ICFR Zululand Regional Field Day Thursday 19 th November 2015 Kwambonambi Town Hall & Mtubatuba, Zululand Thanks are extended Sappi, Mondi & EcoGuard for sponsorship of catering.
ICFR Zululand Regional Interest Group Field Day Date: 19 th November 2015 Venue: Kwambonambi Town Hall & Mtubatuba, Zululand Time: 08h00 for 08h30 PROGRAMME Time Topic Speaker 08h00 08h15 09h00-10h30 11h15-12h00 12h30 13h00 13h30 13h50 14h10 14h30 14h50 15h10 15h30 15h50 16h10 Meet at Kwambonambi Town Hall Leave for field visits Field Visits (tea & coffee at site) Field Stop 1: Early results of Corymbia hybrid x site interaction trials in northern, coastal Zululand (Visit to the Mtuba site); AND An update on pests and diseases of plantation forestry; Drought-induced die-back of a Eucalyptus hybrid clone in Zululand Field Stop 2: Visit to the ICFR harvesting impact trial AND Non-target effects of selective herbicide application Lunch at the Kwambonambi Town Hall Indoor Presentations Yield trends in Zululand: Changing genetics and environment Breeding to mitigate against risk Mapping the risk of Leptocybe invasa in South African plantation forests Second rotation results of the compaction x residue management trial at Rattray Tea & Coffee Rotation-end growth responses of Eucalyptus grandis minicuttings and seedlings and their interaction with planting density and weeding in Zululand, South Africa Harvesting and extraction impacts on Eucalyptus grandis x E. urophylla coppicing potential and rotation-end volume in Zululand, South Africa Eucalyptus stump killing with harvester head herbicide applicator The benefit for forest management The use of glyphosate for the management of secondary coppice regrowth in a Eucalyptus grandis x E. urophylla trial in Zululand, South Africa Field Day ends Robin Gardner (ICFR) Izette Greyling & Casper Crous (FABI) Diana Rietz (ICFR) Louis Titshall (ICFR) Andrew Morris (ICFR) Gert van den Berg (Mondi) Ilaria Germishuizen (ICFR) Diana Rietz (ICFR) Keith Little (NMMU) Kylle Schwegman (NMMU) Simon Ackerman (ICFR) Jonathan Roberts (NMMU) ICFR Zululand Regional Field Day Page 2
Early results of Corymbia hybrid x site interaction trials in northern, coastal Zululand (Visit to the Mtuba site) Robin Gardner robin.gardner@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 Introduction The coastal Zululand plantation forestry environment continues to undergo shifts with respect to factors such as climate, weather, insect pests and diseases, and market requirements. Approximately 20% of the total managed coastal Zululand timber production area is classed as dry (mean annual precipitation (MAP) < 900 mm) and of low productivity potential. Current operational planting choices for sites in these more drought-prone areas are limited. During August 2013, the Institute for Commercial Forestry Research established two new generation site x eucalypt taxa interaction trials in northern, coastal Zululand, in an ongoing search for viable alternatives to the existing commercial clones. The main objective of the trials is to determine the potential of various Corymbia and Eucalyptus inter-specific hybrids for commercial pulpwood production in northern, coastal Zululand. The two sites selected for the trials contrasted strongly with regards to MAP (Table 1). The Corymbia hybrid material that was made available for the trials was developed by Queensland DAFF (Australia), and has demonstrated excellent commercial forestry potential in drier, drought-prone areas of tropical and sub-tropical south-eastern Queensland. This genetic material is based on hybrids between C. torelliana and C. citriodora subsp variegata, C. citriodora subsp citriodora and C. henryi. The Eucalyptus material, consisting of a small range of locally-bred hybrids between E. longirostrata and E. grandis and E. urophylla, has remained largely untested within the Zululand coastal plantation forestry environment until now. At 24 months (2015), the trials were measured and these early results are reported on. Material and methods Table 1: Establishment details for the site-taxa interaction trials in northern, coastal Zululand Trial name Mfezi Flatcrown Latitude 28 o 23.815' S 28 o 35.500' S Longitude 32 o 11.660' E 32 o 07.585' E Altitude (m asl) 90 73 Mean annual rainfall (MAP) (mm) 850 1155 Mean annual temperature ( o C) 22.1 21.8 Distance from sea (km) 22.3 14.2 Soils: Taxonomy Fernwood 1100 Fernwood 1200 Depth (m) >1.2 >1.2 Tree spacing at planting (m) 2.4 x 3.0 2.4 x 3.0 Previous crop Eucalyptus pulpwood Eucalyptus pulpwood ICFR Zululand Regional Field Day Page 3
