Doctoral Degrees (Ecology)

Permanent URI for this collectionhttps://hdl.handle.net/10413/7487

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Foraging specialization of flower visitors in a grassland community: insights from metabarcoding versus traditional methods.
(2024) Streicher, Melanie Bertha.; Johnson, Steven Dene.; Willows-Munro, Sandi.
Ecological networks of plant-pollinator interactions at the community level were traditionally studied using natural history-type direct observations as well as microscope-based palynology. Over the last decade, these methods have been complemented by emerging molecular technologies such as metabarcoding of pollen loads on insects which holds the promise to reveal interactions that would be difficult to observe directly. We compared traditional methods of studying plant-pollinator interactions (observational data, palynology) with metabarcoding data to assess the degree of complementarity of the different approaches and whether the molecularbased approach revealed previously unknown interactions. This was done for a community on Mount Gilboa, KwaZulu-Natal, South Africa. In an initial exploratory study, I demonstrated successful amplification of DNA from fuchsin-fixed pollen which opens the possibility of using this method of pollen barcoding from specific sites on pollinator bodies, including fragile archival specimen. My results showed that networks constructed from metabarcoding data were more complex with a higher resolution of ecological interactions than those obtained using the traditional methods of microscopy of pollen-loads and visitor records. A complete community approach combining both the nocturnal and diurnal components showed a complex network comprising 66 pollinator species and 172 plant species, corresponding to a network with low modularity, high nestedness and high linkage density, and which is likely to be ecologically robust owing to high generality within the network. However, because many of the plants and animals in the community have not yet been barcoded and were not available in the DNA barcode reference library, it was difficult to obtain species-specific names for 72% of the putative plant species and 45% of the putative animal species in these networks. These were assigned to the lowest taxonomic level possible after cross referencing against known occurrence records. Nocturnal pollination networks revealed a 2.5-fold increase in interaction diversity, and 4.5-fold increase in pollinator generality when using metabarcoding data in comparison to conventional microscopy. Hyper diverse countries such as South Africa, however, still require significant resources to build comprehensive reference libraries allowing for sequence data to accurately assign species names. I conclude that the greater resolution and throughput obtained through metabarcoding can increase our understanding of complex ecological interactions and networks.
Assessment of fleshy-fruited invasive alien plants in eastern South African grasslands using community perceptions, seed germination and dispersal, and repeat photography.
(2024) Adams, Lehlohonolo Donald.; Downs, Colleen Thelma.
Invasive fleshy-fruited trees and shrubs have been an increasing problem in many grassland systems over the past few decades because they change vegetation structure and threaten native plant diversity. However, forest ecosystems have received more attention than grasslands because fleshy-fruited plants are relatively dominant in the forest. This study aimed to address gaps in knowledge of fleshy-fruited invasive alien plants in montane grassland ecosystems of South Africa by studying socio-economic and environmental impacts, community perceptions, potential animal seed dispersal and population dynamics over time of dominant fleshy-fruited invasive alien plants. In the grassland biome of South Africa, the dominant fleshy-fruited invasive species come from the Rosaceae family and include Cotoneaster pannosus, Pyracantha angustifolia, and Rosa rubiginosa, which were the focus species for this study. These are widespread and damaging invasive plants within the grassland biome of many other countries, so understanding how each spread may assist in managing the species regionally and internationally. In Chapter 2, I reviewed the research efforts on fleshy-fruited invasive alien plants in grassland ecosystems and mosaics. The systematic review showed seed dispersal was the most studied concept of fleshy-fruited invasive alien plants in grasslands. In Chapter 3, this multifaceted study collated data from communities living within areas invaded by the species on their perceptions of these species through in-person, online and telephonic questionnaires to understand the socio-economic context of invasions and how people contribute to both spread and control. Questionnaire surveys showed that the general public does not regard P. angustifolia as a problem, while landowners and conservationists regard the species as a problem. The community has attempted to use herbicides, fire, and mechanical control, but the population of these invasives is still increasing, and the community has requested clearing assistance from the government. In Chapter 4, the rate of spread was assessed by comparing recent photographs with historical ones. Repeat photography showed that fleshy-fruited invasive alien plants have increased in the grasslands over the past 12 years. In Chapter 5, I also assessed bird potential preference using choice trials. Fruit selection trials revealed significant differences among plant species by various frugivorous birds. In Chapter 6, the collection of excreta and subsequent seedling emergence from mammalian faecal samples assessed the involvement of mammals in the seed dispersal of fleshy-fruited invasive alien plants. Mammalian faeces collection showed medium to large-sized mammals to be effective seed dispersal agents of these invasive plants. The study introduced a novel approach using Google Street View archives to assess vegetation population changes and provide a cost-effective means to study vegetation dynamics and ecosystem responses to environmental change. By identifying factors influencing fruit selection by frugivorous birds and locally occurring terrestrial mammalian species as effective seed dispersers, the research offers insights into the ecological mechanisms driving the spread of these invasive plants. Understanding these dynamics informs targeted intervention strategies for managing invasive plants more effectively, contributing to conservation efforts and biodiversity preservation. This study also highlights the need for further collaborative research to address the multifaceted challenges posed by invasive plant species.
Population assessment and conservation status of African lions (Panthera leo)
(2024) Nicholson, Samantha Karin.; Slotow, Robert Hugh.; Bauer, Hans.; Roxburgh, Lizanne.
For several decades, the lion (Panthera leo) has undergone significant population decline across its range. The aim of this dissertation was to critically assess the current conservation status of Africa’s most iconic carnivore. This included determining methods used to survey them, the conservation status of the global population, how fragile lion subpopulations are, and the perceived threats to the species across their African range. As with most carnivores, several survey methods have been developed to estimate lion population abundance. To assess the current state of lion survey methodologies, I conducted a systematic literature review of peer reviewed scientific publications. The strengths and weaknesses of each method were considered, as well as their reliability and applicability in determining abundance and distribution. Building on from how lions are surveyed, I used current data that are available to assess the current population and distribution of lions to produce the updated IUCN Red List Assessment (RLA). RLAs provide a standardised and comprehensive tool to evaluate the status of species, prioritise conservation efforts, and drive informed decision-making at the global, national, and local levels. Extant lion range was estimated to be ~1,571,296 km² - an estimated 36 % range decline since 2002 (three lion generations). Based on this significant decline in range, which is synonymous with a decline in population size and abundance, a 36 % decline in population numbers for the lions was suspected. Therefore, the species met the requirements for a Vulnerable listing (Red List criteria A2abcd). As effective species conservation is about more than just understanding how many there are, I, in collaboration with other experts in large carnivore conservation, examined the socio-political and ecological fragility (hereafter fragility: defined as a species vulnerability to extinction) of known lion populations. By combining ecological and socio-political metrics, an overall fragility index demonstrated which lion populations were more vulnerable to extinction. The analysis revealed several populations were highly fragile and lion populations in Somalia were the most fragile while those in Botswana are the least. Populations that had the highest fragility included Bush-Bush (Somalia) and Maze National Park (Ethiopia). As the RLA indicated that populations are declining, I sought to determine the severity of the existing anthropogenic threats to lions driving these declines. To do this, I conducted an online questionnaire of experts across lion range. A threat severity index was developed for each subpopulation, and I assessed how this varied between subpopulations and across regions. A resource availability index was also developed to identify lion subpopulations which are not sufficiently resourced (e.g., funding, anti-poaching equipment, vehicles). This allowed me to highlight populations that are perceived as highly threatened and that are under-equipped. I found the total threat index differed significantly among regions, being highest (i.e. most severe) in Central Africa and lowest (i.e. least severe) in southern Africa. Perceived resource availability was highest in Rwanda, Chad and Benin and lowest in six countries including Angola, Burkina Faso, Niger, South Sudan, Sudan and Uganda. This analysis identified how specific threats differ between regions. I offer valuable insights into the species' status and provide innovative recommendations that could enhance the management of lions across their range. This includes conservation interventions that target specific threats while incorporating socio-political and ecological factors which contribute to a population’s fragility. As lions remain listed as Vulnerable, and lion populations continue to decline, I recommend that the regional strategies be updated based on improved data and information available. To ensure that population data gathered and reliable and robust, harmonised survey methods need to be developed and implemented across the species range, especially in areas where survey data are poor or lacking. In a world where we are losing species at an unprecedented rate, effective and targeted conservation is needed, that is guided by the best available data, to ensure that the lion isn’t one of those species that disappears.
