ICFR ZULULAND INTEREST GROUP FIELD DAY

Transcription

1 ICFR Zululand Field Day Wednesday 31 st March 2010 Venue: Dukuduku Village Hall, SQF, St Lucia area, Zululand

2 ICFR ZULULAND INTEREST GROUP FIELD DAY 08h30 09h00 09h10 Date: Wednesday 31 st March 2010 Venue: Dukuduku Village Hall, SQF, St Lucia area Time: 08h30 for 09h00 PLEASE REMEMBER THAT HARD HATS MUST BE WORN TO THE FIELD VISITS PROGRAMME Meet for tea and coffee at the Dukuduku Village Hall Welcome and introduction to the field day A focus on Gonipterus, and other relevant pest problems (Leptocybe, Thaumastocoris) Geoff Galloway Jeff Garnas Sappi FABI 09h40 Sustaining fertility for productive plantations in Zululand Steve Dovey ICFR 10h10 An overview of research projects currently facilitated by Forest Engineering Southern Africa (FESA) Dirk Laengin Mondi/ FESA 10h40 Nutrient addition at two sites in Zululand (Fertiliser for Free) Steve Dovey ICFR 11h10 11h40 12h10 12h30 13h00 13h20 13h50 Travel to 1 st field stop (GPS: 28 17' 54.08" S ;32 18' 57.74" E) Cooldrinks & muffins Visit and walk-through of the Long-term Site Productivity trials looking at quantifying nutrient cycling processes Travel to 2 nd field stop (GPS: 28 17' 14.64" S ;32 16' 47.76" E Volume and Taper response of coppice vs. seedlings for Eucalyptus hybrids Travel to 3 rd field stop at Sappi North, Palm Ridge Plantation Visit to Sappi s cut to length harvesting operation showcasing mechanised harvesting Lunch in-field sponsored by Mondi Steve Dovey ICFR Trevor Morley ICFR Mike Hunter/ Grewar van Huyssteen Sappi ICFR 2010 Page 2 ICFR Zululand Regional Field Day

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4 A focus on Gonipterus, and also on other relevant pest problems in the region (Leptocybe, Thaumastocoris) Jeff Garnas Tree Protection Co-operative Programme (TPCP), University of Pretoria, Pretoria, South Africa ICFR 2010 Page 4 ICFR Zululand Regional Field Day

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7 Monitoring nutrient cycling processes in forest plantations Steven Dovey Institute for Commercial Forestry Research, PO Box , Scottsville, 3209 Introduction One of the aspects to achieving a sustainable timber supply in the southern African Forestry Industry is that plantation sites need to meet tree growth nutrient demands. Sustainable forest management also implies that site quality is not degraded and future land use options are not compromised. Plantation forests undergo various growth stages from felling to planting, post canopy closure to maturity. To understand nutrient supply and demand, numerous processes affecting the fluxes of nutrients during each plantation growth phase need to be monitored. This must include the effect of management on these nutrient fluxes during each phase. Having this knowledge will allow the calculation of the impact of management practices on site nutrient reserves, nutrient supply and long term sustainability. Dukuduku biogeochemical nutrient cycling study A project was set out in 2008 to quantify changes in nitrogen fluxes on a sensitive site after felling, through the inter-rotation period, planting and beyond. The aim was to determine the extent to which the nutrient flux processes can be influenced by management practices and to determine the subsequent consequences to productivity and long term sustainability. The Dukuduku site was considered a high risk site, having low soil nutrient reserves and a rapid growth rate, typifying plantations on the Zululand coastal plain, when compared to numerous other South Africa forestry sites. Experimental approach A site matching all the criteria for rapid growth, turnover and low soil nutrient supply was found at the Dukuduku plantation on the Zululand coastal plain. The site was a six-year-old planted Eucalyptus grandis x camaldulensis clonal crop. Four replications of treatments were arranged in a randomised complete block designed to test the effects of residue management on tree growth. In addition to the treatments, a mature (or standing) crop was left uncut in two replications on the North and South end of the trial site. A number of core treatments were imposed on the site using levels of residue management intensity. These treatments include: Retaining all the harvested residues and broadcasting them across the site (broadcast treatment); Removing all the residues while leaving the forest floor intact (whole tree harvest treatment); A double residue treatment using the trees from the whole tree plot; Residues burning after broadcasting (burn treatment); Replacing all the macronutrients lost with stemwood harvesting (fertiliser treatment). Two of these treatments and the standing crop were monitored for changes in nutrient pools, additions and losses, and cycling processes in the stand from a year before harvesting, through harvesting, site residue management and the planting of the new E. grandis x urophylla clonal crop. These processes will be followed to beyond canopy closure of the new crop to the point where the leaf area index of the new crop is equal to that of the standing crop. Process measurements Only a brief description of methodology will be given here as the numerous and complex methods used will be included in publication. Changes in soil and biomass nutrient pool sizes with the addition and loss of nutrients (fluxes) are being recorded at the site for two replicates of the broadcast, burn and standing crop treatments. In addition, top-soil chemical changes, nitrogen mineralisation, growth and nutrient accretion are being monitored. Hourly weather data, soil water and temperature and leaf area index will be used as support data. ICFR 2010 Page 7 ICFR Zululand Regional Field Day

