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TREES AND FORESTS Topic E IDENTIFY REASONS WHY TREES AND FORESTS ARE VALUED The Value of Forests and Trees • Trees and forests are important to living things on Earth. • Trees and forests are valued for the following reasons: • • • • • • • • • • • They produce oxygen and use the carbon dioxide from the air. Carbon dioxide is one of the greenhouse gases that may cause global warming. They are able to filter out harmful pollutants from the air that everyone breathes. They produce food products used by humans. They provide food and homes for a variety of animals. They serve as a windbreak from strong winds. They give shade and protection from direct sunlight. Also, the transpiration in a forest cools the environment like an air conditioner. They produce natural ingredients that are used for medicines. They provide raw materials for the construction of buildings and paper products. They provide areas for recreation, such as camping and other outdoor activities. They help prevent soil erosion. Tree roots spread out and hold the soil in place. They enrich the soil with chemical nutrients when dead leaves decompose. The Value of Forests and Trees • Forests serve as habitat for a variety of living things and are important to human needs for recreation, for raw materials, and for a life-supporting environment. Which of the following statements about trees is false? A. Trees provide food. B. Trees provide oxygen. C. Trees make the air moister. D. Trees make the air warmer. Lily was camping with her family. She noticed that all of the picnic tables in the campground were located underneath tall trees. The picnic tables were most likely located underneath the trees because the trees: A. Supply dead leaves for fires. B. Prevent animals from eating the food. C. Filter pollutants and give off carbon dioxide. D. Give shade and provide protection from sunlight. Use the following information to answer the next two questions. At one time, western Ireland was covered by oak forests. Several hundred years ago, all the oak trees were cut for building materials. The forests have never grown back. The land is now mostly bare rock with little soil. Which of the following statements best explains why the land in western Ireland is mainly bare rock, with little soil? A. The soil has hardened to rock. B. Soil was removed by farmers for their fields. C. Without trees, the soil was lost by wind and water erosion. D. The land was always mainly rock, even when the forests were there. According to the given information, this change in Ireland’s landscape occurred as a result of the fact that oak A. Is very expensive. B. Is beautiful wood. C. Is useful for building. D. Must be cleared for farms. Use the following descriptions to answer the next question. Diane’s teacher asked Diane to identify the benefits of trees from the following list. 1. Provide food for humans 2. Make the air drier 3. Make the air cooler 4. Can be made into plastic 5. Provide homes for many animals 6. Made into paper 7. Can be used to make lumber Listed in numerical order, the benefits in the given list that describe spruce trees are: _______, ________, ________ and ________. Use the following information to answer the next question. Theresa spent some time learning about her Cree heritage. She learned that the Cree people had many uses for poplar trees. Through her research, Theresa found the following information about poplar trees: • A tea made from poplar shoots contains the chemical bisabolol, which kills the bacteria that cause the lung disease tuberculosis. • A tea made from the buds of balsam poplar trees contains a chemical similar to the drug in aspirin. • When a paste made from the bark of poplar trees is applied to boils, it draws out infection. • The inner bark of poplar trees can be rubbed on muscles to take away soreness.. The given uses of the poplar trees could be best classified as: A. Economic B. Medicinal C. Nutritional D. Recreational The overall relationship between the animals and trees in a forest can be described as: A. Harmful B. Parasitic C. Cooperative D. competitive Which of the given objects is not made from some part of a tree? A. Tissue (Kleenex) B. Chewing gum C. Glass D. cork Barred owls live in densely forested areas all across Canada. Barred owls make their home in which of the following layers of the forest? A. Canopy B. Shrubbery C. Understory D. Forest Floor DESCRIBE KINDS OF PLANTS AND ANIMALS FOUND LIVING ON, UNDER AND AMONG TREES; AND IDENTIFY HOW TREES AFFECT AND ARE AFFECTED BY THOSE LIVING THINGS Parts of the Forest • The forest is made up of different layers. • In each layer, there are plants and animals found living on, under and among trees. Canopy • The first forest layer is the canopy. • The canopy is a very thick blanket of treetops that captures more than 90% of the sunlight. • This is the place where photosynthesis occurs. • A lot of flying animals, such as warblers, owls and insects (butterflies, aphids), can be found in the canopy. • Squirrels make their nests in the canopy. Understory • The second layer of the forest is called the understory. • Many small trees, large bushes, and the trunks of large trees are found in this layer. • This layer also provides a sheltered space for many forest animals. Shrubbery • The third layer is the shrubbery layer. • The shrubbery layer is home to many forest wildflowers, small shrubs, and grasses. • Deer, skunks and rabbits