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Xylem as well as phloem sustains severe damage due to feeding by the Russian wheat aphid

- Saheed, S A, Liu, Lin, Jonsson, L M V, Botha, Christiaan E J

Authors: Saheed, S A , Liu, Lin , Jonsson, L M V , Botha, Christiaan E J
Date: 2007
Language: English
Type: Article
Identifier: vital:6541 , http://hdl.handle.net/10962/d1005983
Description: Investigation of comparative effects of feeding damage by the Russian wheat aphid (RWA, biotype SA1, Diuraphis noxia Mordvilko) on leaf blades of susceptible and resistant wheat cultivars (Triticum aestivum L. var Betta and Betta-Dn1 respectively) were carried out to establish the level of ultrastructural damage caused by this aphid and the possible limitation of damage induced which could be ascribed to the resistance gene Dn1 over the susceptible cultivar. Ultrastructurally, Betta-Dn1 sustained less damage to the vascular tissue as well as to the mesophyll during the experimental period. Both inter- and intracellular probes resulted in considerable saliva deposition as the aphids probed for suitable feeding sites. Salivary tracks were observed between and within mesophyll, bundle sheath cells as well as the vascular tissue, including the xylem. Disruption of organelles and cytoplasm resulted from cell probing and sheath deposition. Cell and organelle damage was more evident in the non-resistant Betta cultivar. The aphids probed for and fed from thin-walled sieve tubes preferentially. Few thick-walled sieve tubes showed evidence of either aphid probing or feeding-related damage. Saliva was deposited when the aphids probed inter- and intracellularly for feeding sites. The aphids appeared preferentially to probe for and feed from thin-walled sieve tubes, as few thick-walled sieve tubes showed evidence of damage. Vessels, apparently probed for water, contained watery saliva that encased the secondary walls and sealed pit membranes between probed vessels and xylem parenchyma. The xylem probed by the RWA was rendered non-functional, probably contributing to symptoms of leaf roll, chlorosis and necrosis, which were observed within two weeks of infestation in the susceptible Betta cultivar. This damage was limited in the resistant Betta-Dn1 cultivar during the same time frame.
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Date Issued: 2007

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An analysis of the influence of question design on learners' approaches to number pattern generalisation tasks:

- Samson, Duncan, Schäfer, Marc

Authors: Samson, Duncan , Schäfer, Marc
Date: 2007
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/141026 , vital:37938 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC20890
Description: This paper reports on a study of the extent to which question design affects the solution strategies adopted by children when solving linear number pattern generalisation tasks presented in pictorial and numeric contexts. The research tool comprised a series of 22 pencil-and-paper exercises based on linear generalisation tasks set in both numeric and two-dimensional pictorial contexts. The responses to these linear generalisation questions were classified by means of stage descriptors as well as stage modifiers. The method or strategy adopted was analysed and classified into one of seven categories. In addition, a meta-analysis focused on the formula derived for the nth term in conjunction with its justification. The results of this study strongly support the notion that question design can play a critical role in influencing learners' choice of strategy and level of attainment when solving pattern generalisation tasks. An understanding of the importance of appropriate question design has direct pedagogical application within the context of the mathematics classroom.
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Date Issued: 2007

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Application of satellite-derived rainfall estimates to extend water resource simulation modelling in South Africa

- Sawunyama, Tendai, Hughes, Denis A

Authors: Sawunyama, Tendai , Hughes, Denis A
Date: 2008
Language: English
Type: text , Article
Identifier: vital:7089 , http://hdl.handle.net/10962/d1012419
Description: Spatially interpolated rainfall estimates from rain-gauges are widely used as input to hydrological models, but deriving accurate estimates at appropriate space and time scales remain a major problem. In South Africa there has been a gradual decrease in the number of active rain-gauges over time. Satellite-based estimates of spatial rainfall are becoming more readily available and offer a viable substitute. The paper presents the potential of using Climate Prediction Center African daily precipitation climatology (CPCAPC) satellite-based datasets (2001-2006) to drive a Pitman hydrological model which has been calibrated using gauge-based rainfall data (1920-1990). However, if two sources of rainfall data are to be used together, it is necessary to ensure that they are compatible in terms of their statistical properties. A non-linear frequency of exceedance transformation technique was used to correct the satellite data to be more consistent with historical spatial rainfall estimates. The technique generated simulation results for the 2001 to 2006 period that were greatly improved compared to the direct use of the untransformed satellite data. While there remain some further questions about the use of satellite-derived rainfall data in different parts of the country, they do seem to have the potential to contribute to extending water resource modelling into the future.
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Date Issued: 2008

