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- Volume 2005, Issue 203, 2005
Southern African Forestry Journal - Volume 2005, Issue 203, 2005
Volume 2005, Issue 203, 2005
Author Dennis OwenSource: Southern African Forestry Journal 2005, pp 1 –2 (2005)More Less
Extracted from text ... Editorial What is expected of the SA Forestry Journal in future? In an editorial on Journal achievements, in SAFJ No 200 (March 2004), I posed the question in closing "What of the future?" and expressed the hope that our Journal would more aggressively promote the SAIF mission and assist forestry practitioners "to achieve and maintain excellence in the practice of forestry". We have now moved on a year and your Editorial team has given attention to the nature and future of the Journal. In this edition an editorial notice welcomes a great new Editorial Advisory Board and expresses disappointment that ..
Application of the 3-PG model to a Eucalyptus grandis stand subjected to varying levels of water and nutrient constraints in KwaZulu-Natal, South Africa : scientific paperSource: Southern African Forestry Journal 2005, pp 3 –13 (2005)More Less
The 3-PG model has shown considerable potential as a tool for predicting forest productivity. As part of a model validation exercise, 3-PG was applied to an irrigated and fertilised <I>Eucalyptus grandis</I> stand in the KwaZulu-Natal Midlands. Simulations were run over a two-year period using appropriate initialisation data and a parameter set developed for <I>E. grandis</I> for the summer rainfall region of South Africa. The model was validated using observed leaf area index, and foliage and above-ground woody biomass, and then used to predict stand volume. Evaluation of 3-PG model outputs against field measurements indicated a generally good correlation for growth data across the control, irrigated, fertilised, and irrigated and fertilised trees. At 3.9 years, the model-predicted leaf area index over all treatments ranged from 3.8 to 5.1, similar to the observed range of 4.3 to 4.9. Stand volume at 3.9 years of age was under-predicted in the non-irrigated treatments. Actual stand volume at this age ranged from 100 to 118 m<sup>3</sup> ha<sup>-1</sup> across all treatments, compared to model estimates of 79 to 121 m<sup>3</sup> ha<sup>-1</sup>. Use of a dynamic fertility rating may improve model predictions and there is possible scope for improvement in the water-balance component of the model. Results from this study have shown 3-PG to be a robust model by producing accurate predictions of growth under varying levels of resource availability.
The effect of harvesting operations, slash management and fertilisation on the growth of a Eucalyptus clonal hybrid on a sandy soil in Zululand, South Africa : scientific paperSource: Southern African Forestry Journal 2005, pp 15 –26 (2005)More Less
Harvesting operations during clearfelling and extraction of timber from commercial plantations result in many processes that may affect long-term site productivity such as soil compaction and residue manipulation. The objective of this work was to evaluate the effects of various harvesting operations and fertiliser applications on soil physical properties and the subsequent growth of a <I>Eucalyptus</I> clonal hybrid (<I>Eucalyptus grandis x camaldulensis</I>) on the sandy soils of the Zululand coastal plain in northern KwaZulu-Natal. Increases in bulk density and penetrometer soil strength and decreases in aeration porosity were recorded on plots where a wheeled harvester had been used and on extraction roads, but these were not of a sufficient magnitude to limit tree growth. Available water capacity increased on the compacted plots. At six years of age there were no significant differences in stand volume between the plots harvested by different methods or between fertiliser treatments, nor was there any interaction between the treatments. However, a significant response to fertilisation was evident after one year. In contrast to the other treatments, trees in plots subjected to the wheeled harvesting operation did not respond to fertilisation, suggesting that an early release of nutrients occurred, caused by the breakdown and incorporation of slash in the topsoil.
