Introduction to Forestry Hoyt Ponder Submitted October 20, 2005
Objectives Upon completion of this course, the student should be able to: • Describe the forest resources of Louisiana and our region. • Explain primary and secondary growth of a tree. • Define and explain techniques used for the management of a forest including: soil, water, and wildlife. • Understand basic economic concepts of the forestry industry.
In terms of woody plants, the two main types are trees and shrubs. What are the main differences in a tree and a shrub? What makes up forest?
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
Photosynthesis Co2 + water in the presence of light = sugar Respiration Oxidation of Carbon Sugar in the presence of Oxygen = CO2 Energy/Food
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 dividing • Apical 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
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. Tolerance
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
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
“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
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. Natural 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 Artificial Regeneration
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
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 Harvesting Timber
Advantages: Easy site preparation Max profits Natural and artificial regeneration can be used Disadvantages: Soil erosion Takes time to regenerate Negative view Clear Cutting
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 High Grading
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 trees • Usually 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