Transactions of The Royal Society of South Africa最新文献

{"title":"Mapping the spatial distribution of Lantana camara using high-resolution SPOT 6 data, in Mpumalanga communal areas, South Africa","authors":"Ngwanamapotu Paschaline Madileng, O. Mutanga, T. Dube, Omosalewa Odebiri","doi":"10.1080/0035919x.2020.1817812","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1817812","url":null,"abstract":"Agroecosystems play a critical role in rural economics and contribute to the national economy. However, these areas are currently threatened by invasive species. Timely information on potential hotspots and affected areas is required for management purposes. We assess the spatial distribution patterns of Lantana camara invasion in savanna rangeland ecosystems before and after clearing (2014, 2016 and 2018), using high-resolution SPOT 6 data, in Agincourt, South Africa. A maximum likelihood classification algorithm was applied to SPOT 6 data to detect and map areas affected by this invasive species. Furthermore, different accuracy assessment measures (e.g. producer accuracy (PA), user accuracy (UA) and overall accuracy (OA)) were used to assess the validity of the classification results, namely built-up areas, bare areas, uninvaded areas and invaded areas. The results demonstrate that Lantana camara occurrence in rangelands ecosystems can be mapped with high accuracy. An overall accuracy of 81.29% was attained for 2014, 86.85% for 2016 and 88.69% for 2018. It was further observed that in 2016 Lantana camara occurrence was minimal when compared to 2014, but the results indicate regeneration in 2018 in previously cleared areas. Approximately 40.84% of the area was covered by Lantana camara in 2014, 25.19% in 2016 and 27.02% in 2018. Overall, the findings in this study underscore the need for continuous monitoring of affected areas, especially after clearing, to continuously advise on areas that are at risk for potential re-establishment of invasive weeds.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"239 - 244"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1817812","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43828949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Night Trains: Moving Mozambican Miners to and from South Africa, circa 1902–1955","authors":"R. Christie","doi":"10.1080/0035919x.2020.1812762","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1812762","url":null,"abstract":"Charles van Onselen has written another good book, this time about the inordinate suffering of the people in the sealed migrant labour steam trains that transported Mozambican miners to and from th...","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"308 - 310"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1812762","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46781794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Living Shores – Interacting with southern Africa’s marine ecosystems; Sea Change – Primal Joy and the Art of Underwater Tracking","authors":"C. McGibbon","doi":"10.1080/0035919X.2020.1813216","DOIUrl":"https://doi.org/10.1080/0035919X.2020.1813216","url":null,"abstract":"Hang up your fins and weep: the definitive tomes on the southern African shoreline have been published and it will be hard to surpass these publications of excellence. The book by the Branches, Geo...","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"311 - 312"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919X.2020.1813216","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43446823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On elementary complex variable theory applied to sinc and related integrals**","authors":"J. Hey","doi":"10.1080/0035919x.2020.1804481","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1804481","url":null,"abstract":"An elementary application of complex variable theory demonstrates that some properties of sinc and related integrals, which have been variously described as “tricky,” “intriguing” and “deluding intuition,” arise as simple consequences of Jordan’s lemma. This approach, in offering an interesting alternative to the established treatment based upon Fourier transform theory, may thus be recommended in addition for its pedagogic value. The present treatment extends the earlier results significantly in applications to both divergent and convergent sequences, by introducing the useful concepts of “turning points” and “ranks” of the various contributions to summations over complex path integrals. Finally, a result stated as a student problem in the well-known treatise of Whittaker and Watson (1927) is similarly extended in its application to sequences of both types.