8 Data and calculations Although much data has been collected from pre-felling to six months after planting, only a portion of the data has been processed as it has become available. Calculations are complete for atmospheric inputs and nutrient pools sizes in the trees, forest floor and soil. Some calculations are complete for the biomass and nutrient pool sizes changes under the various residue management treatments. Statistical analyses and quality checking of methodologies still needs to be done. Early results As is typical of the plantation forestry areas of Zululand, soils are low in all macro-nutrients (Table 1). Significant quantities of nutrients are found in the biomass nutrient pools and although numbers for soil pools are high, these indicate total soil pool sizes and not available nutrient pools size. Nitrogen mineralisation data collected at the site will indicate the rate of nitrogen release from the soil pool into plant available forms. Addition of nutrients from the atmosphere at the Kwambonambi and Dukuduku sampling sites seems to be sufficient to recharge losses incurred with stem-wood harvesting (Table 1 & 2). Off-site debarking may result in a significant calcium loss, not replaced by deposition. Nutrients remaining on the site after harvest are in Table 3. Although much of the calculations are complete, it is not possible to discuss the results without further statistical analyses being performed. These values may change slightly once the data and methodologies have been critically assessed. Table 1: Pre harvest litterfall biomass and nutrients; forest floor and tree nutrient pools and soil nutrient pools to 1 m depth. Biomass (t ha -1 ) Litterfall (per year) Forest floor Stem Bark, branch & leaves cm Soil cm Nutrients (kg ha -1 ) N P K Ca Mg Na Table 2. Nutrients added by atmospheric deposition to the Kwambonambi and Dukuduku sites (kg ha -1 yr -1 ). Site Source N P K Ca Mg Na wet Kwambonambi dry Total canopy Wet Dry Dukuduku Total Canopy Negative values for canopy imply canopy uptake ICFR 2010 Page 8 ICFR Zululand Regional Field Day

9 Table 3: Biomass and nutrients remaining after harvest where residues are broadcast, burned and removed. Residue broadcast Residue burn Whole tree Biomass (t ha -1 ) Nutrients (kg ha -1 ) N P K Ca Mg Na ICFR 2010 Page 9 ICFR Zululand Regional Field Day

