Why do Trees Live so Long?

Superlative Trees

Bristlecone Pine

Giant Redwoods

What features allow humans to live to 100?

Cruz Hernandez died in 2007 at the age of 128.

• Luck

• Good genes

• Good diet

• Healthy behaviors

• Good immune system

• Protection from environment

So, what allows trees to live to 3,000 + years?

• Luck • Protection

– Chemistry – Thick bark – Shelter sensitive tissues from winter

• Redundancy • Continued growth • Clonal growth • Repair mechanisms • Genetics and intense selection

early in life

Tree Morphology

What is woody growth?

• Review

– Primary Growth—all plants • Apical meristems—reaching growth

– Shoot apical meristems in buds

– Root apical meristems at root tips

– Secondary Growth—woody plants • Lateral meristems

– Vascular cambium separating bark and wood

– Cork cambium within bark separating inner-living bark and outer-dead bark

MERISTEM???

Stem cells that are perpetually young and capable of dividing to give rise to new tissues

and organs—think of human stem cells.

Primary Growth

• Occurs near stem and root tips

• Reaching growth

• Establishes pattern of leaf and branch production

• Apical meristem of shoot hidden by protective bud scales

• Length of primary growth displayed between terminal bud scale scars

The Tree that Owns Itself

Athens Georgia

Quercus alba

This white oak in Athens GA owns

something that no other city tree

owns. What does it own?

Rambutan-- Nephelium lappaceum

“hairy” fruit

Related to Lychee

Soapwart Family

Grape-like flesh—seed is bitter

Apple Question

Important Dates

Transport to Labrador Pond

Vascular cambium produces more wood

to the inside and more phloem and inner

bark to the outside.

Secondary Phloem

Secondary Xylem

• Several developmental genes in shoot apical meristems ARE ALSO functioning in the vascular cambium – Gene expression in apical meristem of

Arabidopsis (herb) compared with vascular cambium of Populus (tree)

– Class III Homeodomain-leucine zipper – KANADI Transcription Factor – MIR 165/MIR 166 microRNAs – Meristem Maintenance (SHOOT

MERISTEMLESS) – CLAVATA1-cell receptor kinase, but not

CLV3

• Overlap in use of developmental genes

• NO “tree gene”

Terminal and Lateral Bud Variation

Leaf Scar Variation

Lenticels

Speckled Alder—Alnus incana subsp. rugosa

Lenticels are ruptures in old outer bark

that creates ventilation spaces.

Pith-soft spongy tissue in the center

of stem formed from apical meristem;

function???

Cornus-dogwood

Solid Pith

Nyssa-blackgum

Diaphragmed Pith

Walnut—Juglans

Chambered Pith

Quercus—Oak

Star-shaped in x-section

PITH

Thorns—Modified Branches Originate from Lateral Buds

Branched thorns of Honey Locust--Gleditsia Thorns of Hawthorn--Crataegus

Spines—Modified Stipules Originate adjacent to leaf petiole

Black Locust is an example

Prickles are Epidermal Outgrowths Examples include Rosa and Rubus

Thomas, P. 2000.Trees: Their Natural History.

Chalk Board Illustration of

Primary and Secondary Xylem and Phloem

Vascular cambium

Cork Cambium

Inner and Outer Bark

Suggested Historic Dates between 1628 and 1995?

Sapwood & Heartwood

www.bethlehamolivewood.net

Sapwood-functional in water transport;

1-4 rings in ring porous species;

10+ in diffuse porous

Size of sapwood is proportional to size of canopy (LAI)

Heartwood usually lacks living parenchyma cells

darker color due to tannins, resins,

gums, & polyphenols

English Longbows from Yews

http://www.selfbow.com/

Yew heartwood is compression resistant

inside of bow

Yew sapwood is stretch resistant

outside of bow

Long range heavy-tipped arrows to

penetrate armor

Composition of Wood

• Wood=xylem

– 40-55% cellulose

– 20-40% hemicellulose

– 18-35% Lignin • Large, complex molecule

• Important preservative

• Important in organic soil

• Lignin makes wood hard!

Tannins are generally found in bark

• Inhibit bacteria growth

• Make soil acidic

• Bind proteins and inhibit enzymes

• Anti-herbivore chemical

• Why are their few plants in a hemlock forest?

Annual Rings

• Temperate & polar regions

– Less predictable in tropics

• Story teller of the tree

– Fire

– Frost damage

– Insects

– Precipitation

– Competition

– Temperature

– Sunlight/Volcanism

The Tree that Ate the Bicycle

• “A boy went to war in 1914 and left his bike chained to a tree. He never came home and the family left the bike there as a memorial to the fallen soldier.”

• Puget Sound Washington

Ring versus Diffuse Porous Wood

Ring porous wood has the vessel

elements concentrated in the

spring wood.

Diffuse porous wood has the vessel

elements scattered across spring

and summer wood.