Analysis of individual tree volume equations for Cupressus lusitanica in Munessa forest, Ethiopia : scientific paperAuthor T. TeshomeSource: Southern African Forestry Journal 2005, pp 27 –32 (2005)More Less
Three different volume equations were fitted to individual tree volume (V) data collected on 260 <I>Cupressus lusitanica</I> trees from 49 plantations in Munessa Shashemene Forest, Ethiopia. The data were first split randomly into equation development and equation testing data sets of equal size. Diameter at breast height (D) and height above the stump to the tree tip (H) were used as independent variables to predict volume over bark from a stump height of 30cm to the tip of the tree. The parameters, standard errors and mean square errors for each of the three equations were estimated with weighted least squares regression analysis using the modelling data set. The equations were then compared on the basis of fit statistics using the equation testing data set. The equation form V = <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol">b</SPAN></SPAN><sub>0</sub> + <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol">b</SPAN></SPAN><sub>1</sub>(H/D)<sup> <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol">b</SPAN></SPAN>2</sup>D<sup>2</sup>H+ <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol"><font size="5">e</font></SPAN></SPAN><sub>1</sub> was the best and, therefore, it was fitted to the combined data set.
Author Robert Neil PallettSource: Southern African Forestry Journal 2005, pp 33 –40 (2005)More Less
The Southern African pulp and paper industry has a strong export focus and operates in an open global market. In a global context, wood is a commodity product and an ongoing strategy of reduction in the unit cost of timber delivered to mill gate and understanding wood properties to add value in the mill, is important to low cost "fit for purpose" fibre and to enhancing our competitive advantage. In addition, the plantation area is largely constrained to that which is currently planted. This means that precision forestry for pulpwood production must impact in two key aspects. 1) Sustaining and increasing fibre supply from a fixed production area 2) Understanding and improving the properties of the furnish to achieve uniformity and add value through the supply chain. <br>Forest management units for pulpwood are relatively large compared to other crops. The required degree of refinement to meet product specifications and the accuracy at which input variables can be determined prescribe the resolution of individual components for precision management purposes. Decision criteria for managing six elements of good silviculture are presented as well as factors which explain important variation in wood properties. The land type concept provides a site classification system that maps the spatial distribution of these parameters at a scale that fits the precision required for forest management that is extensive rather than intensive.
Forecasting volume and economic gains from intensive plantation management using different response curves : management paperSource: Southern African Forestry Journal 2005, pp 41 –47 (2005)More Less
Proponents of intensive plantation management do not all use the same type of response curves when predicting future volume gains. As a result, some believe that continuously increasing the intensity of management will increase landowner profits and reduce the unit cost of wood production (i.e. all silvicultural costs per ha/merchantable cubic metres per ha at harvest). A few believe there is no upper limit to stand productivity while others use response curves that follow the law of diminishing returns. Using loblolly pine (<I>Pinus taeda</I>) data from Georgia as a point of reference, we developed four hypothetical production models (where yield is a function of silvicultural effort). The models that produced apparently unrealistic results were (1) an exponential curve and (2) a linear curve where the costs of growing a cubic metre of merchantable wood (at time of harvest) was inversely related to the discounted cost of intensive silviculture. Although increasing silvicultural effort will often result in more merchantable volume at harvest, the extra wood volume might not be enough to prevent a reduction in net present value of the stand. Harvesting intensively managed loblolly pine stands at age 15 years might not prove economical for a private, non-industrial landowner in the USA if the costs of establishment are too high or if no local mills will purchase logs that contain a high percentage of juvenile wood.
The present status of Anaphes nitens (Hymenoptera : Mymaridae), an egg parasitoid of the Eucalyptus snout beetle Gonipterus scutellatus, in the Western Cape Province of South Africa : management paperAuthor G.D. TribeSource: Southern African Forestry Journal 2005, pp 49 –54 (2005)More Less
The egg parasitoid <I>Anaphes nitens</I> (Girault) was successfully introduced into South Africa in 1926 to control the Eucalyptus snout beetle, <I>Gonipterus scutellatus</I> Gyllenhal. However, outbreaks of the beetle on the Highveld in the 1980s questioned the efficacy of the parasitoid as a biological control agent and a programme was instituted to determine its present status. This study represents the Western Cape programme where 20 host egg-capsules were collected at fortnightly intervals for five years from three localities and the percentage parasitism was recorded. The mean parasitism rate varied between Cape Town (76%), George (82%), and Grabouw (89%). The highest parasitism occurred in spring (October) at Cape Town (96%) and (September) Grabouw (92%); and in autumn (May) at George (78%), coinciding with that of maximum host egg production, which in turn was dependent on the availability of fresh foliage. More host eggs were present in Cape Town (42%) than at either George (30%) or Grabouw (28%). Parasitism occurred consistently throughout the year at George which experiences all year rainfall, but the winter rainfall Cape Town and Grabouw localities experienced distinct peaks in parasitism in spring. Biological control of <I>G. scutellatus</I> remains effective in the Western Cape, from where <I>A. nitens</I> could be procured for release in Highveld regions in spring.
