gr e a t l a k e s a l va r s - the ontario aggregate ... · wh y s h o u l d a l va r s b e p r ot...

Gr e a t L a k e sA LVA R S

The earliest visitors to the Great Lakes region were in awe of the magnificent hardwood forests

found there. But, in contrast to these lush groves, early settlers also found scattered examples of

flat, barren and largely treeless limestone openings — unique landscapes now known as alvars.

These rare habitats still exist where flat areas of shallow limestone bedrock have been left undis-

turbed. More importantly, however, we now know that these openings are far from barren, for

they are home to myriad distinctive plants and animals.

G R E AT L A K E S A L V A R S 3

Great Lakes Alvars

opposite: Garden Peninsula, Michigan

below: Prairie smoke, above: Indigo bunting

The term alvar is used to describea type of natural community,much as we use words like prairieor wetland to describe grassy ormoist areas. Alvars are areas of rel-atively flat limestone bedro c kwhere soils were long ago scrapedaway by ice, wind and water.To d a y, alvars thrive where envi-ronmental extremes create natu-rally open landscapes. They sup-port a distinctive set of plants —uncommon wild-flowers, mosses and lichens, many kinds of grass-es and sedges, and even some stunted trees. Theiranimal life is special too, particularly their birds,land snails, leafhoppers and other invertebrates.

The environment of alvar areas is harsh —too harsh, in fact, for most trees to grow.

Alvar, west of Misery Bay, Manitoulin Island

When the summer sun shines,alvars are hot; temperatures canreach 43oC at the rock surface.When the winter winds blow,they are cold; so cold that nee-dle ice crystals churn up whatlittle soil there is.

In spring, most alvars col-lect water in shallow pools andb e d rock pockets, and someareas remain flooded for weeks.

By early summer, with the pools long gone,the shallow soils dry to a crisp and many ofthe flowering plants begin to turn brown.

This combination of flooding anddrought holds off the invading trees. Springflooding and shallow soils discourage treesand shrubs from taking root, and summerdrought, especially during very dry years,finishes off those that have begun to get

established. Somealvars also have are c o rded historyof past fires, andthe presence ofcharcoal on manysites indicates thatwildfires also mayhave contributedto their open char-acter.

above: Barrie Islandalvar grassland,Manitoulin Island

The environment of alvar areas is harsh — too harsh, in fact, for most trees to grow.

4 G R E AT L A K E S A L V A R S

Habitat for the Hardy

C reeping juniper on alvar pavement,Misery Bay, Manitoulin Island



North America’s alvars are concentrated with-in the watersheds that drain into the GreatLakes. Most of them are found in an arc thatextends just south of the Canadian Shieldf rom Michigan’s upper peninsula, thro u g hManitoulin Island, the Bruce Peninsula andthe limestone plains of southcentral and east-ern Ontario, to northern New York state. Inaddition, a few alvars are sprinkled at othersites such as the western end of Lake Ontario,in the western Lake Erie region, Wisconsinand Quebec, and along several rivers wherelimestone ledges are exposed. Elsewhere inthe world, alvars are found in the Baltic regionof Europe, in Estonia and on islands off thecoast of Sweden.

Scientists in Europe have long beenaware of the existence of alvars, but only inrecent years have scientists and naturalists inNorth America recognized that they occurhere as well. When field biologists began toobserve that certain species of plants and ani-mals were found mostly in open and lightlywooded habitats on flat limestone bedrock,they realized that this habitat has its own dis-tinctive ecology. As the awareness of alvarss p read, re s e a rchers documented more than120 alvar sites across the Great Lakes basin,largely through a coordinated study called theInternational Alvar Conservation Initiative.

top: Blue-eyed grass below: Alvar with jack pine, Bruce Peninsularight: Belanger Bay alvar, Manitoulin Island

Globally Rare Habitats

WH Y S H O U L D A LVA R SB E P R OT E C T E D?

