ICFR Central Regional Field Dayaquasoil 5g 5 g Aquasoil TM in 1 L water aquasoil 10g 10 g Aquasoil TM in 1 L water Please note: The use of these products are not endorsed by the ICFR,

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A special thanks to Willie Gevers and the Central Field Day Committee for their help with venue organisation and catering support.

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ICFR Central Region Field Day © ICFR October 2012 Page | 2

ICFR Central Regional Interest Group Field Day

Date: Thursday 18th October 2012 Venue: Ignite Charcoal Factory, near Paulpietersburg

(GPS: 27° 24' 45.83'' S; 30° 40' 33.39'' E) Time: 08h30 for 09h00

PROGRAMME

08h30 Meet for tea and coffee Indoor Presentations

09h00 Welcome and objectives for the field day Johan Nel TWK

09h10 Testing pelargonic acid (Scythe) and pyraflufen-ethyl + glyphosate (Guild) as alternatives to paraquate dichloride (Gramoxone) for the preparation of tracer belts

Keith Little ICFR

09h25 A comparison of different planting methods incorporating hydrogels and fertiliser and their effect on survival and growth at rotation-end in a Eucalyptus grandis trial

Marnie Light ICFR

09h55 Is climate change happening? Comparing local knowledge and global predictions

Ilaria Germishuizen ICFR

10h25 Results obtained from a pot trial to assess several chemical and biological products to potentially control white grub

Ryan Nadel ICFR

10h55 TEA

11h25 Insect pests of Eucalyptus – challenges and opportunities for their management

Brett Hurley FABI

11h55 Precision Forestry Simon Ackerman Stellenbosch University

12h30 The effect of compaction and residue management on soil properties and early Eucalyptus growth on a granite-derived soil

Diana Rietz ICFR

13h00 Forest Engineering research and development’s latest advancements, with a focus on compartment road planning

Glynn Hogg FESA

13h30 LUNCH

14h30 Field Visits

15h00 Mulching for the future Willi Gevers Private

15h45 Discussion in-field on compartment road planning Glynn Hogg FESA

16h15 End of field day

Please note: Hard hats and closed shoes to be worn for the field stop.

www.icfr.ukzn.ac.za


Testing pelargonic acid (Scythe) and pyraflufen-ethyl + glyphosate (Guild)

as alternatives to paraquate dichloride (Gramoxone)

for the preparation of tracer belts

Keith M Little

[email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville, Pietermaritzburg, 3209

Trial Information Company: Mondi Shanduka Newsprint Plantation: Willomere Estate Date Implemented: 22 April 2012 Weather: Clear, sunny and windless Date Completed: September 2012 Altitude: 1706 m Lat & Long: 19o 25.840' E 29o 51.016’ S Treatments

Treatments Rate

1. Control (untreated) - 2. Scythe 2% or 2 L ha-1 3. Scythe 3% or 3 L ha-1 4. Scythe 4% or 4 L ha-1

5. Scythe 5% or 5 L ha-1 6. Scythe mix 2% (pelargonic acid) + 1% (glyphosate) 7. Guild 0.5%

8. Guild 1% or 1 L ha-1 9. Guild 2% or 2 L ha-1 10. Glyphosate 1% or 1 L ha-1

11. Paraquat 3.75% or 3.75 L ha-1

Sequence of events Date Implemented: 22 April 2012

• Time of spraying: 8h00 – 11h30 • Temp: 19-26 0C (shade); 22-29 0C (sun)

1st Assessment: 5 May (14 days after treatment)

• 3 x images analysed for percentage cover of living vegetation per plot

Burning of firebreak: Mid-May 2nd Assessment: Vegetation regrowth on 24 September


Results

Conclusions • Need a product that provides rapid “browning” (desiccation) of above-ground portion of vegetation =

provides opportunity for burning of sprayed area when rest of area still green. • Need product that will not kill below-ground portion of vegetation = erosion + area open to invasion

from unwanted vegetation. • Final assessment in Spring following regrowth (if any) will provide greater insight.