Experimental layout: Design: RCBD with three replicates Treatments (38 per trial, Table 2): o Unimproved: Imported (Australian) C. torelliana provenance bulks (seedlots) and Corymbia inter-specific hybrid seedlots o Improved (controls): Local C. henryi and E. longirostrata orchard bulks and commercial and non-commercial Eucalyptus inter-specific hybrid clones Plots: 25 trees (5 tree x 5 trees) with inner nine trees measured Tree spacing: 2.4 m x 3.0 m (1 389 stems ha -1 ) Trial block buffer rows: Two rows of C. henryi RSA commercial seedlings Table 2: Taxon/ Hybrid Description of seedlots and clones in the site-taxa interaction trials in northern, coastal Zululand Total number of Control seedlot/ clone seedlots and clones description or name 4 Taxa, seedlot or clone abbreviation 4 UNIMPROVED SEEDLOTS: C. torelliana 1 2 - ct C. torelliana x C. henryi 1 22 - ctxch C. torelliana x C. citriodora ssp citriodora 1 2 - ctxccc C. torelliana x C. citriodora ssp variegata 1 4 - ctxccv CONTROLS: C. henryi 2 3 Salpine SO bulk (ZLD) ch Sal bulk C. henryi 2 - Nyalazi SO bulk (ZLD) ch Nya bulk C. henryi 2 - Teza SO bulk (ZLD) ch Tez bulk E. grandis x E. camaldulensis 3 1 GC_1 GC E. grandis x E. longirostrata 4 2 GL_1 GL E. grandis x E. longirostrata 4 - GL_2 GL E. grandis x E. urophylla 3 2 GU_1 GU E. grandis x E. urophylla 3 - GU_2 GU E. longirostrata 2 3 Salpine SO bulk (ZLD) lon Sal bulk E. longirostrata 2 - Salpine SO Fams 3 & 16 lon Sal 3&16 E. longirostrata 2 - Nyalazi SO bulk (ZLD) lon Nya bulk E. urophylla x E. longirostrata 4 2 UL_1 UL E. urophylla x E. longirostrata 4 - UL_2 UL QLD, Queensland; SO, seed orchard; ZLD, Zululand; 1 Imported, unimproved seedlot (ex-qld); 2 South African, 1 st generation improved SO bulk (ex-zld); 3 South African commercial hybrid clone; 4 South African, non-commercial hybrid clone; 5 Abbreviation used in Table 3 ICFR Zululand Regional Field Day Page 4
Results Table 3: Treatments above the trial mean for height at 24 months at Mfezi and Flatcrown. Treatments listed in bold have known good performance in south-eastern Queensland Mfezi Flatcrown Treatment Height (m) # Treatment Height (m) # ctxch x80 1 7.77 a ctxccv x1668 8.49 a GU_2 7.36 ab ctxch x12 8.42 ab ctxch x1605 7.33 ab GU_2 8.19 abc ctxccc x71 7.15 abc GC_1 8.10 abc ctxch x12 7.08 abcd ctxccc x71 7.95 abcd ctxch x62 1 7.07 abcd ctxch x72 7.94 abcd ctxch x72 6.91 abcde ctxch x7315 7.91 abcd ctxch x196 1 6.84 abcde ctxch x7217 7.86 abcde ch Sal bulk 6.68 abcdef ctxccv x135 7.83 abcde ctxccc x1604 6.66 abcdef ctxch x1590 7.59 abcdef ctxch x7292 6.62 abcdef ctxccc x1604 7.41 abcdefg ch Tez bulk 6.49 abcdefg ctxch x1605 7.32 abcdefg ctxch x7217 6.40 abcdefg GL_2 7.26 abcdefg ctxch x7221 6.40 abcdefg ch Tez bulk 7.23 abcdefg ctxccv x1668 6.13 bcdefgh ctxch x7292 7.11 abcdefgh ctxch x7312 6.12 bcdefgh ctxch x1525 7.07 abcedfghi lon Sal bulk 6.04 bcdefghi lon Sal 3&16 7.07 abcdefghi ch Nya bulk 6.02 bcdefghi ctxch x7293 7.00 bcdefghi ctxch x7294 5.99 bcdefghi ctxch x7294 7.00 cdefghi ctxccv x74 1 5.84 cdefghij ch Sal bulk 6.94 cdefghi ctxch x7292 5.84 cdefghij GU_1 6.80 cdefghij GC_1 5.83 cdefghij Mean 5.72 6.64 SED 0.75 0.71 CV (%) 16.0 13.1 # Within this column, values followed by the same letter do not differ significantly (p = 0.001); 1 Seedlot represented at one site only; SED = Standard error of the differences between the means; CV = Coefficient of variation Conclusions At 24 months after planting, based on mean tree height (Table 3), several of the Corymbia hybrid seedlots are performing exceptionally well under the lower than average annual rainfall conditions that have occurred at both sites since the time of establishment. At both sites, the South African C. henryi 1 st generation improved bulk seedlots are also showing good promise compared to the industry controls (commercial Eucalyptus hybrid clones). Acknowledgements The establishment and ongoing maintenance and measurement of research trials depends on a team effort. The ICFR technical staff, in particular Denis Oscroft, David Hockly and Musa Mkhwanazi, and the Mondi Zululand foresters and contractors who contributed in this regard, are gratefully acknowledged for their efforts. ICFR Zululand Regional Field Day Page 5
An update on pests and diseases of plantation forestry Izette Greyling 1, Casper Crous and TPCP/CTHB team 1 izette.greyling@fabi.up.ac.za Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa The rate at which new pests and pathogens are introduced into new areas is increasing at an alarming rate, a trend that is seen worldwide. This is also true for South Africa with the appearance of two new insect pests (Ophelimus maskelii and Spondyliaspis plicatuloides), and a new fungal pathogen (Teratosphaeria destructans) in the past year or two. With the ever increasing movement of goods and people across the world, this trend is set to continue. Adding to the challenge of forest management is climate change and