find their food on this level. Forest Floor • The last level is the forest floor. • The forest floor is dark and damp. • Only plants that can live with very little light grow here. • Branches and leaf litter fall from the trees, and animal feces collect on the forest floor. • Bacteria and fungi decompose these materials. Fungi • Fungi are not plants and they do not have chlorophyll. • They do not produce their own food through photosynthesis. • Instead, fungi get their nutrition from dead plant material. • Mushrooms, conks, and lichens are examples of fungi. Bacteria • Soil bacteria are the main bacterial decomposers found in a forest. • Scavengers or detritivores, such as worms and millipedes, are hard at work in the soil helping the decomposers break down dead matter. Other Inhabitants of the Forest Floor • Inhabitants of the forest floor also include toads, mushrooms, and insects. The Forest is a Habitat • Forests serve as a habitat for a variety of living things. • A habitat is an area or environment in which an organism or ecological community normally lives or occurs. • An ecosystem consists of a living community that depends on each member and its surrounding environment. • A forest is an example of an ecosystem in which living and non-living things interact. Producers, Consumers and Decomposers • The living things in a forest are categorized into three groups: producers, consumers and decomposers. • Producers are living things that use energy from the sun to produce their own food. • Plants are producers. • Consumers are living things that need to eat producers (plants) to live. • There are three types of consumers: herbivores, carnivores and omnivores. • Decomposers are living things that feed off dead plants and animals. • They reduce remains to mineral nutrients for the soil. • Mushrooms (fungi) and bacteria are types of decomposers. Types of Consumers • Herbivores are animals that eat plants. • Eg: Deer, squirrels and caterpillars • Carnivores are animals that eat other animals. • They are considered consumers because they need to eat herbivores to survive. • • Eg: Lynx, coyotes, and wolves Omnivores are animals that eat both plants and animals. • Eg: Bears and foxes Non-Living Things in the Forest • Non-living things in a forest includes: • • • • • • Water Rocks Sunlight Air Soil chemicals Use the following information to answer the next question. The fungus that grows in living and dead trees can be a source of food for many insects. Beetles and other insects burrow into trees to eat the fungus. Woodpeckers make holes in the trees to find beetles to eat. Which of the following food chains is described in the given information? A. Air tree beetle woodpecker B. Soil tree beetle woodpecker C. Tree fungus beetle woodpecker D. Tree beetle fungus woodpecker The original source of energy used by trees is the A. Air B. Sun C. Soil D. water Which of the following tables matches each animal with the type of consumer it is? Horse Carnivore Horse Carnivore Lion Omnivore Lion Herbivore Human Herbivore Human Omniovre Horse Omnivore Horse Herbivore Lion Carnivore Lion Carnivore Human Herbivore Human Omnivore The forest layer in which deer, skunks and rabbits are found is the A. Canopy B. Shrubbery C. Understory D. Forest floor Which of the following statements about decomposers is true? A. Decomposers are non-living things that reduce mineral nutrients in the soil. B. Decomposers are non-living things that increase mineral nutrients in the soil. C. Decomposers are living things that reduce the mineral nutrients added to the soil. D. Decomposers are living things that increase the mineral nutrients added to the soil. Organisms that are consumers are classified as A. Deciduous and coniferous B. Sunlight, air, soil and chemicals C. Maggots, beetles and earthworms D. Herbivores, carnivores and omnivores The loss of even one species can ruin an entire forest ecosystem of plants and animals. The organisms that depend on this missing species as prey lose their food source. In turn, the organisms that it fed on lose a predator. If robins were removed from a forest ecosystem, the initial impact on the forest would most likely be A. An increase in the population of rabbits, followed by a decrease in the population of mice B. A decrease in the population of rabbits, followed by an increase in the population of mice C. An increase in the population of caterpillars, followed by a decrease in the number of poplar leaves D. A decrease in the population of caterpillars, followed by an increase in the number of poplar leaves Which of the following food chains could exist in a forest? A. Moose hare lynx deer B. Hare coyote deer plants C. Plants hare coyote wolf D. Squirrel grouse coyote deer When Ter was hiking through a forest, he observed different types of mushrooms growing from the sides of trees and on the forest floor. Ter knows that mushrooms are a type of decomposer called fungi. Which of the following statements describes what would most likely happen if all the decomposers in a food web were removed? A. The flow of nutrients would stop B. The flow of nutrients would continue C. The herbivore population would increase D. The carnivore population would increase In the forest ecosystem, wildflowers act as A. Decomposers B. Herbivores C. Omnivores D. producers DESCRIBE THE ROLE OF TREES IN NUTRIENT CYCLES AND IN THE PRODUCTION OF OXYGEN The Role of Trees in the Nutrient Cycle and Oxygen Production • Plants make