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Do indigenous street trees promote more biodiversity than alien ones? evidence using mistletoes and birds in South Africa

- Shackleton, Charlie M

Authors: Shackleton, Charlie M
Date: 2016
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/64663 , vital:28587 , http://www.doi:10.3390/f7070134
Description: Trees in urban landscapes provide a range of ecosystem services, including habitat, refugia,food, and corridors for other fauna and flora. However, there is some debate whether the richness and abundance of other biodiversity supported is influenced by the provenance of trees, i.e., native or non-native. This study assessed the presence of mistletoes and birds (and nests) in 1261 street trees. There were marked differences between native and non-native street trees, with the former having a significantly higher prevalence of birds (and nests) and supporting more species and in greater densities, whilst the latter supported a higher prevalence of mistletoes. Additionally, for birds, the proximity to green space, tree size and species were also important, whilst for mistletoes, the proximity to green space, slope aspect, and tree species were significant. Preference ratios indicated that some tree species had a higher than random occurrence of birds or mistletoes, whilst others had a low abundance. The indigenous tree species, Acacia karroo Hayne was the only reasonably abundant street tree species that was important for birds, nests, and mistletoes. At the street scale, there was a positive relationship between street tree species richness and bird species richness. These results emphasise the importance of selecting appropriate tree species if biodiversity conservation is a core outcome.
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Date Issued: 2016

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Do indigenous street trees promote more biodiversity than alien ones? Evidence using mistletoes and birds in South Africa

- Shackleton, Charlie M

Authors: Shackleton, Charlie M
Date: 2016
Language: English
Type: article , text
Identifier: http://hdl.handle.net/10962/60942 , vital:27895 , doi:10.3390/f7070134
Description: Trees in urban landscapes provide a range of ecosystem services, including habitat, refugia, food, and corridors for other fauna and flora. However, there is some debate whether the richness and abundance of other biodiversity supported is influenced by the provenance of trees, i.e., native or non-native. This study assessed the presence of mistletoes and birds (and nests) in 1261 street trees. There were marked differences between native and non-native street trees, with the former having a significantly higher prevalence of birds (and nests) and supporting more species and in greater densities, whilst the latter supported a higher prevalence of mistletoes. Additionally, for birds, the proximity to green space, tree size and species were also important, whilst for mistletoes, the proximity to green space, slope aspect, and tree species were significant. Preference ratios indicated that some tree species had a higher than random occurrence of birds or mistletoes, whilst others had a low abundance. The indigenous tree species, Acacia karroo Hayne was the only reasonably abundant street tree species that was important for birds, nests, and mistletoes. At the street scale, there was a positive relationship between street tree species richness and bird species richness. These results emphasise the importance of selecting appropriate tree species if biodiversity conservation is a core outcome.
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Date Issued: 2016

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Re-examining local and market-orientated use of wild species for the conservation of biodiversity

- Shackleton, Charlie M

Authors: Shackleton, Charlie M
Date: 2001
Language: English
Type: Article
Identifier: vital:6655 , http://hdl.handle.net/10962/d1007071
Description: The hypothesis of attaching and realising market values as one means of conserving biodiversity has gained ground over the last decade. This has been challenged recently after examination of a number of case studies, largely from tropical Amazonia, on high value logging, marketing of non-timber forest products, and bioprospecting. The conclusion was that market-orientated conservation has seldom generated the financial returns envisaged, and as such cannot be used as an incentive to prevent land transformation. This paper reviews the basis of the challenge to market-orientated conservation on a number of grounds, drawing on examples largely from southern Africa. It concludes that generalizations from tropical Amazonia regarding the failure of market-orientated conservation are probably premature, and that it should remain an option, amongst a number of options, for conservation of biodiversity. Additionally, the prerequisite criteria identified as necessary to create an enabling framework for the success of market-orientated conservation are insufficient. Case studies are presented where the prerequisites do not apply, yet current extraction for market purposes is sustainable. Other potential prerequisites are also considered. There is a need for multivariate analysis, based on a large sample size drawn from across a range of environments and resources, of which factors are important prerequisites for successful market-orientated conservation, and under which circumstances.
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Date Issued: 2001

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Observations of the habitats and biodiversity of the submarine canyons at Sodwana Bay

- Sink, K J, Boshoff, W, Samaai, Toufiek, Timm, P G, Kerwath, S E

Authors: Sink, K J , Boshoff, W , Samaai, Toufiek , Timm, P G , Kerwath, S E
Date: 2006
Language: English
Type: Article
Identifier: vital:6771 , http://hdl.handle.net/10962/d1008065
Description: The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them.
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Date Issued: 2006