A comparison of different planting methods incorporating hydrogels and fertiliser

and their effect on survival and growth at rotation-end

in a Eucalyptus grandis trial

Marnie E Light, Paul WM Viero and Keith M Little

[email protected]

Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209

Introduction In 2002, three trials were implemented to assess the effect of Aqua-soil® (a soil-amended hydrogel combined with nutrients) versus regular granular fertiliser, on eucalypt re-establishment across diverse sites covering a range of soils, climate and tree species (Viero and Little, 2006). The aim of the trial series was to investigate the effect that different planting methods incorporating soil ameliorating products had on survival and growth of eucalypts on contrasting sites (Table 1 ). Of the three trials (situated in Piet Retief, Zululand and the KwaZulu-Natal Midlands), two were prematurely terminated, whereas the KwaZulu-Natal Midlands trial at Eston (Table 2 ) was continued until rotation-end. Experimental design and treatments

• Four replicates in a randomised complete block design (RCBD) • 2 x 2 factorial: Stockosorb® 400 K at 0 or 3 g L-1 and/or fertiliser at 0 or 120 g tree-1 • Three additional controls: dry plant, Aquasoil at 5 or 10 g L-1 • Tree spacing of 2 x 3 m (1667 stems ha-1) • Whole plot of 6 x 6 (36 trees); measured inner plot of 4 x 4 (16 trees)

Table 1: Description of treatments for a Eucalyptus grandis re-establishment trial situated at

Eston, KwaZulu-Natal.

Treatment Description (per seedling)

dry plant Seedling placed directly into planting pit (without any water, hydrogel or fertiliser)

water plant 1 L water (added into planting pit) stock 3 g Stockosorb® 400 K in 1 L water

fert 1 L water + 120 g 3:2:1 (N:P:K, 22%) stock + fert 3 g Stockosorb® 400 K in 1 L water + 120 g 3:2:1

aquasoil 5g 5 g AquasoilTM in 1 L water aquasoil 10g 10 g AquasoilTM in 1 L water

Please note: The use of these products are not endorsed by the ICFR, and were used for experimental purposes. The hydrogel, Stockosorb® 400 K, and AquasoilTM are no longer commercially available and have been replaced by other products, which are newly formulated and different to those used in this trial, and thus cannot be used for comparative purposes.


Table 2: Site characteristics and information for a Eucalyptus grandis re-establishment trial situated at Eston, KwaZulu-Natal.

Latitude Longitude

29° 52’ 24” S 30° 24’ 04” E

Altitude 900 m a.s.l.

Mean annual rainfall / temperature 850 mm / 17 °C

Climate Warm-temperate

Soils

Taxonomy (SA) Mispah

Parent material Dwyka Tillite

Effective rooting depth 0.4 m

Texture Loam

Organic carbon 4.12%

Species planted E. grandis seedlings

Date planted 22 November 2002

Conditions 7 days prior to planting

Mean, mean minimum and mean maximum temperatures (°C)

Mean: 23.1 Mean min.: 16.4 Mean max.: 30.7

Rainfall (mm) 0.7

Conditions on the day of planting

Gravimetric soil water content

15.2%

Rainfall (mm) 0.5

Mean temp (°C) 27.4

Conditions 7 days after planting

Mean, mean minimum and mean maximum temperatures (°C)

Mean: 15.7 Mean min.: 9.3 Mean max.: 24.8

Rainfall (mm) 21.8

Date felled 24 June 2010 2 771 d (7y;7m)

Results Table 3: Treatment-related re-establishment operations and associated costs (R ha-1, rounded off

to the nearest R10) for a Eucalyptus grandis re-establishment trial situated at Eston, KwaZulu-Natal. Costs are the total mean value associated with the different operations (2010 pricing), and will differ according to region and company.

Re-establishment operation

Re-establishment treatment dry plant water plant fert stock fert + stock aquasoil

5 g aquasoil

10 g

Site preparation + + + + + + +

Pre-plant spray + + + + + + +

Mark and pit + + + + + + +

Seedlings + + + + + + +

Planting + + + + + + +

Fertilisation - - + - + - -

Water (1 L) - + + + + + +

Stock_3 g - - - + + - -

Aquasoil_5g - - - - - + -

Aquasoil_10g - - - - - - +

Total cost (R) 3540 3940 4890 4200 5150 4380 4810


Table 4: Ranking of treatments in terms of rotation-end tree performance (merchantable volume) and re-establishment input costs (R ha-1) in a Eucalyptus grandis trial situated at Eston, KwaZulu-Natal (South Africa). Re-establishment input costs as per Table 3 , which include costs from site preparation, up to and including planting.