associated extreme weather conditions, and the impact these factors have, not only on pest and pathogen behaviour and spread, but also on the trees. There are a number of tools available to manage these different challenges and more are becoming available as technology improves. However, this requires a team effort. Cooperation and collaboration between researchers, foresters, farmers, managers and government agencies, both nationally and internationally, is needed to successfully navigate and overcome the many challenges posed to the industry. Farmers and foresters are encouraged to report any tree health problems to the TPCP. This will facilitate the detection of new problems and assist in monitoring established pests and pathogens. For any pest and/or disease information please contact: Jolanda Roux (Extension and Diagnostics) 082 909 3202, jolanda.roux@fabi.up.ac.za Izette Greyling (Extension and Diagnostics) 083 269 1983, Izette.greyling@fabi.up.ac.za Darryl Herron (Diagnostic Clinic) darryl.herron@fabi.up.ac.za Brett Hurley (Biological control) brett.hurley@fabi.up.ac.za Jeff Garnas (Entomology) jeff.garnas@fabi.up.ac.za We also host a list server where information regarding various aspects related to tree health are shared. If you would like to subscribe to Treehealthnet, please contact Wilhelm de Beer at Wilhelm.debeer@fabi.up.ac.za or any of the above listed people for assistance. ICFR Zululand Regional Field Day Page 6
Figure 1: A-B: Galls formed by Ophelimus maskelii C-D: Shell lerp psyllid, Spondyliaspis plicatuloides Figure 2: A-B: Chlorotic (yellow) lesions with red coloration at the lesion margins and veins on the upper surface of the leaves C: Fungal fruiting bodies oozing black spores on the underside of leaves ICFR Zululand Regional Field Day Page 7
Drought-induced die-back of a Eucalyptus hybrid clone in Zululand Casper Crous 1, Izette Greyling and Michael Wingfield 1 cjcrous@gmail.com Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa Drought-induced tree decline is increasing globally. Currently, there is an industry phenomenon where a Eucalyptus grandis x urophylla clone (clone 178) is dying after 3-5 years of good growth. No primary biotic pathogen had been isolated from these dying trees. Since the Zululand region has (and still is) enduring severe drought conditions, we hypothesize that this die-back pattern could be related to water stress. We tested this hypothesis by assessing whether various proxies for drought stress, e.g. water-use efficiency, differ between the dying and two non-dying Eucalyptus grandis x urophylla clones. The result suggests that the GU 178 clone is maladapted to extreme drought conditions. Given future climate change predictions, the implication of this result for future clone deployment is evident. ICFR Zululand Regional Field Day Page 8
Non-target effects of selective herbicide application Louis Titshall louis.titshall@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 Weed growth during plantation establishment has been demonstrated to negatively affect tree production due to increased competition for light, nutrients and water. Weed removal prior to planting and during early growth is essential for the optimal growth of trees. Weeding is usually carried-out through manual operations using knapsack sprayers where the most commonly used herbicide is glyphosate, a nonselective systemic herbicide. A concern associated with the use of glyphosate is damage caused by overspray or drift onto young trees that may negatively affect growth. Coning during spraying operations is promoted to avoid tree damage, but increases the operational cost and is thus frequently not done. This study aims to evaluate the effect of sub-lethal doses (three levels) of glyphosate on early eucalypt tree growth when applied directly to the canopy (simulated over-spray/drift) as compared to an untreated control. Additionally, two selective herbicides; namely clopyralid (a systemic broad-leaf selective) and quizalofop-p-tefuryl (a systemic grass selective) are also tested at the recommended rates on the young eucalypt trees to evaluate their effect on early growth relative to the other treatments. Seven month growth data show that at all levels of glyphosate, eucalypt growth is significantly stunted, with severe tree damage at the highest rate. No negative effects on growth measures of the selective herbicides were found, though some evidence of increased disease and leaf deformation was present on clopyralid treated trees. ICFR Zululand Regional Field Day Page 9