food for themselves and others. • This is why they are called producers. • Plants use the energy from the sun, water from the soil, and gases in the air to make their food. • Plants also need chemicals or mineral nutrients to grow. • The mineral nutrients are like the vitamins you may take for healthy growth. • Mineral nutrients are carried in the water from the soil. Animals • Animals need food and mineral nutrients as well. • They cannot make their own food or use minerals directly from the soil. • They need to eat plants to get food and mineral nutrients. • Animals that do not eat plants will eat animals that have eaten plants. • This way, they get the food and mineral nutrients they need to live and grow. • Animals that consume, or eat, other living things are called consumers. Decomposers • Eventually, plants and animals die. • The chemicals that made up their bodies are returned to the soil by decomposers. • Decomposers are bacteria and fungi that break down dead matter. • They replace the basic chemicals or mineral nutrients in the soil. New Life • New plants then start to grow. • They use energy from the sun, water from the soil, and gases in the air to make their food. • These plants use the chemicals or mineral nutrients from the soil to grow healthily. • This is how the nutrient cycle repeats itself. The Nutrient Cycle Elements in the Air • Carbon dioxide and oxygen are cycled on Earth through plants and animals. • Animals need oxygen to survive. • They breathe in oxygen from the air, and they breathe out carbon dioxide. • Plants need carbon dioxide from the air, and they give off oxygen as waste. • This oxygen is then breathed in by animals. Oxygen • Plants make almost all the oxygen found in the atmosphere. • Like most living things, plants use oxygen to live. • Fortunately, plants make much more oxygen than they can use. • This leaves plenty of oxygen for animals to use. Photosynthesis • The process of making food in green plants is called photosynthesis. • The word comes from two different words: • • “Photo” means light “Synthesis” means putting things together • Photosynthesis uses carbon dioxide, water and light energy to make food. • The process of photosynthesis can be shown as the following equation: Photosynthesis • Photosynthesis takes place in the green parts of the plant. • This is in the leaves of most plants. • The light energy that is used in photosynthesis comes from the sun. • It is captured by the chloroplasts in the cells of the leaves. Leaves • The leaves also take in carbon dioxide. • This comes from the air. • Most leaves have tiny openings on their undersides called stomata. • These openings allow air to enter the leaf. • The leaf uses the carbon dioxide from the air to make the sugar and starches. • The oxygen made is released into the air through the stomata. Water • The water needed comes from the ground. • The roots of plants take in water and dissolved chemicals from the ground. • The water moves from the roots up through the stem to the leaves of the plant. • The substances are then changed into food and oxygen. Photosynthesis The Water Cycle • The water cycle plays an important part in the survival of living things. • For example, plants take in water through their roots. • The water is transported up through the stem to the leaves. • The water is used by the leaves during photosynthesis. • The stomata, found on the underside of the leaves, releases water vapour. • This is called transpiration. Transpiration Leaves • Broad leaves have greater surface area than needle leaves. • There are more stomata found in a broad leaf, so more moisture is lost during photosynthesis. • Broadleaved trees transpire a lot of moisture into the air. • On a warm, sunny day, a fully grown tree may release as much as 450L of moisture into the air through transpiration. • In a forest, this moisture has a cooling effect like an air conditioner has on a house. Seasonal Changes • The days get colder and drier in autumn and winter. • If the leaves were allowed to remain on the tree, too much moisture would be lost, or the leaves would freeze. • To prevent this from happening, the tree drops, or sheds, its leaves. Needle-Leaved Trees • Most needle-leaved trees are evergreen. • They are able to keep their leaves because of their shape and size. • Being smaller, needle leaves have much fewer stomata than broad leaves. • Therefore, they transpire less. • The tree is able to keep the needle leaves during the dry and cold months. • Needle leaves are shed gradually throughout the year. Which of the following trees will release the most moisture into the atmosphere through transpiration? A B C D Use the following information to answer the next question. • Patrick saw this illustration in a science book. What process is illustrated in the given picture? A. Respiration B. Photosynthesis C. The water cycle D. The nitrogen cycle Hope concluded her presentation by explaining that the most important benefit trees and forests have is found everywhere on Earth but cannot be credited to a specific area. The most important of trees that Hope was referring to is that trees provide: A. Food for everyone B. Oxygen for everyone C. Jobs for many people D. Homes for many animals Producers, consumers and decomposers are linked in what is known as the A. Animal cycle B. Energy cycle C. Nutrient cycle D. Chemical cycle Leaves produce food for trees by the process of A. Transpiration B. Respiration C. Digestion