Forestry

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Forestry is an identification event for Division B and Division C in the 2024 season which focuses on the study of trees. It is on a 2-year rotation with the other biology identification events: Entomology, Invasive Species, Herpetology, and Ornithology. It is a current event in the 2024 season, and is predicted to return in 2033.

The event was named Tree Identification from 1987 to 1990, and Tree-mendous from 1996 to 1997. For ID tips and information about specific trees, see the Forestry Tree List.

Overview

General Overview

Forestry is an identification-based binder event in which participants learn about North American trees on the National Tree List. Teams are allowed to bring one 2" binder and a commercially published field guide. If it is run as a station, you may not take sheets out of your binder. Live specimens may be provided, and occasionally competitions may be run outdoors.

Test Format

No more than 50% of the competition will require giving a scientifc (scientific has an "I" by the way) and/or common name (e.g. Write the common name of specimen A, Write the scientific name of specimen B, etc.), although follow up questions (what is the leaf shape, what kind of fruits does this tree have, where do you often find this tree, which toxin does this tree produce, etc.) often rely on whether or not specimens are identified correctly.

Forestry can be run as a written exam, but will usually be run as stations. Competitors should be prepared to write quickly, as station time often is short (2 minutes to 5 minutes) to answer 5-20 questions each station (Nationals 2023 had 18 stations with 2:45 each). Stations usually are formatted in this way:

Potential Station Format (this is kind of bad, sorry)
Image/Specimens Question 1 Question 2 Question 3 Question 4
insert specimen here What is the common and scientific name of this specimen? Where is this specimen commonly found? This specimen often produces a toxin. What is the name of this toxin? What are the scientific names of diseases that often infect this tree (give 2)? List common symptoms of the disease.
Question 5 Question 6 Question 7 Question 8 Question 9
What are the leaves of this specimen commonly used for? Is this species invasive? This species is known as a living fossil. Where did this name come from?

Knowledge questions can fall under three general areas: structure, ecological significance, or economic significance. Structure is relatively straightforward: competitors should be able to answer questions about the leaves of a tree, its twigs, bark, and any flowers or other structures it produces. Ecological characteristics include the tree's interactions with other organisms and its place in the environment including its habitat, any specific adaptations to the environment, biomes, and its role in succession. Finally, economic characteristics may include any beneficial or detrimental aspects of the trees including commercial uses or its status as a nuisance species.

Preparing for Competition

Building a Binder

Though in previous years students were only allowed two note sheets for Forestry, the 2023 season changed this by allowing students to bring a 2" three-ring binder with information in any form and from any source. Participants should be familiar with their resources and be able to quickly find what they are looking for in order to take advantage of them.

For additional online resources, see the resources section at the bottom of this page.

A Quick Guide to Binder Building

A binder can be a daunting thing, especially when you have no experience and do not know what can be put in a binder. Here are some suggestions to make it easier :D

  1. ID sheets of all the trees. This can be a lifesaver, especially when a lot of trees look very similar to each other and/or you're not as fluent in ID. I recommend organizing an ID sheet into leaf/fruit/bark category for each tree.
  2. Vocabulary. Vocabulary is crucial as you probably wont know that many of the more complex vocabulary. Tests often have some vocabulary in the general section of the test.
  3. Anatomy & physiology of trees, plants, flowers, roots, and bark. Anatomy (where everything is located) is highly important because you're often asked to identify parts of leaves/flowers/barks. Physiology (the function of stuff) is very important too as tests may ask for explanations of how things work.
  4. Ecology. Include how certain trees might grow near certain trees, relationships between trees, etc.
  5. Photosynthesis.
  6. Diseases and infections/fungi. There are many questions that ask about diseases and pests that trees may get, so this is crucial.
  7. Most importantly, fact sheets of each tree (probably should aim for 1 page per tree). Fact sheets usually have a format/template that you insert information (e.g. Name; Scientific Name; Family; Leaf description; Flower/fruit description; Bark description; Reproduction; Uses, etc.) Include fun facts and interesting things that make certain trees more unique!
  8. The National Tree List.

Selecting a Field Guide

This section will list some of the most common guides and their advantages/disadvantages. For more information on how to tab and annotate field guides, see Field Guides.