Effects of landscape and forest structural characteristics on the avian communities in Southern Mistbelt Forests, Midlands of KwaZulu-Natal, South Africa.
(2023) Bitani, Nasiphi.; Downs, Colleen Thelma.; Ehlers Smith, David Alan.; Ehlers Smith, Yvette Cathrine.
Globally forest ecosystems are under threat from land-use changes threatening biodiversity. Biodiversity conservation in forest systems has become a major concern as these impacts affect ecosystem functioning. Habitat destruction results in highly fragmented forest patches with reduced habitat quality. Therefore, it is essential to assess species' responses to these changes for conservation. Like other parts of the world, South African forests are threatened by destruction, mainly habitat conversion to exotic commercial tree plantations. Forest bird species within this system have been reported to be declining. Considering these impacts, it is important to understand the main drivers at different spatial scales. This study aimed to assess local and landscape drivers of avian communities in the Southern Mistbelt Forests in the Midlands of KwaZulu-Natal, South Africa. The objectives were to assess (1) the local scale drivers and influences on bird species richness, use and functional diversity, (2) microhabitat requirements and occupancy of understorey forest specialist bird species using camera traps, and (3) landscape attributes influencing bird species richness, habitat use and functional groups. Firstly, the influence of forest structure and composition on bird species richness, habitat use and functional diversity in 14 selected Southern Mistbelt Forest patches of KwaZulu-Natal were assessed. The bird species were surveyed using point count surveys. Functional diversity for each surveyed patch was quantified using three indices: functional richness, functional evenness and functional divergence. Species-specific responses were assessed by focusing on three forest specialists, orange ground-thrush Geokichla gurneyi, forest canary Crithagra scotops, and Cape parrot Poicephalus robustus. Bird community and forest bird specialists' responses to forest structure and tree species diversity varied. Forest structural complexity, canopy cover, and tree species richness were the main structural characteristics influencing bird functional diversity. Also, forest composition and structure are important for bird species and functional richness. Secondly, the microhabitat requirements of forest specialist bird species using camera surveys in the selected 14 Southern Mistbelt Forests were assessed. The results showed that the microhabitat requirements of the understorey forest specialist species are specific. Occupancy models showed that forest specialist understorey birds are mainly influenced by tree species richness, understorey cover of leaf litter and water. Lastly, the bird species richness, habitat use and functional groups’responses to selective logging history, livestock grazing and adjacent matrix type were assessed. The bird communities were surveyed using point-counts. Functional diversity was quantified using functional richness, functional divergence and functional evenness estimated using bird functional traits. The disturbance did not affect bird species richness. Forest specialists' responses to disturbance were species-specific depending on the type of disturbance and intensity. The orange ground-thrush and forest canary were affected by livestock grazing, while the Cape parrot was influenced by forest logging history. Functional richness for all functional groups was high in disturbed forests, while functional evenness for forest specialists and insectivores was low in disturbed sites. The results of this study provide insight into the local and landscape drivers of avian species richness and diversity. Forest patches with high tree species diversity and structural complexity should be maintained to conserve forest specialists, bird species richness and functional richness. Also, to maintain the persistence of the understorey forest specialists, forest structures within 5 m of the forest floor should be maintained. It is recommended to use functional diversity indices with taxonomic indices to understand bird species responses to disturbance better.
Anthropogenic impacts on forest mammals in the Southern Mistbelt Forests in the Midlands of KwaZulu-Natal, South Africa.
(2023) Cordier, Craig Paul.; Downs, Colleen Thelma.; Ehlers Smith, David Alan.; Ehlers Smith, Yvette Cathrine.
Habitat loss worldwide is a major threat to biodiversity. Forest loss is affected by numerous factors, including natural climate change and anthropogenic disturbances (e.g., logging, habitat conversion or increased fire activity). Forest fragmentation results in reduced patch sizes, increased edge effects, and connectivity between patches negatively impacted. Forest fragmentation effects on species differ, with some considerably more sensitive to these changes than others, often resulting in their local extinction. By monitoring biodiversity, effective conservation measures can be implemented to conserve the biodiversity in these forests. Remote camera traps have become an increasingly popular tool to study wildlife in a reliable, non-invasive way. Firstly, the use of camera traps as a research tool in Africa using a systematic review was determined. This highlighted the countries with studies that used camera traps the most, as well as determined the terrestrial wildlife and habitat types receiving the most focus. The findings from assessing camera trap research in Africa revealed that most studies were conducted in South Africa, with most studies focusing on the occupancy of mammals, with a particular focus being on large carnivores, the majority of which were leopard Panthera pardus. Most studies were conducted in forests, followed by savannah/bushveld. Secondly, the presence of forest mammalian species was assessed in the Southern Mistbelt forests in the Midlands of KwaZulu-Natal, South Africa. These forests are fragmented because of both natural and anthropogenic factors. An extensive camera trapping survey was conducted between October 2020 and April 2021 (wet season), and between May 2021 and September 2021 (dry season), with 14 indigenous forest patches being sampled. A total of 339 camera trap stations were deployed in this study, with microhabitat conditions, in a 20 m radius around each camera trap, collected to determine their impact on bushbuck Tragelaphus scriptus, a diurnal forest specialist, and Cape porcupine Hystrix africaeaustralis, a nocturnal generalist, and how the microhabitat conditions potentially impacted their occupancy between the austral wet and dry seasons. Bushbuck were the most recorded mammalian species recorded during both seasons. Cape porcupine presence was recorded more during the dry season, with various microhabitat variables influencing their occupancy. Cape porcupines, as generalists, likely use the forest food resources during the dry season. Bushbuck presence was lower in state-owned forests, likely because of the hunting activities observed in these forests. Thirdly, data collected from the camera trapping surveys were used to determine the influence of landscape factors, including patch size, landscape configuration (number of neighbouring patches), and patch isolation (distance from mainland patch), on forest mammalian species diversity in forest patches, between the wet and dry seasons. Patch size strongly influenced forest mammalian species richness, which was relatively low, with more species occupying larger patches than smaller patches. Similarly, landscape configuration affected species richness and was generally higher in those forests surrounded by multiple forest patches. Forest isolation, however, did not seem to be particularly impactful in determining forest mammalian species diversity. Overall, this research showed the value of camera traps as a research tool and their effectiveness in studying rare and elusive mammalian species in Africa. Effects of anthropogenic disturbances on various forest mammalian species were highlighted, with activities such as hunting and uncontrolled resource harvesting, such as collection of fuelwood, medicinal plants and building materials by the local communities, impacting the presence of various forest mammalian species, particularly forest specialist species, such as the blue duiker Philantomba monticola. The importance of maintaining small forest patches, often considered of low conservation value, was highlighted. These act as essential ‘stepping stones’ between forest patches, allowing species to traverse a landscape mosaic. The need for conservation measures not to disregard the importance of these small forest patches is emphasised, as they are vital assets to maintain species richness in landscape mosaics with forest patches.
Effects of biogas slurry on capsicum spp. growth and control of soil-pathogens.
(2022) Wang, Zichen.; Gueguim Kana, Evariste Bosco.; Olaniran, Ademola Olufolahan.; Ye, Xiaomei.
Abstract available in PDF.
Evaluation of lanthanum/iron oxide amended formable biochar for phosphorous and nitrogen removal in wastewater: preparation, mechanism, and application.
(2022) Sun, Enhui.; Hunter, Charles Haig.; Yang, Lingzhang.
Abstract available in PDF.
Aspects of the use of vultures in traditional medicine in KwaZulu-Natal, South Africa, and conservation implications.
(2022) Manqele, Nomthandazo Samantha.; Downs, Colleen Thelma.; Selier, Sarah Anne Jeanneta.