Alvars are important sites for conservation for a variety of reasons:

• They are globally rare habitats found only in a few places on earth;

• They support many rare plants, birds andinvertebrates.

• Some sites have forests of ancient stuntedtrees dating back 300 to 500 years.

• They demonstrate how plants and wildlifeadapt to living in harsh environments.

• They have potential economic benefits to local communities as ecotourism destinations.

G R E AT L A K E S A LV A R S 7

AGreat Lakes Legacy

The limestone bedro c kassociated with alvar com-munities was formed inwarm, shallow tropical seasbetween 460 and 370 mil-lion years ago. More recent-ly, glacial action has shaped

the Great Lakes region, forming the land-scapes we see today. The Wisconsin glacia-tion, beginning around 65,000 years ago, wasthe most recent and most influential in creat-ing the alvars of today.

Alvars have always re p resented a tinyfraction of the landscape. Their curre n textent is estimated to be about one-fifth ofone percent of the land area in the GreatLakes basin. About two-thirds of the totalalvar area is in Ontario. Alvars on DrummondIsland and elsewhere in Michigan account forapproximately 15 percent of the Great Lakestotal, Jefferson County in northern New Yorkstate has about 16 percent, and the Marble-head Peninsula and Lake Erie islands in Ohioaccount for most of the remaining four per-cent of the total.

above: Belanger Bay, Manitoulin Islandinset: Purple-stemmed cliffb r a k e fernright: Maxton Plains, Drummond Island,Michigan, little bluestem grassland

8 G R E AT L A K E S A LV A R S

Scattered across the Great Lakes basin are a small number of alvar sites that

are presently protected, either as publically owned parks or private reserves.

Alvar sites occur primarily within a series of nine clusters:

• Garden Peninsula and Lake Michigan, wherealvars are clustered along the shoreline ofMichigan’s Upper Peninsula;

• Drummond Island and northern Lake Huronsites in Michigan, with many high-qualityalvars in close proximity;

• Manitoulin Island, in Ontario, with many sitesalong the gently sloping south shore and several very significant alvar areas on LaCloche

and other islands along thenorth shore;

• Ontario’s Bruce Pen-insula, where alvars areclustered along the west-ern shore and on the flatpoints and peninsulas ofthe Georgian Bay shore;

• Western Lake Erie, withalvar sites on Pelee Islandin Ontario and Kelley’sIsland and the MarbleheadPeninsula in Ohio;

• Carden Plain, in central Ontario, with alvarsites set among grazed grasslands and forests;

• Napanee Plain, just north of Lake Ontario,with a scattering of related sites;

• Smiths Falls Plain, in eastern Ontario, with the significant Burnt Lands site as well as several smaller alvars;

• Northern New York state, with ChaumontBarrens and several other significant alvar sites.



DifferentTypes of AlvarsAlvars can be divided into five main groupsaccording to the plants found there.

Alvar pavements occur on very exposed rock.They are most frequently found on the BrucePeninsula and southern Manitoulin Island.Moss and lichens are the most important partsof these communities, along with plants suchas early saxifrage, false pennyroyal and tickle-grass. In this barren landscape, plant commu-nities can only take root in bedrock cracks andwhere depressions in the rock have caughtrainwater.

Alvar shrublands have moderate to highcover of shrubs, but very few larger tre e s .These areas support such species as shrubbycinquefoil, creeping juniper, common juniperand fragrant sumac. The dominant shrubs

vary according to each site’s location withinthe Great Lakes basin.

Alvar savannas have scattered trees that coverbetween 10 and 25 percent of their are a .Savannas can look strikingly diff e rent fro mone another. For example, on Pelee Island inLake Erie, chinquapin oak and blue ash savan-na form a very rare community type. Furthernorth along the shores of northern LakeHuron, white cedar and jack pine savannasprovide suitable conditions for such unusualplants as dwarf lake iris and lance-leaved core-opsis.

left: Burnt Lands Alvar pavementleft inset: Oak savanna, Pelee Islandinset above: Early saxifrage on alvar pavementbelow: Dwarf shrub alvar, Manitoulin Island

Little LaCloche Island alvar gra s s l a n d


Alvar woodlands have the densest cover of trees, but patches ofexposed bedrock or openings are still common. Conifers such aswhite spruce, white cedar and white pine are common in alvar wood-lands across the Great Lakes basin and alvar woodlands in easternOntario and New York state are often dominated by red cedar.