Treatment ranked according to level of significance at p < 0.05

for merchantable volume*

a ab bc c

Input costs (Table 3)

Low (< R4 000)

water plant - - dry plant

Medium (R4 000 – R4 500)

stock

- aquasoil 5 g -

High (> R4 500)

fert stock + fert

aquasoil 10 g - -

* Merchantable volume (m3 ha-1) determined on a hectare basis for underbark volume to a thin-end diameter of 5 cm. Conclusions • Planting without water or hydrogel gave the poorest survival and final merchantable volume. • Planting with water or Stockosorb® 400K significantly improved survival. • Application of a granular fertiliser did not improve growth. • The use of AquasoilTM gave inconsistent results and was not shown to be better than the treatments

with granular fertiliser. • In terms of the best improvement at the lowest cost, the addition of 1 L of water into the planting pit

(“puddle planting”) was shown to be the best method. • The use of Stockosorb® 400K (or alternative hydrogel) is also a suitable option under adverse

conditions, as supported by previous research (Viero, 2007; Viero and Button, 2007).

References Viero PWM and Little KM. 2006. A comparison of different planting methods, including hydrogels, and

their effect on eucalypt survival and initial growth in South Africa. Southern African Forestry Journal 208: 5-13.

Viero PWM. 2007. Planting eucalypts using hydrogels. ICFR Technical Note 03/2007. Pietermaritzburg, Institute for Commercial Forestry Research. pp 1-4.

Viero PWM and Button GA. 2007. Eucalypt re-establishment using water or hydrogels in comparison to dry planting for ten trials in South Africa. ICFR Bulletin Series 12/2007. Pietermaritzburg, Institute for Commercial Forestry Research. pp 1-14.


Is climate change happening?

Comparing local knowledge and global predictions

Ilaria Germishuizen

[email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville, Pietermaritzburg, 3209

Introduction Global predictions for the next 50 to 100 years foresee an increase in temperature, increase or decrease in rainfall, and an increase in the frequency and intensity of extreme events such as wind, fire and drought. Most of the climate change research in relation to forests has, up to now, dealt mainly with the role of forests in mitigating climate change, natural forest monitoring, and predicting changes in natural forests composition, whilst very little work has been done on the effects of climate change on plantation forestry. This presentation is made of three sections. The first section deals with the observed changes in weather trends over the past 50 years in Mpumalanga. The second section describes the intermediate (2045-2065) and future (2081-2100) climate change scenarios for South Africa. The third section provides some examples of how spatial models can assist the forestry industry through the change. Mpumalanga Weather: 1950-2007 Thirty-five rainfall stations and three temperature stations located in proximity of forestry areas and for which daily data was available were selected for this study. Changes in climate patterns were analysed by comparing two data subset, 1950-1970 and 1987-2007. The parameters included to detect change are: mean annual precipitation (MAP), number of rainy days per year, number of rainy days >= 40 mm per year, monthly rainfall, average drier season rainfall, mean annual temperature (MAT), mean maximum temperature, mean minimum temperature, average number of “hot” days per year and average number of “cold” days per year. Results showed a general trend of increased rainfall variability from year to year, and a decrease in number of rainy days per year (p<0.01; Figure 1 ).

100.598.1

90.4

81.3

66.6

79.2

0

20

40

60

80

100

120

Northern MP Central MP Southern MP

AV

G n

. R

ain

ev

en

ts

Rain Events 1950-1970 Rain Events 1987-2007

t(11):5.86; p<0.001 t(11):5.54; p<0.001 t(11):3.69; p<0.01

Figure 1. Average number of rainy days/year. Only three temperature stations were available for the analysis, making it impossible to identify trends. However, at the station level, temperature has also become more variable. This simple analysis has confirmed climate changes in line with predicted global trends and has highlighted the need to review common practices such as regional planting windows and revaluate seasonal fire and drought risks.


Predicted MAT and MAP grids: 2045-2065 The Climate System Analysis Group (CSAG; University of Cape Town, South Africa) has applied eight Global Circulation Models (GCM), downscaled at the regional level, to 81 rainfall stations and 43 temperature stations, and made the datasets available to the public in the form of 1’ x 1’ MAP and MAT grids. Overall, future predictions indicate an increase in MAP of 0.82 to 3.89% and an increase in MAT of 1.18 to 1.96%. What does this mean to the forestry industry in Sou th Africa? Some examples on the applications of the predicted MAP and MAT grids. The predicted MAP and MAT grids were used to develop a “future” forestry site classification to interpret current research findings in a future climate scenario. The “future” site classification was developed using the same criteria adopted in the current ICFR forestry site classification (Smith et al., 2005). Predicted site class distribution within the forestry areas is significantly different from the current distribution, with an increase in warmer and moister sites (Figure 2 ).