Host plants of Osyris lanceolata (African Sandalwood) and their influence on its early growth performance in Tanzania : research noteSource: Southern African Forestry Journal 2005, pp 55 –65 (2005)More Less
Identification of the host plants of the hemi-parasitic African sandalwood (<I>Osyris lanceolata</I>) and the influence of some on its early growth performance was investigated at Image, Nundu, Sao Hill and Iringa in the southern highlands of Tanzania. The aim was to identify host plants that support the growth of <I>O. lanceolata</I>, and to evaluate the potential of some in promoting its early growth under artificial establishment. The results revealed that <I>O. lanceolata</I> parasitises a wide range of hosts although some were preferred. The preferred hosts were <I>Rhus natalensis, Dodonaea viscosa, Tecomaria capensis, Catha edulis, Apodytes dimidiata, Brachystegia spiciformis, Maytenus acuminatus</I> and <I>Aphloia theiformis</I>. Of the preferred hosts, <I>Brachytegia spiciformis, Rhus natalensis</I> and <I>Casuarina equisetifolia</I> promoted most effectively the early growth of <I>O. lanceolata</I> in terms of height, diameter and overall root and shoot biomass. Possibly the light crown of these host species and the nitrogen fixing ability of <I>C. equisetifolia</I> played a significant role in conferring this advantage. The species are thus recommended as appropriate host plants when raising <I>O. lanceolata</I> seedlings for planting. However, a decision on whether these hosts will support the growth of <I>O. lanceolata</I> at a later stage is subject to further experimentation as they may only be serving as initial or intermediate hosts as reported in a related species <I>Santalum album</I>.
Source: Southern African Forestry Journal 2005, pp 67 –70 (2005)More Less
Extracted from text ... Southern African Forestry Journal - No. 203, March 2005 67 SAFJ Index 2004 SA FORESTRY JOURNALS INDEX: No 200, No 201, No 202 Note: This is an Abbreviated Index. Paper title shown under name of main author only. 201/25(10pp) means - Journal No 201 Page 25 Pages 10 'et al' means - More than a single author Author Title Journal Email address Ackerman P A et al "Short-haul" pulpwood transport in South Africa: A network analysis case study. 201/43(9pp) firstname.lastname@example.org Ahmed F B 201/3 Allan R 200/19 Allan R 200/27 Bouvet J-M et al Early selection of Eucalyptus clones in retrospective nursery test using growth, morphological and dry matter criteria, in Rep. of Congo. 200/5(13pp) jean-marc.bouvet @cirad.fr Burdzik W ..
Policy that works for forests and people : real prospects for governance and livelihoods, James Mayers and Stephen Bass : book reviewAuthor J.S.B. ScotcherSource: Southern African Forestry Journal 2005, pp 74 –76 (2005)More Less
Extracted from text ... 74 Book Review POLICY THAT WORKS FOR FORESTS AND PEOPLE: Real prospects for governance and livelihoods. James Mayers and Stephen Bass International Institute for Environment and Development Published by Earthscan 2004 ISBN 1 - 84407 - 096 - 4 Soft-cover, 352 pp, 21 figures Price: ? 35 or US$ 60 The first edition of Policy That Works for Forests and People was published in 1999 and was soon established as a key text for students and professionals. Indeed, others beyond the forest sector also began to realise that the ingredients of 'living' policy processes, highlighted in this book, ..