Eighty percent of people in developing countries use traditional medicine either as a primary source of healthcare or as supplementary to western medicine. Traditional medicines are mainly derived from wild plants and animals. There has been a marked global increase in the use of animals and their body parts as ingredients in traditional medicine. The harvesting and use of wildlife resources in traditional medicine are largely unregulated and involve many species of conservation concern. This is true for African vultures, as evidence indicates that traditional medicine is responsible for 29% of African vulture mortalities. Currently, six out of seven vulture species in South Africa face a serious threat of extinction. The threatened species are listed under the Threatened or Protected Species regulations, which prohibit hunting and consumption. However, evidence suggests a long-standing use of vultures in traditional medicine in KwaZulu- Natal, South Africa, yet so much remains unknown about this practice. Understanding the belief system and the socio-economic dispositions underpinning the belief-based use of vultures will favour vulture conservation efforts in the province. Research was undertaken with the aim of advancing the knowledge base regarding the use of vultures in traditional medicine in KwaZulu-Natal. Accordingly, the following objectives were established: 1) to assess human-vulture interactions in a dynamic ecosystem, 2) to evaluate the dynamics behind the illegal harvesting and trade of vultures and their body parts, 3) to investigate the ethnomedicinal use of vultures by traditional health practitioners and 4) report on the efficacy of religion as an alternative for traditional medicine use. The study involved local communities surrounding protected areas and specific groups such as hunters, muthi traders, and traditional healers. A mixed-methodology approach was adopted, and data were collected using questionnaire surveys, in-depth interviews, focus group discussions and observations. A total of 728 respondents contributed to this study. Local people’s perceptions towards vultures were predominantly positive. Respondents appreciated vultures for removing carcases, thus keeping the environment clean. Results also demonstrated that hunting and wildlife consumption were common in the study areas, and that the hunting and use of vultures were a part of this. Vultures were harvested from protected areas and sold directly to traditional healers and also to muthi traders. Vultures were reportedly important in traditional medicine, but their harvesting was limited because it was perceived as a criminal activity, and the birds reportedly occurred in smaller numbers than before. In traditional medicine, seven vulture parts were used, but the head treated the majority (62%) of ailments reported. Seventy-one percent of the uses for vulture-based remedies were spiritual in nature. Religious practices such as church attendance, prayer and fasting, coupled with products like holy water, can provide relief from physical and psychological ailments. In this study, the role of religion in contributing positively to human health and well-being was underscored. Overall, results from this study can be instrumental in guiding efforts to improve vulture conservation in KwaZulu-Natal and other parts of South Africa.
Aspects of the ecology and persistence of vervet monkeys in mosaic urban landscapes in KwaZulu-Natal, South Africa = Izingxenyezici zendawomvelompiliswano kanye nokwanda kwezinkawu zohlobo lwe-vervet ezindaweni zasemadolobheni ezihlukahlukene ngokwezimo zempilo KwaZulu-Natali eNingizimu Afrika.
(2022) Pillay, Kerushka Robyn.; Downs, Colleen Thelma.
The geological era in which we live is termed the Anthropocene and is causing the greatest loss of biodiversity and species brought on by a single species: Homo sapiens. The human population places great demands on the environment, altering and modifying it to suit people’s needs. Urbanisation is one of the greatest anthropogenic land-use modifications, predominantly for infrastructure and housing developments. This results in the loss of natural green spaces where wildlife lives, forcing them into smaller fragmented habitats, often having to share the urban mosaic landscape with humans. These increased interactions often lead to humanwildlife conflict. Generally, urbanisation affects species negatively. However, some species exhibit the ability to persist in urban areas, successfully utilising resources for their natural life traits. One such primate species persisting in urban mosaic landscapes is the vervet monkey, Chlorocebus pygerythrus, particularly in the eThekwini Municipality, Durban, KwaZulu-Natal Province, South Africa. Increased human population growth and associated urban transformation have increased contact between humans and troops of vervet monkeys using residential and industrial gardens. This has led to increased human-wildlife conflict, with vervet monkeys often persecuted because of their damage to human property and harassment. Little is known about the ecology of urban vervet monkeys, so to assess and manage this wildlife conflict, a need to determine the behavioural ecology and persistence of vervet monkeys were investigated in this study. This study analysed vervet monkeys' spatial ecology in the mosaic urban-forest landscape and provided insight into their home ranges and habitat use here. Additionally, the effects of anthropogenic activities and human-wildlife conflict on wild vervet monkeys were documented. The results contribute to understanding the foundation of human-vervet conflict resolution programmes and support for further education and coexistence with wildlife in mosaic urban landscapes. The conservation of vervet monkeys should be supported by all who live in these areas, not by some factions. The presence of primates, such as the vervet monkey, that use managed green spaces, such as gardens, in the eThekwini Municipality should provide the public with the ultimate catalyst and insight into protecting and conserving this species and others for future generations. Overall, the results presented in this thesis provide an understanding of the persistence of this Old World primate in mosaic urban landscapes. Iqoqa Isikhathi esiphila kuso mayelana nesimo sendalo yomhlaba esikuwo saziwa ngele-Anthropocene siyimbangela yokushabalala okusezingeni eliphezulu yokusatshalaliswa kwendawomvelompiliswano kanye nohlobo lwezilwane okubangelwa uhlobo olulodwa: oluyi-Homo sapiens. Izidalwa ezingabantu zinomthelela omkhulu emvelweni ngendlela yokuthi ziguquguqula imvelo ukuze kufezeke izidingo zazo. Ukwakhiwa kwezindawo zasemadolobheni kungenye yezinguquko ezidalwa ngabantu lapho besebenzisa umhlaba ikakhulukazi ukwakha izindawo zokuhlala kanye nezingqalasizinda. Lokhu kuholela ekuthini kuntuleke izindawo okuphila kuzo izilwane zasendle okube sekudala ukuthi lezi zilwane zigcine sezihlala ezindaweni ezimpintshekile zaba zincane. Lokhu kube sekuholela ekuthini zigcine sezibanga indawo nabantu basemadolobheni. Lokhu kwanda kokuhlalisana nabantu kuholela ekushayisaneni phakathi kwabantu kanye nezilwane. Nokho-ke, kunohlobo olukhombisa ukuthi luyakwazi ukuqhubeka nokuphila kahle ezindaweni ezingamadolobha ngokuzizamela kulokho okukhona ukuze luziphilise ngendlela efanele. Uhlobo olukhombise ukuthi luyakwazi ukuqhubeka nokuziphilisa ngaphansi kwesimo sasemadolobheni yilolu lwezinkawu ezaziwa nge-vervet, Chlorocebus pygerythrus,ikakhulukazi endaweni kaMasipala weTheku, eThekwini, esifundazweni saKwaZulu-Natali, eNingizimu Afrika. Ukwanda kwesibalo sabantu kanye nokuguquka kwesimo senhlalo yabantu okuhambisana nakho sekwenze ukuthi kwande nokuhlangana kwabantu nemihlambi yezinkawu ezizitika ezingadini zabantu emakhaya kanye nasezingadini zabalimi abakhulu. Lokhu sekuholele ekushayisaneni phakathi kwabantu kanye nezilwane zasendle okwenza ukuthi izinkawu ezingama-vervet zizithole zisenkingeni ngenxa yokucekela kwazo phansi impahla yabantu kanye nokuba yisicefe esingapheli. Aluluningi ulwazi olukhona mayelana nezinkawu zasemadolobheni ezingama-vervet, ngakho-ke lolu cwaningo lwaphenya mayelana nokuziphatha kwalezi zinkawu ngaphansi kwezimo zendawo eseziguqukile kanye nokwanda kwazo ukuze kuhlolwe kuphinde kulawulwe lokhu kushayisana nezilwane zasendle. Lolu cwaningo lwahlaziya izindawo ezingamahlathi asedolobheni okuhlala kuzo lezi zinkawu ezingama-vervet, lwase lunikeza ulwazi olujulile mayelana nezindawo okuhlala kuzo lezi zinkawu kanye nendlela eziziphilisa ngayo kulezi zindawo. Okunye okwaqoshwa phansi yimithelela yezinto ezenziwa ngabantu kanye nokushayisana phakathi kwabantu kanye nezinkawu ezingama-vervet. Imiphumela yocwaningo yathasisela olwazini olumaqondana nezinhlelo okungakhelwa phezu kwazo ukuxazululwa kokushayisana kwabantu nezinkawu ezingama-vervet, iphinde isekele ukufunda okuqhubekayo mayelana nokuhlalisana nezilwane zasendle ezindaweni ezisakhula zasemadolobheni. Kumele kusekelwe ukongiwa kwezinkawu ezingama-vervet yibo bonke abahlala ezindaweni ezisemadolobheni, kungabi ngabathile kuphela. Ukuba khona kwalolu hlobo lwezilwane ezifana nezinkawu ezingama-vervet ezindaweni ezisetshenziswa nezenganyelwe njengezingadi zomphakathi njengezikaMasipala weTheku kumele kuhlomise amalungu omphakathi ngolwazi nanogqozi lokuvikela kanye nokonga lolu hlobo lwezilwane kanye nezinye izinhlobo ukuze nezizukulwane ezizayo zikwazi ukuzibona ziphila. Ekugcineni kwakho konke imiphumela etholakale kulolu cwaningo iveze ulwazi nokuqonda mayelana nokwanda kwalolu hlobo lwezinkawu ezindaweni ezingamadolobha.