28

29

30

31

32

33

34

35

36

Dry Moist Wet

%

Current (1971-1990)

Intermediate (2046-2065)

Future (2081-2100)

Figure 2. Current and predicted rainfall classes distribution in commercial forestry areas. A decrease in frost and snow prone sites was also observed. The predicted site classification was used to map changes in site-species suitability for the main commercially grown species to identify changes in species importance. Results show that species that are currently marginal may potentially become more prominent in the forestry landscape, and highlight that resistance to certain pest and diseases, drought and generally species robustness are highly desirable traits in a changing environment.


0

10

20

30

40

50

60

70

Cool Temperate Warm Temperate Sub-tropical

%

Current (1971-1990)

Intermediate (2046-2065)

Future (2081-2100)

Figure 3. Current and predicted temperature classes distribution in commercial forestry areas. The predicted site-species suitability maps are a useful tool for determining priorities in tree improvement research and germplasm conservation. Predicted MAP and MAT grids may also be very useful tools in understanding future risk of pest and diseases, as these risks are strongly climate driven and can thrive when trees are under physiological stress. There is a lot of scope for future work in this area, and preliminary work has been done to evaluate the potential impact of the Eucalytpus gall wasp Leptocybe invasa with the predicted MAT increases. Conclusions

• Global predictions for Southern Africa indicate a raise in MAT and MAP and more erratic climate patterns.

• The empirical analysis of weather trends in the forestry areas of Mpumalanga for the period 1950-2007 shows that more erratic rainfall and temperature patterns are already a reality in the areas currently under forestry.

• Spatial modeling based on outsourced regional climate change predictions has proved to be successful in developing climate change datasets to provide a platform for the interpretation of forestry research findings in future climate scenarios and support the forestry industry through the change.

References Smith CW, Pallett RN, Kunz RP, Gardner RAW and du Plessis M. 2005. A strategic forestry site classification for the summer rainfall region of southern Africa based on climate, geology and soils. ICFR Bulletin 03/2005. Institute for Commercial Forestry Research, Pietermaritzburg.


Results obtained from a pot trial to assess several alternative chemical and

biological products to potentially control white grub

Ryan Nadel

[email protected]


Summary

Scarabaeidae larvae (white grubs) are one of the most economically important re-establishment pests, resulting in growth reductions and often the death of newly-planted seedlings. Varying in size (2.6 – 36 mm) and life cycle (one to two years), white grubs occur in organically-rich top soils, feeding on seedling lateral roots. In the past, white grubs were primarily controlled in commercial forestry plantations using synthetic insecticides such as chlorpyrifos and deltamethrin. The use of such insecticides has, however, become highly regulated as a large proportion of South African commercial forestry plantations are certified by the Forest Stewardship Council (FSC), which promotes the production of wood in an environmentally sustainable manner. There is, thus, an immediate need to find effective alternative products for deltamethrin, which although currently registered to control white grubs, only has temporary usage derogation. In this study, we undertook a pot trial to assess the effectiveness of several alternative chemical and biological products to control white grubs feeding on Acacia mearnsii and Eucalyptus grandis seedling roots. New and alternative products were compared to four control treatments and screened for seedling performance and phytotoxicity, white grub control and a combination of phytotoxicity and white grub control. The alternative products assessed in the study included azadirachtin, imidacloprid, potassium silicate and Beauveria bassiana. The four controls included a positive control (white grub present, no chemical product), negative control (no white grub present, no chemical product) and two controls one using the active ingredient (a.i.) chlorpyrifos and the other deltamethrin (both products registered and known to effectively control white grubs). The results showed that for the dry root mass measurements for A. mearnsii and E. grandis seedlings at 55 days after treatment initiation, there were significant interactions between the controls and the alternative products tested, with the positive control (white grub present) having the lowest dry root mass compared to the other controls and alternative products tested. This is positive as it has shown that certain of the alternative products tested are likely to be as effective as deltamethrin in controlling white grubs. Field trials are now planned to assess the infield effectiveness of these promising alternative products.


