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Spear D.,Stellenbosch University | Foxcroft L.C.,Center for Invasion Biology and Conservation Services | Bezuidenhout H.,Scientific Services | Bezuidenhout H.,Applied Behavioural Ecology and Ecosystem Research Unit | And 2 more authors.
Biological Conservation | Year: 2013

Understanding the drivers of biological invasions, across taxa and regions, is important for designing appropriate management interventions. However there has been no work that has examined potential drivers of both plant and animal invasions, for both species considered to be aliens and those that are invasive. We use South Africa's national park system (19 national parks, throughout South Africa and covering ∼39,000km2) as a model to test the generality of predictors of alien species richness in protected areas. We also compare the predictors of alien versus invasive species richness, and alien plant versus alien animal species richness. Species were classified as alien, invasive (having known negative impact on biodiversity) or extralimital, using standard definitions. Potential predictors (numbers of years since the park was proclaimed and since new land was acquired, park area, data availability, human population density in the vicinity of the park, number of roads, number of rivers, indigenous plant species richness and normalised difference vegetation index) of the number of alien and invasive species in national parks were examined for plants and animals using generalised linear models. Human population density surrounding parks was a significant and strong predictor of numbers of alien and invasive species across plants and animals. The role of other predictors, such as NDVI and park age, was inconsistent across models. Human population density has emerged here as an important predictor of alien species richness in protected areas across taxa, providing a basis for guidelines on where to focus surveillance and eradication efforts. © 2012 Elsevier Ltd. Source


Price T.,German Primate Center | Price T.,University of Gottingen | Price T.,Applied Behavioural Ecology and Ecosystem Research Unit | Ndiaye O.,Direction de Parc National de Niokolo Koba | And 3 more authors.
Behavioral Ecology and Sociobiology | Year: 2014

The global diversity of human languages is a remarkable feature of our species, which requires a capacity for rapid vocal learning. Given that primate alarm calling systems have played an important role in the language origin debate, identifying geographic variation in primate alarm calls and understanding the underlying causal mechanisms are important steps to help uncover evolutionary precursors to language. This study investigates geographic variation in the alarm bark of the widely distributed African green monkey (Chlorocebus). To quantify geographic variation in spectral and temporal call structure, acoustic analysis was used to compare the adult male barks of green monkeys (Chlorocebus sabaeus) and two subspecies of vervet (Chlorocebus pygerythrus pygerythrus and Chlorocebus pygerythrus hilgerti). Playback experiments were also carried out to test whether adult male vervets would distinguish between the barks of own-group males, unknown conspecific males and green monkey males. Acoustic analysis showed that, whilst similar in overall structure, the barks of green monkeys could be distinguished from vervet barks with a high degree of accuracy; the barks of vervet subspecies could also be discriminated, although to a lesser degree. Males responded most strongly to unknown conspecific males' barks, and exhibited responses typical of leopard-avoidance and territorial defence. Taken together, these findings indicate that variation in alarm calls can be best explained by phylogenetic distance, and that intra- and inter-species differences are relevant during social interactions. Moreover, barks may function as an alarm and display call, which could explain the observed sexual dimorphism in barks in this genus. © 2014 The Author(s). Source


Karssing R.J.,Ezemvelo KZN Wildlife | Rivers-Moore N.A.,Consulting Freshwater Ecologist | Slater K.,Applied Behavioural Ecology and Ecosystem Research Unit
African Journal of Aquatic Science | Year: 2012

Current literature suggests that little, if any, research has been conducted in South Africa to determine the impact of alien trout on indigenous amphibian biodiversity. The aim of this study was to establish whether waterfalls in the uKhahlamba Drakensberg Park, South Africa, are seasonally important in conserving indigenous Natal cascade frog Hadromophryne natalensis tadpole populations from the threat of predation by alien rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta at Injesuthi and Monk's Cowl Nature Reserves, respectively. Relative abundances of trout and tadpoles of Natal cascade frogs were assessed after sampling using electrofishing. Habitat templates were compared for above- versus below-waterfall sites. Trout predation is the most likely causative agent for an observed abrupt decline in H. natalensis tadpole abundance occurring below waterfalls. Tadpole abundance in the study was reduced by a factor of 4.69 and 15.71 below the selected waterfalls at Injesuthi and Monk's Cowl in association with O. mykiss and S. trutta populations, respectively. © 2012 Copyright NISC (Pty) Ltd. Source


Van der Merwe H.,South African Environmental Observation Network | Van der Merwe H.,University of Cape Town | Bezuidenhout H.,South African National Parks | Bezuidenhout H.,Applied Behavioural Ecology and Ecosystem Research Unit | Bradshaw P.L.,Nelson Mandela Metropolitan University
South African Journal of Botany | Year: 2015

Effective management of conservation areas is critical to ensure the adequate protection of the natural resources. The landscape unit concept can be used as a tool in conservation management as a spatial planning unit. Landscape units are areas with a specific set of biotic and abiotic characteristics that can be classified, mapped and described. These units then form the basis on which a conservation area can be planned and managed.A vegetation map was compiled for Tankwa Karoo National Park (TKNP), when it was originally proclaimed at 27,064. ha. The park has subsequently expanded to more than 145,000. ha and is still growing. A need has been identified by park management as well as scientists working in the park for an effective framework for managing the park, and for conducting scientific research. The latest vegetation map of South Africa is at too coarse a scale for park planning. The purpose of the current study was to classify, map and describe the current extent of the TKNP to fulfill this need.Two primary zones were identified for the park: the Tanqua Plains Zone and the Roggeveld Mountain Zone. These two zones were further subdivided into landscape units using land type units and a combination of field work and satellite imagery. Futhermore, the landscape units were related to habitats and/or vegetation types as identified during previous studies in the area. Environmental parameters for each landscape unit were summarised in order to provide additional information for consideration in management and research decisions. Thirteen landscape units were identified in the current TKNP and are mapped and described.Delineation of the TKNP into landscape units will aid in the effective conservation management of this large national park as well as facilitate scientifc research and monitoring. © 2015 South African Association of Botanists. Source


Steyn H.M.,South African National Botanical Institute | Bester S.P.,South African National Botanical Institute | Bester S.P.,North West University South Africa | Bezuidenhout H.,Scientific Services | Bezuidenhout H.,Applied Behavioural Ecology and Ecosystem Research Unit
South African Journal of Botany | Year: 2013

An updated checklist is provided for the flora of Tankwa Karoo National Park, which occupies an area of 143,600. ha. A total of 730 species and 780 plant taxa (species, subspecies and varieties), representing 267 genera in 73 families, are recorded for the park. This comprises 30 bryophytes, 7 pteridophytes, 189 monocotyledons and 554 dicotyledons. Sixteen species are endemic or near-endemic to the Hantam-Tanqua-Roggeveld subregion. Twenty-eight species are of conservation concern and six species have been declared as alien invasives. © 2013 South African Association of Botanists. Source

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