Local and landscape drivers of avian diversity facets in the naturally fragmented Southern Mistbelt forests of KwaZulu-Natal and Eastern Cape, South Africa = Abashayeli bendawo bezinhlobo zezinyoni ezahlukene emahlathini ase-Southern Mistbelt ahlukaniswe ngokwemvelo ezifundazweni zakwa KwaZulu-Natal nase Eastern Cape eNingizimu Afrika.
(2022) Ngcobo, Samukelisiwe Princess.; Downs, Colleen Thelma.
Forest fragmentation is a process whereby a forest landscape is subdivided into smaller and more isolated fragments embedded within a matrix of anthropogenic land-uses. The effects of increasing anthropogenic practices surrounding forest remnants threaten species persistence as habitat fragments become further isolated by the matrix, which impedes species movement and dispersal, causing local extinctions when conditions become more unfavourable. However, naturally fragmented forest systems harbour resilient species, but the novel challenges presently experienced by these species have unknown consequences. Here, I determined to assess local avian diversity facets in selected naturally fragmented Southern Mistbelt forests of KwaZulu-Natal and Eastern Cape provinces, South Africa. I conducted fixed-radius point-count surveys across 32 (range: 0.03 – 732.42 ha) of these Southern Mistbelt Forests. Data collection was conducted during the breeding (October-February) and nonbreeding (May-August) seasons in 2018 and 2019. Firstly, I used a multifaceted approach to assess the effects of landscape composition (i.e., matrix quality), habitat fragmentation (i.e., isolation distance and fragment-size) and local habitat heterogeneity (i.e., forest-structural complexity) on avian alpha-diversity (taxonomic, functional, phylogenetic and functional-phylogenetic diversity) of the whole community, forest-dependent (i.e. forest specialist) and non-forest-dependent (i.e. forest generalist) assemblages. Secondly, I revealed how key landscape features (i.e. habitat amount, matrix heterogeneity and average isolation distance) affected local bird diversity and determined the importance of each landscape variable using linear mixed-effect models (LMEs). Thirdly, I mapped connectivity of core Southern Mistbelt Forest patches provisioning the highest (≥ 50 %) avian phylogenetic diversity by using a hybrid of least-cost pathway and ecological circuit theory approach to identify landscape features that promote or impede habitat connectivity of a surrogate forest-specialised and dispersal-limited species (Lemon dove - Aplopelia larvata) to guide landscape connectivity for avian forest communities in the fragmented forest mosaic landscape. My findings revealed that: A) 1. matrix quality was a significant positive predictor of functional (FRic, sesFRic) and phylogenetic (sesPD) diversity; 2. habitat fragmentation had significantly negative effects (i.e. increasing isolation distance and decreasing fragment size) on multiple diversity facets; and 3. diversity facets of forest-dependent species unexpectedly declined with increasing local vegetation complexity. B) Habitat amount in the landscape was the main significant positive predictor of local forest bird diversity, and there were no significant influences of the average isolation distance and landscape (matrix) heterogeneity on local avian diversity. C) Landscape connectivity of Southern Mistbelt Forest fragments is predominantly promoted by indigenous forest cover and reduced in regions of unsuitable habitat (i.e. exotic timber plantations, grassland, agriculture, and residential land-cover). I concluded that i) positive effects of surrounding matrix quality in the landscape mediates the negative effects of habitat fragmentation on local forest bird ecological groups; ii) promoting local vegetation complexity could contribute to the loss of forest-dependent species (i.e. forest specialists); iii) habitat amount in the surrounding landscape was the predominantly important predictor of local avian diversity and promoted habitat connectivity among core forest patches of fragmented Southern Mistbelt Forest. Therefore, I recommend preserving and increasing forest cover in the landscape to ensure the long-term survival of forest species in this naturally fragmented ecosystem. Iqoqa Ukuhlukaniswa kwehlathi kuyinqubo lapho indawo yehlathi ihlukaniswa khona ibe yizingcezu ezincane nezizimele kakhulu ezishumekwe ngaphakathi kwe-matrix yokusetshenziswa komhlaba kwe-anthropogenic. Imithelela yokwanda kwemikhuba ye-anthropogenic ezungeze izinsalela zehlathi isongela ukuphikelela kwezinhlobo zezilwane njengoba izingcezu zendawo yokuhlala zihlukaniswa ngokwengeziwe yi-matrix, evimbela ukunyakaza kwezinhlobo zezilwane nokuhlakazeka, okubangela ukushabalala kwendawo lapho izimo ziba zimbi nakakhulu. Nokho, izimiso zamahlathi ahlukene ngokwemvelo zinezinhlobo ezikwazi ukumelana nezimo, kodwa izinselelo ezintsha ezitholwa yilezi zinhlobo manje zinemiphumela engaziwa. Lapha, nginqume ukuhlola ukuhlukahluka kwezinyoni zasendaweni emahlathini akhethiwe ase-Southern Mistbelt ahlukaniswe ngokwendalo KwaZulu-Natali naseMpumalanga Kapa, eNingizimu Afrika. Okokuqala, ngisebenzise indlela enezici eziningi ukuhlola imiphumela yokwakheka kwezwe (okungukuthi, ikhwalithi ye-matrix), ukuhlukaniswa kwendawo yokuhlala (okungukuthi, ibanga lokuhlukaniswa nosayizi wesiqephu) kanye nokuhlukahluka kwendawo yokuhlala (okungukuthi, inkimbinkimbi yesakhiwo sehlathi) ezinhlobonhlobo zezinyoni ze-alpha (i-taxonomic, i-functional, i-phylogenetic kanye ne-functional-phylogenetic diversity) yawo wonke umphakathi, okuhlangene okuncike emahlathini (okungukuthi uchwepheshe wamahlathi) kanye nezingancikile emahlathini (okungukuthi i-forestry generalist). Okwesibili, ngidalule ukuthi izici eziyinhloko zokwakheka kwezwe (okungukuthi inani lendawo yokuhlala, ukuhlukahluka kwe-matrix kanye nesilinganiso sebanga lokuhlukaniswa) kuthinte kanjani ukuhlukahluka kwezinyoni zasendaweni futhi nganquma ukubaluleka kokuhlukahluka kokwakheka kwezwe ngakunye kusetshenziswa amamodeli we-mixed-effect linear (LME). Okwesithathu, ngenze imephu yokuxhumana kweziqephu ezimqoka ze-Southern Mistbelt Forest ezinikeza ukuhlukahluka okuphezulu kakhulu (≥ 50 %) kwezinyoni ngokusebenzisa inhlanganisela yendlela engabizi kakhulu nendlela ye-ecological circuit theory, ukuhlonza izici zezwe ezikhuthaza noma ezithiya ukuxhumana kwendawo yokuhlala kanye nezinhlobo zehlathi ezikhethekile nezinomkhawulo wokuhlakazeka (i-Dove Lemon kanye ne-Aplopelia larvata) ukuze iqondise ukuxhumana kwendawo yemiphakathi yamahlathi ezinyoni endaweni ehlukene ye-mozayikhi yehlathi. Engikutholile kwembula: i) imiphumela emihle yekhwalithi ye-matrix ezungezile endaweni ilamula imiphumela engemihle yokuhlukana kwezindawo zokuhlala emaqenjini endawo ezinyoni zehlathi; ii) ukukhuthaza ubunkimbinkimbi bezitshalo zendawo kungaba nomthelela ekulahlekeni kwezinhlobo ezincike ehlathini (okungukuthi ongoti bamahlathi); iii) inani lendawo yokuhlala endaweni ezungezile laliyisibikezelo esibaluleke kakhulu sokuhlukahluka kwezinyoni zasendaweni kanye nokuthuthukiswa kokuxhumana kwendawo yokuhlala phakathi kweziqephu eziwumgogodla zamahlathi e-Southern Mistbelt Forest ehlukanisiwe. Ngakho-ke, ngincoma ukulondoloza nokwandisa ukumboza kwehlathi endaweni ukuze kuqinisekiswe ukusinda kwesikhathi eside kwezinhlobo zamahlathi kulesi simiso sezinto eziphilayo ezihlukene ngokwendalo.