10 An overview of Forest Engineering Southern Africa (FESA) including current research projects Dirk Laengin Mondi Limited, P O Box 39 Pietermaritzburg 3200 Forest Engineering South Africa (FESA) is an association representing members of the South African Forest Industry, focussing on research, development and promotion of Forest Engineering in Southern Africa. Over the past five years, FESA has initiated a number of projects which have been successfully taken up by the Industry. These include the development and production of handbooks and manuals as well as research and development projects, focusing on pulpwood transport optimisation, harvesting costing models, forest technical surveys, and Road Transport Management System. All of these have benefited key stakeholders in the South African Forest Industry, including large forestry firms, private growers and contractors. FESA has also been effective in informing Government on relevant policy and in supporting training and certification bodies. During 2009, FESA re-launched itself and it was decided to retain the FESA name as one recognised locally and internationally. A new steering committee for FESA has been set up with Dr Dirk Laengin (Mondi) as chairman. FESA has also developed a new logo and set up a website hosted on the ICFR website The programme has a number of broad objectives: To conduct forest engineering research and development aimed at improving the productivity and cost effectiveness of the South African Forest Industry. (One of the key objectives of FESA is the integration of forest engineering and silviculture). To promote and improve co-operation in forest engineering research and development; To create awareness and disseminate relevant information; and To raise the skills and increase efficiencies by promoting and supporting appropriate training and education. Projects are funded collectively through a grant from Forestry South Africa. In most cases, the private sector funding is leveraged through matching THRIP funding from the National Research Foundation. The projects are closely managed through an industry steering committee. In 2009, four research projects were commissioned and completed: 1. South African Harvesting and Transport Costing Model (University of Stellenbosch). 2. Cut-to-length versus tree-length harvesting in eucalypts (Nelson Mandela Metropolitan University). 3. Pine Sawtimber utilisation (Nelson Mandela Metropolitan University). 4. Evaluation of mechanised harvesting systems in sawlog operations in South Africa (University of Stellenbosch). The reports from these are being edited and prepared for final production and will be available on the website by mid In addition, FESA also commenced work on the development of a ground-based harvesting manual which will be completed at the end of In 2009, as part of its Communication and Awareness initiative, FESA also took the decision to place many of its publications in the public domain to ensure that they are easily accessible and available to a wide range of stakeholders. For details of these, visit ICFR 2010 Page 10 ICFR Zululand Regional Field Day

11 A number of projects have been identified as having a high priority for the South African Forest Industry and some will commence in 2010, depending on funding support. These include: 1. The development of a standard work study protocol and manual for the South African Forest Industry. 2. The development of a decision support model for using forest residues as a source of bio-energy in southern Africa. 3. Development of guidelines for steep slope, semi- and fully-mechanised harvesting operations in southern Africa. ICFR 2010 Page 11 ICFR Zululand Regional Field Day

12 Volume and Taper response of coppice vs. seedlings for Eucalyptus hybrids Trevor Morley & Keith Little Institute for Commercial Forestry Research PO Box , Scottsville, 3209 Introduction Although different standards have been developed for the silviculture and management of replanted versus coppiced eucalypts, in South Africa productivity estimates for these methods of regeneration are generally made using taper functions generated from planted eucalypts. Taper functions, which estimate diameters at any point on the stem are used to calculate total stem volume or merchantable volume to any top diameter and are considered essential for forest planning and management. Work in Portugal, that included both planted and coppiced stands, indicated differences in their taper-function parameters but little published information could be found to verify these differences. Similarly no information could be found for taper differences in coppice stems where one, as opposed to two stems had been left per stump. To determine the necessity for separate taper volume equations and possible effects of their bias, rotation-end stem taper data were collected from two Eucalyptus clonal hybrids that had either been planted or coppiced, in Zululand. Materials and Methods Eucalyptus grandis x E. camaldulensis (GC540) was grown at Eteza plantation. Eucalyptus grandis x E. urophylla (A380) was grown at Mavuya plantation. Well stocked, uniform stands, were selected prior to the harvesting of the parent crop (treatment 1R) (Table 1). Table 1. Site characteristics for two Eucalyptus trials comparing taper functions between of coppiced with planted material in Zululand. District, Plantation Enseleni, Eteza Lower Umfolozi, Mavuya Latitude and longitude 28 o S, 32 o E 28 o S, 32 o E Altitude (m a.s.l.) Long-term mean annual rainfall (mm) Long-term mean annual temperature ( o C) Soils Spacing (stems per hectare - sph) Taxonomy (FAO) Haplic Arenosol Haplic Arenosol Parent material Aeolian Aeolian Depth (m) x 2.53 m (1304 sph) 2.69 x 2.65 m (1396 sph) Species coppiced or planted E. grandis x E. camaldulensis (GC540) E. grandis x E. urophylla (A380) Parent clonal hybrids planted (1R) 6/ /1992 Sequence of events Parent clonal hybrids felled (and managed for coppice) (Cop) 14/06/ y (3285 d) 02/02/ y 4 m (2666 d) Clonal hybrids replanted (2R) 12/07/ /02/2000 Coppiced and replanted clonal hybrids felled 19/02/2008 Coppice: 7 y 8 m (2806 d) Replanted: 7 y 7 m (2778 d) 18/02/2008 Coppice: 8 y 1 m (2938 d) Replanted: 8 y (2923 d) Mean 1R 845 mm yr mm yr -1 annual rainfall over 2R 900 mm yr mm yr -1 rotation Coppice 894 mm yr mm yr -1 ICFR 2010 Page 12 ICFR Zululand Regional Field Day

