abstract: The relationship between biodiversity and ecosystem functioning (BEF) is a central issue in ecology, and a number of recent field experimental studies have greatly improved our understanding of this relationship. Spatial heterogeneity is a ubiquitous characterization of ecosystem processes, and has played a significant role in shaping BEF relationships. The first step towards understanding the effects of spatial heterogeneity on the BEF relationships is to quantify spatial heterogeneity characteristics of key variables of biodiversity and ecosystem functioning, and identify the spatial relationships among these variables. The goal of our research was to address the following research questions based on data collected in 2005 (corresponding to the year when the initial site background information was conducted) and in 2008 (corresponding to the year when removal treatments were conducted) from the Inner Mongolia Grassland Removal Experiment (IMGRE) located in northern China: 1) What are the spatial patterns of soil nutrients, plant biodiversity, and aboveground biomass in a natural grassland community of Inner Mongolia, China? How are they related spatially? and 2) How do removal treatments affect the spatial patterns of soil nutrients, plant biodiversity, and aboveground biomass? Is there any change for their spatial correlations after removal treatments? Our results showed that variables of biodiversity and ecosystem functioning in the natural grassland community would present different spatial patterns, and they would be spatially correlated to each other closely. Removal treatments had a significant effect on spatial structures and spatial correlations of variables, compared to those prior to the removal treatments. The differences in spatial pattern of plant and soil variables and their correlations before and after the biodiversity manipulation may not imply that the results from BEF experiments like IMGRE are invalid. However, they do suggest that the possible effects of spatial heterogeneity on the BEF relationships should be critically evaluated in future studies. / Dissertation/Thesis / M.S. Biology 2011

Forest encroachment is understood to be the main reason for prairie grassland decline across the United States. In Texas and Oklahoma, juniper has been highlighted as particularly opportunistic. This study assesses the usefulness of three remote sensing techniques to aid in locating the areas of juniper encroachment for the LBJ Grasslands in Decatur, Texas. An object based classification was performed in eCognition and final accuracy assessments placed the overall accuracy at 94%, a significant improvement over traditional pixel based methods. Image biomass was estimated using normalized difference vegetation index (NDVI) for 1 meter resolution IKONOS winter images. A high correlation between the sum of NDVI for tree objects and field tree biomass was determined where R = 0.72, suggesting NDVI sum of a tree area is plausible. However, issues with NDVI saturation and regression produced unrealistically high biomass estimates for large NDVI. Canopy height model (CHM) derived from 3-5m LiDAR data did not perform as well. LiDAR typically used for digital elevation model (DEM) production was acquired for the CHM and produced correlations of R = 0.26. This suggests an inability for this particular dataset to identify juniper trees. When points that registered a tree height where correlated with field values, an R = 0.5 was found, suggesting denser point spacing would be necessary for this type of LiDAR data. Further refining of the methods used in this study could yield such information as the amount of juniper tree for a given location, fuel loads for prescribed burns and better information for the best approach to remove the juniper and ultimately management juniper encroachment into grasslands.