Forestry Field Guides
Field Guide Information Layout Photos or Drawings Images Range Maps Writing Space Extra Notes
Sibley Includes many species. Not much info apart from IDing tips. Column layout; easy to use. Trees are organized by family. Drawings Many for each tree Yes, for every wild tree. Cultivated species are also included without range maps. Large margins and lots of space. Has an intro section with good reading material.
Audubon Includes all species (2004). Lots of complete basic information. Photos and info separated, organized by family. Photographs 1 color image per tree Yes (every tree) Small margins, not much space Recommended by SO in 2004. Seperated into East and West books. Color photos and info are seperated. User-friendly, but only has basic information.
National Geographic Includes many species. Lots of information for most trees. Easy to use - sorted by family Drawings Many for each tree None Small margins but some empty spaces User-friendly layout and easy for identification
National Wildlife Federation Includes many species. Tree size, habitat, and other info. Easy to use but has many pages - sorted by types of leaves Photographs 1-5 for each tree Yes (most trees) Small margins, not much space Has an intro, glossary, and other reading material.
Sibley Guide to Trees
  • Includes many species; very easy-to-use layout.
  • Has many pictures (drawings) for each tree; including leaves, fruit, twigs, bark, seeds, and sometimes the whole tree.
  • Drawings, not photographs.
  • Has an intro section with a lot of good reading material.
  • Range maps for every tree.
  • Does not include much information (apart from IDing), but has lots of space to write in.
  • Larger and heavier than most other field guides (this does not matter much in SO).
National Audubon Society Field Guide to North American Trees
  • Separated into East and West books. May be a disadvantage, although there are books with majority of East/West trees in one book (link here).
  • Includes all but one species on the 2012 list.
  • Has one photograph for each tree, showing leaves, fruits, and cones.
  • Color photographs and information on separate pages.
  • Not very complicated or confusing layout.
  • Has many pages but is not large in size.
  • Lots of complete basic information on each tree.
  • Range maps for every tree.
  • Has small margins, but some empty spaces to write in on the sides.
  • Recommended for the Forestry event in 2011-12.
National Geographic Field Guide to Trees of North America.
  • Includes many species (but is still missing others); easy-to-use layout sorted by family.
  • Drawings, not photographs.
  • Many drawings for each tree for identification.
  • Does not include range maps.
  • User-friendly layout easy for identification but not all trees' information is complete.
National Wildlife Federation Field Guide to Trees of North America
  • Includes all species (with the exception of a few) and information on tree size, habitat, and more.
  • Thick book has many pages - simple layout sorted by leaf shape/type.
  • 1-5 photographs (not drawings) for each tree.
  • Range maps for most, but not all, trees.
  • Small margins and not much space for writing.
  • Has an intro, glossary, and lots of reading material.

Identification Tips

For ID tips and information about specific trees, see the Forestry Tree List.

Identification is a skill that needs to be developed through practice. One strategy is to make a set of flashcards using a service like Quizlet, practicing it frequently until you become more familiar with the specimens and their characteristics. A community-driven solution also exists in the form of a Discord bot designed to help with practicing tree identification. For more information, see [1].

To start identifying samples, consider the type of sample and any unique characteristics it has. Leaves can be categorized by their shape, broken down into a few distinct families:

Conifers:

  • Needle-Like
  • Scale-Like

Broadleaf:

  • Compound Leaves
    • Pinnate
    • Palmate
  • Lance shaped
  • Acicular
  • Spatulate
  • Ovate
  • Obovate
  • Elliptical
  • Circular
  • Etc...
Leaf morphology


Besides the general shape of broadleaf leaves, the margins and venation can be used to help identify leaves. Red and white oaks, for example, have pinnately lobed leaves while maples (generally) have palmately lobed leaves. Elm leaves are toothed while the American witch-hazel is wavy, and black locust has smooth margins. Ginkgoes have dichotomous venation while many others have pinnate venation, and still others possess other venations.

Many other samples are also given alongside leaves, and few are given alone. If bark, wood, or seeds are given, there is probably something significant about that particular tree (for example, the Paper Birch, Betula papyrifera, has unique bark and a buckeye is a seed unique to the Ohio Buckeye, Aesculus glabra, so they may be given for identification)

Fruits are unique to the species they come from. There may be similarities between fruits, but all are easily differentiated (for example, the Black Cherry, Prunus serotina, has fruits similar to the Chokecherry, Prunus virginiana, except that they are black when ripe). Most fruits come from trees with elm-shaped leaves.





