Landscape modification resulting in habitat loss, fragmentation and intensification of land use is a serious threat to the earth’s biological diversity and the primary cause of the current extinction crisis. Recent research suggests the human-modified area of the landscape (that is not ‘traditional’ habitat for native species but potentially once was), or the ‘matrix’ (as it is hereafter called) has a major influence on wildlife persistence in modified landscapes. However, the matrix is a poorly studied and inadequately understood element of a modified landscape. There are at least two reasons for this. Firstly, the predominance of island biogeography and metapopulation theories in ecological thinking ensured that the matrix has historically been ignored in ecological research. Secondly, it is difficult to analyse matrix effects without confounding effects of habitat loss, habitat fragmentation and other aspects of landscape modification. As landscapes are modified attributes of the matrix co-vary with attributes of patches and landscapes, entangling their relative impacts on wildlife. Thus to investigate the independent influence of the matrix on mammals I selected 19 study landscapes by rigorous criteria to control for all potentially confounding patch and landscape attributes such as remnant forest patch size, shape, vegetation type, condition and position in the landscape, presence of any large (potential ‘source’) native forest patches within the landscape unit, as well as matrix land use composition and history. A study landscape was defined as the area within a 500 m radius of a remnant forest patch edge. Landscapes were selected along a gradient of rural-suburban residential development spanning the broadest achievable range of what I call ‘matrix development intensity’. This gradient was quantified by a novel weighted road-length metric that considered multiple road attributes to give significance to the ecological impact of different roads. Mammals and their habitat were sampled in three landscape elements within each landscape: remnant patch core, remnant patch edge and matrix to allow a landscape level inference. Mammals were sampled by a combination of Elliott traps, wire cage traps, hair funnels, scats and direct sightings. Thirty environmental variables were measured including habitat structure and disturbance and a full floristic survey was conducted. The matrix intensity gradient was characterised by increased anthropogenic disturbance such as increased housing density, closer proximity of sample sites to houses and higher human disturbance across the landscape mosaic, including in the core of remnant patches. However, matrix intensity was not the greatest source of overall variation in structural and floristic habitat attributes. Therefore the confounding of matrix effects with effects of remnant forest patch habitat attributes were successfully ruled out. Management actions of individual landholders can shape habitat attributes essential to mammals across the landscape mosaic. Mammal response to matrix intensity was species specific. Several native species declined in abundance, others were more resilient to moderate levels of matrix intensity, one species increased in abundance, and at least one species appeared unaffected by matrix intensity. Native species richness peaked at moderate levels, while exotic species richness and feral predators increased with matrix intensity and were negatively correlated with native species. Species response to matrix intensity appeared related to their use of edge or matrix habitat. However, an ability to use the matrix per se may not translate into an ability to persist in a landscape where development substantially reduces the habitat or movement value of the matrix. Seven a priori models of various remnant patch habitat, landscape and matrix influences on terrestrial mammal species richness were tested. Matrix attributes were the most important determinants of species richness. Matrix development intensity had a strong negative effect while matrix vegetation structural complexity had a strong positive effect on mammal species richness. Distance to the nearest remnant forest habitat was relatively unimportant. I hypothesised that thresholds of matrix intensity would exist where native species decline in abundance and exotic and native synanthropic species increase to dominate the mammal community. Thresholds were found for abundance of all native terrestrial species combined, macropod abundance and exotic rodent abundance. However, threshold models were only better than linear or cubic models for exotic rodent abundance. Matrix development intensity has a pervasive impact across the whole landscape mosaic that results in a complex range of environmental changes that individually and collectively impact the mammal community. Drawing on all results, I present a conceptual model of the overall impact of matrix development intensity on mammal community integrity. I conclude that a structurally complex matrix within a human-modified landscape can provide supplementary habitat resources and increase the probability of successful species movement across the landscape. Research needs to incorporate empirical data of specific matrix effects into models and theory of species distribution and abundance in human-modified landscapes. This can help guide application of management actions and landscape planning principles across different landscapes. Planning authorities and land managers need to explicitly acknowledge the importance of the matrix and the numerous factors that could be manipulated, such as retention or restoration of a structural vegetation layer that can assist mammal movement across the matrix, for greater landscape-wide conservation outcomes.

