Deterioration Final Review

Wood's 4 Properties

1. Hygroscopic

2. Biological Material

3. Anisotropic

4. Heterogeneous

Hygroscopic

Water exchange

Biological Material

living

Anisotropic

different on every plane (transverse, tangential, and radial)

Wood is a

Natural composite (structural: cellulose, hemicellulose, lignin; non-structural: extractives and ash)

Has many different applications (construction, furniture, fuel, etc.)

Organic material

Important Step of Wood Processing

Drying

Drying

Dry wood = stronger (requires the most time and energy)

Why do we Treat Wood?

To extend its useful life and improve its dependability

So it can compete with other materials

Different Ways to Preserve

Toxic to organisms, not us

Water repellent

Fire retardant

Modify its character

Advantages of Wood

Widely available

Suitable for many applications

Efficient

Durable

Workable with simple and high-tech tools

Renewable - can be used again if replenished

Sustainable - can be used now and in the future if it is replenished

Low embodies energy - low energy required to process

Low carbon impact

Green Building

Increase efficiency (use less energy) and reduce impact on human and environmental health

4 Basic Wood Sciences and why we study them

1. Wood anatomy

2. Chemistry

3. Mechanics

4. Physics

Need to know to understand the material you're working with

Macroscopic Features of Wood

Surfaces of Wood

Earlywood and Latewood

Heartwood

Knots

Resin Canals

Earlywood vs Latewood

EW - less dense - more void space

LW - denser - thicker cell wall

Heartwood

Extractive - naturally resistant to decay

Some have heartwood, all have sapwood

Harder to treat and dry

Odor, color

Softwood Wood Cells

Tracheid (main constituent) - pits (simple, bordered, and half-bordered) - aspirated pits: (happens when dried too fast) torus blocks side of pit - treatment can't penetrate

Parenchyma

Ray cells

Resin canals - pine, spruce, larch, Douglas fir; surrounded by epithelial cells in a fusiform ray

Easier to treat

Longer fibers

Hardwood Wood Cells

Vessels (main constituent) - water transport, tyloses can affect penetration

Fibers

Parenchyma

Tracheid

Ray Cells

Has more extractives, generally denser, and difficult to treat

Shorter fibers

Cell Wall

Inside, out: Lumen, S3, S2 (cellulose), S1, Primary, Middle Lamella (lignin)

Free Water

in lumen

easy to remove

above FSP (>30% MC)

weight change

1st to be removed

Vapor and liquid

Bound Water

In cell wall

Difficult to remove

Below FSP (<30% MC)

Weight change and shrinking/swelling

Last to be removed, 1st to be replaced

Chemical form

Knots

Decrease strength

Characteristic/defect

Sound (strongest), decay (weakest), enclosed

Most Important Wood Property

Density

Density

Easy to find (Mass/Volume)

Related to other wood properties

Most Important Property of Wood Mechanics

Bending

Bending

can find MOE and MOR, also has tension, compression, and shear

Wood is Strongest

Parallel to grain

Fungi Facts

Saprotrophic - decomposers

Heterotrophic - eat

Cosmopolitan - everywhere

Dikaryotic - 2 nuclei

Eukaryotic - protected nuclei

Abundant - over 100,000 known species

Reproduce sexually and asexually

Parts of Fungus

Hyphae

Mycelia

Fruiting Body

Thallus

Hyphae

thin filaments, apical growth; contain septa (separate), nuclei (genetic info), cytoplasm (nucleus + cytoplasm = protoplasm)

Mycelia

group of hyphae

Fruiting Body

reproductive structure

Thallus

single undifferentiated fleshy body of fungus

Vegetative Growth

Asexual - mitosis

Germination

Spread of mycelia

Reproductive Growth

Asexual (mitosis) or sexual (meiosis)

Spore producing

Stages of Meiosis

1. Plasmogamy

2. Karyogamy

3. Meiosis

Plasmogamy

fusion of protoplasm

Karyogamy

fusion of nuclei

Meiosis

division

Asexual Fungi

Sporangiospores

Conidiophores

Sexual Fungi

Basidiomycetes

Ascomycetes

Zygomycetes

Oomycetes

Formation of Dikaryon

1. Germination

2. Combability

3. Dikaryon

Germination

haploid

Combability

fusion of hyphae

Dikaryon

2 nuclei

Advantages of Sexual and Asexual Reproduction

Sexual reproduction is aggressive (fast)

Asexual reproduction is fast and easy

What Makes Wood Decay Fungi Unique?