Pinnate

  • Ailanthus: Ailanthus altissima (Toothed)
  • Bitternut Hickory: Carya cordiformis (Toothed)
  • Black Locust: Robinia pseudoacacia (Toothed)
  • Black Walnut: Juglans nigra (Toothed)
  • Common Honeylocust (Pinnate or Bipinnate): Gleditsia triacanthos (Toothed)
  • Green Ash: Fraxinus pennsylvanica (Toothed)
  • Kentucky Coffeetree (Bipinnate to Pinnate): Gymnocladus dioicus (Toothed)
  • Oregon Ash: Fraxinus latifolia (Toothed)
  • Pecan: Carya illinoinensis (Toothed)
  • Pignut Hickory: Carya glabra (Toothed)
  • Shagbark Hickory: Carya ovata (Toothed)
  • Silktree (Mimosa) (Bipinnate): Albizia julibrissin (Toothed)
  • Smooth Sumac: Rhus glabra (Toothed)
  • Staghorn Sumac: Rhus typhina (Toothed)
  • American Elderberry: Sambucus nigra
  • Blue Paloverde (Bipinnate): Parkinsonia florida
  • Honey Mesquite (Bipinnate): Prosopis glandulosa
  • Sweet Acacia (Bipinnate): Vachellia farnesiana
  • White Ash: Fraxinus americana
  • Velvet Ash: Fraxinus velutina

Needle-like:

  • Baldcypress: Taxodium distichum
  • Balsam Fir: Abies balsamea
  • Black Spruce: Picea mariana
  • Blue Spruce: Picea pungens
  • Douglas-fir: Pseudotsuga menziesii
  • Eastern Hemlock: Tsuga canadensis
  • Eastern White Pine: Pinus strobus
  • Engelmann Spruce: Picea engelmannii
  • Grand Fir: Abies grandis
  • Jack Pine: Pinus banksiana
  • Knobcone Pine: Pinus attenuata
  • Loblolly Pine: Pinus taeda
  • Lodgepole Pine: Pinus contorta
  • Longleaf Pine: Pinus palustris
  • Mountain Hemlock: Tsuga mertensiana
  • Pitch Pine: Pinus rigida
  • Ponderosa Pine: Pinus ponderosa
  • Red Pine: Pinus resinosa
  • Red Spruce: Picea rubens
  • Redwood (Coast Redwood): Sequoia sempervirens
  • Subalpine Fir: Abies lasiocarpa
  • Sugar Pine: Pinus lambertiana
  • Tamarack: Larix laricina
  • White Fir: Abies concolor
  • White Spruce: Picea glauca

Palmate:

  • Red Maple: Acer rubrum (Palmate, often lobed) (Toothed)
  • Silver Maple: Acer saccharinum (Palmate, deeply lobed) (Toothed)
  • American Sycamore: Platanus occidentalis
  • Bigleaf Maple: Acer macrophyllum
  • California Buckeye: Aesculus californica
  • California Fan Palm: Washingtonia filifera
  • Cabbage Palmetto: Sabal palmetto
  • Sweetgum: Liquidambar styraciflua (Palmate, star-shaped)

Lobed (Toothed at the top):

  • California Sycamore: Platanus racemosa (Palmate, deeply lobed) (Toothed)
  • Bigtooth Aspen: Populus grandidentata (Ovate to round, with toothed margins) (Toothed)
  • Black Oak: Quercus velutina
  • Blue Oak: Quercus douglasii
  • Bur Oak: Quercus macrocarpa
  • California Black Oak: Quercus kelloggii
  • Canyon Live Oak: Quercus chrysolepis
  • Chestnut Oak: Quercus montana
  • Coast Live Oak: Quercus agrifolia
  • Northern Red Oak: Quercus rubra
  • Oregon White Oak: Quercus garryana
  • Pin Oak: Quercus palustris
  • Southern Red Oak: Quercus falcata
  • White Oak: Quercus alba

Scale-like:

  • Eastern Redcedar: Juniperus virginiana
  • Monterey Cypress: Cupressus macrocarpa
  • Northern White-cedar: Thuja occidentalis
  • Port-Orford Cedar: Chamaecyparis lawsoniana
  • Western Redcedar: Thuja plicata
  • Rocky Mountain Juniper: Juniperus scopulorum
  • Utah Juniper: Juniperus osteosperma

Elliptical

  • American Hornbeam: Carpinus caroliniana (Toothed)
  • Bitter Cherry: Prunus emarginata (Toothed)
  • American Holly: Ilex opaca
  • Black Cherry: Prunus serotina
  • Coast Live Oak: Quercus agrifolia (Elliptical to Ovate, often spiny)
  • Flowering Dogwood: Cornus florida
  • Hercules’-club: Zanthoxylum clava-herculis
  • Holly/Yaupon: Ilex vomitoria
  • Pacific Dogwood: Cornus nuttallii
  • Pacific Madrone: Arbutus menziesii

Ovate

  • American Elm: Ulmus americana (Toothed)
  • Candlenut: Aleurites moluccanus (Toothed)
  • Common Chokecherry: Prunus virginiana (Toothed)
  • Common Persimmon: Diospyros virginiana (Toothed)
  • Eastern Hophornbeam: Ostrya virginiana (Toothed)
  • Quaking Aspen: Populus tremuloides (Toothed)
  • Slippery Elm: Ulmus rubra (Toothed)
  • Water Birch: Betula occidentalis (Toothed)
  • Witch-hazel: Hamamelis virginiana (Toothed)
  • Yellow Birch: Betula alleghaniensis (Toothed)
  • Balsam Poplar: Populus balsamifera
  • Bigleaf Magnolia: Magnolia macrophylla
  • Black Tupelo: Nyssa sylvatica
  • Box Elder: Acer negundo
  • Gray Birch: Betula populifolia
  • Live Oak: Quercus virginiana (Ovate, some species have lobed leaves)
  • Northern Hackberry: Celtis occidentalis
  • Osage-orange: Maclura pomifera
  • Paper Birch: Betula papyrifera
  • Pin Cherry: Prunus pensylvanica
  • Red Alder: Alnus rubra
  • Southern Magnolia: Magnolia grandiflora

Heart-shaped (Cordate)

  • Eastern Redbud: Cercis canadensis (Toothed)
  • American Basswood: Tilia americana
  • Northern Catalpa: Catalpa speciosa
  • Princess-tree: Paulownia tomentosa
  • Red Mulberry: Morus rubra
  • Southern Catalpa: Catalpa bignonioides

Lanceolate:

  • Bebb Willow: Salix bebbiana
  • Black Willow: Salix nigra
  • Bluegum Eucalyptus: Eucalyptus globulus
  • Desert-willow: Chilopsis linearis
  • Joshua Tree: Yucca brevifolia (part of its unique foliage, not traditional leaves)
  • Narrowleaf Cottonwood: Populus angustifolia
  • Scouler Willow: Salix scouleriana
  • Willow Oak: Quercus phellos

Fan-shaped (Unique):

  • Ginkgo: Ginkgo biloba

Deltoid (Triangular):

  • Eastern Cottonwood: Populus deltoides

Rhomboid or Broadly Ovate, Sometimes Lobed:

  • Chinese Tallow: Triadica sebifera

Linear to Lanceolate:

  • Curl-leaf Mountain Mahogany: Cercocarpus ledifolius

Oblong to Lanceolate, with a Toothed Margin:

  • American Chestnut: Castanea dentata (Toothed)

Tree Lists

State and regional tournaments may modify the National Tree List, restricting it to a smaller amount of local trees. If applicable, tournaments are required to post this modified list on their website prior to November 1st. At any competition without its own tree list (including the national tournament), any tree listed on the current season's National Tree List may be tested.

The current season's National Tree List may be found in the current season's Rules Manual, available for free on soinc.org. The information on this page is provided as reference, and should not be interpreted as an extension of the rules.

Previous Tree Lists

These tree lists are not applicable for the current season and are provided for reference only.

