Forestry K1: Plant Biology

Dendrochronology

Dendrochronology is the technique of dating events, environmental change, and archaeological artifacts by using the characteristic patterns of annual growth rings in timber and tree trunks

Who founded dendrochronology?

Andrew. E. Douglass in late 1800s and early 1900s

Cross-Dating

Cross-Dating is a technique that ensures each individual tree ring is assigned its exact year of formation by matching patterns of wide and narrow rings between cores from the same tree, and between trees from different locations, or matching the patterns of tree rings from one tree to another

Earlywood

Early wood is the light colored portion of a tree ring produced in the spring (cells are large and thin walls)

Latewood

Late wood is the darker part of an annual tree ring produced in the summer season (cell walls grow thicker =dark wood)

What do the rings tell us about the climate at time of growth?

Abundant moisture and long growing season → wide ring

Dry year → very narrow ring

Trees are more sensitive to temperature at high altitudes on mountains or in boreal northern regions like Alaska and Canada

Wide ring → warm year

Narrow ring → cold year

What trees do dendrochronologists use?

Climate sensitive trees; Dendrochronologists need long-lived trees growing in fairly harsh environments marginal environments (high altitudes or arid regions)→ so they are sensitive to surrounding conditions and slow growth to record more lifetimes

Tree increment borer

Tree increment borer pulls out pencil-sized sample of wood from tree w/o harming it. Scientists can dip their tree borers into alcohol to stop spreading any diseases from tree to tree

Tree line

is the elevation above which trees will not grow because it’s too cold. Trees living at or near this line are often stunted and gnarly due to harsh conditions

How do scientists process tree cores?

Scientists collect core samples from 20 or more trees at each site

Cores mounted in special wooden holder, or core mount, then finely sanded to bring out core pattern

crown

Leaves + branches at top of tree

leaves

Chlorophyll, photosynthesis

Branch, Twigs and Boughs

1. Branch = woody part of tree connecting to central trunk

2. Boughs = large branches

3. Twigs = small branches

Flowers and Seeds

Flowers produce seeds

Bark

protects tree from injury from animals, disease, fire, etc; Can be thin, thick, spongy, rough, smooth

Inner Bark or phloem

Inner bark carries sap from leaves to rest of tree

Cambium

Thin layer of growing tissue b/w xylem and phloem

Sapwood or Xylem

Brings water and nutrients up from tree roots

Heartwood

Forms core and made of deadwood and provides strength

Roots

Holds soil in place, anchors trees absorbs water and nutrients from ground; Lateral roots, rootlets, and root hairs

Order of Classification for Trees

Kingdom: Plant Kingdom

Division: Spermatophyta -- all plants that have seeds

Sub-Divisions: Angiospermae (encased seeds) and Gymnospermae (naked seeds)

Monocotyledoneae or Dicotyledoneae for angiosperms

Angiospermae are trees referred to as broad-leaved hardwood trees

• Have flower as organ of reproduction

• Ovary/fruit encloses the ovules/seeds

• Ex.) samara, acorn, nut, pome, drupe, berry

• Angiosperms are further divided into two classes: Monocotyledoneae and dicotyledoneae

Monocotyledoneae

• One initial seed leaf

• No commercially important monocot trees in U.S

• Three large groups of monocots: Bamboo, palm, and rattan

  • They make wood for furniture, fishing rods, and other small items imported to the U.S.

Dicotyledoneae

• Two initial seed leaves

• Produce hardwood lumber

• Divided into 25 families

  • Salicaceae: willows and poplars

  • Fagaceae: beech family that includes oaks, American chestnut, chinkapin, and others

  • Juglandaceae: black walnut

Gymosphermae includes all trees that we call softwoods

• 4 families of softwoods that fall w/in order coniferales

  • Cupressaceae: Cedars, Junipers, Cypress

  • Taxaceae: yews

  • Taxodiaceae: redwood and baldcypress

  • Pinaceae: pines, firs, hemlocks, spruces, and larches

Genus

 subgroup of organisms that have many common characteristics.  (ex. Oaks, willows, or pines)

Species

Organisms that are similar in anatomical form and structure that can interbreed to produce fertile offspring of the species

biome

A biome is a large community of vegetation and wildlife adapted to a specific climate

• Five major types of biomes: aquatic, grassland, forest, desert, and tundra

• Can be further divided into freshwater, marine, savanna, tropical rainforest, temperate rainforest, and taiga

how much money does forests and forest industries contribute to MS economy every year?

Forests and forest industry contributes up to $1.5 billion to the state economy every year

what makes a tree heatlhy?

• should be a single, dominant main stem

  • some species are exceptions w/ multi-stemmed growth formation

• Tree trunk should be straight and the bark intact, w/o bulges or cracks

• Root collar flares at the trunk base as structural roots radiate away from the main stem to support tree in the soil

  • Structural roots enlarge as trees age → form root plate

• During growing season, should have a full canopy of leaves

• Leaves should be green and expanded w/o stunting or wrinkling

• Branches should spread from the main stem w/o crossing one another

cracks

 signs that load is exceeding the capacity of the wood to support the tree or branch

Shear cracks

vertical to the grain of wood

Ribbed cracks

occur as tree tries to grow over a vertical crack and Tree movement or cold temperatures re-open the crack

Unrolled cracks

• occur as wood grows over a cavity

  • Included bark prevents wound from healing completely

  • Crack perpetuates and enlarges

Horizontal cracks

indicates that wood fibers are pulling apart

cracks risk of failure

moderate risk of failure except when:

If crack is splitting, or there are multiple cracks or decay, then the tree has a high risk for failure