Alvar grasslands have enough shallow soil to support grasses andsedges. The mix of species varies from site to site and is related, inlarge part, to the extent of flooding in the spring or after rainstorms.Species characteristic of alvar grasslands include tufted hairg r a s s ,Crawe’s sedge, prairie dropseed and little bluestem.

above: Carden alvar woodland

below: Northern leopard frog

ALVA R S: TH E GR E AT LA K E S’ NE W E S T AN C I E N T FO R E S T

How can an ancient forest be new? Bybeing so well disguised that no one sees itfor what it is! Most people know aboutold-growth forests from images ofmajestic white and red pines in the areaaround Lake Temagami but only now arewe hearing about the s l ow-g row ingancient cedars on the cl i ffs of Ontar io’sNiagara Escarpment. And as recent ly as1995, another class of ancient forestwas identified on some Bruce Peninsulaalvars. On these coastal alvars, an amaz-ing discovery was made —--the twisted,gnarled trees were between 300 and 500years o ld . So now these anc ient , und is -turbed alvar communities have becomethe newest member of the old-growth

Twisted, gnarled trees on Bruce Peninsula coastalalvars are between 300 and 500 years old.


TheSecret Lifeof Alvar Plants


A recent study of the botany of Ontarioalvars lists 19 species of vascular plants thatrarely occur elsewhere. False pennyroyal, ablue-flowered member of the mint family, isone of the most faithful to alvar habitats.Other characteristic alvar plants includeprairie smoke, Crawe’s sedge, early butter-cup and upland goldenrod.

T h e re are other interesting variations ofplant specialties as well. The alvars of theBruce Peninsula, Manitoulin Island andadjacent areas in northern Michigan arenotable for their arctic-alpine species suchas wild chives, red anemone and alpinebluegrass. In contrast, plants more typicalof the southern United States, such asdowny wood mint, are found on the alvarsof western Lake Erie, with other southernspecies on the Napanee and northern NewYork state alvars.

One of the rarest of alvar plants is the yel-l o w - f l o w e red Hymenoxys herbacea. Thisattractive wildflower has few occurrencesbut many names, depending on whom youask and where you are. On ManitoulinIsland, for example, it’s called Manitoulingold, on the Bruce Peninsula, it’s rubber-weed; and on Ohio’s Marblehead Peninsula,it’s known as lakeside daisy.

left: Indian paintbrushtop: False pennyroyalcentre: Lakeside daisybottom: Prairie smoke

At first glance alvars may appear

barren, but they are actually rich

in distinctive plants.

G R E AT L A K ES A L V A R S 15

Blazing star

HarebellBlue-eyed grass

Lance-leafed coreopsis


MO S S E S, LI C H E N S A N D AL G A E

In addit ion to vascular plants, alvars sup-port many other life forms that possess thehardiness needed to survive in an environ-ment of extremes. Lichens are much moreabundant in a lvars than in surroundingwoodlands. As well, a number of mosses andlichens occurring on alvars are quite rare inthe Great Lakes region, including somecharacteristic of arctic-alpine regions andothers typical of northern areas.

