Cover Story
Endangered Ecosystems: Carolinian Zone
By Lorraine Johnson
Botanists have wrangled over its proper name for more than
a century. Scientists still debate its boundaries. But in the 23
years since Ontario Nature first published a special issue of this
magazine (then called Seasons) devoted to Carolinian Canada,
the unique nature of this region has been celebrated by naturalists
and gained currency in the popular imagination.
The Carolinian zone is tucked into the southwestern corner
of Ontario, spreading south from an imaginary line connecting
Toronto to Grand Bend and all the way down to the
southernmost tip of Canada. Surrounded along all but its
northern border by significant bodies of water, the region
has the warmest climate in Ontario.
Though small in size, at approximately 22,500 square
kilometres, the Carolinian zone is rich in biological diversity.
According to Michelle Kanter, executive director of the
Carolinian Canada Coalition, “the Carolinian life zone is one
of the most diverse landscapes in North America in terms
of natural habitat. Still, it is a struggle for Canadians to recognize
what is on their doorstep in southwestern Ontario.”
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Close to 400 bird species have been recorded here, representing
more than half of all bird species in Canada. Two-thirds of
Ontario’s plant species grow in the region. Unique woodlands,
grasslands and wetlands dot the landscape, and southern
species find a home at the northernmost edge of their
ranges. The region provides habitat for many species of
flora and fauna found nowhere else in Canada – from the
majestic tulip-tree (for many naturalists, the region’s iconic
species) to the pointy-faced opossum, North America’s
only marsupial.
The Carolinian zone is perhaps best known for its lush
woodlands. In spring, ephemeral groundcovers bright
with colour carpet the forest floor, and vernal pools in
moist swamps are alive with the chorus of frogs. Trees
with unusual and evocative names – Kentucky coffee-tree,
cucumber magnolia, black gum, and pawpaw – can be found
in the region, which has the highest diversity of tree species
of any forest region in Canada. And species new to Ontario,
such as pumpkin ash and swamp cottonwood, are still being
found, amazing discoveries considering that the Carolinian
zone is not at all remote and is possibly the most heavily
settled region in Canada.
In areas where soil, microclimate and historic fires
(either ignited by lightning or intentionally set by Aboriginal
Peoples) favoured grasslands rather than forests, prairies
and savannahs endure, though many of them are now small,
isolated pockets. The tallgrass prairie, more familiar from
the midwestern United States, extends into Ontario’s Carolinian
zone and slightly beyond, supporting a mix of grasses
such as big bluestem and Indian grass and wildflowers such
as blazing star and culver’s root. Oak savannah shares many
of these grassland herbaceous species but also includes
open-grown trees such as black oak and bur oak.
Of the various wetland types found in Carolinian Canada,
the coastal marshes along the shores of Lake Erie are some of
the best remaining examples of the vast wetland complexes
that existed prior to European settlement.
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Today, the Carolinian region is home to roughly onethird
of the country’s human population, and the natural
habitats of Carolinian Canada are under increasing pressure.
Development, intensive agriculture, pollution and
invasive species have all taken their toll. Though it comprises
less than 1 percent of the nation’s total land area,
Carolinian Canada is home to one-third of the country’s
rare and endangered species.
In 1984, conservation groups including Ontario Nature,
World Wildlife Fund Canada and the Natural Heritage
League banded together to form the Carolinian Canada
Coalition. It works to educate the public about the unique
nature of this special region and to implement the Big
Picture, a collaborative vision for healthy landscapes
in southwestern Ontario. For more information, visit
the Carolinian Canada website (www.carolinian.org).
By Lorraine Johnson
Carolinian Canada Curiosities
Southern Flying Squirrel
A small mammal that glides
through the air, “flying” from tree to tree.
Swamp Rose Mallow
The largest native flower in Ontario,
a member of the tropical hibiscus family.
Eastern Prickly Pear
A native cactus found in the wild in
Canada only at Point Pelee National Park and three other
locations in southwestern Ontario.
Eastern Hog-nosed Snake
A harmless but fierce-looking
snake that raises and inflates its head when alarmed.
Wavy-rayed Lampmussel
Attaches itself at its larval stage to
smallmouth bass.
Eastern Sand Darter
A small, translucent fish that hides in
the sand with only its eyes exposed.
Opossum
North America’s only marsupial, the female of
which raises its young in its small pouch.
Eastern Spiny Softshell
A turtle with a rubbery “pancake”
shell and a snorkel-like nose.
Paw Paw
A tree that bears Ontario’s largest edible native
fruit, which tastes like a tangy cross between banana
and apple.
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AN ENTOMOLOGICAL GEM
It’s a question that sounds more like Zen koan than science: is the
Ojibway Prairie Complex a hot spot for insect diversity simply because
so many naturalists are looking for insects there? Paul Pratt,
City of Windsor’s chief naturalist, acknowledges the notion’s appeal
but ultimately rejects it, citing prairie habitat as the key factor
that accounts for Ojibway being such an entomological gem. “It’s
still pretty easy to find new insect species here,” he says, having
made a number of discoveries himself.
Of the estimated 30,000 known insect species in Canada, more
than 2,000 have been found in the Ojibway Prairie Complex. Recent
records include 16 species new for Canada and six species new for
Ontario. One of the rarest insects, a small Psilidae fly, was discovered
at Ojibway – the only known site in the world for the species –
and is now appropriately named Loxocera ojibwayensis.
Butterflies and Moths
More than 300 species of butterflies and moths have been found
at Ojibway, which often has the highest numbers of any area surveyed
in the North American Butterfly Association’s annual counts.
Three Ojibway butterfly species are considered imperilled in
Ontario, seven are rare to uncommon in the province and 17 are
rare in the region. One prairie moth new to Ontario was discovered
in the Spring Garden Natural Area in 1994.
Grasshoppers, Crickets and Katydids
These jumping insects of the order Orthoptera account for the summer
cacophony of song at Ojibway. The snowy tree cricket even
tells the temperature – the number of chirps in 13 seconds, plus 40,
equals the temperature in Fahrenheit degrees.
“True” Bugs
Distinguished by their piercing and sucking mouthparts, true bugs
(of the order Hemiptera, meaning “half wings”) often use their
needle-like mouthparts to extract fluids from plants. Predatory
ambush bugs hide in flowers such as black-eyed Susan and goldenrod,
waiting to catch bees, flies and butterflies – prey much larger
than themselves.
Mayflies
Adult mayflies live for just a few hours or days, neither drinking nor
eating, simply mating in swarms and then returning to water to lay
their eggs. Clouds of mayflies emerge along the shores of Lake Erie
and Lake St. Clair in mid-June.
Spiders
From the fierce-looking orb weaver spider, with its prominent jaws,
to the camouflaged crab spider, which changes colour to match
its surroundings, Ojibway is home to a large variety of arthropods.
Spider numbers can reach as high as 100,000 per hectare at the
height of summer, when insect prey is likewise abundant.
Lorraine Johnson
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