Yield trends in Zululand: Changing genetics and environment Andrew Morris andrew.morris@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 The northern KwaZulu-Natal coastal plain has experienced a prolonged period of below average rainfall now accentuated by the current El Nino driven drought gripping southern Africa. Current crops are visibly stressed and yields now realised are less than recent historical expectation. This presentation considers the development of eucalypt forestry on the KwaZulu-Natal coastal plain and the improved productivity this has delivered together with the key site characteristics that must ultimately determine production potential. Using inventory records from more than 300 compartments (Mondi and Sappi combined), the growth of crops planted from 2007-2011 is compared to the preceding crop. Spatial and temporal rainfall patterns, soil type and the increasing number and variety of insect herbivores are considered as factors influencing observed yield trends. A key question facing forest managers in this region must be the extent to which genetics of their planting stock needs to change in response to fluctuation, and likely long-term change, in climate and soils if they are to ensure site resilience and sustainable wood supply. This presentation is intended to inform this debate. ICFR Zululand Regional Field Day Page 10
Breeding to mitigate against risk Gert van den Berg gert.vandenberg@mondigroup.co.za Mondi, P O Box 12, Hilton, 3245 This talk will cover the following: Basic breeding principles Mondi s new breeding strategy to mitigate against risks Mondi s new commercial deployment strategy to mitigate against risks Alternative breeding strategies to mitigate against risk ICFR Zululand Regional Field Day Page 11
Mapping the risk of Leptocybe invasa in South African plantation forests Ilaria Germishuizen ilaria.germishuizen@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 Since its arrival in 2007, the Blue Gum Chalcid wasp Leptocybe invasa has been a cause of serious concern to the forestry industry and growers in South Africa. This has led to a coordinated response by the industry involving research institutions (TPCP-FABI, ICFR) and affected industry partners under the umbrella of FSA, through the establishment of the Leptocybe Working Group (LWG). The development of a statistically validated L. invasa risk model was identified by the LWG as a priority in order to evaluate the potential risk posed by this pest and to support the development of an effective management strategy. Pest and pathogen risk models fulfill three main functions: Contribute to the understanding of a pest or pathogen s ecology (ecological niche, potential distribution, environmental barriers) Support decision making in operational activities (eg. prioritisation of areas for biocontrol releases, species/clone selection at re-establishment) Assist in the evaluation of the potential impact of a pest or pathogen In-field and controlled environment studies have shown that L. invasa s life cycle is highly temperature dependent. The first attempt to develop a risk model for L. invasa was based on temperature thresholds and followed a qualitative approach. Although the model was not statistically evaluated, its outputs highlighted quite accurately the areas within the forestry landscape that are mostly affected by the wasp (Figure 1). A quantitative, statistically evaluated L. invasa risk model is currently being developed using the Maxent software. Maxent develops a pixel-based probability model according to two principles: A species probability of occurring in the landscape is perfectly uniform This uniform probability distribution is constrained by the environmental covariates at the points of presence One of the main advantages of using this model is that it only requires points of presence of a species, rather than presence and absence. The model outcome consists of a risk map (probability of occurrence), ranking of the environmental variables according to their contribution to the model and a number of statistical measures of model robustness. The software has scenario capability and can be used to apply risk models to future climate scenarios. ICFR Zululand Regional Field Day Page 12
The L. invasa risk model was developed based on 435 verified points of presence across the forestry landscape and 105 environmental variables. Figure 1. Current and future potential distribution of Leptocybe invasa in the commercial forestry areas based on temperature thresholds Model accuracy was evaluated using the Area Under Curve (AUC) (Figure 2). Results confirmed that L. invasa s risk is temperature driven, with a higher probability of occurrence throughout the year in areas characterised by mild winters and warm springs (Figure 2). The work presented is still in progress and the model is in the process of being refined, particularly by evaluating seasonal risk. In conclusion, the L. invasa risk model confirmed that the warmer forestry areas are more likely to experience severe L. invasa outbreaks throughout the year. Cooler areas are more likely to experience seasonal outbreaks, with the opportunity of recovery time between seasons for the affected stands. Climate change predictions for the summer rainfall region of South Africa show an increase of climatically optimal areas for this pest within the landscape currently under forestry. ICFR Zululand Regional Field Day Page 13