New Trees for 2024 Season

  • Populus alba (White Poplar)--WIllow/Salicaceae
  • Betula nigra (River Birch)--Birch/Betulaceae
  • Quercus phellos (Willow Oak)--Beech/Fagaceae
  • Pyrus calleryana (Bradford Pear)--Rose/Rosaceae
  • Albizia julibrissin (Silktree)--Legume/Fabaceae
  • Rhus typhina (Staghorn Sumac)--Cashew & Sumac/Anacardiaceae
  • Acer macrophyllum (Bigleaf Maple)--Maple/Sapindaceae
  • Acer platanoides (Norway Maple)--Maple/Sapindaceae
  • Yucca brevifolia (Joshua Tree)
  • Fraxinus pennsylvanica (Green Ash)--Olive/Oleaceae
  • Paulownia tomentosa (Princess-tree)--Paulownia/Paulowniaceae
  • Triadica sebifera (Chinese Tallow)--Spurge/Euphorbiaceae

Name Changes for 2024 Season

Note: Leguminosae has been changed to Fabaceae, Basswoods are placed in Malvaceae instead of Tiliaceae, Black Tupelo is placed in Nyssaceae instead of Cornaceae, and Maples are placed in Sapindaceae instead of Aceraceae

  • Notholithocarpus densiflorus (Tanoak)--Beech/Fagaceae
  • Quercus montana (Chestnut Oak)--Beech/Fagaceae
  • Celtis occidentalis (Northern Hackberry)--Hemp/Cannabaceae
  • Liquidambar styraciflua (Sweetgum)--Sweetgum/Altingiaceae
  • Parkinsonia florida (Blue Paloverde)--Legume/Fabaceae
  • Vachella farnesiana (Huisache/Sweet Acacia)--Legume/Fabaceae
  • Ilex vomitoria (Holly/Yaupon)--Holly/Aquifoliaceae
  • Tilia americana (American Basswood)--Mallow/Malvaceae
  • Carnegiea gigantea (Saguaro)--Cactus/Cactaceae
  • Sambucus nigra (American Elderberry)--Muskroot/Adoxaceae

Removed Trees for 2024 Season

  • Pinus albicaulis (Whitebark Pine)--Pine/Pinaceae
  • Pinus aristata (Bristlecone Pine)--Pine/Pinaceae
  • Pinus flexilis (Limber Pine)--Pine/Pinaceae
  • Pinus monophylla (SIngleleaf Pinyon)--Pine/Pinaceae
  • Pinus monticola (Western White Pine)--Pine/Pinaceae
  • Pinus virginiana (Virginia Pine)--Pine/Pinaceae
  • Populus fremontii (Fremont Poplar)--Willow/Salicaceae
  • Populus trichocarpa (Black Cottonwood)--Willow/Salicaceae
  • Quercus bicolor (Swamp White Oak)--Beech/Fagaceae
  • Quercus imbricaria (Shingle Oak)--Beech/Fagaceae
  • Quercus muehlenbergii (Chinkapin Oak)--Beech/Fagaceae
  • Crataegus douglasii (Black Hawthorn)--Rose/Rosaceae
  • Crataegus pruinosa (Frosted Hawthorn)--Rose/Rosaceae

Introduction to Forestry

Trees aren't a formally defined taxonomic group like birds or insects. Trees are just very large plants, and can be found in families and genera which also contain smaller plants and shrubs. There is a sort of continuum between shrubs and trees – even within a species, plants can range from a mere few feet tall to hundreds of feet tall. However, for the purposes of field guides, there are some general characteristics that most trees share which allow classification to be facilitated.

  • Trees are perennial.
  • Trees have a single woody stem which branches into a crown of foliage.
  • Trees reach a height of at least 10-20 feet.

Don't think of this definition as the ultimatum for deciding what a tree is. There are many exceptions to the above, and many people have debated over the definition of a tree throughout history.

A tree is a common vascular plant found almost everywhere in the world. It has three main parts: the root, trunk and crown. The root is the part that grows in the ground and absorbs water and nutrients; the trunk grows above ground and is the "body" of the tree; the crown grows out of the trunk and is made up of limbs, twigs, leaves, buds, flowers and fruit.

Roots

A diagram of a tree root.