Unexpectedly for such a dry summerhab i tat , a d ive rse m ix o f a lgae abound onalvars: gelatinous sheets of Nostoc algaethat dry up to a crunchy crust; microscop-ic blue-green algae that coat the rocks darkgrey; and even orange fuzzy structuresthat look l ike a moss but are actual lyTrentepolia algae. Some 46 k i nd s o f a l g aehave been identified from sites on the BrucePeninsula. But that’s not even scratchingthe surface. One slimy ball of algae wasestimated to contain hundreds of species!

above: Moss and lichen on limestone

Indian paintbrush and bluets

Balsam ragwort


The open grasslands and scatteredsmall trees that characterize somealvar communities are home tomost of Ontario’s remaining popu-lations of the endangered logger-head shrike. Alvar grasslands onManitoulin Island support prairiesharp-tailed grouse; and alvarshrublands are home to rufous-sided towhees, indigo buntings,brown thrashers and clay-coloureds p a r rows. Because most of thesespecies are undergoing long-termpopulation declines across easternNorth America, the conservation ofthese habitats is especially impor-tant.

top: Eastern bluebirdbelow: Brown thrasher right: Loggerhead shrike insets: Upland sandpiper, Bobolink

Alvar Birds The fa

fauna of alvars is just as distinctive as the flora.


Alvar grasslands are home to sharp-tailed grouse seenhere performing their mating dance.

Vesper sparrowClay-coloured sparrowSharp-tailed grouse


A WO R L D O F TI N YCR E AT U R E S

Alvars are particularly remarkable forthe i r d i ve rs i ty of invertebrates .Butterf l ies that are rare in the GreatLakes region can be found on alvars;for example, the Gar i ta skipper onLaCloche Is land north of Manitoul in, asite located over 1,000 k i lometreseast of the next closest population, orthe o l ive ha i r s t reak on Ontar io ’ sNapanee Plain. Many insects more com-mon to the grass lands of the westernplains also live on alvars, includingra re ground beetles, sawf l i es andflightless leafhoppers. As well, some26 species of land snails thought to benew to science have been found onalvars and are in the process of being


olive hairstreak


L a f a rge Quarry, Marblehead Pe n i n s u l a , O h i o

The most notable of the threats to Great Lakes alvars include quarrying,land development, certain recreational activities, cattle grazing, invasion of exotic species, and forestry.

QuarryingLoss of alvar habitats to rock quarries has taken place across the Great Lakesbasin and continues to be the number one threat to alvars in many places. Almostany alvar within trucking distance of a major urban market is threatened.

Development. The construction of rural res-idences, cottages and second homes, trailerparks and other forms of low-density ruraldevelopment is an ongoing threat to manyalvar habitats. Shoreline alvars are especiallyat risk.

Recreation. The disparate activities of gar-dening and off - road motoring both posethreats to alvar habitats. The flat, open ter-rain and remoteness of some alvar are a sattract trail bike, off - road truck, and AT Venthusiasts, whose vehicles cause ruts thatdisrupt critical water flow patterns and createconditions suitable for the invasion of exoticspecies. As well, the removal of stunted old-growth cedars and other trees by bonsai col-lectors is a serious management problem onBruce Peninsula alvars; and showy wildflow-ers such as dwarf lake iris are at risk fromgardeners who try to transplant them.

Exotic Species. An array of foreign plantsand animals have become established onsome Great Lakes alvars. Problematic speciesinclude common buckthorn, honeysuckles,dog-strangling vine and mossy stonecro p .These exotic or foreign species compete forspace and nutrients on alvars and canbecome dominant at the expense of thenative species.

Forestry. The logging of mature trees fromalvar woodland communities can significant-ly alter the vegetation structure of a site.Some alvar areas have been used as skidwaysand log assembly areas, resulting in seriousdamage from ruts and debris accumulation.The establishment of conifer plantations andChristmas tree farms has also destroyed somealvar habitats.

Alvars atRisk

inset: Dog-strangling vinebelow: Cattle grazing at Carden alvar


While alvar habitats might be harsh and inhospitable places for trees andmany other plants, they are also fragile and vulnerable to the threats posed bya growing human population in the Great Lakes basin.

Protected Places

Scattered across the Great Lakes basin are a small number of alvar sites that are presently protected, either as publically

owned parks or private reserves.