They have special enzymes to break down wood components (cellulose, hemicellulose, and lignin)

Basidiomycetes

Most wood decay fungi

Exogenous

Prefer sexual over asexual

Clamp connection on septa

Ascomycetes

Endogenous

Mainly do asexual

More abundant

Sexual spores in ascus

Life Cycle of Fungi

Anamorph

Teleomorph

Holomorph

Anamorph

asexual

Teleomorph

sexual

Holomorph

whole fungus

Metabolism

Chemical reactions an organism goes through to maintain life

Catabolism

Break down

Anabolism

Build up

Primary Metabolites

Necessary for life (growth)

Secondary Metabolites

Not necessary but useful

How do Fungi Grow

Lag

Log

Stationary

Death

Lag

build up reserves

Log

exponential growth

Stationary

maintain life as long as it has resources

Death

doesn't have necessary resources (nutrients, primary metabolites)

What do Fungi Need to Attack Wood?

Air

Water

Temperature

Proximity

pH

Nutrients

Brown Rot

Ex: Gt

Attack cellulose, leave lignin

Attack SW

Appearance: checked, dusty when dried

Basidiomycetes

Faster than white rot

White Rot

Ex: Tv

Attack all wood components (lignin 1st)

Attack HW and SW (mainly HW)

Localized attack

Basidiomycetes

Soft Rot

Need excessive moisture (ground contact)

Surface attack

Ascomycetes

Attack HW

Slow

Sap Stain Fungi

No mechanical effect

Stain surface (hyphae are blue/green and stain wood)

Enzyme Function

Speed up the reaction

Reduce the energy needed to react

Lock and Key Principle

Specific substrate for every enzyme (inhibitor also fits)

Factors that Affect Enzyme Activity

Temp

pH

Cofactors/coenzymes

Inhibitor

Activator

Enzyme Conformation

1. Primary

2. Secondary

3. Tertiary

Primary

linear chain of amino acids

Secondary

folded once (sheets, helix)

Tertiary

folded onto itself (3D)

Types of Enzymes

Intracellular

Extracellular

Intracellular

inside cell

Extracellular

outside cell - breaks down components too large to go into the cell

How to Control Wood Decay (Abiotic Factors)

Moisture content (most important - metabolism, enzymes: proteins, cell well)

Temp (growth)

Nitrogen (wood low in N, so it takes N from soil)

pH (enzyme activity)

Temps for Growth, Death, and Stationary Fungi

Lethal (death, but spores still good) min: -5 to -10 C

Critical (no growth) min: -2 to 3 C

Growth: 18 - 35 C

Critical max: 35 - 45 C

Lethal max (varies): 50-55 C to 70-85 C

Stop Decay

Remove water

Don't put wood where fungi are

Treat

Stop Any Mode of Action

Remove water

Change temp

Remove necessary substrate

Control enzyme activity

Remove proximity

Which biological degrader causes the most damage

Fungi>Termites>Beetles>Marine Borers

Termite Facts

Social (live together)

Incomplete metamorphosis (different jobs depending on colony need)

Hexapod (6 legs)

Isoptera (same wings)

Saprotrophic (decomposers)

Invertebrates (no bones)

Higher

bacteria only in hindgut, more complex

Lower

bacteria and protozoa, came 1st in evolutionary history

Dampwood

above FSP, weight loss

Drywood

below FSP, visual difference

Life Cycle of Termite and their Jobs

Egg -> Nymph (assigned job at this stage)

Worker - eat wood, feed colony, take care of young, groom, build shelter tubes

Soldier - protect colony

Reproducer - reproduce (queen and male)

Coptotermes (Formosan)

Aggressive

Invasive

Prefer warmer climate

Soldiers: round heads

Damage looks like brain damage

Smaller colony - slower

Reticulitermes

Found in the East

Soldiers: rectangular heads

Only eat earlywood

Larger colony - faster

Wood Breakdown by Termites

1. Mechanical

2. Chemical

3. Excretion

Mechanical

chew, mandibles

Chemical

Midgut: endogenous enzyme (produced by the termite)

Hindgut: exogenous enzymes (produced by symbiotic organisms - bacteria/protozoa)

Excretion

poop, feed colony

Largest Beetle Family

Curculionidae - powderpost beetles

Beetle Life Cylcle

Egg -> Larva (eat wood) -> Pupil -> Adult

Complete metamorphosis

What do Beetles Eat in the Tree

Nonstructural components (starch, sugars, lipids)

Lay eggs in vessels of HW

Galleries depend on the size of the beetle (can help ID)

Post-Harvest

ALBOW and Buprestidae

Dried (seasoned) wood

Pre-Harvest Beetles

Unseasoned wood

Bark beetles

Pinhole beetles

TOW

Type of wood