Landscape modification resulting in habitat loss, fragmentation and intensification of land use is a serious threat to the earth’s biological diversity and the primary cause of the current extinction crisis. Recent research suggests the human-modified area of the landscape (that is not ‘traditional’ habitat for native species but potentially once was), or the ‘matrix’ (as it is hereafter called) has a major influence on wildlife persistence in modified landscapes. However, the matrix is a poorly studied and inadequately understood element of a modified landscape. There are at least two reasons for this. Firstly, the predominance of island biogeography and metapopulation theories in ecological thinking ensured that the matrix has historically been ignored in ecological research. Secondly, it is difficult to analyse matrix effects without confounding effects of habitat loss, habitat fragmentation and other aspects of landscape modification. As landscapes are modified attributes of the matrix co-vary with attributes of patches and landscapes, entangling their relative impacts on wildlife. Thus to investigate the independent influence of the matrix on mammals I selected 19 study landscapes by rigorous criteria to control for all potentially confounding patch and landscape attributes such as remnant forest patch size, shape, vegetation type, condition and position in the landscape, presence of any large (potential ‘source’) native forest patches within the landscape unit, as well as matrix land use composition and history. A study landscape was defined as the area within a 500 m radius of a remnant forest patch edge. Landscapes were selected along a gradient of rural-suburban residential development spanning the broadest achievable range of what I call ‘matrix development intensity’. This gradient was quantified by a novel weighted road-length metric that considered multiple road attributes to give significance to the ecological impact of different roads. Mammals and their habitat were sampled in three landscape elements within each landscape: remnant patch core, remnant patch edge and matrix to allow a landscape level inference. Mammals were sampled by a combination of Elliott traps, wire cage traps, hair funnels, scats and direct sightings. Thirty environmental variables were measured including habitat structure and disturbance and a full floristic survey was conducted. The matrix intensity gradient was characterised by increased anthropogenic disturbance such as increased housing density, closer proximity of sample sites to houses and higher human disturbance across the landscape mosaic, including in the core of remnant patches. However, matrix intensity was not the greatest source of overall variation in structural and floristic habitat attributes. Therefore the confounding of matrix effects with effects of remnant forest patch habitat attributes were successfully ruled out. Management actions of individual landholders can shape habitat attributes essential to mammals across the landscape mosaic. Mammal response to matrix intensity was species specific. Several native species declined in abundance, others were more resilient to moderate levels of matrix intensity, one species increased in abundance, and at least one species appeared unaffected by matrix intensity. Native species richness peaked at moderate levels, while exotic species richness and feral predators increased with matrix intensity and were negatively correlated with native species. Species response to matrix intensity appeared related to their use of edge or matrix habitat. However, an ability to use the matrix per se may not translate into an ability to persist in a landscape where development substantially reduces the habitat or movement value of the matrix. Seven a priori models of various remnant patch habitat, landscape and matrix influences on terrestrial mammal species richness were tested. Matrix attributes were the most important determinants of species richness. Matrix development intensity had a strong negative effect while matrix vegetation structural complexity had a strong positive effect on mammal species richness. Distance to the nearest remnant forest habitat was relatively unimportant. I hypothesised that thresholds of matrix intensity would exist where native species decline in abundance and exotic and native synanthropic species increase to dominate the mammal community. Thresholds were found for abundance of all native terrestrial species combined, macropod abundance and exotic rodent abundance. However, threshold models were only better than linear or cubic models for exotic rodent abundance. Matrix development intensity has a pervasive impact across the whole landscape mosaic that results in a complex range of environmental changes that individually and collectively impact the mammal community. Drawing on all results, I present a conceptual model of the overall impact of matrix development intensity on mammal community integrity. I conclude that a structurally complex matrix within a human-modified landscape can provide supplementary habitat resources and increase the probability of successful species movement across the landscape. Research needs to incorporate empirical data of specific matrix effects into models and theory of species distribution and abundance in human-modified landscapes. This can help guide application of management actions and landscape planning principles across different landscapes. Planning authorities and land managers need to explicitly acknowledge the importance of the matrix and the numerous factors that could be manipulated, such as retention or restoration of a structural vegetation layer that can assist mammal movement across the matrix, for greater landscape-wide conservation outcomes.