In New York state, The Nature Conservancy(TNC) owns parcels of alvar habitat at LimerickCedars and Chaumont Barrens. Both sites havesupported research on aspects of alvar ecologyas diverse as hydrology, frost heaving and inva-sion of non-native species. Chaumont featuresa self-guided interpretive trail, an interpretivekiosk and an excellent trail-guide brochure.

Maxton Plains, on Michigan’s DrummondIsland, covers 3,200 hectares and ranks as oneof the largest and least disturbed alvars in theworld. Most of the site is owned by the state,but TNC also has two preserves in the area.Maxton Plains is the best representative alvar inMichigan, with prairie dropseed, prairie smokeand other unusual plants growing in profusion.

Ram’s head lady’s slipper orchidMaxton Plains: shallow water covers most of the alvar in late spring.


t o p : Chaumont pavement barrens ; b o t t o m : f i s s u res at Chaumont Barrens


One of the best places to see lake-side daisy (or whatever you maycall it) is in an Ohio State NaturePreserve on Kelley’s Island, where ahistoric quarry has re g e n e r a t e dinto an interesting plant communi-ty with several alvar species.Lakeside daisy is also abundant atthe Federation of Ontario Nat-uralists’ Bruce Alvar Nature Reserveon the upper Bruce Peninsula. This 68-hectare site, purchased by the FON in 1993,includes alvar pavements dominated by aground cover of moss and herbaceous plantsand coniferous woodlands dominated by jackpine. It provides habitat for the threatened

e a s t e rn Massassaga rat-tlesnake and manyp rovincially rare plants.Several other alvar areasare protected within theBruce Peninsula National

Park and provincial nature reserves on theupper Bruce Peninsula.

On Ontario’s Manitoulin Island, spectac-ular alvar landscapes can be found in aremote, lonely wilderness setting at the MiseryBay Provincial Nature Reserve. Here you willfind lakeside daisy, jack pine alvar savannasand alvar pavements with a complement ofarctic-alpine plant species. In eastern Ontario,a provincial nature reserve and lands acquiredby the Nature Conservancy of Canada protectsignificant sections of the Burnt Lands Alvar.

above left: Burnt Lands Alvar; above right: Massassaga rattlesnake, Bruce Alvar Nature Reserve

below: Lakeside daisy transplant site on Kelley’s Island, Ohio


Boardwalk at FON’s Bruce Alvar Nature Reserve

Misery Bay



WO R K I N G CO O P E R AT I V E LYW I T H PR I VAT E LA N D O W N E R S

Ontario’s Carden Plain is a place where forestsgive way to farmland and ancient granite out-crops yield to younger limestone plains. TheCouchiching Conserv a n c y, a local nonpro f i tland trust, is working with local cattle ranchersto raise awareness about the biological value oftheir lands and to identify farming practicesthat will not harm the alvar. The conservancyhas also enlisted the support of a wide range ofagencies, municipalities and other conservationgroups to develop a joint long-term conserva-tion strategy for Carden. A determined localg roup, strong landowner involvement andstrategic assistance by provincial, national andinternational groups make a potent combina-tion. Carden may well provide a model forcommunity-based alvar conservation elsewherein the Great Lakes region.

While several fine exam-ples of alvar habitats are inparks and re s e rves, thevast majority of alvars inthe Great Lakes region arenot protected. The Intern-ational Alvar Conserv a-tion Initiative, a thre e -year study involving over50 collaborators fro mCanada and the United States, identified highpriority sites for protection. Almost one- thirdof the highest-priority alvar sites occur onManitoulin Island, highlighting its importanceas the epicentre of North American alvar

diversity. The results of thisstudy are summarized in atechnical report, C o n s e r v-ing Great Lakes Alvars,which is available from TheNature Conservancy.

Each of the state andp rovincial jurisdictionswithin the Great Lakesbasin have also produced

summary reports on their alvars, highlightingimportant sites. The FON has sponsored anAlvar Theme Study for Ontario, whichdescribes sites that should be protected infuture land-use planning decisions.


