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Then…. ….and Now. Old growth. Second growth. Stand age vs. percent of juvenile wood. When trees grow rapidly so that they are of harvestable size when relatively young, the percentage of juvenile wood increases dramatically (data shown for Loblolly pine). (Zobel & van Buijtenen). influences.

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Then…

….and Now

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Old growth

Second growth

stand age vs percent of juvenile wood
Stand age vs. percent of juvenile wood

When trees grow rapidly so that they are of harvestable size when relatively young, the percentage of juvenile wood increases dramatically (data shown for Loblolly pine).

(Zobel & van Buijtenen)

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influences

determines

determines

influences

ForestryManagementOptions

TreeGrowth

WoodProperties

TechnicalPerformance

AcceptanceFor End Use

influences

influences

Size

Cost of managementand silviculture

influences

influences

Price

forest management silvicultural options effects on wood quality
Forest Management/Silvicultural options – effects on Wood Quality

Objective

To maximize the value of a plantation over a short rotation.

Value of logs and lumber depend upon:

Logs - large diameters

- long lengths

- clear faces

Lumber - premium lengths and widths

- absence of knots and other defects

softwood lumber pricing mbf
Softwood Lumber Pricing ($/MBF)

Note: Data is not from 2012

forest management silvicultural options and wood quality
Improve site

Cultivate

Irrigate

fertilize

Manipulate crop

Planting stock

Planting distance

Juvenile space

Thin

Prune

Rotation age

Forest management/silvicultural options and wood quality

Foresters’ options

  • These actions influence the growth of the crown and roots which in turn influence:
    • Stem size and form
    • Ring structure (relative ew/lw proportions)
    • Branch size and number
    • Juvenile wood (amount and proportion)
growth rate effect on ring structure

*

Growth rate effect on ring structure

Rapid grown

Slow grown

Softwoods

Diffuse poroushardwoods

Ring poroushardwoods

effects of initial spacing distance at time of planting
Wide spacing

(400-750 stems/ha)

Increased vegetative competition

Trunk with large branches

Maximize piece size

Encourage lower density of mature wood

Lower % of juvenile wood

Narrow spacing

(1500 stems/ha)

Maximize stand volume

Fewer and smaller branches

Encourage higher density of mature wood

Higher % of juvenile wood

*

Effects of initial spacing distance at time of planting
effect of tree spacing on juvenile wood production

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Effect of tree spacing on juvenile wood production

Juvenile

wood

Mature

wood

Narrow spacing

Wide spacing

how to overcome disadvantages of wide spacing
How to overcome disadvantagesof wide spacing
  • Plant genetically selected stock
  • Chemical or mechanical brush control
  • Plant close together initially, then thin
  • Prune
tree improvement programs
Tree improvement programs
  • Select high volume producers
  • Reject low wood density selections
  • Select straight trees
  • Select small branches (perpendicular)
  • Reject extreme spiral grain
thinning
Thinning

Before

After

Loblolly pine plantation – 20% stem removal

http://www.forestryforum.com/board/index.php?topic=39179.0%3Ball

thinning1
Thinning

Skidder with grapple full of thinnings

Take-out row for skidder access

http://www.forestryforum.com/board/index.php?topic=39179.0%3Ball

thinning2

*

Thinning

Schematic sizes and ring width patterns of Douglas-fir logs (sections at 4.5 feet) grown under different regimes (each concentric circle represents six annual rings). Note on a good site, the plantation wood (B) produces wood with large rings at the centre and faster diameter growth than from a natural stand (A). Poor sites will produce narrow rings (C) but still juvenile wood (formed while the cambium is still within the live crown) in both natural stands and plantations. If plantations (B) are not thinned when young, many of them will probably slow down abruptly in growth and appear as D, so that primarily small diameter wood will be available in the future. If they are thinned by removing some of the trees when young (at B), they can produce logs as in E or F, depending on the intensity of the thinning. Future logs such as E or F will be produced primarily if the forest products industry can develop a market for logs such as B, so that such stands can be thinned instead of developing into logs with characteristics such as D. (Oliver)

pruning
Pruning
  • Reduces number of branches (knots)
  • Reduces juvenile wood formation
  • Reduces taper
  • Possibly reduces growth rate
pruning1
Pruning

http://trimblefoundation.org.nz/images/trimble_trees.jpg

http://www.country-works.co.uk/weblog.aspx

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*

Maximum knot sizes allowed on the edge and the centre-line of 2x4, 2x8 and 2x12 lumber

Old-growth log quality zones and products value

  • Clear $1,250-4,000/Mbfm
  • Near Clear $ 600-1,000/Mbfm
  • Appearance merch. $ 450-800/Mbfm
  • Structural lumber $ 350-500/Mbfm
  • Low grade $ 200-350/Mbfm

(Josza)

fertilizing
Fertilizing
  • Increase growth rate
  • Reduce wood density
  • Even out earlywood-latewood differences in wood density
  • Relatively short term effect (3-5 years)
practical consideration for wood quality control
Practical consideration for wood quality control
  • Economics of clear wood, high wood density, large log diameter
  • Tree improvement programs
  • Control of juvenile wood
    • Spacing (planting, juvenile spacing, thinning)
    • Rotation age
  • Develop clear wood by pruning
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