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Introduction to Forestry
Hoyt Ponder
Submitted October 20, 2005
Objectives
Upon completion of this course, the student should be able to:
1. Describe the forest resources of Louisiana and our region.
2. Explain primary and secondary growth of a tree.3. Define and explain techniques used for the
management of a forest including: soil, water, and wildlife.
4. Understand basic economic concepts of the forestry industry.
What makes up forest?
In terms of woody plants, the two main types are trees and shrubs.
What are the main differences in a tree and a shrub?
Trees and Shrubs
A tree is a woody plant, typically large with a well-defined stem and a more or less defined crown.
A shrub is a woody plant, seldom exceeding 10 ft. in height, usually having several persistent woody stems branching from the ground.
Types of Seeds
Angiosperms – trees which produce seeds that are encased in a hull, shell or fruit. (Oaks, Fruit Trees, and Grasses)
Gymnosperm – trees which produce seeds that are naked. (Pines)
Types of Seeds (cont.)
Angiosperms (two kinds) Monocotyledons-embryo with one leaf.
Palm trees and grasses Dicotyledon-embryo with more than one leaf.
Oaks, maples, and magnolias Broadleaved or hardwoods
Gymnosperms Conifers-pines, junipers, spruces, firs, and cypress Softwoods
Types of Trees
Evergreens Retains leaves year round Often a synonym for conifers (except cypress)
Deciduous Trees that loose their leaves every year Often a synonym for hardwood (oaks)
Energy/Food
2 Types of Sugars
Starch – source of energy, excess is converted into wood
Cellulose – structural, makes up 70% of wood
Energy/Food
Photosynthesis Co2 + water in the
presence of light = sugar
Respiration Oxidation of Carbon
Sugar in the presence of Oxygen = CO2
Secondary Chemicals
Lignin – functions as a glue that glues cells together, second most abundant chemical in wood
Tannins, terpenoids, and alkinoids all protect trees from insects, fungi and bacteria
Three Types of Tissue
Ground – biochemistry Dermal – epidermis or skin
of plant (bark) Vascular – transport system
Xylem – transports water
and mineral salts Phloem – transports
organic food and sugars
Growth
Primary Growth – elongation (height) Secondary Growth – diameter (width)
Each year a tree gets
a new growth ring The growth ring can
tell you a great deal
about a tree
Growth (cont.)
Meristems Refers to points of growth that are actively
dividingApical meristems – tips of limbs and trunks (primary
growth – deals with elongation)Cambium meristems – single cell layer wide
(secondary growth – gets bigger in diameter)
Plant Hormones
Auxins Hormones that are made in the shoot tips, and
controls phototropism (ability to grow towards the light)
Apical Dominance Control of auxins in the tips of the limbs and
shoots Suppresses elongation of lateral branches
Symbiosis with Fungi
Symbiosis – both plant and fungi benefit Mycarhizae – fungi that surround the roots
increases uptake of nutrients, increases the surface area of the roots
Rhizobium – bacteria that is symbiotic with legumes (mimosa, black locust) and fixes atmospheric nitrogen
Tolerance
Tolerance is the ability to grow in low light conditions
Tolerance
Intolerant grow best in full sunlight (bald cypress, pines, oaks)
Tolerant has relatively equal growth with different levels of sunlight (southern magnolia, beech)
Many of the important commercial and wildlife species are intolerant trees. Much of forest management has focused on maintaining communities of intolerant species.
Gap Dynamics
Small scale disturbances – small openings in a forest where advanced regeneration occurs Fugitive – easily distributed seeds (pines) Buried seeds – seeds remain viable for a long
time (oaks) Sprouting – roots and stumps sprout to form a
new forest
Competition through Chemistry
Allelopathy – condition when some plants produce chemicals that inhibit, retard, or kill other plants
The black walnut produces juglone which is a phenolic compound that kills most plants.
Prescribed Burning
Uses: Reduction of logging debris Preparation of seed beds Reduction of fuels in forests Control understory vegetation Improvement of wildlife habitat Improvement of forage for livestock
Prescribed Burning
Limitations: Must be controllable (fuels, weather,
topography) Preparation of fire breaks Smoke management (air quality, liability) Cost $7-$20 per acre
“Let It Burn” Policy
Managing Natural Fires Put out the fire or let it
burn?
Yellowstone Park is this policies biggest challenge (contains 2.2 million acres)
“Let It Burn” Policy
In 1988 45% of Yellowstone burned (approx. 1 mil. Acres)
½ were only surface fires 25-30% burned under constant suppression Much of the problem was caused by fuel
build up due to prior fire suppression
Regeneration
Follows harvesting or small scale disturbance
Natural Regeneration – seeds produced in area sprout and regenerate.
Artificial Regeneration – can be accomplished by either Direct Seeding or Planting nursery grown seedlings
Natural Regeneration
Advantages: Usually produces a
thick stand No bed preparation is
required Requires no costs
Disadvantages: Unknown species Unknown genetics Bad seed year Drought Seeds may be eaten by
rodents
Natural Regeneration
Methods: Seed tree method – superior
trees are left to provide seed and are removed after regeneration.
Shelter wood method – similar to seed tree method, but deals with species where shelter is required
Coppice method – using stump and root sprouts.
Artificial Regeneration
Advantages: Control seed supply Increases prompt
reforestation Greater control over
species and genetics Control tree spacing Regenerate in optimal
weather conditions
Disadvantages: Can be costly
Bed prep
Cost of seedlings
Cost of planting
Succession
The orderly replacement of species through time in a given location eventually leading to a stable community
Two types of Succession: Primary – initial invasion of a bare site Secondary – orderly replacement of species over
time
Harvesting Timber
2 Main ways Clear cutting – all trees
are removed at one time High grading – best
quality and largest trees are removed, only poor quality and small trees are left
Thinning – age, corridor
Clear Cutting
Advantages: Easy site preparation Max profits Natural and artificial
regeneration can be used
Disadvantages: Soil erosion Takes time to
regenerate Negative view
High Grading
Advantages: Biggest tallest trees are
harvest Species can be selected
for a market Highest dollar per board
foot
Disadvantages: Appearance Smaller trees and
poorer quality is left Regeneration has
genetics that are inferior
Siviculture
Manipulation of forest vegetation to accomplish a specific set of objectives controlling forest establishment, composition and growth Even aged stand – stands in which relatively
small differences exist between individual treesUsually develop after a large scale disturbance (intol.)
Un-even aged stand – lack of disturbance (tol.)
Un-even Aged Stand
Dominant – project above canopy, direct sun from above and part of the sides
Co-dominant – top of canopy, direct sun from above only
Intermediate – crowded into canopy, sun only directed to the top of the crown
Suppressed – completely overtopped,no constant direct sun (some plants will die)
Review
What is the difference between a tree and a bush?
How does fungi work together with trees? What is the controversy over the “Let it burn
policy”? What are advantages and disadvantages of
clear cutting and high grading?
Tomorrow’s Lesson
Commercial Forest Land NIPF – Non-industrial Private Forests Land Expectation Value (LEV) Mean Annual Increment (MAI) Harvest Scheduling