D. photosynthesis As a tree decays, it will A. Add nutrients to the soil B. Add oxygen to the soil C. Remove nitrogen from the air D. Remove water from the air In a process called photosynthesis, trees use the energy from the sun to make their own food supply. During this process, trees release A. Water vapour and take in oxygen B. Oxygen and take in water vapour C. Carbon dioxide and take in oxygen D. Oxygen and take in carbon dioxide IDENTIFY GENERAL CHARACTERISTICS THAT DISTINGUISH TREES FROM OTHER PLANTS, AND CHARACTERISTICS THAT DISTINGUISH DECIDUOUS TREES FROM CONIFEROUS TREES Parts of a Tree • Most trees have the same basic parts • • • • • • • • • Roots Trunk or stem Crown Outer Bark Inner Bark (Phloem) Cambium Sapwood (Xylem) Heartwood Leaves Roots • A tree’s roots absorb water and nutrients from the soil, store sugar and anchor the tree upright in the ground. Trunk or Stem • The trunk or stem supports the crown and gives the tree its shape and strength. • The trunk is made up of tubes that run between the roots and the leaves. • Some tubes carry the food down from the leaves to the other parts of the tree. • Other tubes carry water and dissolved mineral nutrients from the soil to the leaves. Crown • The crown consists of the leaves and the branches at the top of the tree. • The leaves are the food factories for the tree. • The leaves contain the green pigment chlorophyll that traps the energy of the sun used for photosynthesis. Bark • The bark consists of two parts: • • The outer bark The inner bark Outer Bark • Acts like a suit of armour for the tree. • Protects the tree from insects, disease, storms and extreme temperatures. Inner Bark • Also called phloem • Acts as a food supply line by carrying sugar and nutrients (sap) from the leaves to the rest of the tree. Cambium • Between the outer bark and the inner bark • Very thin layer of growing tissue that produces new cells that become xylem, phloem or more cambium. Xylem and Heartwood • Also called sapwood • Has a network of thick-walled cells that bring water and nutrients up from the roots to the leaves and other parts of the tree. • As the tree grows, xylem cells become inactive and die. • These cells become the tree’s heartwood. • Heartwood supports the tree and stores the dead xylem cells. • The heartwood also stores sugar, dyes and oils. Stems • Both trees and shrubs have woody stems • This sets them apart from other plants • A sunflower can grow fairly tall but because it does not have a woody stem, it is not considered to be a tree or shrub. Differences Between Trees and Shrubs • A tree is a perennial plant meaning it continues to grow year after year. • It does not die off after one growing season as many plants do. • Trees generally have a single, woody stem called a trunk that is self-supporting. • Trees grow to a height of 4m or more. • Trees have a crown of leaves at the top that give it its shape • A shrub is also a perennial plant. • Instead of a single stem, it has many woody stems • Shrubs usually do not grow more than 4m in height, and some stems may lie close to the ground. Deciduous and Coniferous Trees • Trees can be categorized into two types: • • Deciduous Coniferous Coniferous Trees • Have needle-shaped leaves • Are cone-bearing • Most remain green all year long and as such, are referred to as evergreens. • Evergreens lose their needles gradually over the year rather than all at once in autumn. • Much less moisture is lost from a needle leaf than through a broad leaf. • There are various shapes of coniferous trees. Deciduous Trees • Shed their leaves before the cold or dry season. • Before shedding, the leaves often turn orange, red or yellow. • New leaves appear in the spring. • Most have wide-shaped leaves and are often called broadleaved trees. • There are many different varieties and sizes Which of the following statements about deciduous trees and coniferous trees is false? A. Both deciduous and coniferous trees have seeds. B. Both deciduous and coniferous trees have leaves. C. Deciduous and coniferous trees both have flowers. D. Deciduous and coniferous trees both have woody stems. A plant is classified as a tree if it has A. A woody stem B. Leaves or needles C. Leaves that change colour D. Roots that reach 3m in length IDENTIFY CHARACTERISTICS OF AT LEAST FOUR TREES FOUND IN THE LOCAL ENVIRONMENT. BE FAMILIAR WITH AT LEAST TWO DECIDUOUS TREES AND TWO CONIFEROUS TREES. INCLUDE NATIVE SPECIES, SUCH AS SPRUCE, BIRCH, POPLAR AND PINE AND CULTIVATED SPECIES, SUCH AS ELM AND CRAB APPLE. Native and Cultivated Trees in Alberta • A native tree is one that naturally grows in the area. • There are many different native trees found in Alberta. • The types of trees found in your area depend on where you live. White Birch • Small- to medium-sized tree with many stems. • The bark is thin, smooth and marked with brown horizontal lines. • The bark is light, strong and flexible. • It peels off in paper strips. • Birch trees in the forest have a narrow, oval-shaped crown above a slender trunk. • The leaves have a simple, round shape with a fine-toothed margin. • White birch trees are not cone-bearing trees. • In the past, Aboriginal Peoples used birch bark to build canoes. Poplar • Very common in Canada • Used for making paper and makes excellent firewood • The poplar tree has oval-shaped leaves that have a fine-toothed margin. • The bark is smooth and yellowish. • In the past, poplar trees played an important role in natural medicine. • There