Land use regulations are typically established as a response to development activity. For effective growth management and habitat preservation, the opposite should occur. This study considers tree preservation ordinances of the Dallas-Fort Worth metropolitan area as a means of evaluating development regulation in a metropolitan context. It documents the impact urban cores have on regulations and policies throughout their region, demonstrating that the same urban-rural gradient used to describe physical components of our metropolitan areas also holds true in terms of policy formation. Although sophistication of land use regulation generally dissipates as one moves away from an urban core, native habitat is more pristine at the outer edges. To more effectively protect native habitat, regional preservation measures are recommended.

No description available.

Globally urbanisation impacts on 88% of amphibian species and is recognised as a major cause for the observed amphibian declines. This is as result of habitat fragmentation, alteration in habitat morphology and degradation of habitat quality. The interference of anthropogenic noise on anuran communication and the impacts thereof on their breeding success has become a major research focus in recent conservation studies. . However, within the African continent very little research has been conducted on the effects of urbanisation on anuran habitat and the acoustic environment, which is the main focus of this study. The thesis is structured as follows: CHAPTER ONE provides an introduction to the field of urban ecology and relates it to amphibian conservation. The chapter reviews the far reaching and diverse effects of urbanisation on frog populations reported in literature across the world and also supply a broad introduction to the succeeding chapters. It also briefly summarises evidence from literature on the positive contributions brought about by the developed world. Following the vast negative impacts of urbanisation, the importance of amphibians is briefly discussed to motivate their conservation in urban environments, before concluding with a motivation for the need for urban ecological research on amphibians in South Africa. CHAPTER TWO addresses the distribution of amphibian communities across an urban-rural gradient in the city of Potchefstroom and assesses the habitat determinants explaining distribution at both local (pond) and landscape scales. Four surveys conducted spanned the breeding seasons of all species occurring in this region and included three different sampling techniques to detect fish and anuran larvae species. Seven micro-habitat and seven landscape variables were included to evaluate determinants of habitat use among local species and species richness. Using Bayesian modelling, aquatic vegetation, predatory fish and pond size was found to be major determinants shaping species richness on a local scale, whereas surface area of urban central business district had only a slightly negative correlation with species richness on a landscape scale. This is a pioneer study for documenting effects of urbanisation on amphibian communities along an urban-rural gradient in Africa. CHAPTER THREE evaluates the extent of the influence of aircraft acoustic noise on the calling behaviour of the critically endangered Pickersgill’s Reed Frog, Hyperolius pickersgilli. Literature documenting the effects of airplane noise on anuran calling activity is very limited and this study aimed not only to contribute to existing knowledge, but also to provide the first study of its kind within South Africa. Effects on five call properties of H. pickersgilli were determined using passive and directional recording equipment at two sites, reflecting presence and absence of aircraft flybys. Results showed an increase in calling rate of H. pickersgilli during aircraft flybys. Hyperolius pickersgilli was found to call throughout the night until just before sunrise. The calling behaviour, frequency structure and call sound pressure level of H. pickersgilli suggest that this species is prone to be effected by continuous anthropogenic noise. However, the lack of flights between midnight and sunrise provides a period of no disturbance for the frogs. Future studies on the effects of change in calling behaviour should be supported by playback studies at quiet sites and connected to breeding success to determine if these effects are detrimental to the survival of this critically endangered species. CHAPTER FOUR focussed on the Western Leopard Toad, Amietophrynus pantherinus and was divided into two major parts. One component focussed on the migration of this species across roads and aimed to firstly quantify the number of individuals migrating over a 500 m stretch of road using a drift fence system operated by public volunteers. The drift fence proved very successful, with no roadkill observed during the time it was in place. This study also stressed that large numbers of toads (average of 20.47% of 2 384 toads over six breeding seasons) are still being killed on the urban and suburban roads. Road patrol statistics collected by volunteers are biased in the sense that it is prone to human error, but when a drift fence is constructed, bias is excluded and space for human error limited. The study also provided road sensitivity areas analysed using geographic information systems to create digital buffer zones of 250 m, 500 m and 1 000 m around selected breeding sites. Secondly the study aimed to evaluate the use of data collected by these citizens occupying a volunteering role in the toad’s conservation. The second part of this study was directed towards the acoustic analysis of the