Doctoral Degrees (Ecology)

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

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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 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.
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.
Taxonomic, functional, and avian community dynamics in selected Southern Mistbelt Forests of southern KwaZulu-Natal and the Eastern Cape, South Africa.
(2020) Gumede, Silindile Thobeka.; Downs, Colleen Thelma.; Ehlers Smith, David Alan.; Ehlers Smith, Yvette Cathrine.
Human population increase and landscape transformation result in the reduction of natural habitats, such as forests, causing changes in forest patch composition, habitat amount, patch size, isolation, shape, and edges. This is challenging specialist such as Orange Ground-thrush (Geokichla gurneyi) and Lemon Dove (Aplopelia larvata) species unable to survive in fragmented habitats and also influencing the composition and distribution of avian species assemblages. Therefore, the main aims of this multifaceted study were to (1) assess the habitat requirements of two forest specialised bird species, the Orange Ground-thrush (Geokichla gurneyi) and the Lemon Dove (Aplopelia larvata); (2) identify if avian assemblage diversity and species functional trait diversity show consist patterning across different landscapes in a forest ecosystem; (3) determine the influence of vegetation structures on the taxonomic and functional diversity of avian forest species, and (4) modelling how to connect forest patches of higher functional diversity. In 2018-2019, we conducted a series of camera-trap surveys of 21- day periods and fixed-radius point-count surveys at 420 sites across 94 forest patches of Southern Mistbelt Forest of southern KwaZulu-Natal and Eastern Cape, South Africa, during the breeding and non-breeding seasons in conjunction with surveys of microhabitat structural covariates. Firstly, we modelled the probability of occupancy and detection for the selected two species, which showed that forest specialist species prefer a highly diverse habitat structure. Secondly, we quantified functional diversity measures based on species’ trait per patch to measure the influence of habitat and landscape configuration on each measure. This resulted in functional diversity measures which were highly influenced by patch size, the distance between patches and diverse landscape and habitat. Thirdly, we conducted RLQ analyses to examine the association between avian functional traits and microhabitat structures present at each forest patch.We found there was a significant difference in vegetation structure and species richness between forest patches. Lastly, we ranked the functional diversity measures scores of avian communities present at each forest patch to identify core habitat patches responsible for the contribution of high functional diversity measures. Protection of natural forest habitat and diverse landscapes is important in preserving avian communities.

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Browsing Doctoral Degrees (Ecology) by Author "Ehlers Smith, David Alan."