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Towards a plant‐based technique to measure utilization of karoo bushes
Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa • Authors: F.O. Hobson --- Department of Agriculture (eastern Cape Region),The precision of various destructive techniques for estimating utilization of karoo bushes was investigated with the prerequisite that removal of 20 % of the edible material of individual species could be shown to be statistically significant. Where the total mass... -
Evaluation of three objective point‐sampling techniques to measure utilization of karoo bushes
Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa • Authors: F.O. Hobson --- Department of Agriculture, Republic of South Africa A.S.J. Baarnhoorn --- Department of Agriculture, Republic of South AfricaThree techniques to measure utilization of karoo bushes were evaluated. Precision, accuracy and consistency were measured on three species at different times and levels of utilization. The percentage‐cover technique was less sensitive and less efficient than the percentage‐edible‐strikes and percentage‐twigs‐grazed... -
Precision in systematic trawl surveys as assessed from replicate sampling by parallel trawling off Namibia
Item type: Journal Article • Journal: South African Journal of Marine Science • Authors: T. Strømme T. IilendeFollowing independence of Namibia in 1990, abundance of that country's hake stocks was monitored by trawl surveys conducted by the Norwegian F.R.V. Dr Fridtjof Nansen using a systematic survey design. Precision from such designs is considered to be better than... -
Towards a technique for determining basal cover in tufted grasslands
Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: M.B. Hardy --- , Republic of South Africa N.M. Tainton --- Department of Grassland Science, Republic of South AfricaComputer simulation, point‐based field sampling procedures, and step‐wise multiple linear regression were used to establish a relationship between the basal cover (BC) of a sample site and paired observations of the mean distance from a point to the nearest living... -
Precision forestry for pulpwood re-establishment silviculture
Item type: Journal Article • Journal: The Southern African Forestry Journal • Authors: Robert Neil PallettThe 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... -
The effects of ageing biases on stock assessment and management advice: a case study on Namibian horse mackerel
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: MR Wilhelm MD Durholtz CH KirchnerWe explore the influence of age-estimation errors on the results of the age-structured production model (ASPM) used for horse mackerel stock assessment in Namibia for the period 1961–2003. The analysis considered age data from eight readers collected during an otolith-reading... -
Otoliths and vertebrae as potential hard structures for ageing South African yellowfin tuna Thunnus albacares
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: JD Filmalter --- Department of Ichthyology and Fisheries Science, South Africa OLF Weyl --- Department of Ichthyology and Fisheries Science, South Africa W Sauer --- Department of Ichthyology and Fisheries Science, South AfricaSagittal otoliths and vertebrae from 46 yellowfin tuna Thunnus albacares (118-175 cm fork length) collected off the west coast of South Africa were assessed for potential usefulness in age estimation. Growth increments were found on both structures. Comparisons of growth... -
Otoliths versus scales: evaluating the most suitable structure for ageing largemouth bass, Micropterus salmoides, in South Africa
Item type: Journal Article • Journal: African Zoology • Authors: G.C. Taylor --- Department of Ichthyology and Fisheries Science, South Africa O.L.F. Weyl --- Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, South AfricaThe suitability of scales for ageing Micropterus salmoides was determined by comparing the precision of growth zone counts on scales with those obtained from sectioned sagittal otoliths from a sample of 496 fish collected from Wriggleswade and Mankazana Impoundments in... -
Age and growth of redeye round herring Etrumeus whiteheadi off the South African coast
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: Y Geja --- Branch Fisheries Management, Department of Agriculture, Forestry and Fisheries, South Africa MD Durholtz --- Branch Fisheries Management, Department of Agriculture, Forestry and Fisheries, South Africa CL Moloney --- Zoology Department and Marine Research Institute, South AfricaAges of redeye round herring Etrumeus whiteheadi were estimated with associated errors and used to infer life-history information, such as age composition, age-at-maturity and instantaneous mortality rate. Samples were collected in November 2005 during a research survey aimed at estimating... -
Indirect methods of tree biomass estimation and their uncertainties
Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Marco A Njana --- Tanzania Forest Services Agency, TanzaniaTree aboveground biomass (AGB) may be determined using direct (weighing or biomass models) and indirect (involving the use of a form factor [FF]) or volume models, basic density [BD] and biomass expansion factor [BEF]) methods. Focusing on three dominant mangrove... -
Model for cutting force prediction in high precision single-point diamond turning of optical silicon
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: M. K. O. Ayomoh --- Mechatronics Engineering Department, South Africa K. A. Abou-El-Hossein --- Mechatronics Engineering Department, South Africa O. A. Olufayo --- Mechatronics Engineering Department, South AfricaThis paper presents a mathematical model predicated on a finite series convergent scheme and derivative functions of multi-variants obtained from a cutting force constitutive equation for onward prediction of the maximum cutting force at the tip of a single-point diamond... -
