmental variables (Table 1).

-6-

Table 1Summary of variables collected at each sample point

Variable Units Explanation

W ater Table Depth meters Depths w ere measured w ith an auger and measuring tape. This

measurement ref lects the availabilit y of w ater for vegetat ion.

A Horizon Depth meters This w as measured to determ ine the amount of organic mat ter

retained in the surf ace of the soil.

Number of Stems count Stem counts help to determ ine the vegetat ive st ruct ure of the

communit y .

Tree Height meters M easured w ith a clinometer and tape measure. Tree height helps

determine the age and st ructure of the community .

Sand % Textured in the f ield. Soil t ex ture est imates ref lect the w ater

holding capacity and potent ial nut rient amounts.

Silt /Clay % Textured in the f ield. Soil t ex ture est imates ref lect the w ater

holding capacity and potent ial nut rient amounts.

Gravel % V isual est imate. Presence of gravel indicates a higher composit ion

of beach material.

3.3 Sampling Protocol of the Aquatic Vegetation

The aquatic bed was init ially mapped by boat using GPS equipment toestablish the boundary. This preliminary boundary w as dow nloaded into ArcView3.0, and a 25 m grid w as overlaid on top of the digital f ile for the aquatic bed. 2

Using a random number table, 30 points w ere selected w ithin the X and Y axes ofthe grid. In the f ield, GPS equipment w as used to f ind the previously selectedsample points in the appropriate grid cells. Tw o addit ional samples w ere addedlater to spread out the samples further.

The density, structure, and composit ion w ere assessed quantitat ively w ithinthe aquatic plant bed. The aquatic plant bed w as sampled w ith 3 x 3m quadrats. Percent cover of individual species at each sample point w as est imated to thenearest percentage point. Species occurrences and cover values w ere done afterthe quadrat area w as surveyed w ith a grappling hook to identify species and theirabundance. Besides species occurrence data, 10 addit ional environmentalvariables w ere collected (Table 2).

-7-

Table 2Summary of variables collected at each aquatic sample point

Variable Units Explanation

Light penet rat ion meters M easured w ith a secci disk. Light penet rat ion indicates depths

to w hich plants can grow .

Plant cover % V isual est imate. A measure used to est imate plant abundance.

W ater velocit y m/sec The length of t ime a f loat ing dev ice t raveled the length of a 3m

rod. This w as measured to determ ine w hat current speed w as

opt imal for plant grow th.

W ater depth m M easured w ith measuring rod.

Plant height m M easured w ith measuring rod. Plant height w as measured to

determ ine communit y st ructure.

A lgae % Visual est imate. This w as taken to assess the occurrence of

algal dist ribut ion w ith plant cover, w ater velocity , and soil

t ex ture w ithin the aquat ic bed.

Rock % M easured w ith a grab bucket . Used to determine the soil tex ture

of the aquat ic bed.

Gravel % M easured w ith a grab bucket . Used to determine the soil tex ture

of the aquat ic bed.

Sand % M easured w ith a grab bucket . Used to determine the soil tex ture

of the aquat ic bed.

Silt /Clay % M easured w ith a grab bucket . Used to determine the soil tex ture

of the aquat ic bed.

The f inal boundary of the aquatic plant bed w as mapped w ith GPSequipment after the sampling of the bed. During the sampling phase, the boundaryw as ref ined by either ocular observations or by use of a grappling hook. In thef ield, w e decided that the outer edge of the boundary must have 5 percent orgreater plant cover to be considered part of the contiguous bed. This w as donebecause occasional species are scattered across the river bottom in most of thispart of the Niagara River. Later, the bed was subdivided into 5 units based onknow ledge gained during the sampling. These subunits are based on the dominantspecies, plant cover, w ater velocity, w ater depth, and soil texture.

3.4 GPS and GIS Support

The baseline maps w ere developed using the ArcINFO GIS program. Theboundaries of Straw berry Island, aquatic w eed bed, vegetat ion, and the adjacent

-8-

landscape features to Straw berry Island were used as a digital base in the ArcINFOGIS program. The boundaries of Straw berry Island, vegetat ion communit ies, andthe aquatic w eed bed were mapped in the f ield using Trimble ProXL GPS andimported into ArcINFO. The GPS data w ere dif ferentially corrected using a basestat ion at Black Rock Lock, Corps of Engineers, Buffalo, NY, w hich is maintainedby the US Army Corps of Engineers, Buffalo District .