are two main types of poplar trees: • • Aspen poplar Balsam poplar Aspen Poplar • Sometimes called a white poplar, trembling aspen, white cottonwood, quivering aspen, or quaking aspen. • The leaves shake or flutter in the breeze, which is why it is called a trembling or quivering aspen. • The aspen poplar is a slender tree with smooth, greenish-white bark that does not peel away. • The seeds are found in green capsules containing clumps of cottony fluff. • The aspen poplar can sprout from root suckers as well as from seeds. • The leaves are simple and heart-shaped, with long, flat stalks. • The upper surface of the leaf is dark green, and the underside is paler green. • The margins on the leaves are fine-toothed. Balsam Poplar • Sometimes called the black poplar. • Have straight trunks with bark that is greenish grey when young and brown with grooves when old. • The tree produces buds that contain a sticky substance that has a pleasant balsam smell. • The leaves are simple and oval- or wedge-shaped with fine-toothed margins. • The upper surface of the leaf is dark green, and the underside is paler with rustcoloured marks. Spruce Trees • Large trees with narrow crowns • Coniferous, or cone-bearing • Cones are light brown and scaly • Have needles • Needles are four-sided, stiff and sharp • Needles are arranged spirally on a twig • The bark of a spruce tree is scaly and greyish brown • Most common wood used for building in Canada White Spruce • Found in all forest regions in Alberta • Some of the first coniferous trees to start growing in burned-out pine and old aspen poplar forests. Black Spruce • Found in all forested areas, especially in northern parts of Canada • One of the few conifers that grows well in wetland areas such as bogs and muskeg Pine Tree • Most widespread tree in Canada • Cone-bearing • Have needles that appear in pairs • Bark is thin and scaly • Most commonly used for plywood, panelling, furniture and railway ties • Most common trees used by Aboriginal Peoples to build teepees • First trees to grow back after a forest fire Jack Pine • Grows in areas with sandy soil • Common tree in the Boreal Forest Lodgepole Pine • Tall, slim tree that grows to 30m or more • Used as the poles for powerlines, lodges and buildings, which is why it is called the lodgepole pine • Common tree in the Rocky Mountain and Foothills area • This is the provincial tree of Alberta Cultivated Tree • A cultivated tree is a tree that did not grow in the area naturally. • Although these trees were brought from other places, they adapted to the new region and began to thrive. • Two of the many cultivated trees are: • • Elm Crab apple Elm Tree • A deciduous broad-leaved tree • These shade trees grow well in many different soils • The elm leaf has an elliptical shape with serrated margins • The leaves do not grow opposite each other on a branch; they are staggered • Manu streets in Edmonton and Calgary are lined with elm trees • Precautions have been taken to prevent elm populations from Dutch elm disease. Crab Apple • Deciduous broad-leaved tree • May have white or pink flowers on a small, multi-stemmed tree • Apples can be harvested in late summer or early autumn. • The crab apple leaf is dark green and oval- to egg-shaped with a finely notched margin. Which of the following trees has hard cones that open when exposed to heat? A. Jack pine B. White birch C. Aspen poplar D. White spruce Which of the following Albertan trees is deciduous? A. White spruce B. Jack pine C. Birch D. fir Which of the following trees is a deciduous tree that does not tolerate shade and is used to make paper? A. Elm B. Spruce C. Poplar D. Jack pine New growth on trees can best be seen in the spring by looking at a tree’s A. Terminal growth or end bud B. Annual growth ring C. Leaf scar D. lenitcel DESCRIBE AND CLASSIFY LEAF SHAPES, LEAF ARRANGEMENTS, BRANCHING PATTERNS AND THE OVERALL FORM OF A TREE Classifying Leaves, Branching Patterns and Tree Shapes • The features of different species of trees’ leaves, bark, twigs, buds, flowers and fruits are distinctive. • You can identify trees by their shape or silhouette. • For some species, a particular feature stands out. • For example, the white birch has a distinctive bark, and the black spruce has an easily recognizable shape. Leaves • Leaves are the most common feature considered when identifying a tree. • The leaf itself is called the blade. • The stem of the leaf is the petiole. • The tip of the leaf is the apex. • The edge of the leaf is the margin. • The vein in the middle of the leaf is called the midrib or midvein. • The branches coming out from the midvein are the veins. Factors in Leaf Identification • Important factors in leaf identification: • • • • Shape of a leaf Kind of leaf margin Leaf type Arrangement of leaves on the twig Leaf Shapes • There are 10 different leaf shapes: • • • • • • • • • • Linear Oblong Oval Ovate Cordate (heart-shaped) Lobed Deltoid (triangular) Orbicular (round) Four-sided needles Flat needles Linear Oblong Oval Ovate Cordate (Heart-Shaped) Lobed Deltoid (Triangular) Orbicular Four-Sided Needles Flat Needles Margins • Leaves can also be classified by their margins • Leaf edges, or margins can be: • • • • Smooth Finely notched Coarsely notched Wavy Smooth Finely Notched Coarsely Notched Wavy Shape • Another way to classify leaves is by shape. • • • Simple compound Double compound Simple • there is only one leaf on each petiole. Compound • there is more than