It is important that students understand the biology Lifecycle of Trees of trees to further be aware of trees’ role in the ecosystem throughout its life. How to Measure & ID Week 1 Day 3 Seedling Seed Sapling Snag Mature Oak
Background n Like all living things trees have a life cycle: n Birth n Growth n Aging n Death n As trees grow, their physical form changes as does their role in the forest ecosystem
Which came first - the tree, or the seed? Seeds n Seeds come in a variety of shapes, weights, colors, and sizes, depending on the species. n Seeds develop from male and female parts of the trees producing fruits. n Some seeds are in a protective nut like an acorn n Others are in fleshy fruits, like the black cherry. n The fruit of a pine is a cone and the seed is winged and resembles a miniature helicopter when falling. n Wind, water, animals, and people disperse seeds to the forest floor, open fields, yards and roadsides. n Where conditions are favorable for germination, seeds will germinate and grow.
Seedling n The seedling grows and begins to develop woody characteristics. n The stems harden, change color, and develop a thin protective bark. n The stem may bend or develop branches that reach toward light. n Leaves or needles that develop are adapted to shade, but lean or tilt toward light. n Most roots are in the upper soil to absorb water, nutrients and air. n Seedlings compete for nutrients, water, sunlight, and space. n Threats include fire, flood, drought, disease, insect attacks, and animals. n At this stage the tree is most susceptible to being killed.
Sapling n When the tree is about 1 -4 inches in diameter at 4. 5 feet, it is considered a sapling. n standard height where tree’s diameter is measured – diameter at breast height (DBH). n As the tree starts to get taller the trunk thickens and branches develop. n A sapling is the size of a tree growing in a nursery. n In this juvenile state, the tree is not mature enough to reproduce. n Growing rapidly, the sapling has the same competition and threats as seedlings.
What does DBH mean? Mature n With favorable conditions, a sapling will grow into a mature tree (>4 inches DBH). n During this stage, each tree will grow as much as its species and site conditions will permit. n In addition, flowers develop, reproduction ensues, fruits form, and seed dispersal can now occur. n Trees provide the maximum environmental benefits to people during this stage.
What plant in the picture would you say is a mature tree?
Decline n The life span of a tree is a wide-range, yet death is inevitable. n A combination of factors overcome a tree and causes it to die. n Injury, drought stress, followed by disease, rot, root dieback, coupled with a lightning strike or insect infestation contribute to tree decline. n Sometimes a single factor is serious enough to cause mortality.
Dead Tree n Standing dead trees, called snags, play vital roles in the life cycle of many organisms. n A snag slowly breaks down and returns nutrients as limbs, bark, and branches fall. It provides habitat and food for wildlife and insects. n Animals, insects, and fungi help break down the tree. n Eventually, the snag will fall and return nutrients to the soil where they are taken up by other trees. n And, the cycle begins anew.
What stage of the lifecycle are these trees in currently? SEEDLING
What stage of the lifecycle are these trees in currently? SNAG
What stage of the lifecycle are these trees in currently? SAPLING
Have you ever measured anything? WHAT? HOW? WHY? Why do people measure things? In what ways do people measure things?
How many finger lengths little is your book? A Practice n 1. Use the length of your index finger to measure the width of you textbook. n 2. Use the length of your forearm to measure the height of your desk. Why did people get different measurements? Compare your index finger with your neighbors. n Record the results in your packet. How can we make sure our measurements are accurate?
Why would we want to measure trees? n Plan harvesting n Make forest management decisions n Monitor forest health
DBH n Tree diameter is an important forestry measure and is used to indicate how well a tree is growing over time. n It is also one of the standard measures of timber volume used to estimate the commercial value of a forest stand. n By convention, the diameter is measured at a height on the trunk that is 1. 35 m (4. 5 ft) above ground level. n 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?
What is the crown spread of this tree? 2. 5 feet Tree’s Crown Spread n This is a horizontal measurement: n leaf tip to leaf tip of the shortest spread n leaf tip to leaf tip of the longest spread n through the main mass of the tree canopy 3. 5 feet Add the two numbers together, and divide by two for the average crown spread 1. 5 feet n 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 3 rd person can measure the distance at ground level.
What is the crown spread of this tree? 9. 5 feet 11 feet 8 feet
Identifying Trees n What characteristics would you use to identify trees? Look at the twigs on your desk for ideas. n Look at several different features n Leaves n Bark n Twigs n Flowers n Fruit n Seeds. How do you think you use a book like n Shape this to identify trees?
Needles or Broad Leaves n In the simplest sense we have 2 types of trees: n Conifers (coniferous) : n seeds develop in cones, have needle shaped leaves n don’t lose leaves each year so stay green = evergreens n Pines, spruces, hemlocks and firs n Broad-leaf (deciduous) : n broad, flat leaves that they lose each year n Oaks, maples, beeches and aspens
Leaf Shape n Differ in many ways and help identify trees n Tips may be pointed, rounded, tapered… n Bases may be squared, rounded, heartshaped…
What are the shapes of these 3 leaves? 1 PALMATE! HEART-SHAPED! 2 3 ROUND OR OVAL!
Margins n Edges or margins of leaves give clues to tree identity n Teeth (serrated) n Lobed n Smooth (toothless)
What type of leaf margin do these leaves have? LOBED!
Textures n Completely hairy n Hairs on one side n Completely smooth n Thick, thin, rough or waxy
Simple & Compound n Simple leaves have only one piece to them n Maple, oak, aspen and sycamore n Compound leaves are made-up of several leaflets n Ash, walnut and sumac trees
Are these leaves simple or compound? 3 2 1 5 4 6
Leaf Arrangements n The way the leaves are arranged on the twigs n Alternate, opposite, whorls
What kind of leaf arrangements are these? ALTERNATE!
Twiggy Clues n Even leafless twigs can help identify trees. n Look for the leaf scars (leaves used to be there) or buds on the twig to see if leaves grow alternate, opposite or whorled. n Size, color, texture, and shape of buds also help identify trees. n Spines, thorns, prickles and other surface features also help.
What type of leaf scar pattern do these twigs show? 2 OPPOSITE! 1 ALTERNATE!
Fruit and Flowers n Various tree species produce characteristic fruits. n Deciduous tress produce berries, winged samaras, nuts, or drupes. Some have unique names (acorns, walnuts, and chestnuts). n Conifers produce different cones that vary in shape, size, and arrangement of scales.
Bark n Identify with the color and texture n Shaggy, smooth , rough or deep furrows n Example: Paper Birch – white, paper-like n Use bark on trunk, not branches Paper Birch
Crown Shape n Characteristic shapes can identify trees n Rounded, weeping, vase-to Funnel, tabular and conical n Some people are able to look at a tree in the distance and know what kind it is
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6_Powerpoint_Tree_Lifecycle_W1D3.ppt