3.5 Statistical Analyses

Summary stat ist ics, as w ell as various classif icat ion and ordinationtechniques, w ere used to assist in the explanation of the terrestrial and aquaticplant communit ies. Species density data in each sampling location w ere classif iedusing TWINSPAN (Hill 1979). TWINSPAN is a polythetic, divisive classif icat iontechnique w hich bases groupings on percent similarity. Default values (0, 2, 5, 10,and 20) for psuedospecies cut levels w ere used. Subsequent to classif icat ion,Canonical Correspondence Analysis (CCA: ter Braak 1988) and ReciprocalAveraging (RA) w ere used to determine the relat ionship betw een species densityvalues and environmental variable values on the aquatic community. CCA is adirect gradient analysis technique which relies on the assumption of unimodalrelat ionships betw een species and environmental variables. To determine thecomponents w hich explained the greatest proport ion of variance in the aquatic dataset, stepw ise, forw ard select ion of environmental variables w as employed. RA, anindirect gradient analysis technique, w as used to ordinate the terrestrial data set. Subsequent to RA, environmental variables w ere correlated w ith each of the f irsttw o ordination axes, using Pearson’s Product Moment Correlat ions, to determinew hich variables w ere responsible for trends in the plant communit ies.

Finally, species composit ion for each terrestrial and aquatic community w asrated using a f loristic index (Andreas and Lichvar 1995). Species w ere assigned aquality rat ing, called the coeff icient of conservatism, for each species in thecommunity. The sum of the numerical rat ings for each community w as thenobtained by applying the f lorist ic quality assessment index (I). The I values arethen used to compare the quality of the “ nativeness” of communit ies to each other.The index rat ings for this study w ere developed from species observations in thequadrats. The f lorist ic rat ings for individual species used by this index w eredeveloped for northern Ohio, w hich is ecologically similar to w estern New York. Due to this similarity, w e believe that this index is st ill valid at Straw berry Island.

-9-

4.0 RESULTS AND DISCUSSION

Sw eeney (1997) reported 84 vascular plants occurring on Straw berry Islandand in the associated aquatic plant bed. During this study, w e observed anaddit ional 63 species not reported in Sw eeney’s list (Table 3). An updated list ofall species observed at Straw berry Island can be found in Appendix 1. Of these, 3species w ere aquatic species. The remainder w ere either w etland or uplandspecies.

Table 3

Additional Species Reported for Straw berry Island

Acer saccharinum L.Agrimonia striata Michx.Alliaria petiolata (Bieb.) Cavara & Grande*Allium cernuum RothAlnus incana (L.) Moench. ssp. rugosa (Du Roi) ClausenAmaranthus retroflexus L.*Angelica atropurpurea L.Asclepias incarnata L.Capsella bursa-pastoris (L.) Medik.*Carex lacustris Willd.Chelone glabra L.Chenopodium album L.*Cirsium vulgare (Savi) Tenore*Echinochloa muricata (Beauv.) FernEleocharis erythropoda Steud.Eleocharis obtusa (Willd.) J.A. SchultesElodea canadensis Michx.Epipactis helleborine (L.) Crantz* .Equisetum arvense L.Eupatorium maculatum L.Galium parisiense L.Galium trif idum L.Geum canadense Jacq.Glyceria striata (Lam.) Hitchc.Iris sp.Lathyrus palustris L.Lolium perenne L.*Lonicera tatarica L* .Lycopus americanus Muhl. ex. W. Bart.Lycopus unif lorus Michx.Lysimachia nummularia L.*Mentha arvensis L.

Mimulus ringens L.Onoclea sensibilis L.Panicum miliaceum L.*Phalaris arundinacea L.Phragmites australis (Cav.) Trin. Ex Steud.Poa annua L.*Polygonum achoreum Blake*Polygonum amphibium L.Polygonum aviculare L.*Polygonum pensylvanicum L.Rhamnus cathart ica L.*Ribes americanum P. Mill.Rubus idaeus L. ssp. strigosus (Michx.) FockeRumex crispus L.*Sagittaria lat ifolia Willd.Salix discolor Muhl.Salix eriocephala Michx.Salix lutea Nutt.Salix purpurea L.*Scirpus pungens Vahl.Scirpus tabernaemontani K.C. Gmel.Sisymbrium alt issimum L.*Sium sauve Walt .Sphenopholis intermedia (Rydb.) Rydb.Spiraea alba Du RoiStachys tenuifolia Willd.Thelypteris palustris SchottTypha lat ifolia L.Verbascum thapsus L.*Veronica americana Schw ein. ex Benth.Viola canadensis L.