13 After felling of treatment 1R, a one hectare block was replanted to the same clonal hybrid as the parent crop (2R_GC540 or 2R_GUA380). Stumps in the remainder of the 1R block were then subjected two coppice treatments: o One stem per stump: Shoots reduced when 3-4 m high to two stems per stump, with a second reduction at 7-8 m high to the original stocking (Cop_Sngl); o Two stems left per stump: In compartment areas of sub-optimal stocking, the second reduction was not conducted so each stump had two stems (Cop_Dbl). Within each of coppiced and replanted section, four plots consisting of 42 trees (6 x 7 trees) were laid out, with the inner 20 trees (4 x 5 trees) forming the measured plot. Sample taper trees were selected from defect-free measured trees across the Dbh range for each trial treatment at felling (Table 2). Two methods for stem taper determination and treatment comparison were used: o A single value for the overall inside-bark taper of individual trees was calculated (after Clarke et al.1997) and a one-way analyses of variance (ANOVA) with no blocking to test for treatment effects o Measured stem taper data were fitted to the segmented polynomial regression function of Max and Burkhart (1976) to predict the profile of the stem with mean bias, SDD and TSE statistical criteria were used to evaluate attributes of interest. Table 2. Summary of stump and stem attributes used for comparing taper functions between coppiced and planted material in two Eucalyptus trials in KwaZulu-Natal, South Africa. Treatment No. stumps (n) No. stems (n) Sample points (n) Stump # height (cm) DBH ob (cm) DBH ib (cm) Tree top height (m) collected modelled min max min max min max min max Eteza GC540 1R R Cop_Sngl Stem Cop_Dbl Stem Mavuya GUA380 1R R Cop_Sngl Stem Cop_Dbl Stem # Negative stump heights recorded due to felling the coppice stem below the original stump surface ICFR 2010 Page 13 ICFR Zululand Regional Field Day

14 Results When comparing the 1R parent crop with the rest of the treatments (2R planted and coppiced), any differences in rotation length and climate need to be taken into consideration (Table 1). o Mvuya 1R parent crop was felled nine months younger than the subsequent 2R rotation. o Eteza 1R parent cop was in the ground for an additional 14 months compared to the 2R crop. o Climate would have been identical for the 2R treatments (planted and coppiced), differences could be expected between successive rotations (between 1R and 2R); rainfall stations near both sites showed a 52 and 32 mm yr -1 increase in rainfall for the 2R relative to 1R at Eteza and Mavuya. The Clarke et al.1997 approach to stem taper determination for the overall inside-bark stem taper of individual trees detected significant differences (F prob. < 0.01) between the different treatments in terms of these stem taper values at both Eteza and Mavuya (Table 3). o Both trials showed no significant differences between 1R, 2R or Cop_Sngl although their ranking in terms of mean taper differed. o Where two stems were left per stump, the taper was significantly different, with the larger of the two stems (Cop_Dbl_Stem1) having a significantly greater taper than the smaller of the two stems (Cop_Dbl_Stem2) despite evenly matched stems being chosen per stump at the time of reduction/thinning. o Where the two stems were combined into a single taper estimate (Cop_Dbl_Stem1+2) there was a small but noticeable decrease in the taper values (0.028 and cm m -1 for Eteza and Mavuya) relative to the Cop_Dbl_Stem1. o The single value for the combined stems indicates that in addition to the expected differences obtained between the two clones, there are also differences within each clone, with the taper for single stems (1R, 2R and Cop_Sngl) being similar to each other, yet significantly different from stumps with double stems (Cop_Dbl_Stem1, Cop_Dbl_Stem2, Cop_Dbl_Stem1+2). Table 3. Summary of analyses of variance (mean squares) and treatment means in two Eucalyptus trials comparing stem taper of coppiced with planted material in KwaZulu-Natal, South Africa. Eteza GC540 Mavuya GUA380 Source of variation DF Stem taper Stem taper (cm m -1 DF ) (cm m -1 ) Treatments ** ** Trees (residual) Total Summary of data (treatment means) 1R a a Cop_Sngl a a 2R a a Cop_Dbl_Stem b b Cop_Dbl_Stem b b Cop_Dbl_Stem c c Grand mean Standard error Coeff. of var. (units) ** Significance at p<0.01. Within each column, values followed by the same letter are not significantly different; p<0.05 according to Students t-test. ICFR 2010 Page 14 ICFR Zululand Regional Field Day