call of A. pantherinus. The two main objectives of this component were to 1) evaluate the extent of variation of the call properties in order to 2) assess whether the ambient anthropogenic noise have an effect on these properties. Seven call properties for advertisement calls and four for release calls were analysed. Call properties were found to vary significantly between populations (P<0.05). Although sound pressure level was found to have an effect on variation by using canonical redundancy analysis, variation can also be explained by the geographical isolation of the populations. CHAPTER FIVE provided novel data on the extensive repertoire of Amietia quecketti in terms of its unique calling behaviour. Directional recordings were used to examine the extent of the variation in the two-part call (click-note followed by a whine-note). The whine-note was re-described and four different notes were designated, including the tonal-note, creak-note, pulsatile- / rip-note, and whine-note. Furthermore, the newly assigned whine-note was divided into nine phases that differed in frequency structure. Also, evidence is provided that A. quecketti males call at high frequencies. The success of A. quecketti in urban environments as observed in Chapter 2 is described in terms of this species’ extensive repertoire and unusual frequency structure. CHAPTER SIX provides insight into the effects of atmospheric conditions on the calling behaviour of Amietia quecketti, giving the proximate impact urbanisation has on weather conditions as well as the potential impact human activities can have on climate change on the long term. Calling activity was monitored over a nine-week period together with data from a mobile weather station which logged atmospheric variables every five minutes. Amietia quecketti was found to call most intensely between 00h00 and 03h00 in the morning and was most active in May, June and August. Humidity, temperature and wind velocity were found to have significant effects (P<0.05) on the calling activity of A. quecketti. CHAPTER SEVEN is concerned with the attitudes of people towards frogs in South Africa. The first part of this study assessed the attitudes of people towards frogs in Potchefstroom. Surveys were distributed via the internet as well as manually to reach people with no internet access as well. Attitudes of people of Potchefstroom were mostly positive with more than half of the sampled population of 295 respondents indicating a strong liking in frogs. This study provides evidence that the presence of myths and knowledge can highly affects people’s attitudes towards frogs. The second part of this study focussed on the motivations of volunteers saving Western Leopard Toads from roadkill in Cape Town, South Africa. Volunteers were motivated by a strong value-driven approach to saving toads. CHAPTER EIGHT provides a general discussion and outline on the contributions this study presented and also the new areas where more research is needed within the extent of the field of urban ecology from a South African perspective. / hD (Zoology), North-West University, Potchefstroom Campus, 2014

Globally urbanisation impacts on 88% of amphibian species and is recognised as a major cause for the observed amphibian declines. This is as result of habitat fragmentation, alteration in habitat morphology and degradation of habitat quality. The interference of anthropogenic noise on anuran communication and the impacts thereof on their breeding success has become a major research focus in recent conservation studies. . However, within the African continent very little research has been conducted on the effects of urbanisation on anuran habitat and the acoustic environment, which is the main focus of this study. The thesis is structured as follows: CHAPTER ONE provides an introduction to the field of urban ecology and relates it to amphibian conservation. The chapter reviews the far reaching and diverse effects of urbanisation on frog populations reported in literature across the world and also supply a broad introduction to the succeeding chapters. It also briefly summarises evidence from literature on the positive contributions brought about by the developed world. Following the vast negative impacts of urbanisation, the importance of amphibians is briefly discussed to motivate their conservation in urban environments, before concluding with a motivation for the need for urban ecological research on amphibians in South Africa. CHAPTER TWO addresses the distribution of amphibian communities across an urban-rural gradient in the city of Potchefstroom and assesses the habitat determinants explaining distribution at both local (pond) and landscape scales. Four surveys conducted spanned the breeding seasons of all species occurring in this region and included three different sampling techniques to detect fish and anuran larvae species. Seven micro-habitat and seven landscape variables were included to evaluate determinants of habitat use among local species and species richness. Using Bayesian modelling, aquatic vegetation, predatory fish and pond size was found to be major determinants shaping species richness on a local scale, whereas surface area of urban central business district had only a slightly negative correlation with species richness on a landscape scale. This is a pioneer study for documenting effects of urbanisation on amphibian communities along an urban-rural gradient in Africa. CHAPTER THREE evaluates the extent of the influence of aircraft acoustic noise on the calling behaviour of the critically endangered Pickersgill’s Reed Frog, Hyperolius pickersgilli. Literature documenting the effects of airplane noise