* denotes alien species

4.1 Terrestrial Community

The 6 terrestrial vegetat ion communit ies on the island are in various stagesof disturbance or succession (Tables 4 and 5). Appendix 2 lists all species sampledin the ecological communit ies on Straw berry Island and in the surrounding

-10-

Table 4Description of ecological communities

Community Description

Sedge M eadow This com m unit y is f ound in t he nort hern sect ion bet w een t he tw o arm s of t he island. This

herbaceous com m unit y is dom inated by Carex st ric t a, Calam agrost is canadensis, and

M ent ha arv ensis. This com m unit y is com posed of 7 4 percent nat ive species and is in

relat ively good ecological condit ion. The soils in t h is unit are f ine silt y c lays w it h an A

horizon that averages 5 0 cm t h ick . The A horizon is h ighly enriched w it h organic m at t er.

The dept h t o w at er t able v aries depending upon riv er lev els but w as f ound t o about 1 m

during t he st udy . This w et land com m unit y is inf luenced by f luct uat ion of w at er levels in t he

Niagara River. The seasonal f looding and inundat ion of w at er ont o t his sit e rest ric t s t h is

area m ost ly w et land species. This is t he second highest qualit y t errest rial com m unit y on

t he island based on species com posit ion.

Floodplain Forest (FF) This f orest ed com m unit y is assoc iat ed w it h older beach m at erials deposit ed by t he riv er. It

is com posed of 4 st rat a inc luding t rees, shrubs, v ines, and herbaceous. The t ree layer is

prim arily Populus delt oides and Salix f ragilis. The shrub layer is dom inated by Cornus

stolonif era and Rham nus cat hart ica. The underst ory is dom inat ed by m any int roduced

species (e.g. A lliaria pet io lat a and A rct icum m inus) w hich ref lec t s t he prior dist urbances t o

t his habit at . Overall, t h is com m unit y is dom inat ed m ost ly by upland species t hat resu lt

f rom t he w ell drained f luv ial soil m at erials. The soils in t h is unit are a m ix of sand, silt , and

grav el. The A horizon is 0 -1 0 cm but blends int o t he B horizon at a dept h up approx im at ely

1 .7 m due t o t he inf ilt rat ion of organic m at t er int o t he f luv ial m at erial. The w at er t able is on

t he average up to 2 m deep.

Loosestrife M arsh (LM ) The only occurrence of t h is com m unit y is f ound on t he inner shoreline of t he nort hern arm

of t he island. This m ost ly herbaceous com m unit y is dom inat ed by , Carex st ric t a, and

Polygonum lapat hif o lium . Six t y percent of t he species occurring in t h is com m unit y are

nat ive spec ies; how ever plant cover is dom inated by Ly t hrum salicaria. The A horizon is

approx im at ely 3 5 cm t h ick . This com m unit y is af f ect ed by seasonal w at er f luct uat ions

w here w at er t able dept hs can range f rom inundat ed t o 8 5 cm below t he soil surf ace. This

w et land com m unit y is great ly inf luenced by t he f luc t uat ions of t he river level. These

f luc t uat ions plus prior dist urbance t o t he sit e allow f or t he high abundance of Ly t hrum

salicaria.

Planted W illow Shrub

(PW )

This shrub com m unit y is f ound on t he m iddle and w est arm of t he island. This com m unit y

is dom inated by Salix ex igua. Several ot her species are report ed t o have been plant ed but

t hey w ere not observed w it h in t he sam ple plot s. This shrub com m unit y had a 6 2 percent

occurrence of nat ive species. The so ils in t h is un it are dom inat ed by silt and c lay w it h t race

am ount s of sand and grav el. The A horizon average w as 3 5 cm and t he dept h t o w at er

t ables w as 1 .5 M . This shrub com m unit y is t h ick w it h Salix st em s. The Salix p lant cover is

so high t hat it shades out any potent ial underst ory species.