Roots are sometimes called the underground branches of the tree. They reach down into the ground to get the minerals and water necessary for the tree's growth. The roots also anchor the tree in the ground to prevent it from being washed away or knocked over. A tree's root system is its foundation and is at least somewhat proportional to the size and dimension of the tree it will support.

The more the branches grow and expand in the crown, the more the roots grow deep and wide under the ground. The tree's roots form an amazingly intricate and complex system in order to access and transport the necessary nutrients. Root tips may be covered with fine hairs to make it easier for the tree to absorb water and minerals. Trees absorb small amounts of moisture from the air through their leaves and their bark. Most of their water, however, comes via the roots.

Water enters the roots through thin membranes that cover the roots. The tree's vascular system draws the water up through the trunk and distributes it to the leaves. The leaves use the water to dissolve minerals. Excess water goes back to the air through pores in the leaf - a process called transpiration.

Roots are made up of a number of specialized components. The root hairs, tiny structures extending from the main root stems, have very thin walls which absorb water and minerals. This mixture of minerals and water is passed into the vascular core of the root from where it is transported throughout the tree. At the tip of the root, there is a protective structure called the root cap. The cells of the root cap are loose and are shed as the root grows into the soil.

Different trees have different root systems. Pine trees have a strong central root called the taproot. This is usually larger than any other roots and often extends deep into the ground. Because damage to this root can be fatal to the tree, trees with taproots are generally difficult to transplant. Other trees, such as the elm or maple, do not have a dominant taproot. Their root systems are characterized by a large number of roots often closer to the surface.

Generally, root growth is influenced by moisture and gravity. Unless there are substantial amounts of moisture near the surface, roots tend to grow far downwards through the soil. Roots are always growing and, like a tree's trunk, they grow both longer and wider. At the tip of the roots, the growing region is called the meristem. This is where most of the lengthwise growth takes place. In addition to this, wood is added to the inside of the root and phloem is added towards the outside.

The Trunk

This is the strong mainstay of the tree that begins as a tender stem from which leaves begin to sprout. The trunk is the body of the tree, which not only supports the crown, but in addition internally channels sap and tree food from one part of the tree to another.

A tree grows taller by adding new growth at the tip. In the spring, a new shoot starts to grow at the very tip of the tree. This is called the leader. Its length indicates how much a tree has grown over the course of a year. New shoots grow out sideways from the base of the leader. Each end of each branch has a similar growth of shoots. By summers' end, buds form on the new shoots, and from these buds will develop next year's shoots.

The girth of a tree develops in quite a different way. Between the bark and the wood is a thin soft layer called the cambium. Each year this cambium produces a new layer of wood. You cannot see these layers as they are hidden by the bark. However, the age of cut trees may be determined by counting these layers, called annual growth rings, on the stump.

The Crown

On broad-leaved, deciduous trees such as maples, oaks and elms, a bud forms during the summer at the point where each leaf joins the twig or branch. This bud remains when the leaf falls off the tree in the autumn, and the following spring when the warmth of the sun touches the bud, it bursts and sends out a new shoot at an angle from the branch. This shoot grows into a new branch, and as it grows during that summer, new buds again form along which in turn become other branches. This continues year after year until finally the tree is a fully matured maze of twigs and branches.

On the evergreen or coniferous trees, the formation of buds is different. On pine trees, the buds form only at the tips of the twigs. In spruce, buds form not only at the tips, but also back on the new shoot. On cedar trees, you cannot see any buds at all.

Leaves and branches perform necessary and symbiotic functions. The branches bring water and minerals to the leaves, where food is manufactured, and then return that nourishment back to the different parts of the tree.

The Leaf

A chart describing different leaf shapes. Click to view in greater detail.

Although there is an incredibly very wide variety of size, shape, and texture of leaves, they all have one important thing in common. The leaf is where a tree's food is manufactured. Water and minerals from the soil combine with carbon dioxide from the air to ensure growth and development. A tree will suffer if insects eat all the leaves, as the nourishment needed cannot be made without them.

The leaf is divided into three parts - blade, vein system and stem. The blade of each leaf is made up of hundreds of tiny cells and is the "main" part of the leaf. The cells contain a green substance called chlorophyll, which is an important part of the food-making machinery. The veins of the leaf are the conduits, bringing in the sap that has been drawn up from the roots. Leaves collect carbon dioxide from the air and the sun provides the power to run the "machinery". A product is formed that is much like starch. This food is sent to every part of the tree where it is used in building food, bark and other tissues.