on anuran calling activity is very limited and this study aimed not only to contribute to existing knowledge, but also to provide the first study of its kind within South Africa. Effects on five call properties of H. pickersgilli were determined using passive and directional recording equipment at two sites, reflecting presence and absence of aircraft flybys. Results showed an increase in calling rate of H. pickersgilli during aircraft flybys. Hyperolius pickersgilli was found to call throughout the night until just before sunrise. The calling behaviour, frequency structure and call sound pressure level of H. pickersgilli suggest that this species is prone to be effected by continuous anthropogenic noise. However, the lack of flights between midnight and sunrise provides a period of no disturbance for the frogs. Future studies on the effects of change in calling behaviour should be supported by playback studies at quiet sites and connected to breeding success to determine if these effects are detrimental to the survival of this critically endangered species. CHAPTER FOUR focussed on the Western Leopard Toad, Amietophrynus pantherinus and was divided into two major parts. One component focussed on the migration of this species across roads and aimed to firstly quantify the number of individuals migrating over a 500 m stretch of road using a drift fence system operated by public volunteers. The drift fence proved very successful, with no roadkill observed during the time it was in place. This study also stressed that large numbers of toads (average of 20.47% of 2 384 toads over six breeding seasons) are still being killed on the urban and suburban roads. Road patrol statistics collected by volunteers are biased in the sense that it is prone to human error, but when a drift fence is constructed, bias is excluded and space for human error limited. The study also provided road sensitivity areas analysed using geographic information systems to create digital buffer zones of 250 m, 500 m and 1 000 m around selected breeding sites. Secondly the study aimed to evaluate the use of data collected by these citizens occupying a volunteering role in the toad’s conservation. The second part of this study was directed towards the acoustic analysis of the call of A. pantherinus. The two main objectives of this component were to 1) evaluate the extent of variation of the call properties in order to 2) assess whether the ambient anthropogenic noise have an effect on these properties. Seven call properties for advertisement calls and four for release calls were analysed. Call properties were found to vary significantly between populations (P<0.05). Although sound pressure level was found to have an effect on variation by using canonical redundancy analysis, variation can also be explained by the geographical isolation of the populations. CHAPTER FIVE provided novel data on the extensive repertoire of Amietia quecketti in terms of its unique calling behaviour. Directional recordings were used to examine the extent of the variation in the two-part call (click-note followed by a whine-note). The whine-note was re-described and four different notes were designated, including the tonal-note, creak-note, pulsatile- / rip-note, and whine-note. Furthermore, the newly assigned whine-note was divided into nine phases that differed in frequency structure. Also, evidence is provided that A. quecketti males call at high frequencies. The success of A. quecketti in urban environments as observed in Chapter 2 is described in terms of this species’ extensive repertoire and unusual frequency structure. CHAPTER SIX provides insight into the effects of atmospheric conditions on the calling behaviour of Amietia quecketti, giving the proximate impact urbanisation has on weather conditions as well as the potential impact human activities can have on climate change on the long term. Calling activity was monitored over a nine-week period together with data from a mobile weather station which logged atmospheric variables every five minutes. Amietia quecketti was found to call most intensely between 00h00 and 03h00 in the morning and was most active in May, June and August. Humidity, temperature and wind velocity were found to have significant effects (P<0.05) on the calling activity of A. quecketti. CHAPTER SEVEN is concerned with the attitudes of people towards frogs in South Africa. The first part of this study assessed the attitudes of people towards frogs in Potchefstroom. Surveys were distributed via the internet as well as manually to reach people with no internet access as well. Attitudes of people of Potchefstroom were mostly positive with more than half of the sampled population of 295 respondents indicating a strong liking in frogs. This study provides evidence that the presence of myths and knowledge can highly affects people’s attitudes towards frogs. The second part of this study focussed on the motivations of volunteers saving Western Leopard Toads from roadkill in Cape Town, South Africa. Volunteers were motivated by a strong value-driven approach to saving toads. CHAPTER EIGHT provides a general discussion and outline on the contributions this study presented and also the new areas where more research is needed within the extent of the field of urban ecology from a South African perspective. / hD (Zoology), North-West University, Potchefstroom Campus, 2014

