Lifecycle of Trees

1
Lifecycle of Trees
It is important that students understand the
biology of trees to further be aware of trees
role in the ecosystem throughout its life.

• How to Measure ID
• Week 1 Day 3

2
Background

• Like all living things trees have a life cycle
• Birth
• Growth
• Aging
• Death
• As trees grow, their physical form changes as
  does their role in the forest ecosystem

3
Seeds
Which came first - the tree, or the seed?

• Seeds come in a variety of shapes,
• weights, colors, and sizes, depending on the
  species.
• Seeds develop from male and female parts of the
  trees producing fruits.
• Some seeds are in a protective nut like an acorn
• Others are in fleshy fruits, like the black
  cherry.
• The fruit of a pine is a cone and the seed is
  winged and resembles a miniature helicopter when
  falling.
• Wind, water, animals, and people disperse seeds
  to the forest floor, open fields, yards and
  roadsides.
• Where conditions are favorable for germination,
  seeds will germinate and grow.

4
Seedling

• The seedling grows and begins to develop woody
  characteristics.
• The stems harden, change color, and develop a
  thin protective bark.
• The stem may bend or develop branches that reach
  toward light.
• Leaves or needles that develop are adapted to
  shade, but lean or tilt toward light.
• Most roots are in the upper soil to absorb water,
  nutrients and air.
• Seedlings compete for nutrients, water, sunlight,
  and space.
• Threats include fire, flood, drought, disease,
  insect attacks, and animals.
• At this stage the tree is most susceptible to
  being killed.

5
Sapling

• When the tree is about 1-4 inches in diameter at
  4.5 feet, it is considered a sapling.
• standard height where trees diameter is measured
  diameter at breast height (DBH).
• As the tree starts to get taller the trunk
  thickens and branches develop.
• A sapling is the size of a tree growing in a
  nursery.
• In this juvenile state, the tree is not mature
  enough to reproduce.
• Growing rapidly, the sapling has the same
  competition and threats as seedlings.

6
Mature
What does DBH mean?

• With favorable conditions, a sapling will grow
  into a mature tree (gt4 inches DBH).
• During this stage, each tree will grow as much as
  its species and site conditions will permit.
• In addition, flowers develop, reproduction
  ensues, fruits form, and seed dispersal can now
  occur.
• Trees provide the maximum environmental benefits
  to people during this stage.

7
What plant in the picture would you say is a
mature tree?
8
Decline

• The life span of a tree is a wide-range, yet
  death is inevitable.
• A combination of factors overcome a tree and
  causes it to die.
• Injury, drought stress, followed by disease, rot,
  root dieback, coupled with a lightning strike or
  insect infestation contribute to tree decline.
• Sometimes a single factor is serious enough to
  cause mortality.

9
Dead Tree

• Standing dead trees, called snags, play vital
  roles in the life cycle of many organisms.
• A snag slowly breaks down and returns nutrients
  as limbs, bark, and branches fall. It provides
  habitat and food for wildlife and insects.
• Animals, insects, and fungi help break down the
  tree.
• Eventually, the snag will fall and return
  nutrients to the soil where they are taken up
  by other trees.
• And, the cycle begins anew.

10
What stage of the lifecycle are these trees in
currently?
SEEDLING ?
11
What stage of the lifecycle are these trees in
currently?
SNAG ?
12
What stage of the lifecycle are these trees in
currently?
SAPLING ?
13
Have you ever measured anything? WHAT? HOW? WHY?
Why do people measure things?
In what ways do people measure things?
14
A little Practice
How many finger lengths is your book?

• 1. Use the length of your index finger to measure
  the width of you textbook.
• 2. Use the length of your forearm to
• measure the height of your desk.
• Record the results in your packet.

Why did people get different measurements?
Compare your index finger with your neighbors.
How can we make sure our measurements are
accurate?
15
Why would we want to measure trees?