Degraded Floodplain

Forest (DF)

This com m unit y occurs on the east ern arm of t he island. This com m unit y is highly

dist urbed due t o t he presence of Black Billed Gulls. These gulls are act ively brow sing,

t ram pling, and def ecat ing t he veget at ion in t h is com m unit y . The veget at ion of t h is

com m unit y is dom inated by Spart ina pect inat a, Rhus t yphina, and Populus delt oides

saplings. The soils are m ost ly a silt y c lay t ex t ure w it h m ix of sand and grav el. The A

horizon is 3 5 cm and the dept h t o w at er t able is 1 .3 5 m .

Great Lake Aquatic Bed

(AQ)

This aquat ic com m unit y is locat ed m ost ly t o t he nort h and w est of St raw berry Island. The

aquat ic bed is dom inated by Pot am oget on pect inat us, P. pusillus, V allisneria am ericana, and

Zannichellia palust ris. This com m unit y is com posed of 8 0 percent nat ive species. The bed

is f ound on bot h a silt and hard rock bot t om . The largest part of t he bed is sit uat ed on silt y

deposit s. The densit y of t he bed is t he great est w here t he current is slow est . This large

river aquat ic bed has plant cov er values t hat range f rom 5 t o great er t han 1 0 0 percent

cov er. The cent er ax is, in a nort h t o south d irect ion of t he bed, has t he great est densit y of

plant cover and diversit y . The dredge area w it hin t he arm s of t he island eit her lacks aquat ic

species ent irely or has a sparse presence of alien species.

-11-

aquatic bed. The sedge meadow (SM) has 74 percent composit ion of nat ivespecies (I= 18.92) w hile the f loodplain forest has 62 percent (I= 9.04). TheFlorist ic Index for the f loodplain forest community is low er than expected becauseof the relat ively low index rat ings for the trees present in this community, as w ellas the high number of exotics in the understory. The community w ith the highestoccurrence of native species is the shallow emergent marsh (EM). This areaappears to have been connected to the sedge meadow at sometime but now isisolated by an elevated sect ion of ground covered by a wall of river grape (Vit isriparia) and dow ned trees.

Table 5Summary of terrestrial communities at Strawberry Island

Ecological Community Code Size

(acres)

#

Samples

Average

Richness

Average

% Cover

% Native

Species

Floristic

Index (I)

Sedge m eadow

Floodplain f orest

Loosest rif e m arsh

Shallow em ergent m arsh

Plant ed w illow shrub

Degraded f loodplain f orest

Great Lakes aquat ic bed

SM

FF

LM

EM

PW

DF

A Q

1 .7 1 6

3 .4 9 2

0 .1 6 3

0 .0 8 2

0 .8 3 9

1 .3 2 2

2 7 8 .1 8

6

5

1

1

3

5

3 2

1 4 .0

1 2 .0

1 5 .0

1 4 .0

1 8 .0

1 3 .8

3 .4

7 6 .1

1 8 3 .3

4 2 .5

1 0 1 .0

9 2 .0

1 0 9 .0

7 8 .3

7 4

6 2

6 0

8 5

6 2

5 8

8 0

1 8 .9 2

9 .0 4

1 0 .3 3

1 3 .2 8

1 4 .9 2

1 2 .8 4

1 9 .0 9

The most disturbed area is the east arm of the island (DF). This area had thelow est percent of plant cover, species richness, and occurrence of nat ive species. The degradation in this community is largely due to the trampling, grazing, andnutrient inputs from the high populat ion of Black Billed Gulls. In spite of thedegraded nature of this community, its Florist ic Index (I) value is comparable w iththat of the other, less disturbed communit ies. This higher than expected indexvalue is primarily due to the presence of a few high quality species (Alnus rugosa,Iris vesicolor, and Spart ina pectinata). The highly degraded gravel bar on the eastarm and planted w illow shrub (PW) on the w est arm of Straw berry Island do not f itany of Reschke’s community descript ions. Nevertheless, based on speciescomposit ion and TWINSPAN analysis (Figure 3), the degraded east arm appears tobe most similar to the f loodplain forest community that dominates the upstreamside of the island.