Aspects of monitoring wild and captive Nile crocodile (Crocodylus niloticus) populations in southern Africa = Izingxenye zokubhekelela uhlobo lwengwenya yasendle nevalelwe yaseNile (Crocodylus niloticus) e-Afrikha eseningizimu.
(2021) Myburgh, Hendrik Albert.; Downs, Colleen Thelma.
As biodiversity across the globe declines because of anthropogenic activities, the need for conservation efforts increases. For conservation efforts to be successful, it is imperative that detailed information about species and their populations; size and status within and outside of protected areas be collected. In freshwater systems, crocodile population demographics can provide an integrated view of ecosystem state, but the habitat and cryptic nature of crocodilians confound the derivation of population demographics for the taxa. Crocodile populations were historically monitored by fixed-wing aircraft, helicopter or limited spotlight surveys in those areas that are navigable by boat. These techniques are costly and labour-intensive; require specialised personnel and equipment, and are subject to observer bias and low accuracy in size class estimations. Furthermore, they produce population demographic data that is not verifiable as they rely on decisions and opinions of observers in the moment of surveying, often fromfast-moving platforms. Lately, unmanned aerial vehicle (UAV) techniques have been shown to accurately and effectively count crocodiles, but they still require costly software and hardware packages. In this study, low-cost, open-source UAV techniques were developed as an alternative method to monitor and survey crocodilians, particularly Nile crocodiles (Crocodylus niloticus), both in captivity and in the wild. In South Africa, Nile crocodiles occur in open bedrock systems with relatively little riparian vegetation, an ideal scenario for the application of UAVs. The possibility of improved population demographic data for wild Nile crocodile populations by converting size data derived from UAVs to age data was explored by radiocarbon dating Nile crocodile claws. Morphometric correction factors applicable to UAV census are derived, and a fixed-wing survey is compared with a commercial-grade UAV survey of wild Nile crocodile populations in the Kruger National Park. The limitations and applicability of these approaches for crocodilian and other ecological studies were assessed. Their future applications in ecology and management are proposed. Iqoqa Njengoba impiliswanomvelo kuwo wonke umhlaba yehla ngenxa yezenzo ezidalwe ngabantu, isidingo sokongiwa kwemvelo siyakhula. Ukuze imizamo yokongiwa kwemvelo ibe impumelelo, kuyaphoqa ukuthi kuqoqwe ulwazi olunzulu mayelana nokuphilayo kanye nezinhlobo zakho, ubungako kanye nesigaba phakathi kanye nangaphandle kwezindawo ezivikelwe. Emanzini aphilayo, uhlobo lwemiphakathi yezingwenya zingasinika iso eliyinhlanganisela lesimo sohlalonhlaliswano yokuphilayo nokungaphili, kodwa isimo sendawo yokuhlala kanye nesingachazeki sididisa ukwehlukanisa ukutholakala komphakathi wezinhlobo zezingwenya. Imiphakathi yezingwenya yayibhekelelwa emandulo ngendizamshini ehlala phezulu emoyeni, indiza enophephela emhlane noma amasaveyi angemaningi agqamile kulezo zindawo okuhambekayo kuzo ngezikebhe. Lawa masu ayabiza futhi adinga amandla okusebenza, adinga abasebenzi abaqondene kanye nemishini yokusebenza, kanti futhi ancike ekuchemeni kobukelayo kanye nezinga eliphansi ngobungako besihlawumbiselo sohlobo. Okunye futhi, akhiqiza imininingo yohlobo lwemiphakathi engathembakali njengoba ethembele ezinqumeni kanye nemibono yababukela ngesikhathi sokwenza amasaveyi, okujwayele ukuthi kube izinhlaka ezihamba ngokushesha. Kamumva nje, amasu esithuthi ezingasetshenziswa muntu ezisemoyeni, i-unmanned aerial vehicle (UAV) asevezwe njengakhombisa ukubalwa kwezingwenya okuqondile nokunemiphumela emihle, kodwa asadinga ubuchwepheshe obubizayo kanye nezindodla zobuxhaxhaxha bobuchwepheshe. Kulolu cwaningo, okungabizi, amasu ezizinda ezivulekile e-UAV kwaqanjwa njengenye yendlela engasetshenziswa ukubhekelela nokusaveya izingwenya, kakhulukazi izingwenya zaseNile (Crocodylus niloticus), zozimbili ezivalelwe kanye nezasendle. ENingizimu Afrikha, izingwenya zaseNile zivela ekusetshenzisweni kwamadwalamsuka avulekile anotshalovikelo olungeluningi, okuyisibonelo esincomekayo sokusebenzisa ama-UAV. Ukuba khona kwemininingo ethuthukile yezinhlobo zemiphakathi yezingwenya zasendle zeNile ngokushintsha ubungako bemininingo etholakale kuma-UAV ukukhulisa imininingo kwaphenywa ngekhabhoni yomoya ukubona izindlawu zengwenya yaseNile. Izimo zokulungisa ukusebenza kokubala kwe-UAV kutholakele, kanti futhi isaveyi yophiko olunganyakazi luqhathaniswa nesaveyi ye-UAV yohlobo lokusebenza lwemiphakathi yohlobo lwengwenya yasendle yaseNile e-Kruger National Park. Imikhawuko kanye nokusebenzeka kwalezi zindlela zokubhekelela izingwenya kanye nezinye izicwaningo zezemvelo kwahlolwa. Ukusebenza kwayo kwesikhathi esizayo emvelweni kanye nokwenganyelwa kuyaphakanyiswa.
The influence of the conservation of forests and public attitudes on the persistence of African crowned eagles in the mosaic of eThekwini Municipality, KwaZulu Natal, South Africa.
(2022) Maseko, Mfundo Sibongakonke Terrance.; Downs, Colleen Thelma.; Zungu, Manqoba Moses.
Abstract available in PDF.
Crocodile (Crocodylus niloticus) meal diets as a potential for replacement of fishmeal protein in commercial production of Mozambique tilapia (Oreochromis mossambicus)
(2022) Luthada-Raswiswi, Rendani Winnie.; Mukaratirwa, Samson.; O'Brien, Gordon Craig.
Fishmeal production is mainly sourced from the forage fish species. Fish caught for fishmeal production potentially represents a loss in producing higher trophic level species in the ecosystem. Low stock abundance reduces ecosystem services such as food provisioning to other elements of the ecosystem. Increasing demand, unstable supply, and the high price of the fishmeal with the expansion of aquaculture made it necessary to search for alternative protein sources. Crocodiles are farmed mainly for producing skins used in the production of high-quality fashion accessories. However, the demand for crocodile meat, especially in South Africa, is very low and strict regulations are imposed onto the industry about the use and disposal of crocodile carcasses. This study was conducted to assess the nutritional value of crocodile meals and their suitability as a fishmeal replacement in animal feeds, especially fish. Systematic review and meta-analysis results showed the gap that some animal by-products, including crocodile meat, had not been assessed as protein sources in aquaculture or animal feeds. Different size groups of fish are not considered in studies when testing different alternatives for fishmeals. The nutritional values of Crocodylus niloticus derived meal obtained in the current study is of comparable quality for use in aquaculture feeds, compared to by-products meal quality reported for meal derived from bovine bones and meat, feathers, blood and other poultry by-products. There were similarities in the gross feed conversion ratio for fry and the specific growth rate for fingerlings of Oreochromis mossambicus among all the experimental diets fed. That means the Crocodylus niloticus meal is a suitable animal protein source for replacing fishmeal in Oreochromis mossambicus diets. Some haematological parameters such as red blood cells count, and haemoglobin concentrations were significantly different among Oreochromis mossambicus fed crocodile-based and commercial diets. However, platelets count, haematocrit value, mean cell volume, mean cell haemoglobin, and mean cell haemoglobin concentrations were not significantly different among all diets fed. More future studies are recommended for different levels of Crocodylus niloticus meal in other fish species, different size groups, and haematological parameters. This study provides new information to the aquaculture industry regarding reducing supply constraints imposed by high cost and competitive uses for fishmeal and waste management on crocodile farms.
Forest mammalian community dynamics and human wildlife interactions in the Southern Mistbelt Forests of KwaZulu-Natal and Eastern Cape, South Africa.
(2021) Sosibo, Mbalenhle Thabile.; Downs, Colleen Thelma.; Ehlers Smith, Yvette Cathrine.; Ehlers Smith, David Alan.