Figure 2. Probability distribution of Leptocybe invasa in the forestry landscape. The sensitivity versus specificity chart indicates excellent prediction accuracy by the model ICFR Zululand Regional Field Day Page 14
Second rotation results of the compaction x residue management trial at Rattray Diana Rietz diana.rietz@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 There are concerns that the long-term productivity of forest plantations in South Africa may be declining due to management practices. Evidence from literature shows that in cases where plantation productivity has conclusively declined, it has been due to decreasing soil porosity (particularly macroporosity), soil organic matter or site nutrients. Of the practices most likely to decrease porosity, harvesting and site preparation practices that involve machinery result in significant soil compaction. Residue management and the movement of machinery over the residues are most likely to affect the soil organic matter and site nutrient content. In order to investigate some of these effects, a trial was implemented at the Rattray plantation in 1996 to determine the effects of mechanised harvesting practices, residue management and initial fertiliser applications on long-term site productivity of Eucalyptus grandis x E. camaldulensis. Treatments imposed were combinations of different machinery (resulting in different levels of compaction and soil disturbance), residue management and fertilisation. In 2004, a new trial was implemented on this trial site that was specifically designed to investigate the effect of gradients of both soil compaction (rather than specific mechanised operations) and harvest residue management under Eucalyptus grandis. These treatments were applied in a factorial manner to allow separation of single and combined treatment effects. This presentation reports on the rotation end results of this trial, and considers them in conjunction with the results from the first trial. ICFR Zululand Regional Field Day Page 15
Rotation-end growth responses of Eucalyptus grandis mini-cuttings and seedlings and their interaction with planting density and weeding in Zululand, South Africa Keith Little 1 and Marnie Light 1 keith.little@nmmu.ac.za School of Natural Resource Management, Nelson Mandela Metropolitan University, Private Bag X6531, George 6530, South Africa Background The difference in growth response between Eucalyptus grandis cuttings (macro-, mini- or micro-cuttings) and seedlings of similar genetic source, when established in-field under the same environmental conditions has not been well documented. In addition, there is little information regarding the interaction between cuttings and seedlings and other silvicultural practices in terms of: Below ground competition (weeds in eucalypt plantations are in general controlled before they compete for light) with respect to water/nutrients and growing space; Differences in root growth between cuttings and seedlings and their susceptibility to early weed competition; Row planting density and intensity of manual weeding operations, and how does row planting density interact with tree (seedlings versus cuttings) root morphology. To improve this understanding, a trial was implemented in September 2001 to compare growth differences between mini-cuttings and seedlings, as well as the interaction with different silvicultural practices. Treatments 4 x 2 x 2 factorial (16 treatment combinations) arranged in a strip-split plot design 4 replications = 64 plots (1.4 ha) Sub-plots = 6 x 6 trees with inner 4 x 4 measured Factor A: Planting densities (whole plot) 1. 2 m in the row (2 m x 2.7 m = 1851 stems ha -1 ) 2. 2.5 m in the row (2.5 m x 2.7 m = 1481 stems ha -1 ) Factor B: Tree type (sub-plot) 1. mini-cuttings 2. seedlings ICFR Zululand Regional Field Day Page 16
