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

Transcription

1 A COMPARISON OF HARVESTER PRODUCTIVITY AND STUMP VOLUME WASTE IN COPPICED AND PLANTED EUCALYPTUS GRANDIS PULPWOOD COMPARTMENTS Muedanyi Ramantswana Focus on Engineering 2013

2 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

3 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?

4 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 (m 3 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

5 Silviculture, why coppicing? Eucalyptus species have the ability to resprout after felling Enables second timber rotation without complete reestablishment Silvicultural establishment costs reduced No pro-longed delays between felling and establishment as in replanting

6 Harvesting system Locality Activity Stand Extraction route Forest Road Depot Hitachi excavator base with Waratah 616 harvesting head - Fell, debranch, debark, crosscut and stack Extraction

7 Coppice stems

8

9

10

11 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) Age (yrs) Average DBH (cm) Average Height (m) Trees per hectare Average tree volume (m 3 ) Volume per hectare (m 3 ) Sample size

12 Data collection

13 Data collection: Productivity

14 Data collection: Stump waste

15

16 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

17 Results and discussion Productivity and stump waste

18 35 Results: Effect of tree volume on harvester productivity coppice double stems coppice single Productivity (m3/pmh) Productivity (m 3 /PMH) CCS volume (m 3 ) Tree v olume (m 3 ) Productivity (m 3 /PMH) Planted Tree volume (m 3 )

19 Productivity model coefficients Model adequacy checking: Normality test, homoscedasticity test and evaluation Effect Coppice double stems Coppice single stems Planted trees Intercept (β0) CCS volume / tree volume (β1) CCS volume 2 / tree volume 2 (β2) R 2 Value For example : Planted Regression = (0.2) (0.2) 2

20 Comparison of harvester productivity between coppiced double, coppiced single and planted trees Productivity (m 3 /PMH) Planted Coppiced single Coppiced double Tree volume (m 3 )

21 Harvester productivity under various coppiced double and coppiced single proportions and tree volumes Proportions (%) Predicted productivity (m 3 /PMH): different mean tree volumes Coppiced double % Coppiced single % 0.1m 3 0.2m 3 0.3m 3 0.4m 3 0.5m 3 0.6m

22 STUMP WASTE Han and Renzie (2005)

23 THE GRAVEYARD Does this look familiar?

24

25 Relationship between stump volume wasted and tree volume

26 coppice double stems coppice single Scatterplot:Coppice single tree volume vs. Stump waste volume Stump waste volume (m 3 ) Tree volume (m 3 ) 0.95 Conf.Int Tree volume (m 3 ) 0.95 Conf.Int Stump waste volume (m 3 ) Planted Tree volume (m 3 ) 0.95 Conf.Int.

27 Average stump volume waste Variable Coppiced double Coppiced single Planted trees stems trees Average stump volume waste (m 3 ) 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

28 Waste volume per hectare (m 3 ) Stump volume per hectare for coppiced double, coppiced single and planted stumps Coppiced double stumps Coppiced single stumps Planted stumps Coppiced double stumps Coppiced single stumps Planted stumps

29

30

31 Factors influencing stump heights Multiple stems or leaning stems Obstacles within the compartment Species Tree form Operator efficiency

32 Good vs bad practice

33

34 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

35 Possible alternatives? Consider other harvesting systems in coppice compartments Stump harvesting where applicable Mulch/ grind

36 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?)

37 More detailed information

38 Ndo livhuwa! Thank you! Acknowledgements Sappi NMMU (Saasveld) Mondi A McEwan J Steenkamp Fellow NMMU students Struan and Mxolisi DS Preen Contracting