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- Volume 2006, Issue 206, 2006
Southern African Forestry Journal - Volume 2006, Issue 206, 2006
Volume 2006, Issue 206, 2006
Author J.S.B. ScotcherSource: Southern African Forestry Journal 2006, pp 1 –3 (2006)More Less
Extracted from text ... Southern African Forestry Journal - No. 206, March 2006 1 Guest Editorial Comment Forest certification in South Africa BACKGROUND There has been much interest in the sustainable management of natural resources since the publication in 1980 of the World Conservation Strategy. This is reflected in the number of intergovernmental, international non-governmental and country-level initiatives to address sustainable resource issues. From a forestry perspective, the most significant was the international acceptance of the Forest Principles - a non-legally binding authoritative statement of principles for a global consensus on the management, conservation and sustainable development of all types of forests - ..
Age determination of miombo species Brachystegia spiciformis (Leguminosae - Caesalpinoideae) in Zimbabwe using growth rings : scientific paperAuthor I.M. GrundySource: Southern African Forestry Journal 2006, pp 5 –12 (2006)More Less
The objective of this study was to determine whether <I>Brachystegia spiciformis</I> Benth. (Leguminosae - Caesalpinoideae), one of the dominants of dry miombo woodland in Zimbabwe, forms annual growth rings. In the past the production of effective cutting rotations and sound management plans for native miombo woodland in southern Africa has been hindered by the difficulty in determining the ages of the trees, and therefore their growth rates, because it was assumed that tropical trees did not form annual rings. This research indicates that <I>B. spiciformis</I> does form annual rings, made up of xylem cells terminated (or marked) by a narrow band of marginal axial parenchyma cells, even in dry years. The rings may sometimes be associated with a darkening of the xylem due to the production of flatter and thicker fibres, but the darker bands are not always produced at the end of the growing season as they would be in temperate species and may also be present at the beginning of the new season. Only in particularly wet or dry years do the changes in the width of the annual rings correspond closely with fluctuations in mean annual rainfall. These results provide a means to estimate the age and annual increment of this species, which will enable woodland managers to predict future yields more accurately and monitor of the effects of management on tree growth.
Strategies for the selection of uncontaminated Eucalyptus explants for shoot multiplication in a temporary immersion system (RITA(R)) in a commercial laboratory : scientific paperSource: Southern African Forestry Journal 2006, pp 13 –21 (2006)More Less
The potential high yields of Eucalyptus shoot multiplication achieved with a temporary immersion culture system such as RITA<sup>(R)</sup> are compromised by losses caused by microbial contamination particularly bacteria, characteristic of the explants used to initiate the cultures. Disinfection of the explants through antibiotic treatments has on occasion been effective but this approach is unreliable and costly. In the present study, antibiotics were found to have only a bacteriostatic and not a curative effect. A strategy was, therefore, required to achieve uncontaminated explants via a rapid and accurate screening procedure. Of the approaches tested, that which was considered most appropriate for a commercial laboratory involved inducing bud break on a semi-solid medium, screening axillary buds for endogenous contamination on a semi-selective microbial medium and initiating RITA<sup>(R)</sup> cultures with buds identified as being microbial-free.
A survey of cossid moth attack in Eucalyptus nitens on the Mpumalanga Highveld of South Africa : research noteAuthor G.R. BorehamSource: Southern African Forestry Journal 2006, pp 23 –26 (2006)More Less
During July 2004, an infestation of an unknown larval insect in ten- year and older <I>Eucalyptus nitens</I> was reported on the Mpumalanga highveld of South Africa. Samples of wood containing larvae were collected from the field and taken to the Forestry and Agricultural Biotechnology Institute, University of Pretoria. The adult specimens were subsequently identified by the Transvaal Museum as the native <I>Coryphodema tristis</I>. No records have been found of the insect on any member of the Myrtaceae. A total of approximately 3000 hectares of <I>E. nitens</I>, within 95 compartments greater than eight years of age on the Mpumalanga Highveld were surveyed in September 2004. The older age classes and lower elevation sites had significantly higher infestations than the younger, higher elevation sites. Low infestations are present in young stands of <I>E. nitens</I> (< 6 years of age), and not restricted to lower productivity sites, an indication that the pest risk potential is higher than originally anticipated.
Wood supply and forest regeneration consequences of integrated log allocation in western Kenya : research noteSource: Southern African Forestry Journal 2006, pp 27 –33 (2006)More Less
The present system of log sales from softwood plantations in Kenya is by stumpage to single product mills. This harvesting system leads to pulping of large diameter logs while allocation of small diameter logs to sawmills is a major cause of low recovery. This study examined future roundwood supply from softwood plantations in Western Kenya under the existing log sales system and under integrated allocation of sawlogs, plylogs and pulpwood to processing mills with a forest estate model. The present log sales system leads to a roundwood deficit over the planning horizon while wood supply under integrated harvesting meets demand over the same period. Under the present scenario, 56% of the harvested stands are replanted into a pulpwood-working circle as opposed to 11% under the integrated harvesting scenario. The rest of the area is regenerated into sawlog crops. Matching wood processing options and log production strategies to stands scheduled for harvest can therefore improve sustainability of roundwood supply from the existing softwood plantation area.
Contractor selection : a quantitative, consensus-friendly, transparent and objective method : management paperSource: Southern African Forestry Journal 2006, pp 35 –42 (2006)More Less
About eighty percent of all physical forestry work is executed by contractors. The total number of formal contractors in South Africa is about 300 of which all must be selected to execute activities. This article offers a method for selecting contractors in an objective, transparent and participative way. The use of the Decision Analysis System (DAS), also referred to as decision-making by objectives, makes it possible that a large number of objectives can be taken into account to select the best amongst a wide range of alternatives, while still ensuring that rational decision-making takes place.
Source: Southern African Forestry Journal 2006, pp 43 –49 (2006)More Less
Applications of sampling theory together with the technical developments in the field of remote sensing have opened new paths in forest inventory. This paper presents an overview of ongoing research in the field of automatic feature extraction and pattern recognition, which may provide options towards a fully automated forest inventory system. Forest information systems have to provide sufficiently reliable and current information in a suitable form, whilst being both efficient and economical. <br>The methods described, have to be seen as a first step towards an automated forest inventory system. The results presented are satisfying for the specific forest situation, but cannot be generalized for other situations and forest types. More comprehensive research on a variety of stand types, tree species and age classes is required, as different feature extraction approaches may be required on different sensors and different image scales. <br>Given a specific need for information the cost of providing the data should not be higher than the benefit achieved by using modern techniques. In the South African plantation forestry situation with homogenous stands, short rotation and relatively extensive silvicultural operations, stand-oriented image analysis approaches could provide sufficient information at acceptable costs.