Factor C: Row weeding (sub-sub-plot) 1. 0 m (weedy check) 2. 0.9 m (0.45 m on either side of tree) 3. 1.8 m (0.9 m on either side of tree) 4. 2.7 m (weed free check) Height, crown and groundline diameter measurements were made at regular intervals over the first 14 months, with more detailed above and below ground morphological assessments made of the minicuttings and seedlings at 0, 28 and 112 days after planting. Diameter and height were measured annually until the trees were felled at rotation-end (7 years 7 months). Results In terms of growth responses during the establishment phase (up till 14 months), planting density had no significant impact on initial tree performance. Differences occurred between the different weeding treatments (from 55 days), with improved tree growth occurring with increased weeding distance. At 14 months groundline diameter growth in the 2.7, 1.8 and 0.9 m row weeding treatments had increased over the weedy control (0 m) by 50, 37 and 19%. Although the mini-cuttings were initially larger than the seedlings, by 93 days these difference were no longer significant. In term of post-establishment growth (from 14 months to rotation-end), neither tree type nor planting density had a significant impact. In contrast, the degree of weed control remained significant through to rotation-end with a significant increase in merchantable volume of the 2.7, 1.8 and 0.9 m row weeding treatments over the weedy control (0 m) of 23, 13 and 4.5% (Figure 1). There were no significant interactions at any stage during the trial between the different treatments. Figure 1: Rotation-end (7 yrs 7 mths) merchantable volume differences for the main treatment factors in E. grandis trial comparing mini-cuttings and seedlings and their interaction with planting density and weeding in Zululand, South Africa ICFR Zululand Regional Field Day Page 17
Conclusions These results highlight the importance of weed control during the establishment phase in this region, especially as these early impacts are likely to remain significant through to rotation-end. The two planting densities tested (1 481 and 1 851 stems ha -1 ) fall within the optimum stocking range for these sites, and although no significant differences were detected in terms of volume, harvesting costs (in terms of stem number/size) will determine which planting density is more appropriate. The non-significant differences between seedlings and mini-cuttings of the same genetic source, when planted on the same site (in addition to the lack of any interaction), indicates that more attention should be focused upon other nursery practices that may influence field performance. ICFR Zululand Regional Field Day Page 18
Harvesting and extraction impacts on Eucalyptus grandis x E. urophylla coppicing potential and rotation-end volume in Zululand, South Africa Kylle Schwegman 1, Keith Little, Andrew McEwan and Simon Ackerman 1 kylle.schwegman@nmmu.ac.za 1 Nelson Mandela Metropolitan University, Private Bag X6531, George, 6530, South Africa: Introduction Until the late 1990 s, the most commonly used harvesting systems within South Africa consisted of various combinations of manual, motor-manual and mechanical operations. Although these systems are still utilised, there has been a general shift from the early 2000 s to the use of semi- or fully-mechanised systems. Any increase in mechanisation (as is occurring in Zululand), will need to take into consideration damage to stumps and the subsequent ability to regenerate by coppice. Concern was expressed as to the impact of these mechanical methods of harvesting on the damage/removal of bark from the stumps during these operations, and how this damage would influence the ability of that stump to produce adequate coppice shoots. In 2002, four levels of harvesting (from manual, through semi-mechanised to fully mechanised) were used to fell a stand of E. grandis x E. urophylla to quantify the impact of mechanisation at felling, such that management decisions could be made regarding the potential to re-establish through coppice regeneration, or whether one should consider re-planting. Trial Location, Design and Treatments Where: Trust Plantation, Sappi Forests Central Area Felled: September and October 2002 Species: E. grandis x E. urophylla A380 Site history: Palmveld; many rotations of E. grandis MAP: 1033 mm MAT: 21.8 0 C The four harvesting treatments were replicated 4 times and laid out in RCBD Within each treatment plot, 3 sub-plots of 20 stumps were measured per plot Trial size = 6 ha ICFR Zululand Regional Field Day Page 19
Harvesting Systems Tested: Method of felling, debarking, cross-cutting, stacking and extraction Harvesting Crosscutting Extraction Loading and Felling De-barking Stacking systems motormanuamanual tractor and trailer motor- Bell 3W onto Bell Manual (Man) manual manual motormanuamanual tractor and trailer motor- Bell 3W onto Bell Man_Mech_3W mechanical manual motormanuamanual tractor and trailer motor- Flexiloader onto Bell Man_Mech_Flex mechanical manual Mechanised Flexiloader onto Bell mechanical mechanical mechanical mechanical (Mech) forwarder (T17) Results Figure 1. Bark damage in relative to the top/bottom half of stumps and swathe position in a trial to determine the impact of four harvesting systems on Eucalyptus grandis x E. urophylla coppicing potential in Zululand, South Africa Figure 2. Presence of coppice relative to top/bottom half of the stump and swathe position in a trial to determine the impact of four harvesting systems on Eucalyptus grandis x E. urophylla coppicing potential in Zululand, South Africa ICFR Zululand Regional Field Day Page 20