In addit ion to TWINSPAN, RA exhibits the clear boundaries betw een theplant communit ies on Straw berry Island (Figure 4). While the second ordinationaxis is not signif icantly correlated w ith any of the environmental variables collectedin this study, the f irst ordination axis is negatively correlated w ith Depth to WaterTable (r= -0.642, p< 0.002), Tree Height (r= -0.650, p< 0.002), and Number ofWoody Stems (r= -0.581, p< 0.006). These correlat ions show the environmentalvariables w hich are responsible for the separat ion of the upland and wetlandcommunit ies in ordinat ion space. RA, like TWINSPAN, suggests the f loodplain

Figure 3. TWINSPAN analysis of vegetation communities of Strawberry Island.

Figure 4. RA analysis of the plant community on Strawberry Island.

-13-

forest and degraded east arm have similar plant communit ies. In addit ion, RAsuggests that the plant communit ies of the loosetrife marsh and the sedge meadoware also associated. Appendix 3 contains a summary of the environmentalvariables in each ecological community.

4.2 Aquatic Community

A total of 10 plant species w ere identif ied in the aquatic bed. Potenillacrispus w as the only exotic species found in this community. While the aquaticbed was delineated originally as one community, classif icat ion and ordinationtechniques suggested that the bed has two separate zones. TWINSPAN separatedthese tw o zones by the presence of dense stands of Potentilla pect inata (Potpec5)and traces of Potentilla pusillus (Potpus1) in the northern zone and traces ofPotentilla richardsonii (Potric1) in the southern zone (Figure 5). The northern zoneis represented in the * * Attached map* * as subzones 1 and 2, w hile the southernzone is comprised of subzones 3, 4, and 5. CCA also identif ied the northern andsouthern zones. Sample points in the northern zone w ere dispersed acrossquadrants II, III, and IV of the ordinat ion scattergraph (Figure 6), w hile the southernzone was largely restricted to quadrant I. The f irst axis of the CCA ordination w asmost strongly correlated w ith Plant Height (r= 0.88), and % Gravel (r= 0.61),w hile the second ordination axis w as correlated posit ively w ith % Algae (r= 0.49)and negatively w ith % Silt /Clay (r= -0.63). This suggests that the vegetat ion inthe northern zone is characterized by low gravel content, high silt /clay content, anddense plant cover. It should be noted that the f ive subzones in * * the attachedmap* * are merely f ield observed boundaries and not the result of a strict samplingeffort . Thus, they should be seen as generalized regions and not specif icvegetat ion communties.

Figure 5. TWINSPAN analysis of aquatic bed surrounding Strawberry Island.

Figure 6. CCA analysis of vegetation ad environmental variables in aquatic bed.

-15-

5.0 LITERATURE CITED

Andreas, B. K. and R. W. Lichvar. 1995. Floristic Index for EstablishingAssessment Standards: A Case Study for Northern Ohio. Technical ReportWRP-DE-8, U.S. Army Engineer Waterw ays Experiment Stat ion, MS.

Fenneman, N. M. 1938. Physiography of the eastern United States. McGraw -HillBook Company, New York.

Hill, M. 1979. TWINSPAN: A FORTRAN program for arranging mult ivariate datain an ordered tw o-w ay table by classif icat ion of the individuals andattributes. Department of Ecology and Systematics, Cornell University,Ithaca, NY, USA.

Kartesz, J. T. 1994. A synonymized checklist of the vascular f lora of the UnitedStates, Canada, and Greenland. Timbers Press, Port land, Oregon.

Kindle and Taylor. 1913. The geologic at las, Niagara Folio, New York. Cited In H.Bossert, Regional Director, Region 9, New York State Department ofEnvironmental Conservation letter dated May 3, 1973.

Reschke, C. 1990. Ecological communit ies of New York State. New YorkHeritage Program, N.Y.S. Department of Environmental Conservation,Latham, NY.

Sw eeney, C. 1997. A f lorist ic study of Straw berry Island in the upper NiagaraRiver, Tonaw anda, NY. Clintonia 12(3): 1-7.

ter Braak, C. 1988. CANOCO - a FORTRAN program for canonical communityordination by [part ial] [detrended] [canonical] correspondence analysis andredundancy analysis (version 2.1). Technical Report: LWA-88-02,Agricultural Mathematics Group, AC Wageningen, The Netherlands.