PR I O R I T I E S F O R PR OT E C T I O N

The Belanger Bay alvar site on Manitoulin Island boasts thousands of specimens of

lakeside daisy as well as other rarities such as dwarf lake iris and Houghton’s goldenrod.


ALVA R MA N AG E M E N TJust because a site is owned by a publicagency or conservation organization does notmean that it is entirely protected. Many pro-tected alvar sites require ongoing manage-ment in order to preserve their natural her-itage values. TNC preserves in Michigan andnorthern New York have been used as sitesfor a range of research projects, includingexperimental treatments of invasive plantspecies to evaluate potential control meth-ods. Interpretive signs and materials, alongwith boardwalks and parking facilities, havebeen developed to increase the educationaldimension of these sites and to contro laccess. The FON’s Bruce Alvar NatureReserve includes an interpretive boardwalkdesigned to minimize pedestrian damage tothe site.

Prescribed burns have been used to renewStone Road Alvar on Pelee Island, and exper-imental transplanting and seeding of lakesidedaisy have been successfully carried out onOhio’s Kelley’s Island nearby.

PR I VAT E ST E WA R D S H I PWith so much of the Great Lakes’ limestoneplain in private ownership, private steward-ship is an essential means of conserving alvarhabitats. Interested landowners can makeimportant contributions to alvar conserv a-tion by not overgrazing areas, by restrictingre c reational vehicles, and by minimizingother disturbances. Several landowners areparticipating in research projects to help fur-ther clarify alvar ecology and managementquestions; others allow access to naturalistsand scientists to gather field data. Stew-ardship information can be obtained fromthe contact groups listed opposite.Prescribed burn at Stone Road Alvar, Pelee Island


PR OT E C T I N G T H E GR E AT LA K E S’ LI M E S TO N E LE G AC Y

We now know that alvars are special places that form a valuable part of the natural legacy ofthe Great Lakes region. We also know that their future is in jeopardy. Conservation groupsand government agencies, from the local to the international, have begun working to pre-serve alvar habitats, but they need your help. If you are fortunate enough to be an alvarlandowner, take the time to learn about their ecology and how they can be protected. Buteven if you are not a landowner, you can still be involved by supporting the projects of con-servation organizations and enlisting the support of others. By working together, we canensure that this unique limestone legacy will be passed on undamaged to future generations.

For more information aboutalvars and their natural heritagevalues, please contact:

Federation of Ontario Naturalists355 Lesmill Road, Don Mills, Ontario M3B 2W8(416) 444-8419 or 1-800-440-2366

The Nature ConservancyGreat Lakes Program8 South Michigan Avenue,Suite 2301, Chicago, Illinois 60603(312) 759-8017

The Nature ConservancyEastern Lake Ontario Project Office7 South Jefferson Street, Suite 3, Pulaski, New York 13142(315) 298-2040

Natural HeritageInformation Centre,Ontario Ministry of Natural ResourcesBox 7000, Peterborough,Ontario K9J 4Y5(705) 755-2167

Division of Natural Areas and Preserves, Ohio Department of Natural ResourcesFountain Square, Building F,Columbus, Ohio 43224(614) 265-6471

Michigan Natural Features Inventory8th Floor Mason Building,P.O. Box 30444, Lansing, Michigan 48909(517) 373-1552

The information in this booklet was compiled by Anthony Goodban,based on research from the International Alvar Conservation Initiative.Technical advice was provided by Ron Reid, John Riley, Heather Potterand Carol Reschke. Financial assistance was received from the CharlesStewart Mott Foundation and the Great Lakes Protection Fund.

Cover photo: Lakeside daisy / Robert McCaw

Layout and design: Judie Shore

Printed in Canada by Dolco Communications

Early saxifrage / Robert McCaw

Great Lakes Program

gr e a t l a k e s a l va r s - the ontario aggregate ... · wh y s h o u l d a l va r s b e p r ot...

Documents