African and Asian forests are well known for their high faunal and floral diversity; however, many forests have been left degraded or cleared because of anthropogenic activities from the past and present. In particular, African forests have been heavily exploited for their timber resources and land conversion for anthropogenic activities such as agriculture,. South African forests, specifically the Southern Mistbelt Forests, have been subjected to heavy logging by colonial settlers and subsistence harvesting in recent times because of the logging of trees such as yellowwood species (Podocarpus and Afrocarpus spp.) and hunting of bushmeat species blue duiker (Philantomba monticola). The aim of the study was to assess the anthropogenic impacts on mammals occurring in the Southern Mistbelt forests of KwaZulu-Natal and Eastern Cape provinces, as well as other uses of the forest and human-wildlife interactions. Study areas included the disjunct Southern Mistbelt Forests of the northern Eastern Cape and southern KwaZulu-Natal provinces, South Africa. It was conducted in three different forest cluster areas: uMthatha, Glengarry/Weza [termed iNgeli hereafter] and Creighton with forest patches of varying size. We conducted camera-trap surveys between May 2018 – February 2019 during the wet (summer/spring) and dry (winter/autumn) seasons, resulting in one full 21-day survey for each camera-trap location per season. We used infrared motion detection camera-traps to monitor mammalian forest species at set camera-trap locations determined using a 400 m x 400 m systematic grid system overlaid onto Southern Mistbelt Forest patches in Arc GIS v10.5.1. We also conducted semi-structured interviews in all three areas from October to November 2019. When assessing microhabitat use by mammalian species, we found that mammalian species most often photographed during sampling seasons were bushbuck (Tragelaphus scriptus) and samango monkey (Cercopithecus albogularis labiatus), with the least photographed species being serval (Leptailurus serval) and African wild cat (Felis silvestris cafra). Land-use data around each forest patch were extracted, with settlements, exotic timber plantations and grasslands identified as the dominant adjacent land-uses. The importance of exotic tree plantations surrounding indigenous forest patches to the persistence of mammalian species was highlighted. The maturity and condition of exotic timber plantations surrounding forest patches in our study also varied and may have influenced the area's use and suitability by mammalian species. Creighton was the only study area where human settlements were a dominant land-use around patches. The samango monkey had the second highest mean occupancy across all sampling areas and land-use types. Forest mammals make considerable contributions to the functioning of forest ecosystems. We evaluated the response of forest mammal functional diversity and species richness to factors such as patch size. Species β-diversity was greatly driven by turnover and functional β- diversity was driven by nestedness; therefore, management implications of these forests and associated mammalian communities suggest that all patches should be considered a priority for conservation. Due to different management implications, if nestedness is dominant, forest patches that have a higher diversity of species traits and species richness should be prioritised for conservation. Lastly, we aimed to quantify and assess the dynamics of forest use and hunting of mammalian species in communities close to forest patches and found that ungulates are the preferred choice for consumption in lower-income settlements which is supported by many other studies. Different species were hunted for various reasons such as: consumption, monetary gain (bushmeat trade and selling of hides) as well as retaliatory killing of predators hunting livestock. However, respondents shared that the forests are important to them and to protect them guards would be a good choice as well as education and awareness about sustainable use. There is a paucity of information about the overall mammal community inhabiting these forests and this study has highlighted which species inhabit these forests as well as their forest utilisation and how anthropogenic activities affect species populations. Furthermore, it highlighted that communities close to these forests see these forests as areas of high conservation importance.
Controlling woody plant encroachment in a southern African savanna.
(2021) Monegi, Piet.; Tsvuura, Zivanai.; Ward, David Mercer.; Tjelele, Julius Tlou.
Woody plant encroachment is considered one of the most extensive forms of degradation affecting savannas in arid and semi-arid ecosystems. Thus, reactive interventions such as chemical and mechanical controls, as well as fire application remains the norm in management of woody plant encroachment. I conducted a series of woody plant control experiments at the Agricultural Research Council’s Roodeplaat experimental ranch, situated in Gauteng Province, South Africa. The first experiment was a tree-thinning study at two savanna sites that differ in soil texture and woody species. Site 1 was on previously cultivated clay-dominated soils characterized by severe soil erosion and was encroached by Vachellia tortilis. Site 2 has never been cultivated and was on sandy soils with several woody species. At each site, 24 30 m × 30 m plots separated by 5 m wide fire breaks were established. Trees were removed to the approximate equivalents of 0% (control-no removal), 10%, 20%, 50%, 75% and 100% (complete removal of trees), followed by herbicide application on half of the stumps for each plot. I also investigated the effectiveness of Tree Poppers® (weed wrench) as a low-cost mechanical control tool to physically uproot seedlings and saplings of woody plants. To examine the effectiveness of the Tree Popper®, I used eight dominant tree species that were grouped into three height classes (0-49 cm, 50-99 cm, 100-150 cm) of ten seedlings and saplings per species per height class. In addition, investigated the effects of five years of annual burning on vegetation dynamics in a Vachellia karroo woodland. To determine the effects of annual burning on vegetation dynamics, plots (0.25 ha) established in 2013 were used. These studies are summarized below: (1) I determined the combined effects of tree species, tree thinning, stump diameter and herbicide application on resprouting patterns of woody plant species (Dichrostachys cinerea, Ehretia crispa, E. rigida, Gymnosporia buxifolia, Pappea capensis, Searsia lancea, S. caffra, Vachellia karroo, V. nilotica, V. robusta, V. tortilis and Ziziphus mucronata) that encroach study site 1. All the tree species in this study resprouted after cutting. Herbicide application significantly reduced the resprouting ability of D. cinerea, E. rigida, V. robusta and Z. mucronata. Tree removal positively influenced the resprouting ability and vigour of E. crispa only. The diameter of stumps was an important factor in determining resprouting ability, with shoot production decreasing with increasing stump diameter. The findings from this study suggest that woody plants are more likely to resprout and survive as juveniles than as adults after cutting. (2) I found no significant differences in the number of seedlings and saplings uprooted by Tree Popper®. However, there were significant differences in the number of juveniles uprooted using a Tree Popper® with a few individuals of Vachellia species uprooted. The effectiveness of the Tree Popper® may be due to differences in plant morphological structure, particularly the root system. The Tree Popper® is not an effective tool for controlling the Vachellia species used in this study. However, communal ranchers may mechanically control shallow-rooted tree seedlings with the Tree Popper® but not deep-rooted ones, specifically Vachellia species. (3) In the tree thinning experiment, I determined the effects of different tree thinningintensities on grass species-richness, composition, cover, β diversity, and soil fertility. I found that tree thinning did not have any significant effects on grass species-richness in either study site. However, we found a clear separation of different grass species among the treatments over the study period. Different levels of tree thinning increased the abundance of two dominant grass species (i.e. Digitaria eriantha and Panicum maximum) in both study sites, particularly in moderate (50%) and high removal (75% and 100%) treatments. However, the nitrophilous grass (i.e. P. maximum) will likely decline in abundance with time, particularly in the 100% thinning treatment because the ecological process that is responsible for N-fixation is no longer existent. Contrastingly, I found no evidence that tree thinning affects the amunt of soil cover. In addition, tree thinning did not have a significant impact on soil fertility in either study site. I recommend maintaining a stand density of 50% in rangeland affected by woody plant encroachment. In this study, 50% thinning created an opportunity for different palatable grass species to increase in abundance, which may help to increase forage production. (4) I determined the effects of different tree removal-intensities on grass production, tree-seedling establishment and growth, and the growth of the remaining large trees. In site 1, tree-removal treatments (i.e. 75 and 100%) significantly reduced grass biomass production after the first growing season, with no effect after the second season. In site 2, tree removal significantly increased grass biomass production. I found no significant effect of tree removal on tree seedling establishment in site 1. In site 2, tree removal had a significantly negative effect on overall tree seedling establishment. In both sites, there were no significant differences in tree seedling growth. Moderate (50%) to high (75%) removal of trees had a positive effect on the growth of remaining large trees in both study sites. I found that increased and/or diminished grass biomass production plays a vital role on tree seedling recruitment. Reduced tree competition facilitates the growth of the remaining large trees. An implication of these findings is that regardless of the substantial costs of woody plant control, the recovery of key ecosystem services such as an increased forage production may not be realised. However, this may be system-specific. In other systems, the absence of management interventions such as tree removal may compromise provision of ecosystem services and ecosystem functioning. (5) In the fire experiment, I investigated the effects of five years of annual burning on the density of young and adult Vachellia karroo plants. This study also aimed to investigate the effects of annual burning on tree growth (i.e. height, stem diameter and canopy size). The results supported the “fire-trap” paradigm by demonstrating substantially higher densities of young plants in the burned plots than in the unburned plots. In addition, the recruitment of young plants and saplings into adult trees was significantly higher in the unburned plots than in the burned plots. V. karroo populations substantially increased in growth (height and basal diameter) in the unburned plots. Different grass species changed in abundance in response to annual burning. However, I found no significant changes in grass species diversity and richness between the treatments. I found that the removal of the grass layer by fire and repeated topkill increased the number of young V. karroo individuals. Annual burning limited V. karroo juveniles and saplings from reaching an adult size class that may have detrimental effects on the herbaceous layer. I demonstrated that grass species composition is more prone to fireinduced changes than species diversity and richness in our study area. In conclusion, I show that managers of savanna rangelands may use annual burning to achieve specific vegetation structural objectives. This thesis demonstrated that mechanical- and chemical -control, as well as fire application influences the structure and functioning of savannas. By creating gaps that promote grass production, these management practices may assist increase the economic viability of savanna ecosystems. However, despite the popular belief that reduced tree densities promote ecosystem functions, this thesis demonstrates that the impact of control techniques (especially tree thinning) on forage production vary across savanna sites. This thesis also shows that management with prescribed annual fire reduced woody plant encroachment across the 5-year study, suggesting that fire management can be beneficial and should be explored as a management method.