15 Optimum model selection through fitting of the Max Burkhart function was based on a combination of the mean bias, SDD and TSE having the lowest values. Irrespective of site or treatment, all models tended to over-predict inside bark diameter slightly, with overpredictions of 0.34 to 1.35% for trees at Eteza, and 0.31 to 1.20% for those at Mavuya (Table 4). To determine whether variances in the model bias translates into meaningful differences, derived utilisable volumes for the different treatments were compared against each other, with the results presented in a two-way table (Table 5). o For Eteza, GC540, use of the 1R model tended to under-predict utilisable volume of treatments while Cop_Sngl and 2R tended to overpredict; o For Mavuya, GUA380, the 1R, 2R and Cop_Sngl model tended to overpredict other treatments, notably overpredicting treatments containing two stems; o For both clones, use of models based on stumps containing two stems generally tended to under-predict the utilizable volume for single stem treatments. Conclusions Both stem taper analysis approaches used indicated differences between clones, as well as between treatments, with the models based on single stems (1R, 2R or Cop_Sngl) being significantly different from those containing two stems (Cop_Dbl_Stem1, Cop_Dbl_Stem2, Cop_Dbl_Stem1+2). Regardless of any non-significant model differences (for example between 1R, 2R and Cop_Sngl) it is suggested that individual models need to be compared against each other, since the magnitude of any differences may have importance in terms of the volume prediction for product planning. Although different ages and different rotation-growing conditions may confound any taper differences (particularly between 1R and 2R), this data set indicates comparisons between rotations of the same clone is of lesser importance than whether the trees were planted or coppiced, or how that coppice was managed (single or double stem stump -1 ). Importance of these findings in terms of commercial application of these results can only be determined through the collection of a larger taper data-set that covers a range of age classes and rotation-growth conditions for different source material. In addition to a larger data-set, use of mixed modelling statistical approaches to analysing stem taper data should also be investigated. References Clarke CRE, Garbutt DCF and Pearce J Growth and properties of provenances and trees of nine Eucalypt species. Appita Journal 50: Max T and Burkhart H Segmented polynomial regression applied to taper equations. Forest Science 22: ICFR 2010 Page 15 ICFR Zululand Regional Field Day

16 Table 4. Parameter estimates and predictive performance and of inside diameter bark models using a segmented polynomial equation for comparing taper functions between coppiced and planted material in two Eucalyptus trials in KwaZulu-Natal, South Africa. Sample Parameter estimates of models Predictive performance of models points Treatment modelled Mean bias Β 0 Β 1 Β 2 Β 3 Β 4 (a 1 ) Β 5 (a 2 ) (n) (cm) (%) SDD TSE Eteza GC540 1R R Cop_Sngl Cop_Dbl_Stem Cop_Dbl_Stem Cop_Dbl_Stem Mavuya GUA380 1R R Cop_Sngl Cop_Dbl_Stem Cop_Dbl_Stem Cop_Dbl_Stem Table 5. Utilisable volume (inside bark volume to 5cm D ib ) comparisons for the different coppiced and planted treatments in two Eucalyptus trials in KwaZulu-Natal, South Africa (values expressed as percentage bias). Eteza GC540 Treatments 1R Cop_Sngl 2R Cop_Dbl_Stem1 Cop_Dbl_Stem1+2 Cop_Dbl_Stem2 1R Cop_Sngl R Cop_Dbl_Stem Cop_Dbl_Stem Cop_Dbl_Stem Mavuya GUA380 Treatments 1R Cop_Sngl 2R Cop_Dbl_Stem1 Cop_Dbl_Stem1+2 Cop_Dbl_Stem2 1R Cop_Sngl R Cop_Dbl_Stem Cop_Dbl_Stem Cop_Dbl_Stem ICFR 2010 Page 16 ICFR Zululand Regional Field Day