US Army Corps of Engineers, Buffalo District . 1997. Blackrock Lock, Pre-Inspection Brochure. Unpublished report, Buffalo District , 1776 NiagaraStreet, Buffalo, NY 14270.

US Department of Agriculture, Soil Conservation Service. 1981. Land ResourceRegions and Major Resource Areas of the United States. AgricultureHandbook 296, Washington, DC.

US Department of Agriculture, Soil Conservation Service. 1968. Erie County SoilSurvey, New York. Washington, DC.

-16-

Zander, R. H. and G. J. Pierce. 1970. Flora of the Niagara Frontier Region; secondsupplement and checklist. Bull. Buffalo Soc. Of Nat. Sci. (Vol. 16 Suppl. 2),Buffalo, NY.

APPENDIX I

Species list of vegetation found on Strawberry Island, NY

Appendix 1 Species list of vegetation found on Strawberry Island, NY

Species Species Acer negundo L.‡ Acer platanoides L.‡ Acer saccharinum L. Agalinus purpurea (L.) Pennell‡ Agrimonia striata Michx. Ailanthys altissima (Mill.) Swingle‡ Alisma plantago-aquatica L.‡ Alliaria petiolata (Bieb.) Cavara & Grande* Allium cernuum Roth Alnus incana (L.) Moench. ssp. rugosa (Du Roi) Clausen Alnus rugosa Amaranthus retroflexus L.* Ambrosia artemsiafolia Andropogon gerardii Vitm.‡ Angelica atropurpurea L. Apocynum cannabinum L.‡ Arcticum minus (Hill) Bernh.*‡ Armoracia aquatica (Eat.) Wieg. Asclepias incarnata L. Asclepias syriaca L.‡ Aster lateriflorus (L.) Britt.‡ Aster novae-angliae L.‡ Avena sativa* Astragalus neglecta (T. & G.) Sheldon‡ Brassica nigra (L.) Koch‡ Calamagrostis canadensis (Michx.) Beauv.‡ Calystegia sepium (L.) R. Br.*‡ Capsella bursa-pastoris (L.) Medik.* Carex lacustris Willd. Carex straminea Carex stricta Lam.‡ Castillerja coccinea (L.) Spreng.‡ Chelone glabra L. Chenopodium album L.* Cicuta maculata Cirsium arvense (L.) Scop.*‡ Cirsium vulgare (Savi) Tenore* Conyza canadensis (L.) Cronq.‡ Cornus sericea L.‡ Cornus stolonifera Cuscuta gronovii Willd. ex Schultz‡ Cyperus bipartitus Torr.‡ Cyperus strigosus L.‡ Echinochloa crusgalli* Echinochloa muricata (Beauv.) Fern Eleocharis erythropoda Steud. Eleocharis obtusa (Willd.) J.A. Schultes Elodea canadensis Michx. Epilobium ciliatum Raf.‡ Epilobium hirsutum L.‡

Epipactis helleborine (L.) Crantz. Equisetum arvense L. Erechtites hieracifolia (L.) Raf. ex DC.‡ Eupatorium maculatum L. Eupatorium perfoliatum L.‡ Fragaria virginiana Mill.‡ Gaura biennis L.‡ Galium parisiense L. Galium trifidum L. Geum canadense Jacq. Glyceria striata (Lam.) Hitchc. Helenium autumnale L.‡ Hibiscus moscheutos L.‡ Impatiens capensis Meerb.‡ Iris sp. Iris versicolor L.‡ Juncus tenuis Willd.‡ Lactuca serriola L.*‡ Lathyrus latifolius* Lathyrus palustris L. Leersia oryzoides (L.) Sw.‡ Lepidium virginicum L.‡ Linaria vulgaris L.‡ Liparis loesellii (L.) Rich.‡ Lobelia kalmii L.‡ Lolium perenne L.* Lonicera tatarica L. Ludwigia palustris (L.) Ell.‡ Lycium barbatum L.‡ Lycopus americanus Muhl. ex. W. Bart. Lycopus uniflorus Michx. Lysimachia nummularia L.* Lysimachia quadriflora Sims‡ Lythrym salicaria L.*‡ Melilotus alba Desr. ex Lam.‡ Mentha arvensis L. Mimulus ringens L. Mimulus ringens L.‡ Myriophyllum exalbescens Fern.‡ Myriophyllum spicatum Najas flexilis (Willd.) Rostk. & Schmidt‡ Nepeta cataria L.*‡ Oenothera biennis L.‡ Onoclea sensibilis L. Oxalis stricta Panicum capillare L.‡ Panicum miliaceum L. Parnassia glauca Raf.‡ Penthorum sediodes L.‡