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In vivo/in vitro assessments of topical hydrocortisone availability: correlation between blanching assay and laboratory cell experiments

- Smith, Eric W, Haigh, John M

Authors: Smith, Eric W , Haigh, John M
Date: 1995
Language: English
Type: Book chapter
Identifier: vital:6438 , http://hdl.handle.net/10962/d1006624
Description: From introduction: Topical corticosteroids are still the most widely used drugs in the treatment of dermatological conditions. Early corticosteroid dosage forms consisted of simple creams or ointments where more emphasis was placed on the potency of the drug molecule than on the intrinsic delivery potential of the vehicle. More recently, the effect that the composition of the semisolid base has on the extent of drug delivery has been researched to a much greater extent. These advances in the science of dosage form design have necessitated the refinement of precise and accurate methods for testing the drug delivery efficacies of the developed products. Obviously, the best method for the assessment of the effectiveness of corticosteroid formulations is in a therapeutic situation. Clinical trials, however, are fraught with methodological problems that make duplication of a trial impossible. Alternatively, a number of pharmacological models4 exist for this type of assessment, but it is often problematic to obtain correlation with the true dermatological conditions. The human skin blanching assay is one of the most reliable and reproducible of the ill vivo methods available for the assessment of topical corticosteroid formulations. The skin whitening (blanching or vasoconstriction) side-effect that follows corticosteroid application was first utilized in 1962 as a measure of the percutaneous absorption of corticosteroids from topical formulations. Optimization of this initial procedure7.s has produced a reliable and precise bioassay methodology for the assessment of the efficacy of topical corticosteroid formulations. One criticism of this assay has been the subjective nature of the observation procedure. Although these points have repeatedly been addressed in the literature, it has been suggested that it would be beneficial to have some ill vitro penetration data to supplement ill vivo observations, as this would strengthen the assessment of the topical equivalence of similar delivery formulations. With this objective in mind, a comparison of hydrocortisone release from two proprietary cream formulations was compared by in vivo and ill vitro techniques to determine if any correlation could be established between the methodologies.
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Date Issued: 1995

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Impacts of gum-resin harvest and Lantana camara invasion on the population structure and dynamics of Boswellia serrata in the Western Ghats, India

- Soumya, Kori V, Shackleton, Charlie M, Setty, Siddappa R

Authors: Soumya, Kori V , Shackleton, Charlie M , Setty, Siddappa R
Date: 2019
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/177549 , vital:42832 , https://doi.org/10.1016/j.foreco.2019.117618
Description: Assessing the effects of harvesting on the population dynamics of important non-timber forest products (NTFPs) species is important for informing species conservation options, guiding sustainable harvesting practices and offtake and supporting local livelihoods. However, harvesting is rarely the only pressure on NTFP populations, and it is vital that the effects of interactive pressures be considered. This applies to Boswellia serrata, an NTFP tree species which is widely harvested for gum-resin used in religious practices. However, in many settings populations are in decline, presumably due to heavy harvesting, but other factors may play a role, such as altered fire regimes and invasive species. Here we report on the effects of harvesting and invasion by Lantana camara on B. serrata populations in three protected areas in the Western Ghats biodiversity hotspot in southern India. We considered tree and juvenile density, size class distribution, and growth, mortality, and recruitment rates in harvested and unharvested populations over two years.
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Date Issued: 2019

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Ilam's Archival Revitalisation: the past five years at the International Library of African Music