We might imagine plants having an arrangement with other animals and human beings in terms of respiration. Animals use oxygen from the air, giving back carbon dioxide to the air. The leaves take in the carbon dioxide, keep the carbon to build up the wood, and release oxygen into the air for all animals to use.

Acting as an enormous "carbon sink", trees soak up carbon dioxide from the air, producing life-giving oxygen in return. In fact, a medium-sized tree generates the same amount of oxygen as each one of us needs to breathe.

In a tree, 'breathing' takes place in the leaf. Chlorophyll (the substance causing the green color) absorbs the CO2 and uses it along with water to dissolve minerals taken up through the roots. After the chemical reaction is completed, the leaf releases oxygen and water vapor through its pores.

Photosynthesis is a process by which CO2 and water are combined with sunlight and a pigment called chlorophyll. The chemical reactions result in the production of sugars which provide energy to the tree. The leaves use some of this energy, but the majority is transported, in the form of sugar solutions, to other parts of the tree that require it.

Transpiration, or water loss, also takes place in the leaves. As this occurs, water is drawn up from the roots through the vascular system to replace lost moisture.

In autumn broad-leafed trees display a brilliant coloring. This occurs when the removal of the green pigments (chlorophyll) takes place, leaving the yellow pigments. These along with other materials are stored in the branches during the winter are used by the tree to start further growth in the spring. Even the fallen leaf performs a necessary function. They benefit the soil by keeping it from being washed away by heavy rains and they prevent the ground from becoming too hard so that melting rain and snow can sink into the ground rather than flooding the surface of the earth.

The evergreen tree is a conifer. The leaves are in the shape of needles. These trees actually do get a new set of needles every year, but as the needles stay on the tree for more than a year they remain green. Amongst conifers there are exceptions. The larch in autumn turns yellow and the leaves fall off. The arbutus, native to the Pacific Northwest is a broad-leafed tree that keeps its green leaves all year round.

Leaf Shapes

Name Needlelike/Scalelike Leaves Simple Alternate Leaves Simple Opposite Leaves Compound Leaves
Image EasternRedcedar.jpeg
Error creating thumbnail: File missing
SimpleOpposite.jpeg PalmatelyCompound.jpeg
Description These are the leaves of coniferous trees. Needlelike trees are found mostly on pines and firs, while scalelike leaves are common on junipers and redcedars. The image above depicts scalelike leaves on an Eastern Redcedar. Simple alternate leaves are when two leaves alternate on either side of the branch. Simple opposite leaves are when two leaves meet at the same point on a branch. Compound leaves are leaves that are divided into leaflets. Compound leaves can be alternate or opposite - but are also pinnately compound or palmately compound. Pinnately compound is when leaflets branch off from a rachis (the axis of the compound leaf). Palmately compound is when the leaflets all meet at one point. A good example of a palmately compound leaf can be seen above.

Bark

Just like human beings have a protective outer layer all over their bodies known as skin, trees have a protective outer layer called bark. Damage to the bark can prove fatal to the tree. If someone cut the bark, around a tree down to the wood beneath, the flow of food would be disrupted and the tree will starve to death.

Many kinds of trees can be immediately recognized by their distinctive bark. Variations in markings, color and texture denote not only the type of tree, but even the age of the tree within that particular species.

The bark of a young tree and that on young parts of a mature tree are quite thin, but the bark of an older tree is thick and rough. For instance, the bark of the giant and ancient west-coast Douglas-fir tree, may be more than a foot thick.

Every tree has two layers of bark, an inner layer and an outer layer. The inner bark, through which food passes up and down he trunk and along the branches, is soft and moist. The outer bark is hard and firm. The hardness and thickness of the bark protects the tree from injury and from the elements.

The older the tree, the thicker the bark grows. This is because each year a layer of inner bark hardens and becomes part of the outer bark. In this way the outer bark builds off, even though some of it will eventually fall off the tree in the form of scales.