Relationship between somatic growth and otolith growth: a case study of the ornate jobfish Pristipomoides argyrogrammicus from the coast of Réunion (SW Indian Ocean)
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: K Mahé --- Ifremer, Fisheries Laboratory, Sclerochronology Centre, France Y Aumond --- Ifremer, Le Port, France K Rabhi --- Ifremer, Fisheries Laboratory, Sclerochronology Centre, France R Elleboode --- Ifremer, Fisheries Laboratory, Sclerochronology Centre, France E Bellamy --- Ifremer, Laboratoire Environnement Ressources Languedoc Roussillon, France J Huet --- Ifremer, Le Port, France M Gault --- FRS Marine Laboratory, Scotland D Roos --- Ifremer, Le Port, FranceThe ornate jobfish Pristipomoides argyrogrammicus Valenciennes 1832 occurs in the Indo-West Pacific Ocean, where it is harvested by small-scale coastal fisheries. Management of this species is hindered by lack of adequate biological data. We sampled a total of 113 individuals... -
Achievement of interventions on HIV infection prevention among migrants in China: A meta-analysis
Item type: Journal Article • Journal: SAHARA-J: Journal of Social Aspects of HIV/AIDS • Authors: Rui Zhang --- , , People’s Republic of China Ling Chen --- , , People’s Republic of China Ya deng Cui --- , , People’s Republic of China Ge Li --- , , People’s Republic of ChinaIn China, migrants with acquired immunodeficiency syndrome (AIDS) have become a serious problem in the field of AIDS prevention. This study aimed to evaluate the efficacy of interventions for human immunodeficiency virus (HIV) infection prevention for migrants in China and... -
Precision agriculture and the prospects of space strategy for food security in Africa
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Lere Amusan --- North West University, South Africa Samuel Oyewole --- North West University, South AfricaPrecision agriculture generally refers to the methods of crop, livestock and fish farming that are meant to eliminate or minimize uncertainty and maximize products with relative accuracy that matches predetermined expectations. Amidst these, the relevance of space assets such as... -
A systematic review of remote sensing and machine learning approaches for accurate carbon storage estimation in natural forests
Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Collins Matiza --- University of KwaZulu-Natal, South Africa Onisimo Mutanga --- University of KwaZulu-Natal, South Africa Kabir Peerbhay --- University of KwaZulu-Natal, South Africa John Odindi --- University of KwaZulu-Natal, South Africa Romano Lottering --- University of KwaZulu-Natal, South AfricaThe assessment of carbon storage in natural forests is paramount in the ongoing efforts against climate change. While traditional field-based methods for quantifying carbon storage pose challenges, recent advancements in remote sensing and machine learning offer efficient and innovative alternatives... -
Zoning the occurrence of
Thyrinteina arnobia in eucalypts and its relationship with the spectral behaviour of canopies and soil attributesItem type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Caíque Carvalho Medauar --- , Brazil Samuel de Assis Silva --- , Brazil Luis Carlos Cirilo Carvalho --- State University of Santa Cruz, Brazil Willian Bucker Moraes --- Federal University of Espírito Santo, Brazil Marcus Vinicius Masson --- State University of Paulista, Brazil Ricardo Previdente Martins --- , Brazil Sidinei Dallacort --- , Brazil João Mendes Cicarini Hott --- Federal University of Espírito Santo, BrazilThis study aimed to outline areas at risk of the occurrence of eucalypt defoliator caterpillars and their relationship with variations in the spectral behaviour of canopies and soil attributes. The study was conducted in three eucalypt plantation areas of the... -
Adoption of precision agriculture practices in South African field crop production systems: a national survey
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: KJ Truter --- Stellenbosch University, South Africa H Glas --- Bureau for Food and Agricultural Policy (BFAP), South Africa M Delport --- Stellenbosch University, South Africa FH Meyer --- Bureau for Food and Agricultural Policy (BFAP), South Africa PA Swanepoel --- Stellenbosch University, South AfricaThe implementation of precision agriculture practices can enhance agricultural productivity, sustainability, and on-farm profitability. Nonetheless, adoption rates vary widely across regions and farming operations, particularly in South Africa’s diverse agricultural landscape. This study builds on prior regional analyses by providing... -
Assessment of near-infrared reflectance spectroscopy for monitoring soil carbon, nitrogen and organic matter in South African forestry plantations
Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: DR Ramesar --- Institute for Commercial Forestry Research, South Africa DS Naidoo --- Institute for Commercial Forestry Research, South Africa GD Cooper --- Institute for Commercial Forestry Research, South Africa RJ Burgdorf --- Institute for Commercial Forestry Research, South AfricaSoil organic matter, carbon and nitrogen contribute to soil quality, which influences plant growth. In forestry planta- tions soil carbon, nitrogen and organic matter significantly influence site productivity. In South Africa, plantation forestry occurs across a diverse landscape requiring assessment...