one blade on each petiole Double Compound • there are several blades attached to several petioles Arrangement • Leaves can also be classified by their arrangement on a twig. • • • • • Opposite Alternate Whorl Basal Needle arrangements can be: • • • • In bundles of 2 and 5 Singly on a twig Scalelike In clusters of more than 5 Bark • Tree bark can be differentiated according to: Colour • Texture • Bark patterns • • The bark of most trees changes colour and thickens as the tree ages. • Bark can be reddish brown, grey or white. • Texture of bark can be smooth or rough. • Bark patterns include: • • • • • Scaly patches Horizontal Vertical Horizontal and wavy Vertical and scaly Bark Patterns Grey, rough, vertical Grey, rough, scaly patches Reddish-brown, smooth, horizontal White, smooth, horizontal Overall Shape • The overall shape or silhouette of a tree may also be used to differentiate between tree species. • Trees can have the following shapes: • • • • • Triangle or cone Oval Circle Spreading Rectangular • Most trees are easily identified by their shape or silhouette. • For example, a fir tree is easily identified by its triangular shape. Tree Shapes Triangular or cone Circle Oval Spreading Rectangular Branch Patterns • Typically, trees develop different branch patterns. • Branching patterns on trees can be arranged in a whorled, opposite, alternate or spiral arrangement. • Branches can also be arranged in relation to the trunk. • Sometimes, trees have excurrent branches, which means the tree’s branches go all the way up the trunk. • For some trees, the branches only begin halfway up the trunk. • If the trunk is split to form two or three main branches, it forms a decurrent pattern. • A columnar pattern is one where the branches are all clustered at the top of the trunk. • Palm trees have a columnar branch pattern. Branch Patterns Columnar Decurrent excurrent Factors Affecting the Shape of a Tree • The shape of a tree is dependent on many factors • • • • Relative amount of growth of the trunk Branches Site condition If the tree is in an area where there is a lot of wind or it is growing on a slope, the tree’s shape or branching pattern may be changed by these conditions. Using a Dichotomous Key Which of the following trees were used by Aboriginal Peoples to make canoes? A. Pine B. Birch C. Poplar D. Spruce The lodgepole pine, Alberta’s official tree, was named by the first European settlers. They chose this name because it describes the way in which the tree was used by A. Settlers to make fences B. Settlers to make flagpoles C. Aboriginal Peoples to make canoes and other boats D. Aboriginal Peoples to make frames for their bison-skin homes INTERPRET THE GROWTH PATTERN OF A YOUNG TREE, DISTINGUISHING THIS YEAR’S GROWTH FROM THAT OF THE PREVIOUS YEAR AND FROM THE YEAR BEFORE THAT. RECOGNIZE DIFFERENCES IN COLOURATION AND TEXTURE OF NEW GROWTH AND OLD GROWTH, AND LOCATE SCARS THAT SEPARATE OLD AND NEW GROWTH Growth Pattern of Trees • Foresters study tree cross sections, or discs, which are sometimes called tree cookies, in order to learn about the pasts of individual trees. • The study of trees can tell people things about the history of the area surrounding the tree. • For example, a scar can show that there was a fire, or the last drought in the area may result in a very narrow growth ring. • The study of tree discs is called dendrochronology. Growth Rings • Trees form new wood in the spring and summer only. • Springwood is lighter in colour than summerwood. • This growth shows up in a series of light (spring growth) and dark (summer growth) rings called annual rings. • Growth rings vary in size according to each year’s growing season. • Environmental conditions, such as weather, the amount of growing space, soil conditions, insect attacks, and fire influence their size. • The study of growth rings can tell people a lot about a tree’s history. • The centre of the ring indicates the birth of the tree. • An evenly spaced ring indicates rapid growth. • Rings wider on one side than the other indicate that it was growing on a slope, or that something may have been leaning against it, forcing the growth to one side. Narrow Rings, Fire Damage and Scars • Narrow rings could indicate either overpopulation or a lack of water. • Several narrow rings indicate a series of drought seasons. • A dark, black area with the rings growing in toward the black area indicates possible fire damage. • Sometimes, a scar is left where a branch breaks off or dies. • The scar goes around several years of growth as the tree tries to build new growth rings around it. • This scar is different from a fire scar, which occurs only in one year. Identifying Age of Trees • Another way of identifying the approximate age of trees is by counting the number of terminal bud-scale scars on a broad-leaved tree branch or by counting the number of whorls on an evergreen. Bud • A bud is the bump found on branches and twigs of a tree. • It can become a leaf, a flower or stem material that will begin to grow in the next spring. • Buds form in the late summer and remain dormant until the following spring. • When the bud opens, the scales usually fall off. • The scales leave little tiny grooves or scars where they were attached. • Each year, as the branch grows, a set of scars is left behind. • You can determine the age of a branch by counting these scars. Terminal Bud Scars • Terminal bud scars show the growth of a branch. • This method of determining the