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Forestry Introduction
1) Types of Trees
2) Types of Forest
3) Forests in Manitoba
Types of Trees
• There are essentially 3 types of trees,
however 2 of them can overlap into 1
category:
– Deciduous Trees
– Evergreen Trees
– Conifer Trees
Deciduous Trees
• The word Deciduous means "falling off at
maturity" or "tending to fall off“.
• In a more general sense, deciduous
means the dropping of a part that is no
longer needed, or falling away after its
purpose is finished.
Deciduous Trees
• These are trees or shrubs that lose their
leaves seasonally.
• They will also lose other plant structures
such as petals after flowering or fruit when
ripe
Abscission
• The process of losing leaves or parts of
the tree is called abscission.
• Leaf loss typically coincides with the winter
months.
• These will be in temperate or polar
climates.
Abscission
• In other parts of the world, including
tropical, subtropical, and arid regions,
plants lose their leaves during the dry
season or in seasons with reduced rainfall.
Semi- Deciduous
• Some trees will be semi-deciduous; they
lose old foliage as new growth begins to
appear. This does not depend on the
season or the rainfall.
• Mimosa bimucronata
Semi- Deciduous
• Some Deciduous trees even keep their
leaves through the winter. For example, a
few species of oak, have desiccated (dried
out) leaves that remain on the tree through
winter.
• These leaves are called marcescent
leaves and are dropped in the spring as
new growth begins.
Process of Leaf Colour Change
and Drop
• Lots of signals and changes have to
happen for leaves to change their colour
and then drop.
• Plants make food through a process called
photosynthesis.
• Leading up to and into the fall months,
plants will stop replenishing the pigment
chlorophyll in their leaves.
Other Pigments
• This allows for other pigments in the
leaves to become apparent, resulting in
yellow, orange or brown folliage made
from a pigment called Carotenoid. Leaves
can also be red or purple and made from a
pigment called Anthocyanin.
Dropping the Leaves
• Lots of bright colours will only come in
areas where the autumn days are short
and the nights are cool. If the autumn is
too cool, leaves will simply fall without
changing colour.
• To physically drop a leaf, the leaves stop
producing a hormone called auxin. In the
absence of this hormone there is a break
in the connection from the leaf, called the
petiole, and the leaf drops off.
Nitrogen and Carbon Storage
• Lots of trees will pull nitrogen and carbon
from their leaves before they drop, and
deposit in the bark or the roots.
• Come spring, the stored nitrogen and
carbon are used for new growth of flowers
and leaves.
Flowers in Deciduous Tress
• During the end of the leafless season
(early spring), many deciduous trees will
flower.
• Forsythia is an example of a tree that
flowers during the leafless season
• This increases the chances of pollination
(pollen reaching another tree either
through wind, birds or insects).
• The absence of leaves improves the
chances of pollen getting transferred by
wind and makes sure that insects will see
the flowers (leaves don’t get in the way of
either).
• This is risky for the tree because the
flowers can be easily damaged by frost
OR put lots of water stress on the plant to
keep the flowers.
• However, if a spring ice storm was to
happen, the absence of leaves helps to
prevent branch breakage.,
Types of Deciduous Plants
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Maple
Oak
Elm
Aspen
Birch
Honeysuckle
Grape vine
Poison Ivy
Evergreen Trees
• Evergreens do not lose their leaves in
seasons, but will shed and replace leaves
over time.
• Some tropical rainforest plants are
considered to be evergreens, replacing
their leaves gradually throughout the year
as the leaves age and fall.
Why be an Evergreen?
• Being an evergreen plant is usually an
evolutionary adaptation to low nutrient
levels
• In the boreal forest it can become too cold
for organic matter in the soil to decay
rapidly, so evergreens are favoured there.
• In warmer climates where evergreens are
present, they can even create their own
fertilizer.
Advantage to Evergreen Trees
• When they do lose their leaves, as the
leaves break down, they add carbon and
nitrogen to the soil.
• This is ideal for evergreen growth
because:
– Deciduous trees do not like high levels of
carbon and nitrogen and therefore will not
crowd the evergreens.
– The fallen needles provide protection for
newly growing evergreen trees.
Disadvantage to Evergreen
Trees
• Due to the fact that they hold onto their
leaves for longer, they will also hold onto
any pollutants for the duration of the leaf
life.
Wintertime Adaptations
• If an evergreen tree is going to keep
it’s leaves over the winter, there are a
few adaptations that must be in place:
–Shape
–Hardening
Shape – Wintertime Adaptation
• The overall shape
of the tree, being
narrow and conical
with downwarddrooping limbs help
them shed snow.
• Excess snow can
break or damage
branches.
Hardening – Wintertime
Adaption
• Many of them seasonally alter their
biochemistry to make them more resistant
to freezing, called "hardening".
• They will store high concentrations of
glucose within their cells to prevent
freezing.
• This is not sap – not maple syrup!
Examples of Evergreens
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Hemlock
Blue Spruce
White Pine
Eucalyptus
Welwitschia, an African plant that
produces only two leaves, which grow
continuously throughout the plant's life but
gradually wear away at the end, giving 20–
40 years' persistence of leaf tissue.
Conifer Trees
• The word conifer comes from the fact that
these trees bear cones.
• Majority are trees, some are shrubs
• Dominant plants over large areas of land –
boreal forest in the north, mountain
ecosystems in the south.