Conclusions Methods of harvesting and extraction had no impact on stump survival, or the number of stems after the final reduction operation Irrespective of the method of harvesting or extraction, there was more damage and less coppice on: o The upper half of the stump than the lower half; o The stumps in the extraction route or immediately adjacent. Three main harvesting associated factors that contributed to stump damage were vehicle movement, tear-outs and log stripping There were no significant difference between the four harvesting systems in terms of rotation-end volume GU A380 coppices exceptionally well ICFR Zululand Regional Field Day Page 21
Eucalyptus stump killing with harvester head herbicide applicator The benefit for forest management Simon Ackerman simon.ackerman@icfr.ukzn.ac.za Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, Pietermaritzburg, 3209 There is a shift in forestry towards optimisation of operations in plantations with the aim of improving the full value chain. Performing operations at the right time or combining certain operations can improve efficiency of producing timber for the market. The presentation gives highlights of the concept testing of a mechanised harvesting herbicide applicator that delivers a predetermined volume of herbicide to a eucalyptus stump as the tree is being cut. Operational trials show that this method has been successful in preventing coppice growth on cut stumps. The benefits of this form of stump kill application are: Potential increase in the effectiveness of eucalyptus stump killing; Reduction of the time between harvesting and planting (reduced TUP); Increase safety of workers; Potential reduction in costs. ICFR Zululand Regional Field Day Page 22
The use of glyphosate for the management of secondary coppice regrowth in a Eucalyptus grandis x E. urophylla trial in Zululand, South Africa Jonathan Roberts, Keith Little 1 and Marnie Light 1 keith.little@nmmu.ac.za School of Natural Resource Management, Nelson Mandela Metropolitan University, George Campus (Saasveld), George, South Africa Introduction In the early 1990 s, questions were raised as to the importance of controlling secondary coppice regrowth (2 ndry coppice regrowth) in terms of the suppressive impact it may have on the remaining coppice stems if left uncontrolled. At this stage, if it was controlled, then bushknives, or axes were used. Besides being labour intensive, questions were also raised as to the suitability of this method of control, particularly with respect to damage to the remaining coppice stems. A trial was therefore initiated in Zululand on an E. grandis coppice stand where low rates of glyphosate or paraquat were sprayed onto the coppice regrowth when knee/hip height. This proved to be equally effective as manual control, with the added cost benefits and limited damage to the remaining stems. This method of control has subsequently been retested in additional trials and is currently used extensively by the forest industry worldwide. However, questions still remain as to the effectiveness of this form of control, particularly in relation to the optimum rates of herbicide application, and how this is affected by species, age and coppice height. A trial was thus initiated whereby various rates of herbicide application were used in conjunction with coppice regrowth height. Trial Location, Design and Treatments Where: Southern Area, Sappi Felled: July - August 2006 Species: E. grandis x E. urophylla W962 Soils: Yellow Fernwood - +1.5m MAP: 1148 mm MAT: 21.5 0 C The trial consisted of a 3 x 4 factorial combination of twelve treatments, replicated three times, and laid out in a randomised complete block design. The main factors were Secondary Coppice Regrowth Height (SCRH), where the 2 ndry coppice regrowth was treated whenever it reached a mean height of 0.5, 1.0 and 1.5 m, and Herbicide Rate (HR) where glyphosate (360 g a.i. l -1 ) was sprayed at 0.0, 0.6, 1.2 and 1.8%. The 2 ndry coppice regrowth was manually removed in the 0.0% HR treatment plots at the appropriate heights, and would act as a no-herbicide control. Also included as one of the treatment combinations was the current recommendation of 0.6% glyphosate applied to the 2 ndry coppice regrowth when at 0.5 m in height. ICFR Zululand Regional Field Day Page 23