Appendix 1 (continued) Species list of vegetation found on Strawberry Island, NY

Species Species Phalaris arundinacea L. Phragmites australis (Cav.) Trin. Ex Steud. Physocarpus opulofolius (L.) Maxim.‡ Phystostegia virginiana (L.) Benth.‡ Plantago major L.*‡ Poa annua L.* Poa palustris L.‡ Polanisia dpedcandra (L.) DC‡ Polygonum achoreum Blake* Polygonum amphibium L. Polygonum aviculare L. Polygonum convolvulus*‡ Polygonum hydropiper L.‡ Polygonum lapathifolium L.‡ Polygonum pensylvanicum L. Polygonum persicaria L.*‡ Polygonum punctatum Ell.‡ Pontederia cordata L.‡ Populus deltoides Bartr. ex Marsh.‡ Potamogeton crispus L.‡ Potamogeton illinoensis Morong‡ Potamogeton pectinatus L.‡ Potamogeton praelongus Potamogeton pusillus L.‡ Potamogeton richardsonii Potentilla anserina L.‡ Prunus virginiana L.‡ Rhamnus cathartica L.* Rhus typhina L.‡ Ribes americanum P. Mill. Ribes sativum* Robinia pseudo-acacia L.*‡ Rorippa palustris (L.) Besser‡ Rubus idaeus L. ssp. strigosus (Michx.) Focke Rubus occidentalis L.‡ Rumex crispus L.* Sagittaria latifolia Willd. Salix discolor Muhl.

Salix eriocephala Michx. Salix exigua Nutt.‡ Salix fragilis* Salix lutea Nutt. Salix nigra Marsh.‡ Salix purpurea L. Sambucus canadensis L.‡ Saponaria officinalis L.‡ Scirpus acutus Muhl. ex Bigel.‡ Scirpus atrovirens Willd.‡ Scirpus fluviatilis Scirpus pungens Vahl. Scirpus tabernaemontani K.C. Gmel. Scutellaria galericulata L.‡ Setaria glauca (L.) Beauv.‡ Sisymbrium altissimum L.* Sium sauve Walt. Solanum dulcamara L.*‡ Solidago canadensis L.‡ Spartina pectinata Link.‡ Sphenopholis intermedia (Rydb.) Rydb. Spiraea alba Du Roi Stachys tenuifolia Willd.‡ Teucrium canadense L.‡ Thalictrum revolutum DC‡ Thelypteris palustris Schott Tussilago farfara L.‡ Typha latifolia L. Vallisneria americana Michx.‡ Verbascum thapsus L. Verbena hastata L.‡ Veronica americana Schwein. ex Benth. Viola canadensis L. Viola soraria Willd.‡ Vitis riparia Michx.‡ Xanthiuum strumarium L.‡ Zannichellia palustris L.‡

*indicates alien species ‡ indicates species identified by Sweeney (1997)

APPENDIX II

Summary table of major plant species that compose the vegetation of Strawberry Island (terrestrial and aquatic)

Appendix 2Summary table of major plant species that compose the vegetation of StrawberryIsland (terrestrial and aquatic)

