Forests are almost always spoken of in terms of the trees that define
their appearance. Carolinian forest in Ontario are dominated by
two tree species: American Beech (Fagus grandifolia) and
Sugar Maple (Acer saccharum), but they also commonly contain
Basswood (Tilia americana), Red Maple (Acer rubrum),
Red Oak, (Quercus rubra), White Oak (Quercus alba)
and Bur Oak (Quercus macrocarpa).
Photo by Alan Ernst.
Photo by Alan Ernst.
of Spring. Photo by Daniel Reed at www.2bnthewild.com.
makes the Carolinian forest unique though is the presence of rare
plants found only in this ecosystem including trees and shrubs such
as the Kentucky Coffee Tree (Gymnocladus dioicus), Black
Gum (Nyssa sylvatica), Black Walnut (Juglans nigra),
Sassafras (Sassafras albidum), Pawpaw (Asimina triloba)
and Tulip Tree (Liriodendron tulipifera), together with herbaceous
plants like the Harbinger of Spring (Erigenia bulbosa). Forty
percent of Ontario's rare plants can be found only in the Carolinian
have a way of surviving that is different from smaller plants. Trees
must compete with each other for light: the more mature a forest
is the taller the trees are, the fewer trees are present and the
higher up the tree canopy is.
the layer formed by tree branches and their leaves.
deciduous forests, lower tree branches do not receive enough light
to be useful to the tree and they do not persist, resulting in
a high canopy. Trees must be able to transport water and nutrients
a great distance from their roots to their leaves. This is done
via the trees vascular system, which is a ring of vertical tubes
that exists in the youngest tree layer, just under the bark, called
the vascular cambium.
transportive; as veins and arteries are to animals. 'cambium':
is why cutting into a tree beyond its protective bark can be very
harmful. Trees need to produce new vascular tissue every year as
the old tissue dries out and becomes part of the tree's central
heartwood. This is a major difference from herbaceous plants, which
die to the ground every year. Herbaceous plants have vascular tissue
in the centre of their stems, where it is most protected in the
Carolinian forests are almost entirely deciduous, they look very
different in winter than they do in summer. Deciduous trees shed
their leaves every fall and grow new leaves in the spring.
forests are aglow with light green in the spring when there is still
a great deal of light penetrating to the forest floor and new leaves
are opening from their buds. In summer, these forests become darker,
as the leaves darken and grow to capture sunlight, blocking sunlight
from the plants below. As a result, many herbaceous plants in these
forests flower in spring to take advantage of the available sunlight
and become dormant in summer, losing their leaves and disappearing
from view during the time when there is less light.
Lily. Photo by John MacRae.
Photo by John MacRae.
Trilliums. Photo by Alan Ernst.
such as ferns that are adapted to lower light levels remain. Where
taller trees are not growing as densely, there is a greater number
of shrubs in the understory. These shrubs are often spindly and
tall and take on horizontally branching forms as they stretch up
and out to enable their leaves to reach the filtered light. Many
of these shrubs have intriguing flowers, such as Witch-hazel (Hamamelis
virginiana), as do many Carolinian tree species (e.g. the Tulip
Tree, Liriodendron tulipifera). The presence of many flowering
trees and shrubs is another unique feature of Carolinian forests.
group of organisms that is very important in forests is the fungi.
Fungi used to be considered plants that lack chlorophyll.
the molecules that plants use to convert sunlight and carbon
dioxide to energy in the form of carbohydrates and that are
responsible for the green colouration of most plants.
Photo by Barry Cherriere.
are now considered to be a distinct group, separate from plants,
but are still often discussed in the same context. Fungi are composed
mostly of thin, threadlike structures that live underground or inside
plant tissues. We only notice fungi when they send out their fruiting
bodies, some of which are commonly called mushrooms, but it is the
invisible networks that do the work that fungi are famous for: decomposition.
fungi exist with other organisms in associations called symbiosis.
In some cases structures called mycorrhizae are formed from the
tissues of both fungus and plant acting in a mutualistic way so
that fungus habitat is often limited to the area around or inside
the actual tissue of other organisms, often trees.
term 'symbiosis' means 'living together, and may be
'parasitism' where one organism feeds off the other
in a harmful relationship or may be 'mutualism' where
both organisms benefit.
on tree. Photo by Barry Cherriere.
main location for forest fungi is on or near trees where you can
easily find them on both living and dead trunks or on rotting
fungi may be living parasitically on the tree, might be behaving
in a mutualistic way, or might be simply feeding of already dead
tissue which is called saprophytism.
Other less conspicuous organisms in forests include the mosses...
are non-vascular plants.
are organisms that are actually an algae and a fungus living
in a mutualistic symbiotic state on trees or rocks.
groups rely on outside moisture because they lack vascular tissue
and so are often found in moist woods. In times of drought they
go dry and dormant but do not necessarily die. Lichens are very
sensitive to pollution and have been greatly reduced in numbers
locally over the last century.
and Shrub Species of Carolinian Forests
Photo by Alan Ernst.
Herbaceous and Vining Carolinian Forest Plant
of Spring (very rare)
Ivy (often a woody vine)
Poppy (very rare)
Trillium (very rare)
Mustard - invasive alien