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

• 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 downward-drooping 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 • 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).

Gingko Baloba

Cones

• 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

• 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 • The spiral growth of branches, needles, and cone scales are

arranged in Fibonacci number ratios

• In mathematics, the Fibonacci numbers are the numbers in the following integer sequence:

• 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.

• 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/worldnews/europe/russia/5152953/Surgeons-find-fir-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.

Cedar Tree - Cedrus

• 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 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. • Disintegrate to release seeds. • In order to protect against squirrel

predation, they have a unpleasant resin like taste.

What do you notice about the cedar cone that is different from all the other cones?