Urbanisation is an ever-growing global phenomenon which creates altered environments characterised by increased human habitation, exotic species, impermeable surfaces, artificial structures, landscape fragmentation, habitat loss, and modified energy– and resource pathways. The vulnerable Rand Highveld Grassland vegetation unit in the Tlokwe Municipal area, South Africa, has been extensively degraded and transformed by urbanisation and agriculture. Only 1% of this endangered ecosystem is currently being actively conserved. Grassland fragments in urban areas are considered to be less species rich and less functional than their more “natural” counterparts, and are therefore not a priority for conservation. In this study the effects of landscape matrix quality on intra patch variables, namely plant species diversity and functional diversity, and fine-scale biogeochemical landscape function (as determined by Landscape Function Analysis or LFA) of 30 fragments of the Rand Highveld Grassland vegetation unit were explored. Four urbanisation measures (percentage urban land cover, percentage grass land cover, edge density, and density of people), acting as indicators for patterns and processes associated with urban areas, were calculated for matrix areas with a 500m radius surrounding each selected grassland fragment to quantify the position of each grassland remnant along an urban-to-rural gradient. Using the specific urbanisation measures, the grassland fragments were objectively classified into two classes of urbanisation, namely “rural/peri-urban” and “urban”, to allow for statistical comparisons between intra-patch variables for grassland remnants exposed to similar urbanisation pressures. Plant species composition and diversity were determined in the selected grassland fragments and nine functional traits were described for each species. Plant functional diversity was determined by five functional diversity indices, namely functional richness, evenness, divergence, dispersion, and specialisation. Fine-scale biogeochemical landscape function was determined by executing the LFA method. LFA assesses fine-scale landscape patchiness and 11 soil surface indicators to produce three main LFA parameters (stability, infiltration, and nutrient cycling), which indicates how well a system is functioning in terms of resource conservation and soil processes. Possible relationships between fine-scale biogeochemical landscape function and plant species- and functional diversity were also investigated. NMDS ordinations and basic statistics were used to determine trends and effects within the data. The results indicated that urban grassland remnants had lower mean plant species richness, Shannon species diversity (significantly), and Pielou species evenness than rural/peri-urban grassland fragments. Urban grassland fragments also contained significantly higher percentage of exotic species. Correlations were found between the four urbanisation measures and percentage species of the total species richness possessing certain functional attributes. This indicated that increased urbanisation may influence the species composition and the occurrence of certain plant traits in the selected grassland fragments. Urbanisation seems to have no effect on fine-scale landscape heterogeneity of the selected grassland fragments. Rural/peri-urban grassland fragments had higher infiltration capacity, nutrient cycling potential, and total SSA functionality (although not significantly), which may be ascribed to differences in management practices, such as mowing in urban areas and grazing in rural areas. Rand Highveld Grassland fragments in the urban landscape matrix of Potchefstroom city are just as conservable in terms of plant species diversity and functional diversity, as well as on a biophysical function level involving soil processes than rural/peri-urban grassland fragments. High plant species diversity and the presence of certain plant traits did not contribute to high soil surface stability, infiltration capacity, nutrient cycling potential and total soil surface functioning. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Urbanisation is an ever-growing global phenomenon which creates altered environments characterised by increased human habitation, exotic species, impermeable surfaces, artificial structures, landscape fragmentation, habitat loss, and modified energy– and resource pathways. The vulnerable Rand Highveld Grassland vegetation unit in the Tlokwe Municipal area, South Africa, has been extensively degraded and transformed by urbanisation and agriculture. Only 1% of this endangered ecosystem is currently being actively conserved. Grassland fragments in urban areas are considered to be less species rich and less functional than their more “natural” counterparts, and are therefore not a priority for conservation. In this study the effects of landscape matrix quality on intra patch variables, namely plant species diversity and functional diversity, and fine-scale biogeochemical landscape function (as determined by Landscape Function Analysis or LFA) of 30 fragments of the Rand Highveld Grassland vegetation unit were explored. Four urbanisation measures (percentage urban land cover, percentage grass land cover, edge density, and density of people), acting as indicators for patterns and processes associated with urban areas, were calculated for matrix areas with a 500m radius surrounding each selected grassland fragment to quantify the position of each grassland remnant along an urban-to-rural gradient. Using the specific urbanisation measures, the grassland fragments were objectively classified into two classes of urbanisation, namely “rural/peri-urban” and “urban”, to allow for statistical comparisons between intra-patch variables for grassland remnants exposed to similar urbanisation pressures. Plant species composition and diversity were determined in the selected grassland fragments and nine functional traits were