Insect pests of Eucalyptus – challenges and opportunities for their management

Brett Hurley

[email protected] Department of Zoology and Entomology, Tree Protection Cooperative Programme (TPCP), Forestry and Agricultural

Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002

Summary Insect pests pose a serious threat to sustainable Eucalyptus plantation forestry in South Africa. This includes native insect pests, mainly the larvae of numerous moth species, but also the larvae and adults of numerous beetle species. The native insect pests are most often generalists, feeding on different plantation species, but more specific host associations between native insects and plantations species, such as the cossid moth Coryphodema tristis feeding exclusively on E. nitens, also exist. The number of native insects pests, both with broad and narrow host ranges, is likely to increase in the future. In addition to native pests, there are also a number of non-native insect pests of Eucalyptus plantation forestry that have been accidentally introduced into South Africa. This includes Phorocantha spp. (Eucalyptus long-horn beetles; detected 1906), Gonipterus scuttelatus (Eucalyptus snout beetle; detected 1916), Ctenarytaina eucalypti (Bluegum psyllid; detected 1958), Trachymela tincticollis (Eucalyptus tortoise beetle; detected 2003), Thaumastocoris peregrinus (Bronze bug; detected 2003), Blastopsylla occidentalis (Eucalyptus psyllid; detected 2006), Leptocybe invasa (Eucalyptus gall wasp; detected 2007), and most recently, Glycaspis brimblecombei (Red gum lerp psyllid; detected 2012). The importance of these pests vary, and some are currently confined to certain hosts or certain areas, but it is clear that in combination, insect pests pose a serious threat to plantation forestry on a national level. Of added concern is that new pest arrivals are imminent. These include the anticipated arrival of Ophelimus eucalypti and O. maskelli which have already been introduced and become established in various parts of the world, but also the introduction of numerous other Eucalyptus feeding insects from Australia, some yet unknown to science. To combat the increasing threat of insect pests to Eucalyptus plantation forestry in South Africa, innovative and effective management strategies are required. Control methods currently most suitable for the management of forestry pests include silviculture (cultural control), using host resistance, and biological control. Silvicultural practices that increase the health and vigour of a tree will likely increase the tree’s ability to defend itself against insect attack. However, exceptions to this do exist, for example where insects prefer vigorous growth. The relationship between plant vigour and susceptibility is not always well understood (for example with L. invasa), and requires further investigation. The use of resistant species or genotypes is an effective tactic for various insect pests, including L. invasa, G. brimblecombei and C. tristis. Limitations associated with this strategy include the insects’ ability to overcome host resistance over time, the trade-off between insect resistance and host performance, and the difficulty of managing an increasing number of insect pests with different host preferences. The use of biological control is a long-term, low cost approach, which has been used for various pests of Eucalyptus in South Africa, most recently including L. invasa. Of some relief, there is also the potential to use biological control for recent pest arrivals such as T. peregrinus and G. brimblecombei, as well as for the anticipated arrival of O. eucalypti and O. maskelli. Limitations to biological control include the identification of suitable agents, knowledge of biology and host specificity, bureaucratic hurdles, and the potential incompatibility between the biocontrol agent and the insect host genotype and / or the environment. Continued research is required for all these management approaches in order to ensure their successful implementation. Where possible, a combination of strategies should be used to compensate for potential shortcomings of the individual strategies, and new management approaches such as mating disruption should be investigated. In addition, early detection by means of effective monitoring tools as well as awareness campaigns is essential for the successful management of forestry pests.


Precision Forestry

Simon Ackerman

[email protected]

Department of Forest and Wood Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602

Summary

Since its inception in the early 2000's, Precision Forestry has advocated the use of technology-based tools to support site specific forestry sustainable decision making. The University of Stellenbosch has become the international custodian of the Precision Forestry initiative, hosting international symposia and events. These include research focused on using advanced ICT such as Remote Sensing, LIDAR and analytical software to provide high resolution operational results. This presentation will provide an introduction into the world of precision forestry, its progression in the world of science and recent applications. The presentation will also include an update on some recent research done at Stellenbosch University.


