- A-Z Publications
- Southern African Forestry Journal
- Previous Issues
- Volume 2004, Issue 201, 2004
Southern African Forestry Journal - Volume 2004, Issue 201, 2004
Volume 2004, Issue 201, 2004
Source: Southern African Forestry Journal 2004, pp 1 –2 (2004)More Less
Extracted from text ... 1 Guest Editorial Productivity in the South African forestry industry over the past decade IMPORTANCE OF PRODUCTIVITY Why are some countries so rich, why are their companies so prosperous and why are their citizen's standard of living so high? Why do we have Developed and Developing countries? It could be because some countries have vast natural resources. But then a very rich country such as Japan has few and a very poor country such as Mocambique has vast natural resources. There is no consensus on how much of a country's wealth is due to productivity but there is ..
Estimating the leaf area index (LAI) of black wattle from Landsat ETM+ satellite imagery : scientific letterSource: Southern African Forestry Journal 2004, pp 3 –12 (2004)More Less
Remote sensing techniques have the potential to provide resource managers with a rapid and economical method of acquiring information related to forest productivity and water use. This study evaluated the utility of Landsat ETM+ satellite imagery to predict canopy attributes of Black Wattle (<I>Acacia mearnsii</I>). The study encompassed ground-based measurements of leaf area index (LAI) and plant area index (PAI) using destructive sampling and LI-COR LAI-2000 plant canopy analyzer, respectively. Vegetation indices (VIs) were estimated from Landsat ETM+ images covering four study sites of pure stands of <I>A. mearnsii</I> located in the KwaZulu-Natal Midlands. The indices included: normalized difference vegetation index (NDVI), ratio vegetation index (RVI), transformed vegetation index (TVI) and vegetation index 3 (VI3). Relationships between the various vegetation indices, SLA, actual LAI and PAI values were tested using correlation and regression analyses. <br>Results showed strong correlations between LAI and PAI (to calculate LAI), LAI and NDVI, and between PAI and NDVI. No significant correlations were found between VI3 and either PAI or actual LAI. Regression analysis revealed that actual LAI had significant relationships with PAI and NDVI. The results indicate the potential of the Landsat ETM+ satellite imageries to estimate values of important canopy attributes of <I>A. mearnsii</I> that are related to stand productivity that may be used as inputs into process-based models such as 3-PGS which attempt to estimate stand productivity and water use of commercial plantation tree species.
Influence of the origin of stem cutting, season of collection and auxin application on the vegetative propagation of African Sandalwood (Osyris lanceolata) in Tanzania : scientific paperSource: Southern African Forestry Journal 2004, pp 13 –24 (2004)More Less
An investigation into the possibility of propagating <I>O. lanceolata</I> through stem cutting was carried out at Tanzania Tree Seed Agency, Iringa Zone, Tanzania. The aim was to test the potential of stem cuttings in providing an alternative/supplement to the use of seeds that are constrained with germination and storage problems. Three treatments were investigated on the rooting success and subsequent nursery performance of the cuttings: the effect of season at which cuttings are collected i.e. December, February, June and September; the effect of origin of stem cutting in a shoot, i.e. basal and terminal portions; and the effect of different levels of IBA as root promoters, i.e. 0, 50, 100 and 150 ppm. The results revealed that stem cuttings collected from the sprouting stumps have a potential to be used in propagating <I>O. lanceolata</I>. Season at which cuttings are collected; origin of the stem cuttings in a shoot and application of auxins influenced the rooting success. Stem cuttings collected in September, originating from the basal portion had the best rooting (43.8 <u>+</u> 3.9%). This is possibly related to the high levels of stored food in the plant after undergoing active photosynthesis during the rain season, November-May. Auxin application in interaction with the season at which cuttings were collected enhanced the number of cuttings that rooted, the number of roots formed (13 <u>+</u> 0.4), the length (14 <u>+</u> 0.3 cm) and biomass of roots (6.95 <u>+</u> 3.9 g) produced. The concentration to be applied for effective rooting depended on the season at which cuttings were collected. Of the origin of stem cuttings, basal portions had better rooting than the terminal portion. The high nutrition status and low nitrogen content of basal portions may play a role in enhancing their performance. Thus when raising O. lanceolata from stem cuttings, best rooting is obtained from those raised between June and September using cuttings from the basal origin of the juvenile shoots. Application of IBA between 50 and 100 ppm further enhances rooting success.