age of a tree is unreliable. • As the branch grows, it becomes thicker. • Since the scars cannot stretch around the tree, they disappear. Whorls • The branches of some evergreens, such as the white spruce, are arranged in groups of whorls around the trunk of a tree. • The number of whorls can give the age of the tree. • This method of determining the age of a tree is unreliable because as the evergreen tree ages, branches can break or die off. Insect Attacks • An area of one or two narrow rings may indicate an insect attack. • In the years of insect attacks, the leaves of the tree would be damaged and very little food would be made that year. Sorida and her father are studying the tree cookie shown. Sorida wants to know how old the tree was when it was cut. Her father says that they can find out the age of the tree by examining the tree cookie. To determine the age of the tree when cut, Sorida and her father can count A. All the dark rings, including the bark B. All the dark rings, excluding the bark C. All the dark and light rings, including the bark D. The dark and light rings, excluding the bark Which of the following statements about tree rings is true? A. A thin ring indicates that the tree grew more that particular year than in other years. B. A thick ring indicates that the tree grew more that particular year than in other years. C. An unusually dark ring indicates that the tree probably suffered from a disease that particular year. D. An unusually light ring indicates that the tree probably suffered from too much sunshine that particular year. The four parts of a tree’s life cycle are as follows: A seed germinates. 2. First roots and leaves form. 3. The mature tree produces flowers. 4. The trunk adds a ring of growth every year. • List in the order in which they occur, the four parts of a tree’s life cycle are: _____, _____, _____, and ______. IDENTIFY HUMAN USES OF FORESTS, AND COMPARE MODERN AND HISTORICAL PATTERNS OF USE Past and Present Use of Forests • Humans began life on the planet as forest dwellers • They were food gatherers and depended on the forest for all their needs • • • Food Clothing Shelter • Humans gradually became food growers, clearing small patches in the forest to grow food. • But they continued to depend on forests to meet a lot of their needs. Modern Uses for Forests • Even today, people depend on forests for • • • • • Paper Timber Fuel wood Medicine Trees are used in timber-based products such as • • • • Plywood Paper Pulp particleboard Medicinal Uses • Humans have depended on forest herbs and plants to fight and prevent various ailments • Today, leaves, bark and other parts of trees have medicinal values and are used to make various medicines. Use the following information to answer the next two questions Taxol is a chemical found in the bark of the Pacific yew tree. Taxol is a chemical that is sometimes used in drugs that fight cancer. The entire bark of one Pacific yew tree contains enough Taxol to make one pill. A fungus that grows inside the Pacific yew tree also produces Taxol. The fungus helps protect the tree from disease and predators. However, if the soil becomes very dry, the fungus becomes a disease of the Pacific yew trees. Logging by lumber companies is affecting the Pacific yew trees’ habitat. As more trees are cut down, more of the ground is exposed to the sun and wind. This tends to make the soil very dry. Which of the following conclusions can best be made from the given information? A. Trees are sources of medicine B. Trees that have fungus are generally healthy. C. More research about trees is needed to find useful chemicals in them. D. More research about trees is needed before humans alter their environment. A useful goal of researchers would be to try to: A. Learn how to identify the Pacific yew tree B. Grow the Taxol-producing fungus in a lab C. Find better ways to remove the yew bark D. Grow Pacific yew trees in Alberta Use the following information to answer the next two questions. Liam was researching the historical and modern uses of forests. By comparing forest use in the seventeenth century with forest use in the twenty-first century, Liam found many things that had changed. He noted that forest use for shelters, leisure and jobs had increased over time, while forest use for fuel and transportation had decreased. Liam discovered that the main reason that forest use for shelters had increased is that A. More people need homes today B. People live in smaller homes today than they did in the past C. Log cabins have become more popular in the twenty-first century D. Many of today’s campers know how to use temporary shelters made from trees Liam inferred that the main reason that forest use for fuel and transportation had decreased is that A. There are fewer demands for fuel and transportation needs today B. Better materials are now used to meet fuel and transportation demands C. Conservationists have banned the use of forests for these types of needs D. Clear cutting has reduced forests, thereby reducing what they can be used for IDENTIFY HUMAN ACTIONS THAT ENHANCE OR THREATEN THE EXISTENCE OF FORESTS Actions That Enhance or Threaten Forests • Biotic stress is stress resulting from the harmful actions of a living organism, such as insect attacks, disease-causing fungi and overgrazing of animals such as deer and cattle. • Abiotic stress is stress resulting from natural factors that are not alive. • • These factors include snow, ice, fire and