• Plan harvesting
• Make forest management decisions
• Monitor forest health

16
DBH

• Tree diameter is an important forestry measure
  and is used to indicate how well a tree is
  growing over time.
• It is also one of the standard measures of timber
  volume used to estimate the commercial value of a
  forest stand.
• By convention, the diameter is measured at a
  height on the trunk that is 1.35 m (4.5 ft) above
  ground level.
• This height above the ground is used because
  uneven swelling and irregular growth at the base
  of the tree and upper roots could mask the true
  growth of the trunk.

What would happen if people measured tree
circumference at different heights?
17
Trees Crown Spread
What is the crown spread of this tree?
2.5 feet?

• This is a horizontal measurement
• leaf tip to leaf tip of the shortest spread
• leaf tip to leaf tip of the longest spread
• through the main mass of the tree canopy 
• Add the two numbers together, and divide by two
  for the average crown spread
• Crown spread is difficult to measure when
  branches are high. Have 2 people stand where the
  tips of the farthest branches are directly
  overhead. A 3rd person can measure the distance
  at ground level.

3 .5 feet
1 .5 feet
18
What is the crown spread of this tree?
9.5 feet?
11 feet
8 feet
19
Identifying Trees

• What characteristics would you use to identify
  trees? Look at the twigs on your desk for ideas.
• Look at several different features
• Leaves
• Bark
• Twigs
• Flowers
• Fruit
• Seeds
• Shape

How do you think you use a book like this to
identify trees?
20
Needles or Broad Leaves

• In the simplest sense we have 2 types of trees
• Conifers (coniferous)
• seeds develop in cones, have needle shaped leaves
  
• dont lose leaves each year so stay green
  evergreens
• Pines, spruces, hemlocks and firs
• Broad-leaf (deciduous)
• broad, flat leaves that they lose each year
• Oaks, maples, beeches and aspens

21
Leaf Shape

• Differ in many ways and help identify trees
• Tips may be pointed, rounded, tapered
• Bases may be squared, rounded, heart-shaped

22
What are the shapes of these 3 leaves?
1
PALMATE!
HEART-SHAPED!
2
3
ROUND OR OVAL!
23
Margins

• Edges or margins of leaves give clues to tree
  identity
• Teeth (serrated)
• Lobed
• Smooth (toothless)

24
What type of leaf margin do these leaves have?
LOBED!
25
Textures

• Completely hairy
• Hairs on one side
• Completely smooth
• Thick, thin, rough or waxy

26
Simple Compound

• Simple leaves have only one piece to them
• Maple, oak, aspen and sycamore
• Compound leaves are made-up of several leaflets
• Ash, walnut and sumac trees

27
Are these leaves simple or compound?
3
2
1
5
6
4
28
Leaf Arrangements

• The way the leaves are arranged on the twigs
• Alternate, opposite, whorls

29
What kind of leaf arrangements are these?
ALTERNATE!
30
Twiggy Clues

• Even leafless twigs can help identify trees.
• Look for the leaf scars (leaves used to be there)
  or buds on the twig to see if leaves grow
  alternate, opposite or whorled.
• Size, color, texture, and shape of buds also help
  identify trees.
• Spines, thorns, prickles and other surface
  features also help.

31
What type of leaf scar pattern do these twigs
show?
2
OPPOSITE!
1
ALTERNATE!
32
Fruit and Flowers

• Various tree species produce characteristic
  fruits.
• Deciduous tress produce berries, winged samaras,
  nuts, or drupes. Some have unique names (acorns,
  walnuts, and chestnuts).
• Conifers produce different cones that vary in
  shape, size, and arrangement of scales.

33
Bark

• Identify with the color and texture
• Shaggy, smooth , rough or deep furrows
• Example Paper Birch white, paper-like
• Use bark on trunk, not branches

Paper Birch
34
Crown Shape

• Characteristic shapes can identify trees
• Rounded, weeping, vase-to Funnel, tabular and
  conical
• Some people are able to look at a tree in the
  distance and know what kind it is