Equations for predicting the biomass of Acacia cyclops and Acacia saligna in the western and eastern Cape regions of South Africa : Part 1 : tree-level models : scientific paperSource: Southern African Forestry Journal 2004, pp 25 –34 (2004)More Less
A forest inventory was carried out in coastal areas infested by the alien tree species <I>Acacia cyclops</I> and <I>A. saligna</I> on the West Coast, Agulhas and Eastern Cape Plains. Sample trees were felled to construct prediction equations, which were subsequently used to obtain regression estimates of wood mass for knee height diameter classes below 2.5 cm, between 2.5 and 5.0 cm and above 5.0 cm respectively. Various regression models were tested. The single biomass component was regressed on log-transformed diameter, log-transformed commercial stem length and log-transformed biomass. The results were compared with a 10-parameter equation, which used the linear and quadratic term of diameter at knee height (<I>DKH</I>), and commercial stem length as well as four interaction variables as predictors. For practical reasons, it was recommended to use basal area and squared basal area as predictors and to ignore commercial stem length as independent variable. This produced a tariff-type estimator for biomass components. In addition, equations were developed to estimate leaf biomass from <I>DKH</I> and to evaluate the relationship between leaf biomass and wood biomass.
Equations for predicting the biomass of Acacia cyclops and Acacia saligna in the western and eastern Cape regions of South Africa : Part 2 : stand-level models : scientific paperSource: Southern African Forestry Journal 2004, pp 35 –42 (2004)More Less
The study deals with stand-level models for estimating wood biomass for different tree sizes and different biomass categories. It was carried out on farms and nature reserves in three regions. The stratification was identical with that in part 1 of the study, which dealt with tree-level models. The three regions (Western Cape Plains, Agulhas Plains, and Eastern Cape Plains) were sampled independently. Within each region the two species involved, <I>A. cyclops</I> and <I>A. saligna</I>, were also sampled independently. No sample plots were measured in <I>A. saligna</I> in the ECP region. Within each of the five strata, the number of sample plots was approximately proportional to the size of the locality. In consequence the sampling method can be described as stratified random sampling with Probability of Selection Proportional to Size. In addition, the leaf biomass per unit area was estimated for each stratum. Equations were fitted for each stratum, which produced estimates for the parameters of the decreasing diameter distributions. An analysis of variance based on a nested model was carried out to estimate the between-locality and between-plots within localities variances.
Source: Southern African Forestry Journal 2004, pp 43 –51 (2004)More Less
Shorthaul transport, also known as secondary intermediate transport (SIT), is a feature of pulpwood transport in South Africa. SIT is an additional transport phase within traditional secondary transport. It originates at roadside landing or depot and terminates at another depot, rail siding or merchandising area (not the final destination). The reason for the inclusion of SIT is identified as the result of the poor and steady decline of forest road conditions to the extent that highway type vehicles are unable to reach roadside landings. This necessitates the use of intermediate storage sites, from where timber is once again loaded and transported to its final destination. A network analysis model, assisted by newly developed and industry accepted terminology, and pixel-based geographic information system (GIS) were combined to analyse various transport scenarios within three study areas in the KwaZulu/Natal Midlands of South Africa, employing SIT on poor, high-density forest road networks. The simple pixel-based GIS contained information on the forest road network, surface cover and slope.The results of the economic analysis highlighted the need for the reduction of road network densities and for the improvement of the remaining network. This would eliminate the need for extended primary transport and allow the use of highway vehicles transporting from compartment roadside to and past plantation exits. Results show the average annual cost penalty to the industry, by maintaining SIT and related transport, to be R43.25 million or R8.24/m<sup>3</sup>. SIT accounts for between 10 and 15% of the total delivered cost of round wood pulpwood.
A review on the effects of donor maturation on rooting and field performance of conifer cuttings : review paperSource: Southern African Forestry Journal 2004, pp 53 –63 (2004)More Less
The maturation and ageing effects of parent or donor plants have been reported to have both positive and negative influences on the performance of rooted cuttings. A general decline in rooting ability, root quality and speed of rooting in the nursery, and a reduction in tree survival, growth and form in the field, have been associated with donor plants that have reached a state of reproductive or ontogenetic maturity. Increased maturation has also been shown to affect wood quality negatively. Provided that donor plants are still relatively young, positive effects from increased donor age have been observed through an improvement in tree form and branching habit, as well as a reduction in bark thickness and stem taper. These improvements have resulted in increased timber yields over seedlings of the same genetic origin. This report summarises current understanding of the effects of donor maturation.
Author W.J.A. LouwSource: Southern African Forestry Journal 2004, pp 65 –76 (2004)More Less
"Adapt or die" is a cliché that is often used to emphasise the need to change to ensure survival and sustained growth. During the 1990s the Forest Industry had to do just that. Never in the history of forestry did so many changes take place on so many fronts. The industry responded well to most of the challenges to ensure its long term viability. Two of the major events during this period were the privatisation of the former Safcol and the democratisation process of South Africa. These and other main events in the history of the forest industry are presented in this paper under: forest law and policy, privatisation of State forests, afforestation, economics, outsourcing, protection, environmental matters, research, education and training and professionalism.