wind. Drought, extremes of heat and cold, and pollution are three abiotic stresses that have played parts in the decline of forests. Natural Factors • Sometimes, natural factors can have both a negative and a positive effect on forests. • For example, snow and ice break tree branches and can cause flooding leading to soil erosion. • On the positive side, snow and ice provide moisture for the soil needed for trees to grow. Humans Threaten Forests • Humans have threatened forests by the following actions: • • • • • • • Overlogging in an area Careless use of fire Overuse of recreation areas such as lakes found in forests Use of pesticides Building roads Littering and polluting Clearing forests for farms or new housing developments Forestry • Alberta’s forest industry has provided the province with a major source of economic growth over the past 30 years. • Reforestation is one way that industry works to ensure forests are maintained. • Reforestation requires that the forest industry either plants seeds for new trees to grow, or they plant small trees that have been grown in nurseries. Government Programs • Other ways forests have been enhanced and preserved is through government programs. • These programs enhance and preserve forests by the following actions: • • • • Establishing provincial and federal parks Setting up wilderness protection sites and animal sanctuaries Hiring forest managers and park rangers to monitor and police forested areas Enhancing recreation areas by restocking lakes or planting trees for campsites Which of the following statements indicates that Canadians are taking action to enhance forests? A. Forestry industries employ over 800 000 Canadians B. Over 350 communities have economies that depend on forests C. Hundreds of clear cutting projects are carried out today in all provinces of Canada. D. Millions of hectares of forests in Canada are protected by law so they can remain in their natural states. IDENTIFY AN ISSUE REGARDING FOREST USE, IDENTIFY DIFFERENT PERSPECTIVES ON THAT ISSUE, AND IDENTIFY ACTIONS THAT MIGHT BE TAKEN Forest Issues and Actions • Forests are affected by a number of interacting stresses. • Most people agree that forest ecosystems are suffering from a combination of natural stresses and man-made stresses. • Air pollution, harvesting, fire and overuse by humans are some examples of things that threaten forests. • The management and preservation of today’s forests continues to be an issue in Alberta’s forest industry. Acid Rain • Serious damage to forests can also result from acid rain. • Acid rain is formed when rain falls through polluted air. • Acid rain kills leaves and trees. • It can cause permanent damage to the soil of the forest floor, which, in turn, kills tree roots. Clear Cutting • Clear cutting of Alberta’s forests has detrimental effects on the entire ecosystem of the forest. • Clear cutting requires the use of large machinery that cuts down entire sections of the forest. • This exposes soil, which then erodes. Selective Harvesting • Instead of clear cutting, a much preferred method of harvesting trees is selective harvesting. • This is where only the largest trees are chosen, and smaller trees are planted to replace them. Which of the following actions would help to preserve or enhance a forest? A. Increase hunting activities B. Clear more land for campsites C. Plant seedlings in a previously harvested area D. Spray insecticides on trees infected with pine beetles Use the following information to answer the next two questions • Clear cutting: Large machines cut the trees, remove the branches, cut the logs into eight-foot lengths and load them onto large trucks, all at one spot. The size of the machines allows the company to cut all the trees in the area. Smaller plants often get run over, and the soil is compacted by the tires of the heavy machinery. • Selective cutting: This is a small-scale operation. One or two operators cut trees with a chain saw on the property they own. They select the largest trees to cut, allowing space for the smaller trees to grow. A horse may be used to drag the logs out of the bush because vehicles are usually too large. • Strip cutting: Heavy machinery is used but the trees are cut in strips, leaving sections between the strips uncut. From the air, the land looks like zebra stripes. This limits the effect of wind erosion. As well, strips of vegetation are left along lakes and rivers to reduce soil erosion into the water. In order of the least harmful to the environment to the most harmful to the environment, these techniques are: A. Selective cutting, strip cutting and clear cutting B. Clear cutting, strip cutting and selective cutting C. Strip cutting, selective cutting and clear cutting D. Strip cutting, clear cutting and selective cutting In order of the fastest way to cut trees to the slowest way to cut trees, these techniques are: A. Selective cutting, strip cutting and clear cutting B. Clear cutting, strip cutting and selective cutting C. Strip cutting, selective cutting and clear cutting D. Strip cutting, clear cutting and selective cutting A small logging company employs one or two operators to cut trees with a chain saw. They select large trees, allowing smaller trees more space in which to grow. A horse may be used to drag the logs out of the bush because vehicles are too big to manoeuver through the forest. This logging technique is known as A. Strip cutting B. Clear cutting C. Natural logging D. Selective cutting