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"295 - 306"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1804481","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48795289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Activity concentration of natural radionuclides in sediments of Bree, Klein-Brak, Bakens, and uMngeni rivers and their associated radiation hazard indices","authors":"A. O. Ilori, N. Chetty, B. Adeleye","doi":"10.1080/0035919X.2020.1815894","DOIUrl":"https://doi.org/10.1080/0035919X.2020.1815894","url":null,"abstract":"A hyper-pure germanium (HPGe) detector was used to measure the activity concentrations in sediment samples of rivers in South Africa, and the associated radiological hazard indices were evaluated. The results of the study indicated that the mean activity concentrations of 226Ra, 232Th and 40K in the sediment samples from the oil-rich areas are 11.13, 7.57, 22.5 ; 5.51, 4.62, 125.02 and 7.60, 5.32, 24.12 for the Bree, Klein-Brak and Bakens Rivers, respectively. In contrast, the control site (UMngeni River) values were 4.13, 3.28, and 13.04 for 226Ra, 232Th, and 40K. The average excess lifetime cancer risks are 0.394 × , 0.393 × , 0.277 × and 0.163 × for sediment samples at Bree, Klein-Brak, Bakens, and uMngeni rivers. All obtained values indicated a significant difference between the natural radionuclide concentrations in the samples from the rivers in oil-rich areas compared to those of the non-oil-rich area. The values reported for the activity concentrations and radiological hazard indices were below the average world values; hence, the risk of radiation health hazard was negligible in all study areas.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"258 - 265"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919X.2020.1815894","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44101361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterisation and issues with the use of a conductivity meter to monitor the level of liquid in a cane diffuser bed","authors":"D. S. Segura Angel, R. F. Fonseca","doi":"10.1080/0035919x.2020.1801534","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1801534","url":null,"abstract":"The extraction of sucrose in a cane diffuser depends mainly on the percolation rate, and its optimisation requires the monitoring and control of the liquid holdup with the cane bed. However, most conventional methods that measure liquid levels are not suitable for this application. Operators control the observed liquid level through diffusers’ sight glasses, adjusting the spray position according to visual inspections. The method is inefficient, and a more accurate and reliable measurement process should be implemented towards maximising the sucrose extraction. This article proposes a novel methodology that uses conductance measurements as indicators of the liquid level in cane beds. Conductance, observed liquid level and flow rate variations were analysed under several conditions, such as steady and unsteady states. The effects of the main variables on the observed liquid level and their mathematical relationship were assessed for the validation of the measurements, and experimental tests were conducted on a BMA cane diffuser at Maidstone factory in South Africa. The results are reproducible and show conductance can qualitatively characterise a flooded cane bed.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"282 - 294"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1801534","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46147703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dominant wetland vegetation species discrimination and quantification using in situ hyperspectral data","authors":"Mafuratidze Pride, Muumbe Tasiyiwa Priscilla, T. Gara","doi":"10.1080/0035919x.2020.1798301","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1798301","url":null,"abstract":"Wetland vegetation is an important bio-indicator of wetland physical or chemical degradation. Wetland vegetation continually faces threats from natural disturbance and unsustainable human activities. Traditionally, routine field observations are used to monitor wetlands. However, these methods are expensive and require a lot of human resources, as destructive sampling is required. Remote sensing offers non-destructive and real-time information useful for sustainable and effective management of wetland vegetation. The aim of this study was to explore the potential of hyperspectral remote sensing for wetland vegetation discrimination at the species level. In particular, the study focuses on enhancing or improving class separability among wetland vegetation species using hyperspectral data. In situ hyperspectral measurements were conducted on four dominant grass species in a wetland in Harare. One-way analysis of variance demonstrated significant statistical differences between hydrophytic vegetation species. Vegetation indices performed better compared to red-edge algorithms at discriminating wetland vegetation, with overall accuracy of 82% and 60%, respectively.