Any large branch (>4 in diameter) with a crack has a high risk for failure

Decayed Wood

is the result of long-term interaction of fungi w/ the wood of the tree and begins w/ wound in tree from injury, insects, or disease

• Several stages: stain, to rot, to a cavity

Signs of decomposition

• Loose bark → underneath wood is dead

• Fruiting bodies → advanced decay w/in tree

• Mushrooms or conks → identify decay/fungus

• Open crack/cavity might reveal decayed wood or completely hollow tree

effects of decay

Weakened structural integrity

• Generally a hollow trunk needs ⅓ thickness

• If there is a cavity it should occupy ⅓ or less of the tree’s diameter

• Less sound wood → high risk for failure

decay risk for failure

• Evidence of decay across 25-40% of trunk/root collar circumference  → moderate risk for failure

• Greater than 40% → high risk for failure

• Any large branch (>4 in diameter) with decay has a high risk for failure

Species more prone to branch failure due to weak joints/brittle wood

Ashes, basswood, birches, black locust, cottonwood, elms, maples, pears, pines, or sugarberry

How are weak branch unions formed?

species more prone to failure due to weak wood

branches or stems that have bark b/w them

epicormic branches

what is epicormic branching

• Epicormic branches grow from buds beneath the bark

  • Released when stressed

  • Originates from outer growth rings →branch unions are weaker

cankers

• Caused by injury, insects, or disease → deforms and weakens branch or stem as it spreads → sound wood cannot cover the wound

canker risk for failure

• Makes trunk or branch more prone to failure in wind

• Canker + associated decay across 25-40% of tree’s circumference → moderate risk for failure

  • More than 40% indicate a high risk for failure

root collar

Where tree trunk meets the roots and usually there is a flare at the base of the trunk where roots radiate away

Root Problems

• Tree does not have flare at root collar

• Crossing/circling roots

• can cause Canopy decline

• Mowers or string trimmers damage roots

• Construction

Crossing/circling roots

• May impair water uptake and kill the tree

• Girdling roots that constrict more than 40% of root collar circumference → high risk for failure

Species sensitive to root damage or soil compaction

American hornbeam, basswood, black cherry, black oak, black walnut, Eastern hophornbeam, pin oak, and white oak

canopy decline risk for failure

Moderate crown dieback (30% pine -50% hardwoods) → moderate risk for failure

critical root area to stay away from in construction

• Critical root area = radius of 1.5 ft for every inch of diameter measured at breast height (4.5 fit above the ground)

• Root damage beyond 40% of critical root area → high risk for tree failure

Poor Tree Architecture

• Tree should grow plumb with the earth (perpendicular)

• Unbalanced crown

leaning tree risk of failure

• Leaning tree more prone to failure (15-40 degrees from plumb)

• Defects: 

  • Horizontal crack may form opposite of the lean

  • Bulges in the bark of side of lean

  • Soil failure where root-ball rises out of ground → mound opp of lean

• Excessive lean (>40 degrees) or with other defects → high risk for failure

dead wood risk for hazard

Dead wood is a high risk for hazard

Risk Management 3 things to be evaluated

• 1. Conduct tree health assessment to find defects

• 2. Consider size and weight of tree or limb

• 3. Proximity to potential targets

Corrective Actions for Cracks or co-dominant stems

braced with a bolt

Corrective Actions for leaning tree

 could be cabled to mitigate its risk of failure

Corrective Actions for weak branches

pruning

how should you plant a tree?

• Plant at same depth as their root mass, with root collar at ground level

  • Root flare exposed to air

benefits of a regular pruning schedule

• Easily eliminate co-dominant stem when young

• Prevent crossing branches

• Faster healing of small branches

Fusiform rust

Fusiform rust, caused by the fungus Cronartium quercuum f. Sp. fusiforme, is the most destructive disease of loblolly and slash pine in the SE U.S.

fusiform rust problems

• Greatest economic losses in pine plantations and significant losses in seed orchards and natural pine stands

• Severe problem from eastern North Carolina to central Louisiana. Characterized by spindle-shaped galls

  • Fusiform rust galls frequently girdle and kill trees less than five years old

  • Older trees can survive but weakened structurally → reduced quality and value of stem and increased hazard risk

fusiform rust biological cycle

galls on pines exude droplets of liquid called pycnia which contain pycniospores —>galls produce yellow to white aecia where pycnia were —>Aecia filled with yellow-orange aeciospores → wind-disseminated Aeciospores infect immature leaves of red oaks —> uredinia on oaks produce and release urediniospores which reinfect oak  → develop hairlike telia which produce teliosphores —> four basidiospores —> pines

Identification of galls

• Spring yellowish aecia

• Other times galls have similar bark to normal pine bark → look at gall shape

identification of uredinia and telia

• Uredinia and telia on oaks are small

  • Bottom surface of oak leaves

  • Uredinia = clumps of yellow particles on leaf surface

  • Telia = dark brown hairs on leaf surface

control measures of fusiform rust in seedlings

Do not plant infected trees/seedlings

control measures of fusiform rust in forests

• Monitor plantations for fusiform rust during first five years

  • Replant heavily infected stands

  • Lightly infected stands should be left alone until first thinning → mark and remove

• Avoid skinning trees when stand is thinned

• Herbicides/prescribed fire to control oaks w/in stand

control measures of fusiform rust in lawn trees

• Do not fertilize soil around pines until they are at least 10 years old

• Small galls can be cut out of tree → must remove ALL of infected tissue

• Large galls usually cannot be removed → weakens tree

  • Remove the tree

  • Galls are on branches and >1 foot from trunk → prune the infected trees

  • If galls on branches <1 foot from trunk, trunk probs infected as well

• Can plant more resistant species like shortleaf pine