Evolution of tangle-veined flies: systematics, biogeography and functional traits in southern African Nemestrininae (Nemestrinidae)
(2021) Theron, Genevieve Lee.; Van der Niet, Timotheus.; Ellis, Alan G.; Anderson, Bruce C.; Johnson, Steven Dene.
The evolution of traits and biogeography of the three southern African endemic genera of the Nemestrinidae: Moegistorhynchus, Prosoeca and Stenobasipteron. These genera are of particular interest due to the exaggerated mouth parts of some species and their role as important pollinators of numerous plants, including rare and endangered species. Most taxonomic studies on southern African nemestrinids date back 50 or more years ago, and the group lacks a phylogenetic framework, thus hindering comprehensive study of their systematics, trait evolution and biogeography. In this thesis, I evaluate the boundaries of a species complex in Prosoeca and reconstruct a phylogenetic framework for the southern African Nemestrininae. Furthermore, I use the phylogenetic framework to reconstruct the evolution of proboscis length and biogeographic patterns. To delimit species in the Prosoeca peringueyi complex, I quantified morphological variation and established whether this was associated with genetic variation within and between gene regions. Phylogenetic analysis of the complex using the mitochondrial COI gene revealed two well-supported clades, that are supported by morphological traits, one of which is described as a new species. Four gene regions were also used to reconstruct a phylogenetic tree of the three southern African Nemestrininae genera, including 58 morphospecies. The topology suggests that a monophyletic Moegistorhynchus is sister to a paraphyletic Prosoeca, with Stenobasipteron nested within Prosoeca. Half of the morphospecies in this phylogeny did not correspond to described species, thus highlighting a substantial taxonomic impediment in this group. The phylogenetic tree was used to reconstruct the evolution of proboscis length in the southern African Nemestrininae. Stochastic character mapping showed transitions between all states (short, long and very long), but shifts occurred more frequently from shorter to longer lengths. The ancestral proboscis state was estimated to be longer than the median proboscis length of the clade. Lastly, I reconstructed the biogeographical patterns of the southern African Nemestrininae. A Fynbos origin during the Miocene was estimated for this clade, with multiple shifts between biomes along the tree. Together, these results illustrate the need for further systematic and taxonomic work in this clade, as well as in the Nemestrinidae more broadly to gain a firmer understanding of their phylogenetic relationships and diversity. The evolution of proboscis length and biome occupancy appear to be labile within this clade. This work provides a phylogenetic framework for the southern African clade of Nemestrininae and contributes to our understanding of the patterns of evolution, diversification and migration of these ecologically important pollinators.
Effects of land-use changes on the distribution and use of Ficus species by frugivores in the urban mosaic landscape of Durban, KwaZulu-Natal, South Africa.
(2021) Raji, Islamiat Abidemi.; Downs, Colleen Thelma.
Land-use change is one of the greatest threats to biodiversity. Over the years, these changes potentially reduced ecosystems capacity to sustain food production for vertebrates. Ficus (figs; Moraceae) is one of the largest plant genera in lowland tropical rainforests, with more than 850 described species distributed worldwide and 124 species in Africa. Fig trees occupy diverse habitats and attain a wide range of growth forms, including large woody climbers, hemiepiphytes, trees, and shrubs. Over 1200 species globally feed on Ficus fruits and over 10% of the world’s birds and 6% of mammals consume figs, making them the most widely consumed plant genus. Fig-fruiting phenology is such that they are generally available during periods of food scarcity and may influence entire faunal communities, particularly as a dry season staple food. Therefore, it is a well-known key fruit resource component in tropical forests and one of the most important genera sustaining numerous frugivores across different landscapes. In a mutually beneficial relationship, the plants also benefit from seed dispersal by frugivores taking seeds away from the parent plants to locations of fewer pathogens, enhancing germination and plant recruitment. This study was concerned with the interactions between fruit-producing plants and fruit-eating animals across an urban mosaic landscape in KwaZulu-Natal, South Africa. Specifically, the study focused on Ficus spp. of conservation importance and keystone species. Despite the critical role that figs play in many frugivores' ecology, there is relatively little information on the distribution and diversity of Ficus species along forest-urban gradients in relation to different land uses and frugivore foraging behaviours in the study area. Details of the relationships between different components of the frugivore-seed disperser and different fig species also remain unclear. Thus, this study enhances the understanding of the role of birds, bats and other mammals in seed dispersal, germination, and the effect of land-use changes on fig-frugivore interactions, which is critical for informing conservation and management strategies.
Diversity of edible insects and their related indigenous knowledge: evidence from KwaZulu-Natal and Limpopo provinces, South Africa.
(2021) Hlongwane, Zabentungwa Thakasile.; Munyai, Thinandavha Caswell.; Slotow, Robert Hugh.
Entomophagy is an ancient indigenous practice that has played a significant role in human nutrition around the world. In addition, the traditional use of edible insects forms an important part of food culture in Africa. Edible insects are widely consumed across the African continent for their taste, nutritional value, or as an emergency food source during times of food shortage. They have been proposed and recommended as a sustainable food source that can assure food security, because edible insects are rich in protein, fats, amino acids, iron, zinc, and energy. As a result, edible insects play an essential role in human nutrition. In addition, the trade of edible insects plays an important role in improving livelihoods in developing countries. However, little is known about the diversity and nutritional composition of various insects consumed in South Africa. In addition, little is being done to document traditional knowledge on the consumption of insects, and processes involved in harvesting, processing, and preparing edible insects. This study aimed to document indigenous knowledge regarding the consumption of edible insects, their diversity and distribution, and their nutritional composition. This was done by (i) reviewing existing literature on the diversity of insect and their nutritional status in Africa. (ii) documenting consumption patterns, methods, or techniques used in collecting and preparing insects in South Africa. (iii) determining the nutritional composition of some major insect groups consumed in Africa, (iv) determining the most preferred insect groups, and (v) by documenting the socio-economic benefits of trading insects. Closed and open-ended questions were conducted in various rural areas in five and four local municipalities in KwaZulu-Natal (KZN) and Limpopo. To document indigenous knowledge about trading, consumption, collection and preparation methods used in these provinces. Dried samples of four insect groups were procured from different markets across Vhembe district, Limpopo Province. The nutritional composition of the procured insect types was analysed using the standard Association of Official Analytical Chemist (AOAC) methods. A systematic review was conducted to determine the diversity and nutritional composition of edible insects consumed in Africa. A systematic review search resulted in 98 eligible papers listing 212 edible insect species from eight orders that are used as food in Africa. The highest protein (range: 20–80%) and fat (range: 10–50%) content were recorded in order Lepidoptera. While the highest carbohydrates (range: 7–54%) content was reported in order Coleoptera. Majority of the people still practice entomophagy in Limpopo while, there are only a few people consuming insects in KwaZulu-Natal. Gynanisa caterpillar, Gonimbrasia belina (mopane worm), termites, Encosternum delegorguei (stink bug), Cirina forda (emperor moth), Locustana spp. (brown locust), Zenocerous spp. (grasshopper), Carebara vidua (ant), and Cicadoidea spp. (cicada) were used as food in Limpopo and KwaZulu-Natal. From these, mopane worms and termites were the most preferred species. These insects were primarily collected from the wild, and consumed either fried, boiled, roasted, sundried, or as relish. Nutritional benefits and tradition were the primary reason for consuming insects in the two provinces. However, religion and discomfort associated with consuming insects were the main reasons for not consuming insects. Findings from the nutritional analysis of four insect types showed that termite (soldiers/ workers) had the highest protein and iron content, while Gynanisa caterpillar had the highest zinc content. The ranges of the percentage contribution of the insects studied relative to the Estimated Average Requirement (EAR) for protein amongst different age groups, indicated that the insects would contribute significantly to addressing protein deficiencies, 89.5-160.4% EAR for 4-8 years old children and 29.9-53.6% EAR for childbearing women (19-50 years). However, because Gonimbrasia belina are consumed in a relatively higher portion size than the other edible insects, it would be a good source of protein for different population groups. Generally, boiling with or without salt added resulted in a significant increase in protein, iron, and zinc content of Gonimbrasia belina samples. On the other hand, frying resulted in a significant decrease in protein content of Gonimbrasia belina samples. Five insect groups were traded for cash income in Vhembe district, Limpopo province. Of these, mopane worm was the most traded insect. Trading insects provided financial support and cash income to unemployed people in this province. Income generated from trading insects range from R100 - R200 ($6, 2 - $12, 3) per week to above R2000 ($123, 3) per week with the majority of traders making an income of R600 -R1000 ($36, 9-$61, 6) per week. Unemployment and poverty were the main reason for trading insects. Despite the economic benefit associated with trading insects, few governmental organizations in Limpopo included edible insects in economic development strategies. In addition, insect trading took place in the informal markets along the street, pavements, and on table stalls made of cardboard and wood. Safety and hygiene were the major issues of concern stated by the respondents in Vhembe district. Therefore, government need to provide infrastructure and financial support to improve the trading conditions of edible insects. Also, policy and legislation that recognise and govern the consumption, trading, and harvesting of edible insects are required, because edible insects play an important role in income generation. In addition, edible insects contribute to food and nutrition security in developing countries with chronic nutrient deficiencies. Therefore, the consumption of insects should be promoted and encouraged in poor communities.