The effect of compaction and residue management on soil properties and early

Eucalyptus growth on a granite-derived soil

Diana N Rietz

[email protected]


Of the soil types under commercial forestry plantations in South Africa, granite-derived soils have been identified as highly susceptible to soil compaction. Furthermore, these soils do not possess properties that enable them to recover naturally from soil compaction, and are often nutrient poor. Therefore, any plantation operations that compact the soil or reduce their nutrient status could have negative impacts on tree productivity. The operations most likely to result in soil compaction are those involving ground-based machinery, while the management of harvest residues can have a large effect on site nutrient status. Thus, a study was designed and implemented in 2010 to quantify the effect of soil compaction and residue management on a granite-derived soil, and the growth of the following rotation of trees. Treatments were applied to the site after felling of the previous rotation in May 2010, in a factorial design (Table 1 ) with four replications, and consisted of three compaction treatments, and two residue management treatments (applied after compaction treatments) implemented as follows: No compaction (N) : No machinery was allowed onto the plots. High compaction (H) : A grapple skidder performed twelve passes up and down each row,

straddling the stumplines. Ameliorated compaction (A) : A grapple skidder was used in the same manner as in the H treatment

plots, but was then followed by a tractor-drawn ripper that ripped along the interrow to 0.3 m depth. This treatment was included, since the site was not a virgin grassland site, but had already been under several rotations of trees, and was suspected to be partially compacted.

Burned harvest residues (B) : Harvest residues were burned with a cool burn. Mulched harvest residues (M) : Harvest residues were mulched using a tractor drawn mulcher. Table 1. Factorial combinations of compaction and harvest residue management treatments

applied. Compaction Residue management

No (N) High (H) Ameliorated (A)

Burned (B) NB HB AB Mulched (M) NM HM AM Results showed that soil bulk density in the top 0.3 m of soil was not significantly different between treatments. However, penetrometer soil strength (PSS) was significantly affected and decreased in the order H>N>A. If interrow and stumpline PSS results were separated for the treatments, soil strength values in the interrows were substantially (a) lower where amelioration by ripping occurred, and (b) higher in the H treatment where the greatest traffic occurred. Residue masses measured at planting (6 months after treatment implementation) were significantly different between burned and mulched harvest residues, approximately 17.7 and 50.9 t ha-1, respectively. Consequently, this had an effect on the quantity of nutrients in the different treatments. For example, mulched residues contained 478 kg N ha-1, while burned residues contained only 122 kg N ha-1. If nitrogen was replaced in burned plots using lime ammonium nitrate (LAN) fertiliser, approximately 1270 kg ha-1 would be required. Average biomass index of 7-month old Eucalyptus dunnii trees on the site showed a significant effect of compaction treatments, decreasing in the order N>A>H. This trend carried through to basal area


measurements made when trees were 19 months old, although it was not significant. No significant effects of residue management treatments were found on the growth of the trees on site at either 7 or 19 months of age. Tree growth will be monitored until rotation-end to assess if early growth responses to the treatments carry through to differences in final yield. Although no significant tree growth responses to the treatments were obtained at this trial (with the exception of growth in the 7 month old trees), results from older, but similar trials on different sites have shown that early tree growth responses to treatments often differ from those obtained at rotation-end, and results often vary with site (notably soil properties). Results from these trials have also shown that compaction and residue management can affect the long-term productivity of sites.


Forest Engineering research and development’s latest advancements,

with a focus on compartment road planning

Glynn Hogg

[email protected]


Forest Engineering Southern Africa (FESA) has seen the completion of several industry-advancing projects over the last year. Some of the more prominent research and development projects completed or in the completion stages during 2011 and 2012 include:

1. Review of International Work Study Protocols and Their Applicability to South Africa. 2. State of the Art Use of Forest Residue for Bioenergy in Southern Africa. 3. Guidelines for difficult terrain ground based harvesting operations in South Africa. 4. A Comparison of the Costs and Productivities of Wattle Debarking Systems.

The final studies listed above has been summarised in the sections which follow. All completed FESA studies are freely available online at: www.icfr.ukzn.ac.za/collaboration/forest-engineering-southern-africa.

Wattle Debarking Study Status: Complete, on website Objective: This study aimed to compare alternative methods of debarking wattle trees in the Kwa-

Zulu Natal region. Methodology: Five different methods of debarking (and their accompanying systems) were studied.