• Largest terrestrial carbon sink – absorbs
carbon from the atmosphere that could be
harmful to the atmospheric layers and
stores it in wood.
Conifer Wood
• They are also of great economic value,
primarily for timber and paper production.
• The wood of conifers is known as
softwood.
Gymnosperms -Seeds
• Seed producing plants.
• The word ‘gymnospoerm’ comes from the
Greek word gymnospermos meaning ‘naked
seeds’.
• Most seeds are encapsulated in a covering.
(Think sunflower seeds) .
• Gymnosperm seeds develop either on the
surface of scale- or leaf-like appendages of
cones, or at the end of short stalks (Ginkgo
baloba plant).
Cones
Gingko Baloba
• Conifer seeds develop inside a protective
cone called a strobilus.
• The cones take from four months to three
years to reach maturity, and vary in size
from 2 mm to 600 mm long.
Reproduction
• When mature the cones will open and
allow the seeds to fall out and be
dispersed by the wind.
• In some species, the cones disintegrate to
release the seeds.
• Some seeds need to be eaten by birds to
break up the cones. (pine nuts).
• In some fire-adapted pines, the seeds may
be stored in closed cones for up to 60–80
years, being released only when a fire kills
the parent tree.
Mature Cone
Jack Pine
Why is a pine
cone opening
only after a fire a
good adaptation
for the Jack
Pine?
Pine Nuts
What’s the difference?
• All conifers are evergreens…
• HOWEVER...
• Not all evergreens are conifers...
Types of Conifers
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Pine Trees - Pinus
Fir Trees –Abies
Spruce Trees - Picea
Cedar Tree - Cedrus
Pine Trees - Pinus
• Grow between 3m and 80m in height
• Smallest is Siberian Dwarf Pine at 1-3 m
tall and the Ponderosa Pine at 82 m tall.
• Long lived between 100- 1000 years old.
• The oldest is the Methuselah tree at 4,600
years old.
Siberian Dwarf Pine
Ponderosa Pine
Fibonacci number
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The spiral growth of branches, needles, and cone scales are
arranged in Fibonacci number ratios
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In mathematics, the Fibonacci numbers are the numbers in the
following integer sequence:
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By observing the spiral arrangement on a pine cone or
pineapple we notice that similar to the seed spirals on
sunflowers, the numbers of spirals in each direction are
consecutive Fibonacci numbers.
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Like the sunflower seeds, the structure of the pine cone serves
for optimum packaging of the seed scales. The seeds are of the
same size, are uniformly packed, do not crowd each other in the
center, and are not thinly spread at the edges.
Fir Trees –Abies
• 48-55 species
• Found in North/Central America, Europe,
Asia and North Africa.
• Prefer mountain climates.
• Closely related to cedar trees.
• All are tree, no shrubs.
Fir Trees –Abies
• Heights of 10-80 m tall.
• 2-12 feet in diameter when mature.
• Needle like leaves, attached to the base of
the branch by ‘suction cup’ looking
attachments.
• Cones will disintegrate upon maturity to
release seeds.
• Seeds have wings for dispersal.
Wood of Firs
• Wood is not good for timber use, so it
is more commonly used for plywood.
• Wood can only be used on the inside
of buildings as it is very susceptible to
decay and insects.
• Wood left outside will only last 12-18
months.
Types of Firs
• Common types of fir plants for
Christmas trees are: Nordmann
Fir, Noble Fir, Fraser Fir and
Balsam Fir.
Nordmann Fir
Noble Fir
Fraser Fir
Balsam Fir
Fir in a Lung??!!
• http://www.telegraph.co.uk/news/worldnew
s/europe/russia/5152953/Surgeons-findfir-tree-growing-inside-patients-lung.html
Spruce Trees - Picea
• 35 species
• Northern climates with cool
temperatures, such as the
boreal forest.
• 20-60 meters tall when
mature.
• Branches are whorled and
the whole tree has a cone
type shape.
Spruce Needles
• Needles are attached in a single form in a
spiral fashion.
• Each needle is attached on a small peg
like structure called a pulvinus.
• Needles will be shed at 4-10 years and be
replaced rapidly. They are easy to identify
when the needles are dropped because
the twigs are covered in pulvinus.
Old Tjikko
• In the mountains of western
Sweden, scientists have
found a Norway Spruce tree,
nicknamed Old Tjikko, which
has reached an age of 9,550
years and is claimed to be
the world's oldest known
living conifer tree.
• It has reproduced by layering
new tissue onto itself,
therefore it technically is the
same tree it was when first
started growing.
• Prefer high altitudes.
• Found in the mountains
of the western Himalaya
and the Mediterranean
region, occurring at
altitudes of 1,500–
3,200 m in the Himalaya
and 1,000–2,200 m in
the Mediterranean.
• Cedars are trees up to
30–40 m.
• Their wood is highly
fragrant, their bark is
typically in a cracked,
square shaped pattern
and branches are usually
broad and very level.
Cedar Tree - Cedrus
Cedar Needles
• Needles are arranged
on a more open spiral
than other conifers.
• Colors range from
light to dark green
and even blue green.
The colors are due to
the amount of a white
wax layer that covers
the needles.
Cones
• The seed cones can be very long, up
to 12cm long and up to 8cm broad.
What do you notice
• Disintegrate to release seeds.
about the cedar cone
is different from all
• In order to protect against squirrel that
the other cones?
predation, they have a unpleasant
resin like taste.