2016/10/21

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Mechanised Pine Thinning Harvesting

Simulation: Productivity and Cost Improvements

as a Result of Changes in Planting Geometry

Simon AckermanResearch Scientist, Institute for Commercial Forestry Research, South Africa

Co- Authors: Stefan Seifert, Pierre Ackerman, and Thomas Seifert

This summary paper was originally published in the Croatian Journal of Forest Engineering under: Ackerman, S.A., Seifert, S.,

Ackerman, P.A., Seifert, T., 2016. Mechanised Pine Thinning Harvesting Simulation: Productivity and Cost Improvements as a

Result of Changes in Planting Geometry. Croatian Journal of Forest Engineering. 37(1): 1-15.

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Introduction

• Geometric planting patterns and advanced

harvesting systems:

– Removal of rows throughout the

compartment (7th)

– Selectively marked remaining trees

• Row thinnings are easy to implement and can

lead to high production

• Irregular stand structure affects tree growth

• Need to find a balance between high production

and residual compartment quality

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Introduction

• Can a change in planting geometry optimise

harvesting and minimise stand impact?

• To do this we need to:

– Develop a stand thinning and harvesting

simulator

– Understanding productivity and costs

associated with these simulations

– Evaluate options to provide a theoretical

optimum planting geometry

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Objectives

• Maintain stand regularity

• Changing the planting geometry

– Increase simulated harvesting productivity

– Reduce harvesting costs

• Reducing stand impact and still allowing access

to the stand by CTL machinery

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Mechanised row thinning

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Study area for mechanised

row thinning

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8.1m

5.4m

9.45 m

• Change from square to

rectangular

• Maintain current

compartment stand

density (1372 spha)

• However…

– Distance to furthest tree

within 10m

– Width of the machine trail

not less than 4.4m

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rChanging planting geometry -

Planting spacing considerations

Geometry Rows removal

2.7m x 2.7m 7th and 8th

2.5m x 2.9m 7th, 8th and 9th

2.4m x 3.1m 7th, 8th and 9th

2.3m x 3m 7th, 8th and 9th

7

8 rows

7/9 rows

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Changing planting geometry –

Sample compartments

• Using the selected planting geometries, compartments

were created as a matrix of coordinates

• Initially created using Silva a single tree based growth

simulator

• In-between thinning tree grown inline with the actual

enumerated plantation data means

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rChanging planting geometry -

Thinning simulator

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Before

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Changing planting geometry -

Thinning simulator

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More likely to be thinned

Less likely to be thinned

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rChanging planting geometry -

Thinning simulations

20 40 60 80 100

20

40

60

80

100

x

y

After Thinning

20 40 60 80 10020

40

60

80

100

x

y

After Thinning

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After 2nd thinningAfter 1st thinning

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Changing planting geometry -

Harvesting simulations

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Trees marked Trees remaining per stopHarvesting procedure

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rChanging planting geometry -

Time study

• Lack of South African time and motion study

information – Used international time models

• Machine costing

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Harvester Forwarder

1. Move to harvesting position (m·cmin-1) 1. Travel empty (m·cmin-1)

2. Harvesting (cmin·m-3) 2. Loading (cmin·m-3)

a. Moving boom to cut 3. Travel partially loaded (m·cmin-1)

b. Felling 4. Travel loaded (m·cmin-1)

c. Processing 5. Unloading (cmin·m-3)

d. Boom in

e. Cleaning

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geometry

(m x m)

Machine

Trail width

(m)

Distance to

furthest tree

(m)

Row

removed

(machine

trail)

Spacing

between

trails (m)

Trail

length.ha-1

(m)

No. rows

removed.

Ha-1

2.7x2.7 5.4 9.45 7th 18.9 599.4 6

2.5x2.9 5 10 9th 22.5 500 5

2.3x3.1 4.6 9.2 9th 21.6 504 5

2.4x3 4.8 9.6 9th 20.7 506 5

Changing planting geometry -

Results

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-16%

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rChanging planting geometry -

Results

Thinning

Planting

geometry

(m x m)

Cycles

Harv.

Total Time

(cmin)

Forw.

Total Time

(cmin)

VolumeHarvester

m3.PMH-1

Forwarder

m3.PMH

First 2.7x2.7 78 259.66 245.8 30.75 7.11 7.51

2.5x2.9 119 240.95 349.72 28.22 7.03 4.84

2.4x3 72 244.74 226.47 28.50 6.99 7.55

2.3x3.1 58 251.79 180.77 28.84 6.87 9.57

Second 2.7x2.7 47 132.2 192.33 35.70 16.20 11.14

2.5x2.9 54 122.88 220.21 35.61 17.39 9.7

2.4x3 44 124.78 179.61 36.20 17.41 12.09

2.3x3.1 43 134.34 185.5 39.24 17.53 12.69

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Harvesting time per harvesting stop machine productivity

+21%

+12%

-3%

+8%

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Changing planting geometry -

Results

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Thinning Planting geometry

(m x m)

Harvester cost

(R.m-3)

Forwarder cost

(R.m-3)

Total system cost

(R.m-3)

First 2.7x2.7 153.06 99.86 252.92

2.5x2.9 154.81 154.95 306.76

2.4x3 155.69 99.33 255.02

2.3x3.1 158.41 78.37 236.78

Second 2.7x2.7 67.18 67.32 134.50

2.5x2.9 62.58 77.32 139.90

2.4x3 62.51 62.03 124.54

2.3x3.1 62.08 59.10 121.18

Machine and system cost results

-7%

-10%

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rChanging planting geometry -

Conclusion

Benefits of changing planting geometry to accommodate

9th row thinning

– Minimal influence on tree growth/form (studies)

– Residual damage to trees limited and stand impact

– Large gaps in canopy reduced

– Can ease implementation of mechanised harvesting

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Changing planting geometry -

Conclusion

• Harvesting

– Match tree spacing with harvester limitations

– Optimising harvester reach

– Make operations more cost effective

• Silviculture

– New insight into stand management

– Potential wider spacing for other activities (fuel load

management and fire fighting)18

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rInfluence on South African

Forestry

• Factors are relatively un-researched in South Africa

• Potential to reduce irregular tree growth through better

marking for thinning

• Feasibility of testing systems using a simulation

• Dedicated machine trails can be used for multiple

rotations

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Influence on South African

Forestry

• Informed decisions at planning level >> optimal

silvicultural regimes >> productive low cost harvesting

• Shows that changing planting geometry can benefit

both the stand and harvesting

• Show potential to increase economic viability of

operations

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rBenefit for the forestry supply

chain

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• Improved genetics leads to more

systematic thinning (assuming no

disasters)

• Predictable productivities of machines

• Tree size vs machine capability

relationship

• Profitable volume driven first thinnings

• Overall understanding of influences parts

of the supply chain on others

Planning

Enable G&Y

predictions

Improves

silviculture

Harvesting and

transport

Market

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Thank you

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Study area

• Spacing was 2.7m x 2.7m

1372spha (P. Patula saw)

• Thinned at 8 to 650 spha

13 to 400 spha

• Tree growth information

• Apply adjustments from this

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Changing planting geometry -

Conclusion

Harvester and forwarder productivity

• Overall benefit in terms of harvester reach optimisation

• The change has the greatest benefit in second thinning

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S7

Slide 24

S7 slide 29-32 too wordy

> reduce font size increase distance bewteen sentences and introduce sentence by sentence in

animation (simple blend in , no squirls etc.)S, 2013/11/20