Debarking methods/equipment included: • Demuth (ring debarker) • Hyena processor • Excavator-based harvester • Hypro processor • Manual debarking (benchmark)

Findings and Outputs

o Bark-Wood Bond Strength (i.e. stripability): � An increase in bark-wood bond strength class led to a general decrease in productivity

for all four machines. � The Hyena debarking system was most affected the by an increasing bark-wood bond

strength. � The Demuth showed increase in productivity from bark-wood bond strength class one to

class two, then decreases again for the remaining classes.


o Tree Volume: � Debarking time per tree for trees with a higher volume was greater than those with a

smaller volume for all debarking methods. � Productivity or debarking time per volume (m³) was less for higher volume classes for all

debarking methods. o Tree form:

� All machines showed a decrease in productivity with an increase in form class. � The Hypro debarker was affected the most by poor form.

o Bark Quality: � All bark produced by the machines was acceptable to the mill based on same-day tests. � Potential for faster oxidisation and thus faster quality deterioration from machines than

manual operations due to damage and smaller bark pieces than the manual system. o Labour Requirements:

� The manual system required the highest number of labour, followed by the Hyena, Demuth, Hypro and then the harvester.

� The Hyena and Hypro high labour requirement was due to the need to collect and bundle the bark.

� The Demuth high labour requirement was due to the handling of extracted timber and bark required.

Calculated debarking system costs when the bark is not utilised (i.e. thrown away) were found to be as follows:

System Tree size (m³)

0.1 0.15 0.2

Demuth R 126.83 R 104.15 R 88.82

Hyena R 121.66 R 93.22 R 77.21

Hypro R 190.31 R 148.60 R 114.83

Harvester R 119.65 R 94.66 R 83.14

Manual R 121.32 R 88.85 R 75.11


Calculated debarking system costs when the bark is utilised (i.e. bundled and sold) were found to be as follows:

System Tree size(m 3)

0.1 0.15 0.2

Demuth R 126.83 R 101.94 R 88.82

Hyena R 136.01 R 107.46 R 91.11

Hypro R 206.45 R 163.36 R 128.78

Harvester R 134.15 R 107.72 R 95.97

Manual R 127.29 R 93.35 R 78.18

Since all machines tested apart from the Hypro were comparable with the manual system of debarking, the study concluded that the use of appropriate machinery is a viable option for wattle debarking in South African operations.


Forest Roads The situation of South African road density is as follows:

RSA forest road density 75 m/ha

International guidelines 15 – 20 m/ha

According to the above figures, the South African Forest Road network is too dense. The South African Forest Road Handbook makes the following recommendations regarding road densities in South Africa:

General Slope (%) Road Spacing (m) Road Density (m/ha)

0-15% 800 27

15-30% 600 – 800 37-27

30-60% 300 – 400 73-55

>60% <400 (uphill yarding) > 55

The estimated average annual cost penalty to the industry due to forest road network structure and associated transport systems in 2004 was R43.25 million or R8.24/m3 (SAFJ Vol.201, 2004: 43-51). It is therefore clear that road planning, optimisation and correct maintenance is vital for the survival of the South African Forest Industry. Basic cost analysis of road spacing and cost is shown in the graph below (note: actual figures are incorrect, but the graph’s concept is correct).

For more information on forest roads, please consult the South African Forest Road Handbook or to get a copy of the presentation given at the field day, please contact the ICFR in Pietermaritzburg.

Where: Cr = road cost Cf = fixed EPT cost Cv = variable EPT cost Ct = total cost


Mulching for the future

Willi Gevers

[email protected]

Summary

We all know the advantages of mulching in the forestry and this presentation will not focus on the detail of the advantages, but rather on practical experience of the last 10 years. These include

• The start: A light machine bought from Mondi secondhand. • The introduction of a proper mulcher that is designed for the job. • Finding the right tractor to pull the mulcher with low cost and still use the equipment for other

work on the farm. • How the operation is financed and the cost per ha. (Costs for last 5 years will be shown). • The impact of cost per ha on the harvesting method. • Wattle gum and pine. • A practical pine demonstration will follow on a mulched pine compartment. • The way forward: In this operation the aim is to work towards a lighter brush pile, less kw tractor

with less fuel per hr with more of the raw material spread over the compartment. • Latest cost comparisons on the same mulching machine with a cheaper and smaller tractor.

“To give our children and their children a future in forestry, I believe we must look after our environment and especially our soils. So look at mulching as the future for forestry.”

Documents

ICFR Central Regional Field Dayaquasoil 5g 5 g Aquasoil TM in 1 L water aquasoil 10g 10 g Aquasoil TM in 1 L water Please note: The use of these products are not endorsed by the ICFR,