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"229 - 238"},"PeriodicalIF":0.0,"publicationDate":"2020-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1798301","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43292653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fault Lines: A Primer on Race, Science and Society","authors":"S. Dubow","doi":"10.1080/0035919x.2020.1789239","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1789239","url":null,"abstract":"This excellent scholarly intervention is misleadingly subtitled a “primer”. While it does introduce readers to key conceptual and analytical problems around “race” (Does it exist? Is it meaningful?...","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"307 - 307"},"PeriodicalIF":0.0,"publicationDate":"2020-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1789239","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43758678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing spatiotemporal settlement patterns in Eastern Free State, South Africa, pre and post transition from apartheid to majority rule","authors":"Titilope F. Onaolapo, Tom W. Okello, S. Adelabu","doi":"10.1080/0035919x.2020.1755743","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1755743","url":null,"abstract":"Spatial patterns of human settlements, their changes and their geographical implications are important for understanding the drivers of land use and land cover change. This paper examines the spatiotemporal pattern of settlement development in three different settlements of Thabo Mofutsanyane municipal district namely Harrismith, Vrede and Ladybrand using GIS, remote sensing and spatial metrics techniques. The study is based on 30 years of time-series data compiled from satellite images with emphasis on pre and post 1994’s (the year of change in government from apartheid to majority rule) spatial change in settlement development. Landsat 4–5 imageries for 1989, 1999, 2009 and Landsat 8 OLI for 2018 were downloaded and classified for land use/land cover change (LULCC). Also, landscape and class metrics were computed using Fragstats QGIS 2.18.9 to generate spatial analysis. A dynamic spatial pattern is observed in the settlements under study. Urban built-up areas had a rapid trend of growth in Harrismith from 1989 (5 years before transition from apartheid to majority rule) to 1999 (5 years after transition from apartheid to majority rule) but later slowed down in the subsequent years under study while Ladybrand and Vrede had moderate growth trend in the subsequent years under study. The settlement development process has developed fragmented and heterogeneous land use combinations in the years after 1994. At landscape level, land fragmentation occurred due to land use changes and significant urban expansion; Ladybrand experienced more physical connectedness than Harrismith and Vrede. While at class level, Harrismith and Vrede are more aggregated or physically connected than Ladybrand; this means Ladybrand was relatively more fragmented than the other two settlements. The study results show that a LULCC and landscape metrics integrated approach is effective to analyse and describe the spatial patterns of urban landscapes.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"140 - 158"},"PeriodicalIF":0.0,"publicationDate":"2020-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1755743","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45392741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Farmers’ perceptions of climate change and their adaptation strategies: The case of Ngamiland East, Botswana","authors":"Amogelang Sekelemani, P. K. Mogomotsi, L. S. Stone, G. Mogomotsi, Oarabile Lekhane","doi":"10.1080/0035919x.2020.1748749","DOIUrl":"https://doi.org/10.1080/0035919x.2020.1748749","url":null,"abstract":"Over the years, climate change and variability have led to a substantial decline in agricultural productivity in both developing and developed countries. Small-scale farmers are particularly at risk. The responses of farmers to climate change and variability are often dependent on their perceptions of climate change. Therefore, it is important to understand the nature of adaptation strategies that are feasible and practised at farm level. Despite this need, in some developing countries such as Botswana, there is a dearth of studies that use mixed research methods to critically analyse farmers’ perceptions of climate change and their adaptation strategies. This study uses empirical data collected from farming households in the Ngamiland East region of Botswana to (i) analyse the perceptions of small-scale farmers regarding climate change, (ii) analyse small-scale farmers’ adaptation strategies to climate change, and (iii) determine constraints faced by farmers in adapting to climate change and variability. The results show that there is a direct relationship between the farmers’ adaptation strategies and education. Unlike findings from other studies, the results of the study show that there is no significant relationship between gender and farmers’ adaptation strategies. The results verify that there is high heterogeneity characterising the case studies, making adaptation studies case-specific. Farmers in the Ngamiland region are faced with several challenges in their attempt to adapt to climate change. Chief among the constraints is the lack of financial resources and lack of appropriate skills. The government should empower the farmers through provision of subsidies and skills training.","PeriodicalId":23255,"journal":{"name":"Transactions of The Royal Society of South Africa","volume":"75 1","pages":"213 - 221"},"PeriodicalIF":0.0,"publicationDate":"2020-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0035919x.2020.1748749","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47501081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}