Ring Porous Wood

• More common in mid-latitudes; uncommon in tropics

• Ring porous species have determinate annual growth

• Earlier growth in spring than diffuse porous

• Quercus, Carya, Juglans, Castanea, Ulmus, Platanus

Diffuse Porous Wood

• Vessel elements medium sized—smaller than ring porous vessels

• Most common, especially in tropics

• More likely to experience indeterminate growth

• Acer, Aesculus, Betula, Fagus, Tilia

Angiosperm versus Gymnosperm Wood

• Angiosperm wood

– Hardwoods-fibers make wood hard

– Heterogeneous—fibers, tracheids, vessels

– Wide rays

• Gymnosperm wood

– Softwoods—mostly tracheids

– Homogeneous—wood cells of similar size and shape

– Thin rays

– Presence of resin ducts

– No pattern of ring or diffuse porous

Gymnosperm Wood Soft woods—no fibers

• Tracheids with bordered pits are the dominant support and water transport cell.

• Air embolisms are sealed as torus is drawn towards edge of tracheid

• Gymnosperm advantage in cold & dry environments.

• Slower water movement

• Slower water loss from leaves

• Survive winter cavitation and drought

• Other traits?

Gymnosperm Advantage

in Boreal Forest and the Adirondacks

Tell me about this photo

• Temperate zone

• Ring porous

• Distinct vessel elements

• Identify summer & spring wood

• How old is the sample

• Determinate or indeterminate growth

Quercus rubra

Wood Grain—Spiral vs. Straight

• Rarely vertical

• Up to 40°

• Pine breeders select for straight grain—why?

• Advantage to Spiral – Even distribution of water,

minerals, and carbohydrates

– Greater wood strength

Frost Scars (i.e., frost ribs)

• Freeze drying in winter

– Wood shrinks & cracks in winter

• Repeat scaring along branches and trunk

• Snap, crackle, and pop

Winter Sun Scald

• Low winter sun warms bark and stimulates day time growth

• Extreme cold kills these cells after sunset

• What side of the tree trunk will this be found?

• What can one do to protect the tree?

• Usually thin-bark young trees

Burls Cancer-like growth of wood where the cause is largely unknown; virus,

bacteria, insects—result in abnormal growth of dormant buds.

Betula alleghaniensis-Tree Sloth

Camp Huntington Sequoia—Phallus Burl

Quercus alba just north of Aurora NY

Burls can be Desirable

Redwood Burl Guitar found

on Ebay and Redwood Burl Furniture

Burls have “confused grain”

http://www.portmcneillbc.com/

World’s Largest Burl

361 year old Sitka Spruce from Vancouver

22 tons

45 feet in circumference

Tree Branching and Knots Longitudinal section of Trunk and Branch

Annual Rings

Annual rings in branch grow

confluent with annual rings in trunk

This area will form a TIGHT knot.

Tight Knots

Tree Branching and Knots

When the branch dies, the trunk slowly engulfs

the branch by adding more secondary growth.

A LOOSE knot forms where the trunk grows

around a dead branch leaving a collar

of deadbark around the knot.

Loose Knots

How to eliminated Loose Knots?

• Branch collar

How to eliminated Loose Knots?

• Remove branches as they die.

• Cut back to branch color to improve recover—not flush with the trunk.

• 1st-underneath and away from collar

• 2nd-above and closer to collar

• 3rd—remove left over stub to collar

1

2

3

Reaction Wood in Conifers

Gravity

Reaction Wood = abnormal wood that

is produced in leaning trunks

and horizontal branches.

In Conifers, reaction wood forms

on the lower surface and

is referred to as compression wood.

Smaller tracheids

with heavily lignified cell walls

Reaction Wood in Angiosperms

Gravity

Wood fibers in tension wood have a layer of

gelatinous cellulose in the cell wall.

Wide rings with many fewer vessels,

if present then conspicuously smaller.

Compression & tension wood make poor lumber!

Trees and Music

Amazon Rosewood

African Padauk

-hard dense tropical woods

that resonate for long

periods of time

Spruce & Maple -softwoods that vibrate easily

Keys-beech or hornbeam -longevity and hardness

-does not change shape

Bassoons—Norway Maple --precision drilling, moisture abs without shape change

Tropical Pernambuco -stiffness and hold tension on strings

Concert Hall Acoustics

Didgeradoo Music

Bark

Inner Bark contains functional, living phloem;

Bulk flow of sucrose to growing tissues.

Inner Bark parenchyma are totipotent

and capable of wound responses.

Bark Arrows indicate Cork Cambium

Outer bark (i.e., periderm) contains dead phloem;

new and old cork, new cork cambium

Cork Cambium regenerates every year.

Bark Variation

Differences in bark

are due to the pattern

of periderm formation.

Bark Characteristics Change with Age

Betula alleghaniensis

Spandex Bark

Fagus grandifolia

Periderm of Quercus suber

http://www.heartsong.typepad.com/goodearth/

Cork Harvest Portugal

http://www.cuyamaca.edu/ohweb/Australia%20Photos/Melbourne%20Photos.asp

Summary of Secondary Growth in Trees

• Patterns in Wood

– Annual rings

– Heartwood & sapwood

– Ring vs. diffuse porous

– Loose vs. Tight knots

– Reaction wood • Compression

• Tension

– Scarring • Burls

• Frost ribs

• Sun scald

• Patterns and Functions of Bark

– Inner bark

– Outer bark or Periderm

– Regenerative properties