A Comparison of Harvester Productivity and Stump Volume Waste in Coppiced and Planted Eucalyptus Grandis Pulpwood Compartments

A COMPARISON OF HARVESTER PRODUCTIVITY AND STUMP VOLUME WASTE IN COPPICED AND PLANTED EUCALYPTUS GRANDIS PULPWOOD COMPARTMENTS

Muedanyi Ramantswana Focus on Engineering 2013 Outline

1. Research objectives 2. Silviculture, why coppicing? 3. Harvesting system 4. Research data collection 5. Research data analysis 6. Results (productivity & stump fibre) and other main findings 7. Conclusion Questions?

• What is the productivity (PMH) when operating in coppiced and planted Eucalyptus grandis compartments?

• Is stump fibre being wasted when operating in coppiced and planted Eucalyptus grandis compartments? If so how much?

Research objectives

• Analyse the effect of the factors affecting the productivity of the harvester in coppiced double, coppiced single and planted E. grandis pulpwood compartments;

• Determine the productivity rate (m3 per productive machine hour) and develop models in order to predict the productivity of a harvester in coppiced double, coppiced single and planted E. grandis pulpwood compartments in relation to the identified factors;

• Compare the productivity of the harvester when operating in coppiced double, coppiced single and planted pulpwood compartments;

• Quantify the amount of volume lost due to excessive stump heights in coppiced double, coppiced single and planted compartments Silviculture, why coppicing?

• Eucalyptus species have the ability to resprout after felling

• Enables second timber rotation without complete re- establishment

• Silvicultural establishment costs reduced

• No pro-longed delays between felling and establishment as in replanting Harvesting system

Locality

Stand Extraction route Forest Road Depot

Activity

Hitachi excavator base with Waratah 616 harvesting head - Fell, debranch, debark, crosscut and stack

Extraction Coppice stems

Data collection

• Research area data • Mondi Newlands farm

Compartment D006 D014 D022 D020

Species E. grandis E. grandis E. grandis E. grandis (Coppiced) (Coppiced) (Coppiced) (Planted)

Area (ha) 11.20 25.60 22.60 5.3

Age (yrs) 8 11 8 7

Average DBH (cm) 13.1 17.7 17.6 18.3

Average Height (m) 21.0 32.1 29.4 23.3

Trees per hectare 1296 921 855 1229

Average tree volume (m3) 0.165 0.275 0.253 0.214

Volume per hectare (m3) 213.84 253.28 216.32 263.00

Sample size 734 97 378 542 Data collection Data collection: Productivity Data collection: Stump waste

Data analysis

• Tree volume and cycles times used to determine productivity

• Descriptive statistics conducted

• Outliers remove through evaluation of scatter plots

• Data divided into coppice double, coppice single and planted stems

• To derive productivity models raw data was transferred to STATISTICA for analysis Results and discussion

Productivity and stump waste Results: Effect of tree volume on harvester productivity coppice double stems coppice single 35 45 40 30

35 25

/PMH) 3 25

15 20

Productivity(m3/PMH)

Productivity Productivity (m 10 15

10 5

0 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 3 CCS volume (m3) Tree v olume (m )

/PMH)

3 25 Planted

Productivity (m Productivity 15

0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Tree volume (m3) Productivity model coefficients

Model adequacy checking: Normality test, homoscedasticity test and evaluation

Coppice single Effect Coppice double stems Planted trees stems

Intercept (β0) 1.6472 2.4940 1.5782

CCS volume / tree volume (β1) 38.3300 61.9498 83.9645

CCS volume2/ tree volume2 (β2) -15.3379 -26.5277 -56.0942

R2 Value 0.88 0.87 0.88

For example : Planted Regression = 1.5782 + 83.9645(0.2) – 56.0942(0.2)2

Comparison of harvester productivity between coppiced double, coppiced single and planted trees

35.0

29.5 30.0

26.2

25.0 26.8

21.7 23.0

/PMH) 20.0 3

16.1 Planted 18.7 17.0 Coppiced single 15.0 14.5

Coppiced double Productivity(m 13.8 11.8 9.4 10.0 8.7 8.4 5.0 5.3

0.0 0 0.1 0.2 0.3 0.4 0.5 0.6 Tree volume (m3) Harvester productivity under various coppiced double and coppiced single proportions and tree volumes

Proportions (%) Predicted productivity (m3/PMH): different mean tree

volumes

Coppiced double Coppiced single

3 3 3 3 3 3 % % 0.1m 0.2m 0.3m 0.4m 0.5m 0.6m

100 0 5.3 8.7 11.8 14.5 17 19.1

75 25 6.1 10.0 13.5 16.7 19.4 21.9

50 50 6.9 11.3 15.2 18.8 21.9 24.6

25 75 7.6 12.5 17.0 20.9 24.4 27.4

0 100 8.4 13.8 18.7 23.0 26.8 30.1 STUMP WASTE

Han and Renzie (2005) THE GRAVEYARD

Does this look familiar?

Relationship between stump volume wasted and tree volume coppice double stems coppice single

0.040 Scatterplot:Coppice single tree volume vs. Stump waste volume 0.022

0.035 0.020

0.018 0.030

0.016

) 0.025

)

3 0.014

0.020 0.012

0.010 0.015 0.008

Stump waste volume (m volume waste Stump

Stump waste volume (m volume waste Stump 0.010 0.006

0.004 0.005 0.002

0.000 0.000

0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 3 Tree volume (m ) 0.95 Conf.Int. 3 Tree volume (m ) 0.95 Conf.Int.

0.016

0.014

0.012

)

3 0.010

0.008 Planted

0.006

Stump waste volume (m

0.004

0.002

0.000 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

3 Tree volume (m ) 0.95 Conf.Int. Average stump volume waste

Variable Coppiced double Coppiced single Planted trees

stems trees Average stump 0.00307 0.00195 0.001650 volume waste (m3)

Little volume is lost when waste volume is evaluated on a tree-by-tree basis, however when accumulated across all trees harvested with waste in a hectare/plantation or region the timber value overlooked maybe high – in addition to all the other forms of waste Stump volume per hectare for coppiced double, coppiced single and planted

1.600 stumps

1.395

)

3 1.400

1.200

1.000

Coppiced double stumps 0.800 Coppiced single stumps

Waste per volume hectare (m Planted stumps 0.600 0.498 0.472

0.400

0.200

0.000 Coppiced double stumps Coppiced single stumps Planted stumps

Factors influencing stump heights

• Multiple stems or leaning stems

• Obstacles within the compartment

• Species

• Tree form

• Operator efficiency Good vs bad practice

Benefits of low stumps

• Efficient timber extraction and transport

• Reduced machine damage

• Lower site preparation cost because of less obstacles

• During harvesting – few breakages and obstacles during processing

• Enables mechanised silviculture operations Possible alternatives?

• Consider other harvesting systems in coppice compartments

• Stump harvesting where applicable

• Mulch/ grind Conclusion: summary

• Refer back to research objectives

• Evaluate fibre loss as a whole – tops, stumps, breakages and operation losses

• Holistic view: compare gain as a result of silviculture coppicing and harvesting productivity loss because of coppicing( stump waste and costs?) More detailed information Ndo livhuwa! Thank you!

Acknowledgements • Sappi • NMMU (Saasveld) • Mondi • A McEwan • J Steenkamp • Fellow NMMU students Struan and Mxolisi • DS Preen Contracting