Aspects of common hippopotamus (Hippopotamus amphibius) behavioural ecology and their consequences in managed systems in South Africa.
(2020) Fritsch, Camille Jacques-Armand.; Downs, Colleen Thelma.
Abstract available in PDF.
Aspects of the ecology of three mongoose species along a rural–urban landscape gradient of KwaZulu- Natal, South Africa.
(2020) Streicher, Jarryd Peter.; Downs, Colleen Thelma.; Ramesh, Tharmalingam.
Many small carnivore species are of particular concern for conservation because of their elusive behaviour, diminutive size and crepuscular habits. Management and research tend to be challenging and thus is often limited. Several members of the Herpestidae family fall into this research dead zone, including the large grey mongoose (Herpestes ichneumon), slender mongoose (Galerella sanguinea), white-tailed mongoose (Ichneumia albicauda) and marsh or water mongoose (Atilax paludinosus). The distribution range and other aspects of the ecology of these and other such species, has remained vague for much of the sub-tropical regions of southern Africa because of the scarcity of comprehensive data. There is little understanding of the basic ecology of these mongoose species, and limited progress has been made in understanding the tolerance of these species within a changing environment. These species of mongoose appear to persist across KwaZulu-Natal’s (KZN), South Africa, anthropogenically modified habitats (farmlands and urban). Small carnivore species, such as mongooses, can provide models of how medium-sized carnivores tolerate differing degrees of anthropogenic land-use change. A global review of the current knowledge and research effort for urban mammalian mesocarnivores was conducted. In the last decade, there has been a dramatic increase in the number of studies that focus on medium-sized mammalian carnivores. Disproportionate levels of urban studies exist for mesocarnivores. Several species have been comprehensively studied in the United States of America and the United Kingdom. These two developed countries held more than half of all studies on urban mammalian mesocarnivores. Areas of the world that are undergoing rapid urbanisation have the most significant deficiency of research. Across Africa, the spatial ecology of the Herpestidae family remains relatively poorly studied. We investigated how anthropogenic land-use change affects aspects of the ecology of three co-existing mongoose species (large grey, water and white-tailed) in the agricultural setting of the KZN Midlands. Individuals of these three species of mongooses were trapped, collared and tracked using GPS-UHF (ultra-high frequency). The results presented show that the three focal species have different spatial requirements and movements from previous stated in literature. The natural habitat and farmland mosaic of the KZN Midlands are segregating the preferred habitats into small fragments. These niche fragments are intensely used by each species and allow them to co-exist in these anthropogenically modified environments. Besides these species’ generalist nature, their behavioural plasticity may assist them in persisting in anthropogenically modified landscapes. In the absence of apex predatory control, an expansion in the range and population number of Herpestidae species is expected. This study provides crucial information on the spatio-temporal ecology of large grey, water and white-tailed mongoose in the KZN Midlands. The spatial movements of the three co-existing species in this study highlighted the variability that is present at a species and individual level. Further research is required to address the human–wildlife conflict that takes place locally. The urban aspect of the large grey, water and white-tailed mongoose ecology is also understudied, and we recommend further research be targeted. The spatial ecology of water mongoose in the urban green space matrix of the Upper Highway Area of eThekwini, KZN, was subsequently investigated. This was to compare aspects of their ecology between fragmented natural farmland and urban mosaic using similar methods. Water mongooses occurred at a high density in the fragmented green Durban Metropolitan Open Space System (D’MOSS). Insight into the spatial ecology of urban water mongoose (home range, core area utilisation, overlap and habitat use) determined using GPS telemetry data from 14 water mongooses from July 2018 - October 2019. Water mongooses had constricted spatial movements that were highly dependent on natural refugia, and individuals intentionally avoided built-up areas of the urban matrix. The confined nature of these green spaces consequently resulted in home range sizes that were significantly smaller than their farmland conspecifics. However, the species behavioural plasticity and generalist nature has allowed the species to occur at higher population densities in the green spaces of the urban matrix of the Upper Highway Area. Furthermore, the effects of urban sprawl on the dietary ecology of water mongooses using faecal analyses was conducted. Water mongooses scat samples (n = 104) were opportunistically collected and with the aid of members of the Kloof Conservancy during the study. Urban water mongooses consume a diverse array of dietary items (9 categories), which is dominated by three categories (relative frequency of occurrence: crustaceans 35.7%, invertebrates 19.9%, small mammals 19.1% and other 25.2%). Seasonal variation in the diet only occurred for crustaceans and invertebrates with the other dietary categories consumed equally throughout the seasons. Additionally, it was demonstrated that urban water mongooses are supplementing their diets with anthropogenic waste (chicken bones, plastic particulates and cigarette butts). The broad diversity in dietary categories and supplementation of anthropogenic waste demonstrates the generalist opportunistic feeding behaviour and adaptability of the species in an urban matrix. An online questionnaire survey was conducted to investigate socio-ecological attitudes and general perspectives towards mammalian mesocarnivores across a land-use gradient (rural–urban) from the uMgungundlovu to eThekwini Municipalities of KZN. Significant trends were assessed using the frequency of responses. The public held a range of different perspectives. Overall, respondents viewed mesocarnivores as non-threatening and vital for the environment. However, black-backed jackals (Canis mesomelas) were commonly identified as a problematic pest species, that subsequently are targets of predator control pressures by rural participants. The survey also identified that smaller, behaviourally flexible species (mongoose species and cape genet Genetta tigrina) were commonly sighted and are potentially increasing in both land-use types in the absence of competition and predatory control. Vehicle collisions are the primary cause of mesocarnivore fatality reported by participants of the survey. The impact of mesocarnivores was perceived differently along a land–use gradient which links to levels of interaction. The study emphasises the importance of citizen science and community engagement when attempting to understand the drivers of human–wildlife interactions and potential mitigation strategies. The present multifaceted study has improved our understanding of solitary members of the Herpestidae family and how anthropogenic changes affect them across a land-use gradient. Furthermore, the behavioural flexibility and adaptability of mongooses in enabling them to persist at differing degrees of anthropogenic pressure were evident. However, the size class of mammalian mesocarnivores remains understudied in Africa, and this is of concern in a rapidly developing region.

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