- Still-Drewett, F

Authors: Still-Drewett, F
Date: 2011
Language: English
Type: Article
Identifier: vital:6983 , http://hdl.handle.net/10962/d1006719
Description: The International Library for African Music (ILAM) was begun in 1954 by ethnomusicologist Hugh Tracey (1903–1977). Since 2007, an active set of projects in preservation and digitisation of both sound and photographic archives have meant that this highly important archive of traditional African music has been stabilized and conserved. New outreach education projects are helping distribute the wealth of the collection back to the African people. ILAM now has a more secure future and makes seminal contributions in the fields of research, publication and education for African music. French Abstract La Bibliothèque Internationale pour la Musique Africaine (ILAM) a été établie en 1954 par l’ethnomusicologue Hugh Tracey (1903–1977). Depuis 2007, un ensemble de projets actifs dans la préservation et la numérisation des archives sonores et photographiques, a eu comme résultat que ces archives très importantes de la musique traditionnelle africaine ont été stabilisées et conservées. De nouveaux projets d’éducation et de sensibilisation aident à distribuer la richesse de cette collection à la population africaine. ILAM a maintenant un avenir plus sûr et apporte une contribution fondamentale dans les domaines de la recherche, la publication et l’enseignement de la musique africaine. German Abstract Die International Library for African Music (ILAM) wurde im Jahr 1954 durch den Musi kethnolo - gen Hugh Tracey (1903–1977) gegründet. Seit 2007 laufende Projekte zur Bestandssicherung und Digitalisierung des Schall- und Fotoarchivs helfen, dieses überaus wichtige Archiv für traditionelle afrikanische Musik zu erhalten und in seiner Existenz zu stabilisieren. Neue, nach außen wirkende Bildungsprojekte tragen dazu bei, den Reichtum der Sammlung an die afrikanische Bevölkerung zurückzugeben. Durch seine nun gesicherte Zukunft kann ILAM für die afrikanische Musik grundlegende Beiträge in Forschung, Veröffentlichung und Bildung leisten. Afrikaans Abstract Die International Library of African Music (ILAM) is in 1954 deur die etnomusikoloog, Hugh Tracey (1903–1977), gestig. Aktiewe preserverings- en digitaliseringsprojekte van beide klank- en foto-argiewe sedert 2007, het tot gevolg gehad dat hierdie hoogs belangrike argief van tradisionele Afrikamusiek gestabiliseer en bewaar kon word. Nuwe ontwikkelings-uitreikprojekte dra daartoe by dat die rykdom van hierdie versameling teruggeploeg word aan Afrika. ILAM het tans ‘n meer versekerde toekoms en lewer invloedryke bydraes op die gebied van navorsing, publikasie en opleiding in Afrikamusiek. IsiXhosa Abstract Ithala lehlabathi lomculo wase-Afrika, i- International Library for African Music (ILAM) laqalwa ngo- 1954 yingcali yomculo weentlanga ngeentlanga, uHugh Tracey (1903–1977). Ukususela ngo-2007 umsebenzi wokulondoloza nokugcina ngekhompyutha isandi seengoma kwakunye neefoto uthetha ukuba le mbali ibalulekileyo kumculo we-Afrika wemveli iqiniselwe kwaye igcinwe ngononophelo. Iiprojekti ezintsha zokolulela isandla kwabanye abantu ziyanceda ekusasazeni le ndyebo kwabo bantu isuka kubo, ama-Afrika. Ngoku i-ILAM inekamva elingagunqgiyo kwaye inegalelo elibonakalayo kuphando, upapasho nemfundo ngomculo wase-Afrika.
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Date Issued: 2011

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South African music libraries : collegial, institutional and geographic isolation, an examination

- Still-Drewett, F

Authors: Still-Drewett, F
Date: 2009
Language: English
Type: Article
Identifier: vital:6984 , http://hdl.handle.net/10962/d1006723
Description: Music libraries are relatively recent additions to South African library collections and attempts at forming a music library association have been thwarted through a number of financial and historical societal limitations. Consequently, many South African music librarians feel isolated from the field. This paper examines the effects of this isolation and the benefits that closer association for the librarian could bring. Future outlooks for music libraries in South Africa are discussed and suggestions made for a more positive future. Les bibliothèques de musique sont des additions relativement récentes aux collections des bibliothèques en Afrique du sud. Les tentatives de création d'une aßociation de bibliothécaires de musique ont été contrariées pour des raisons financières, historiques et sociales. Par conséquent, beaucoup de bibliothécaires de musique se sentent isolés du milieu. Cet article examine les effets de cette isolation et les bénéfices que pourrait apporter une aßociation qui rapproche les bibliothécaires. Il aborde des discußions sur des perspectives futures et émet des suggestion afin d'appréhender un avenir plus positif. Musikbibliotheken sind eine relativ neue Erscheinung im Bibliothekswesen Südafrikas. Die Gründung einer musikbibliothekarischen Vereinigung ist aus finanziellen und anderen Gründen heraus immer wieder gescheitert. Daher fühlen sich viele südafrikanische Musikbibliothekare beruflich isoliert. Der Artikel untersucht die Auswirkungen dieser Isolation und die Vorteile, die ein engerer Zusammenschluß den Bibliothekaren bringen könnte. Er wagt einen Ausblick in und macht Vorschläge für die Zukunft südafrikanischer Musikbibliotheken.
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Date Issued: 2009

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Local government and coloured residential segregation in Port Elizabeth, 1964-1976

