Then…

….and Now

2

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)

ForestryManagementOptions

AcceptanceFor End Use

TreeGrowth

WoodProperties

TechnicalPerformance

Size

PriceCost of managementand silviculture

influences influences

influences influences

influences influences

determines determines

5

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)

Product Length (ft)

8 10 12 14 16 18 20

2 x 4 215 245 245 240 270 260 270

2 x 6 215 245 240 235 265 260 270

2 x 8 220 240 255 240 275 270 290

2 x 10 195 200 290 300 300 315 300

Note: Prices are not from 2015

7

Forest management/silvicultural options and wood quality

Improve site• Cultivate• Irrigate• Fertilize

Manipulate crop• Planting stock• Planting distance• Juvenile space• Thin• Prune• Rotation age (harvest)

Foresters’ options

8

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)

9

Growth rate effect on ring structure

Ring porous hardwoods Diffuse porous hardwoods Softwoods

Rapid grown

Slow grown

10

Growth rate effect on ring structure

Ring porous hardwoods

Rapid grown Slow grown

11

Growth rate effect on ring structure

Diffuse porous hardwoodsRapid grown Slow grown

12

Growth rate effect on ring structure

SoftwoodsRapid grown Slow grown

13

Forest management/silvicultural options and wood quality

Improve site• Cultivate• Irrigate• fertilize

Manipulate crop• Planting stock• Planting distance• Juvenile space• Thin• Prune• Rotation age

Foresters’ options

14

Effects of initial spacing distance at time of plantingWide 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

15

Juvenilewood

MaturewoodNarrow spacing

Wide spacing

Effect of tree spacing on juvenile wood production

16

How to overcome disadvantagesof wide spacing

• Plant genetically selected stock

• Chemical or mechanical brush control

• Plant close together initially, then thin

• Prune

17

Tree improvement programs

• Select high volume producers

• Reject low wood density selections

• Select straight trees

• Select small branches (perpendicular)

• Reject extreme spiral grain

Thinning

18

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

Before After

Loblolly pine plantation – 20% stem removal

Thinning

19http://www.forestryforum.com/board/index.php?topic=39179.0%3Ball

Take-out row for skidder access

Skidder with grapple full of thinnings

LightThin

HeavyThin

NoThin

10 in.

13 in. 16 in. 24 in.

48 yrs.

A

18 yrs.

48 yrs.

B 48 yrs.

C

Effect of Thinning on Stem Development at Breast Height

21

Pruning

• Reduces number of branches (knots)

• Reduces juvenile wood formation

• Reduces taper

• Possibly reduces growth rate

Pruning

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

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

Pruning

Pruning

25

Old-growth log quality zones and products value

1. Clear $1,250-4,000/Mbfm2. Near Clear $ 600-1,000/Mbfm3. Appearance merch. $ 450-800/Mbfm4. Structural lumber $ 350-500/Mbfm5. Low grade $ 200-350/Mbfm

(Josza)

26

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

(Josza)

27

Fertilizing

• Increase growth rate

• Reduce wood density

• Even out earlywood-latewood differences in wood density

• Relatively short term effect (3-5 years)

Effect of fertilization on wood density

29

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