Results No significant treatment differences were detected for any of the tree growth variates (Dbh, Ht, BA and Vol) for the duration of the trial, or at rotation-end. Possible reason may include that the 2 ndry coppice regrowth was controlled before it developed beyond 1.5 m (and less in the 1.0 and 0.5 m treatments), and competition from this source never occurred. Stump and stem survival was not impacted by the treatments, with 1 605 stumps ha -1 and 1 668 stems ha -1 remaining at rotation-end. Stump visits Using the actual presence of 2 ndry coppice regrowth stump -1 visit -1, the mean number of times each treatment would need to be reapplied (referred to as Stump visits) over a 21 month period was calculated. Both SCRH and HR were significant (p < 0.01) in terms of the mean number of times each stump was treated (Stump visits) for 2 ndry coppice regrowth (Figure 1). No significant differences were detected between the number of Stump visits for the 1.0 and 1.5 m SCRH treatments, while the 0.5 m SCRH required significantly more visits (Figure 1). This may be due to the quicker recovery of 2 ndry coppice regrowth in the 0.5 m SCRH treatment. In terms of HR, both the 1.8 and 1.2% rate of application was not significantly different from each, but were significantly different from the manual control (0.0%). The 0.6% HR were significantly different from both the 1.8% HR and manual control treatments, while no significant differences occurred between 1.2 and 0.6% HR. There was no interaction between SCRH and HR. Figure 1: Mean number of visits per stump required to control 2 ndry coppice regrowth following reduction operations on Eucalyptus grandis x E. urophylla in Zululand, South Africa. Letters on bars indicate significance at p < 0.05. Cost-effectiveness of treatments Differences in terms of the costs for each treatment occurred due to the different number of operations required in addition to the total glyphosate used. To compare the different treatments in terms of their overall cost-effectiveness, they were ranked according to a combination of Stump visits and treatment costs. For Stump visits, the HR treatments were separated according to differing levels of significance (Figure 1), with the associated overall costs divided into five equal classes (Table 2). ICFR Zululand Regional Field Day Page 24
The most effective treatments were the 1.5 m SCRH at either a HR of 1.2 or 1.8 % (Table 2). As there were no significance differences between these two treatments in terms of Stump visits, the 1.2% would be preferred due to lower overall costs. Manual control, irrespective of SCRH required a significantly higher number of visits and were therefore excluded as they were not cost effective. When comparing the similar rates of glyphosate application across different SCRH, there was a general grouping, with the 0.5 m treatments costing more than the 1.0 m and 1.5 m respectively. If reduced chemical use is a requirement, then manual control is feasible if controlled at a SCRH of 1.5 m. Table 2: Comparison of treatment effectiveness and associated treatment costs for the various treatments applied for the commercial control of 2 ndry coppice regrowth following reduction operations on Eucalyptus grandis x E. urophylla in Zululand, South Africa. The different letters used in Stump visits indicate significant differences at p < 0.05. Dark Shaded block indicate optimum treatment. Light Shaded blocks indicate acceptable treatments. Mean number of times stump were treated (Stump visits ha -1 ) 1.8% HR (a) 1.2% HR (ab) 0.6% HR (b) 0.0% HR (c) Total cost to control 2 ndry coppice regrowth (R ha -1 ) 2 100 2 400-1.5 m SCRH 1.5 m SCRH - 2 400 2 700 1.5 m SCRH 1.0 m SCRH - 2 700 3 000 1.0 m SCRH - - 1.5 m SCRH 3 000 3 300-1.0 m SCRH 0.5 m SCRH 0.5 m SCRH 1.0 m SCRH > 3 300 0.5 m SCRH - - 0.5 m SCRH Conclusions There were no significant differences in coppice yield for the various rates and timing of glyphosate application tested, treatment efficacy in terms of treating 2 ndry coppice regrowth increased with an increase in HR (0 > 0.6 > 1.2 > 1.8%), especially when treated at either 1.0 or 1.5 m in height. These rates and timing of application also proved to be more cost-effective when compared to the current practices of either manual control, or the spraying of the 2 ndry coppice regrowth at 0.5 m with 0.6% glyphosate. If reduced herbicide-use is a major criteria within a company portfolio, then the 2 ndry coppice regrowth can be cost-effectively controlled when 1.5 m, or alternatively manually removed if cost is not a major criterion. Various scenarios exist, with the most appropriate method used dependent on that specific company. ICFR Zululand Regional Field Day Page 25