Seeds

The seed is the part of the plant that contains the speck of life that has the capacity to grow into another plant like the one from which it came. Although differing in size and shape, all seeds contain small leaves and the beginning of a trunk and root. Another thing all seeds have in common is the need for heat and moisture to begin the 'sprouting' process.

For a time the young tree will live on nourishment enclosed in the seed coating, but soon the root will reach down into the ground and the leaves will expand into the air and from that time on the young 'seedling' makes its own food from the materials it finds.

In order to grow, seedlings must have water, heat, light and air. In nature seeds fall from the ripened trees laying on the forest floor until they begin to sprout. Commercially, the forester will collect these tree seeds and transport them to nurseries where they are planted and tended in seedbeds. Two years later these 'seedlings' are then taken from the seedbeds and planted into fields called transplant beds. They are allowed to stay there from one to three years before finally being set out in rows to form a plantation, where they will eventually grow to maturity.

Photosynthesis

Photosynthesis is a process in which a plant (including trees) uses energy from sunlight to produce sugar then uses it to make adenosine triphosphate (ATP). Photosynthesis occurs in the chloroplasts, a feature found only in plant cells.

The process of photosynthesis is done mostly in the leaves of a plant. Water from the roots travels to the leaves through passages called xylem. Water, carbon dioxide, and sunlight work together to produce sugar and oxygen.

A diagram of a plant cell.

Electron Transport Chain (Light-Dependent Reactions)

The electron transport chain (ETC) takes place in the thylakoid membrane. It begins with light hitting a photosystem, which is essentially a bundle of light-recepting molecules. At the core is chlorophyll, which, when hit by a photon of light, loses an electron. This electron is later replaced by splitting a molecule of water into 2 protons, 2 electrons, and an oxygen molecule. Using the energy from the excited electron, specialized channel proteins pump protons across the thylakoid membrane from the outside fluid, called the stroma, into the inside of the thylakoid, which resembles a hollow discus. A gradient is then formed , where there are too many protons in the thylakoid, and they want to come out. They come out through a special protein channel, called ATP synthase. As they are entering the stroma, the protons release potential energy, which is harnessed by the synthase molecule to make ATP.

Meanwhile, the electron that started this whole cycle, after it loses energy, gets stuck to a molecule called NADP+, adding on another hydorgen molecule, to form NADPH. This, and the ATP that is formed, move into the Calvin Cycle, and the oxygen is excreted as waste.

The Calvin Cycle (Light-Independent Reactions)

This process takes place on the interior of the thylakoid. In the Calvin Cycle, the carbon dioxide molecule is combined via carbon fixation with a molecule of ribulose bisphosphate (RuBP) to form the molecule 3PG. 3PG is then altered to form the molecule G3P, also called PGAL. Since there are 6 G3P formed, one G3P is sent to other locations within the plant cell to be converted into glucose (which needs 2 G3P molecules). The other 5 G3P molecules are converted, with the aid of an ATP molecule, back into ribulose bisphosphate. The new RuBP molecule is then ready to fix the next carbon dioxide molecule. The enzyme used to fix carbon dioxide is Ribulose Bisphosphate Carboxylase, better known as Rubisco. Rubisco is the most abundant enzyme on the planet.

The ETC is a part of the light-dependent reaction because it cannot occur without light. The light energy allows for the excitation of electrons, which results in the electron transport chain being able to function. Similarly, the Calvin Cycle is a light-independent reaction because no light is needed to run it. However, if there is no light, the ETC would soon stop, leading to the Calvin Cycle stopping as well. Therefore, light is still needed for photosynthesis to continually occur.

Example Questions

Most Forestry questions fall under two main categories, ID and then follow-up questions, or general forestry questions.

An example for ID and follow-up questions includes:

MysteryLeaf.jpg

Identify this specimen.

  1. What is the common name of this specimen?
  2. What time of year does this species flower?
  3. What is the main commercial use of this tree?


Answer

Cercis canadensis

  1. (Eastern) Redbud
  2. Spring
  3. Ornamental


An example for general forestry questions includes:

  1. What is the job of the heartwood of a tree?
  2. What is the purpose of the shape of samaras?


Answer
  1. The heartwood is the strong central, supporting pillar of a tree, which helps stabilize the trunk and thus the entire tree.
  2. The shape of a samara allows for it to be easily dispersed by wind.


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