- Taylor, Beverley J

Authors: Taylor, Beverley J
Date: 1994
Language: English
Type: text , article
Identifier: vital:7108 , https://doi.org/10.1080/03736245.1994.9713566 , http://hdl.handle.net/10962/d1010736
Description: preprint , Studies of racial territorial segregation affecting the coloured population in Port Elizabeth tend to perceive it as an outcome of a power struggle between central and local government over the implementation of apartheid legislation. This paper explores the underlying economic forces on the local government to bring about residential segregation and address the coloured housing crisis in the city. It is proposed that whereas central government motives for segregation were primarily political, local government was influenced largely by economic considerations. Local government objectives were severely compromised through both local industrial interests and the implementation of central government Group Areas policies.
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Date Issued: 1994

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Phylogeographic structure of Octopus vulgaris in South Africa revisited: identification of a second lineage near Durban harbour

- Teske, P R, Oosthuizen, A, Papadopoulos, I, Barker, Nigel P

Authors: Teske, P R , Oosthuizen, A , Papadopoulos, I , Barker, Nigel P
Date: 2007
Language: English
Type: text , article
Identifier: vital:6951 , http://hdl.handle.net/10962/d1013236 , http://dx.doi.org/10.1007/s00227-007-0644-x
Description: preprint , In a previous study that investigated genetic structure of Octopus vulgaris along the South African coast by sequencing the mitochondrial cytochrome oxidase III gene (COIII), all sequences generated were identical. Such a finding is unusual, because mitochondrial DNA mutates quickly, and several marine invertebrates present in southern Africa show considerable genetic variation and structure. We reanalysed the samples using two different mitochondrial markers, namely cytochrome oxidase I (COI) and the large ribosomal subunit (16S rRNA). Sequences of both these markers showed variation. The conclusion of the previous study, that South Africa’s O. vulgaris population is characterised by a lack of genetic structure along the coast, is rejected. Some specimens from Durban (southeast Africa) were genetically more different from those found in the remainder of the country than were specimens from other regions (Tristan da Cunha and Senegal). We suggest that the lineage in Durban may have been recently introduced.
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Date Issued: 2007

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Local institutions, actors, and natural resource governance in Kgalagadi Transfrontier Park and surrounds, South Africa

- Thondhlana, Gladman, Shackleton, Sheona E, Blignaut, James

Authors: Thondhlana, Gladman , Shackleton, Sheona E , Blignaut, James
Date: 2015
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/67689 , vital:29130 , https://doi.org/10.1016/j.landusepol.2015.03.013
Description: Publisher version , Crafting local institutions to allow more effective decision-making in the management of and access to natural resources in and beyond parks has long been considered key to collaborative governance. South Africa, in particular, has vigorously pursued collaborative governance as a desired approach to managing natural resources as evident in the new arrangements for previously restricted parks. However, though the discourse of collaborative governance has occupied conservation thinking and practice globally, few studies have looked at the interplay between local institutions, actors and collaborative governance involving indigenous hunter–gatherer communities in Southern Africa. In response, we assess the local actors and institutions that were put in place to facilitate collaborative governance of natural resources in the Kgalagadi Transfrontier Park and its surrounds in South Africa. Our findings show that though collaborative governance has a practical appeal, it is hampered by lack of participation in decision-making, information dissemination, transparency, trust and accountability, power relations, divergent interests and unequal access to natural resources. The findings also draw our attention to issues of heterogeneity, even within indigenous communities assumed to be homogenous by local conservation authorities as reflected in land settlement agreements in co-managed parks. We argue that collaborative governance arrangements need to reflect and be understood within the broader background of complex local realities.
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Date Issued: 2015

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Non-material costs of wildlife conservation to local people and their implications for conservation interventions:

- Thondhlana, Gladman, Redpath, Stephen Mark, Vedeld, Pål Olav, van Eden, Lily, Pascual, Unai, Sherren, Kate, Murata, Chenai

Authors: Thondhlana, Gladman , Redpath, Stephen Mark , Vedeld, Pål Olav , van Eden, Lily , Pascual, Unai , Sherren, Kate , Murata, Chenai
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/150174 , vital:38946 , https://doi.org/10.1016/j.biocon.2020.108578
Description: In assessment of costs (and benefits) of wildlife conservation, conventional economic valuation frameworks may inadequately address various non-tangible values and neglect social, cultural and political contexts of resources and their use. Correspondingly, there seems to be much more focus on quantifying the economic, material benefits and costs of wildlife conservation than the non-material aspects that also affect human well-being. In addition, current research on the costs of wildlife conservation tends to be discipline-focused which constrains comparability, often causing conceptual ambiguity. This paper is an attempt to address this ambiguity. While there is growing acknowledgement of the material costs of wildlife conservation, we contend that employing a broader, composite social well-being approach may provide better conceptual insights on—and practical options for—managing various non-material impacts of wildlife conservation for local people.
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Date Issued: 2020

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