described for each species. Plant functional diversity was determined by five functional diversity indices, namely functional richness, evenness, divergence, dispersion, and specialisation. Fine-scale biogeochemical landscape function was determined by executing the LFA method. LFA assesses fine-scale landscape patchiness and 11 soil surface indicators to produce three main LFA parameters (stability, infiltration, and nutrient cycling), which indicates how well a system is functioning in terms of resource conservation and soil processes. Possible relationships between fine-scale biogeochemical landscape function and plant species- and functional diversity were also investigated. NMDS ordinations and basic statistics were used to determine trends and effects within the data. The results indicated that urban grassland remnants had lower mean plant species richness, Shannon species diversity (significantly), and Pielou species evenness than rural/peri-urban grassland fragments. Urban grassland fragments also contained significantly higher percentage of exotic species. Correlations were found between the four urbanisation measures and percentage species of the total species richness possessing certain functional attributes. This indicated that increased urbanisation may influence the species composition and the occurrence of certain plant traits in the selected grassland fragments. Urbanisation seems to have no effect on fine-scale landscape heterogeneity of the selected grassland fragments. Rural/peri-urban grassland fragments had higher infiltration capacity, nutrient cycling potential, and total SSA functionality (although not significantly), which may be ascribed to differences in management practices, such as mowing in urban areas and grazing in rural areas. Rand Highveld Grassland fragments in the urban landscape matrix of Potchefstroom city are just as conservable in terms of plant species diversity and functional diversity, as well as on a biophysical function level involving soil processes than rural/peri-urban grassland fragments. High plant species diversity and the presence of certain plant traits did not contribute to high soil surface stability, infiltration capacity, nutrient cycling potential and total soil surface functioning. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Dans un monde où plus de la moitié de la population mondiale vit en ville, les espaces verts constituent une composante fondamentale du paysage urbain car ils fournissent de nombreux services environnementaux (e.g. purification de l'air et de l'eau, filtrage du vent et du bruit, atténuation de l’îlot de chaleur urbain), mais également des services sociaux et psychologiques (e.g. développement des liens sociaux, réduction du stress) qui revêtent une importance cruciale pour l'habitabilité des villes modernes et le bien-être des citadins. L’efficacité des services écologiques rendus par les espaces verts en ville dépend de la qualité de leur sol et de leur fonctionnement général, et des conditions abiotiques et biotiques dans lesquelles ils se trouvent. De nombreuses études ont mis en évidence l’impact direct et indirect des activités humaines sur les sols urbains. Les pressions anthropiques qu’ils subissent modifient d’une manière très complexe leurs caractéristiques, et impactent donc leur qualité. La qualité des sols urbains est donc aujourd’hui un enjeu majeur pour la durabilité des villes de demain. Le présent projet de thèse a ainsi cherché à évaluer les effets de la pression urbaine sur les composantes de la qualité des sols d’espaces verts publics de la région Île-de-France à travers l’utilisation d’un gradient de pression urbaine innovant, et selon deux usages de sols (pelouses et bois). Dans un deuxième temps, ce travail de thèse a également cherché à déterminer si la calorimétrie différentielle couplée à l’analyse infra-rouge gazeuse (DSC–EGA) était une méthode adaptée à l’évaluation de la qualité de la matière organique des sols (MOS) urbains, et sur une échelle régionale. Tous les sols sélectionnés dans ce projet de thèse sont classifiés comme Anthrosol... / In a world where more than half of the world's population lives in cities, green spaces are a fundamental component of the urban landscape, providing many environmental services (e.g. air and water purification, wind and noise filtering, urban heat island attenuation), but also social and psychological services (e.g. development of social bonds, stress reduction) which are of crucial importance for the habitability of modern cities and the well-being of urban dwellers. The effectiveness of ecological services provided by green areas in the city depends on the quality of their soils and their general functioning, but also on the abiotic and biotic conditions in which they are located. Numerous studies have highlighted the direct and indirect impact of human activities on urban soils. The anthropogenic pressures they undergo alter their characteristics in a complex way, thus affecting their quality. Urban soil quality is therefore a major challenge for the sustainability of the cities of tomorrow. This thesis project sought to assess the urban pressure effects on the soil quality components of the Paris region public green spaces through the use of an innovative urban pressure gradient, and according to two land-use types (lawns and woods). Secondly, this work also sought to determine whether differential scanning calorimetry coupled with evolved gaz analyzer (DSC–EGA) was a suitable method for assessing the organic matter of urban soils (SOM), and on a regional scale. All soils selected in this thesis project are classified as Anthrosol...

No description available.