Species Community

FF DF PW EM LM SM A Q

A cer saccharum x

A rc t icum m inus* x

Capsella bursa-pastoris* x

Ep ipac t is helleborine x

Prunus v irg in iana x

Rham nus cat hart ica* x

Ribes sat iv um * x

Solidago canadensis x

A lliaria pet io lat a* x x

A st er lat erif lo rus x x

Geum canadense x x

Lact uca serrio la* x x

Lep id ium v irg in icum x x

Rubus occ ident alis x x

Salix f rag ilis* x x

V io la so roria x x

Cornus st o lon if era x x x

Poa annua* x x x

Populus delt o ides x x x

V it is riparia x x x

Im pat iens capensis x x x x x

Sam bucus canadensis x x x x x x

A cer negundo x

A m arant hus ret ro f lexus* x

A sc lep ias sy riaca x

A v ena sat iva* x

Panicum capillare x

Poly gonum av icu lare x

Rhus t y ph ina x

Robinia pseudoacac ia* x

Salix d isco lo r x

Spart ina pec t inat a x

A m brosia art em isiif o lia x x

Chenopod ium album * x x

Plant ago m ajor* x x

Rum ex crispus* x x

Sp iraea alba x x

X ant h ium st rum arium x x

Polygonum persicaria* x x x

Caly st eg ia sep ium * x x x x

Sisy m brium alt issim um * x x x x

So lanum du lcam ara* x x x x

A grim onia st riat a x

A pocynum cannab inum x

A st er nov ae-angliae x

Chelone g labra x

Equisetum arv ense x

Nepet a cat aria* x

Ox alis st ric t a x

V io la canadensis x

Lolium perenne* x x

Appendix 2 (continued)Summary table of major plant species that compose the vegetation of StrawberryIsland (terrestrial and aquatic)

Species Community

FF DF PW EM LM SM A Q

Salix ex igua x x x x

Carex st ram inea x

M im ulus ringens x

Oenot hera b ienn is x

Onoc lea sensib ilis x

Poy gonum am phib ium x x

St achy s t enu if o lia x x

Echinoch loa crusgalli* x

Po ly gonum achoreum * x

A lnus rugosa x x

Po ly gonum lapat h if o lium x x

Ty pha lat if o lia x x

Cirsium arv ense* x x x

Ly t hrum salicaria* x x x x x

A lism a p lan t ago-aquat ica x

Cicut a m aculat a x

Ep ilob ium c iliat um x

Lat hy rus lat if o lius* x

Ly copus unif lo rus x

Ly sim achia num m ularia* x

M ent ha arv ensis x

Phy sost eg ia v irg in iana x

Poa palust ris x

Poly gonum conv olv u lus* x

Rorippa palust ris x

Sag it t aria lat if o lia x

Sc irpus f luv iat ilis x

Scut ellaria galericu lat a x

Sium suav e x

Teucrium canadense x

Calam agrost is canadensis x x

Cirsium v u lgare* x x

Cuscut a gronov ii x x

Leersia ory zoides x x

Ly copus am ericanus x x

Polygonum hy drop ipero ides x x

Carex lacust ris x x x

Carex st ric t a x x x

Gly ceria st riat a x x x

Iris v ersico lo r x x x x

Elodea canadensis x

M y riophy llum sp icat um * x

Pot am ogeton crispus* x

Pot am oget on illinoensis x

Pot am oget on pec t inat us x

Pot am oget on praelongus x

Pot am oget on pusillus x

Pot am oget on richardsonii x

V allisnera am ericana x

Zannichellia palust ris x

APPENDIX III

Means (Std) of environmental variables on Strawberry Island by plant community

Appendix 3Means (Std) of environmental variables on Strawberry Island by plantcommunity

W ater Table

Depth

(m)

A-

Horizon

Depth

(m)

Number

of Stems

Tree

Height

(m)

% Sand %

Silt/Clay

% Gravel

Sedge Meadow 1.05

(0.48)

0.50

(0.17)

0.00

(0.00)

0.00

(0.00)

3.33

(8.16)

96.76

(8.16)

0.00

(0.00)

Floodplain Forest 2.09

(0.42)

1.73

(2.12)

3.70

(2.11)

24.44

(2.97)

35.60

(42.00)

59.00

(47.50)

5.40

(10.99)

Degraded Floodplain

Forest

1.35

(0.24)

0.26

(0.13)

0.20

(0.45)

0.37

(0.82)

2.80

(3.56)

97.20

(3.56)

0.00

(0.00)

Planted Willow Shrub 1.53

(0.16)

0.50

(0.20)

0.00

(0.00)

0.00

(0.00)

28.3

(44.80)

71.70

(44.80)

0.00

(0.00)

Shallow Emergent Marsh 1.40

(n/a)

0.65

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)

Loostrife Marsh 0.85

(n/a)

0.35

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)

0.00

(n/a)