Thesis (M. Sc. (Botany)) -- University of Limpopo, 2019 / The Woodbush Granite Grassland (WGG) is the most threatened vegetation type in Limpopo Province of South Africa. However, it has a high conservation value, because few examples of this vegetation type remain in southern Africa. Unfortunately, a large part of it is not formally conserved, making this the vegetation type most urgently in need of conservation. The study aimed at mapping transformation of the WGG, identifying species of conservation importance, and providing a management plan required for maintenance of the WGG. The objectives of the study included compiling a transformation map for the WGG, which also involved describing the remaining patches of the WGG that are in a natural or near-natural state. It also provides information on species of conservation importance, medicinal plants and threats to the WGG. On the four main study sites (Iron Crown Grassland, Haenertsburg Grassland, Ebenezer Dam Nature Reserve Grassland, and Ebenezer Dam Perimeter Grassland), quadratic plots were randomly set with a size of 25 x 25 m, and subplots of 1 x 1 m. Vegetation mapping was done during summer and winter. At each plot data was collected on all plant species occurring within the quadrat. A cover score was assigned to each plant species. A modified Braun-Blanquet data collection sheet was employed to obtain baseline data. For transformation mapping GeoTerra Image (GTI), land cover data were extracted for the WGG, using the modelled boundary as a mask, with 5 categories of transformation defined. Of the surveyed sites, the Ebenezer Dam Nature Reserve Grassland has the highest number of species, while the Haenertsburg Grassland contained the most endemic species of conservation importance. Rare species such as the Aloe zebrina, which does not occur in any formally protected area, and medicinal plants such as Athrixia phylicoides, occur on the WGG. All sites have importance with regard to WGG conservation. Identified threats include the spread of alien invasive plants, uncontrolled collection of medicinal plants, urban development, and poorly timed anthropogenic fire. vi The WGG underwent transformation to other land classes. Grassland clearing for plantations and cultivation were the main causal factors behind the observed WGG losses, with a total of 55.25% transformed. Transformation by afforestation is considered irreversible. It is concluded that the WGG is of conservation importance, and that some of it has been transformed to exotic timber plantations. The grassland is under various threats; therefore it is recommended that: (1) The proposed management plan provided in this study be adopted, (2) further research on the WGG be done on medicinal plants, (3) phytosociological and floristic studies be conducted and, (4) the effects of fire and alien invasive plant species on the grassland be investigated.

As rural populations decrease and cities expand, the importance of urban ecological research becomes globally significant. Urban ecology seeks to understand the complex relationships between human settlements and their ecological contexts in an attempt to ensure sustainable futures. The discipline of urban ecology is at the forefront of the conflict between human perceptions, economy, and politics. Despite numerous studies conducted in urban areas in South Africa, no one city has yet synthesized all the amassed research conducted within its city limits. A shortage of detailed ecological data, therefore, led to an extensive study of urban open spaces in some cities of the North-West Province encompassing multiple disciplines. Consequently, this study attempts to consolidate and evaluate all the existing urban ecological research in South Africa and specifically, in the city of Potchefstroom. Firstly, a comprehensive overview of South African urban ecological literature discussing the early development, research themes and the future of urban ecology in South Africa was carried out. Three hundred and fourteen publications were reviewed and categorized into the following research themes: physical environment, biodiversity, management, conservation, planning, human needs, sustainability, public participation, ecosystem services, and resilience. Secondly, as researchers have long been interested in studying and explaining patterns of biodiversity in natural and anthropogenic landscapes, many theories have been proposed on the drivers of these patterns and numerous studies compare current land-use effects with biotic assemblages. However, a much-neglected perspective in urban ecological research is the impact of the history of the landscape. Consequently, the second paper investigated the possible time lags in the response of temperate natural grasslands to urbanization and the factors driving these changes. Thirdly, a study of the temporal vegetation dynamics of urban grasslands in Potchefstroom over a 17-year period was carried out. Open grasslands, woody vegetation sites, and vacant lots were resurveyed within the city limits. The potential change in species richness and abundance of species, and the differences in species composition between these three habitat types were compared. Lastly, the fourth paper synthesizes all the relevant existing interdisciplinary research carried out of urban open spaces in Potchefstroom. This is evaluated against municipal governance and management strategies, environmental law, public opinion and the steep spatially organized socio-economic gradient found in Potchefstroom, informing the progress towards a sustainable, liveable city. The results of the literature study indicated that there were various gaps within each theme that need to be addressed in future. In the study on the effects of urbanization history on observed vegetation patterns, the woody vegetation showed important time lags in the response of indigenous species richness to urbanization. The measures altitude and the road network density of natural areas were the most frequent predictors of species richness. Results of the temporal vegetation dynamics of urban grasslands indicated that in the relatively short 17 year period most vegetation diversity indices changed significantly, specifically a significant decrease in indigenous species richness of both grasslands and woody communities were noted. The synthesis of all the studies carried out in Potchefstroom revealed an impressive number of studies carried out, however most of the biodiversity groups were represented by a single investigation only. Evaluating the results with the IDP revealed than much of the known ecological information in Potchefstroom remains undiscovered by municipal policymakers. Moreover, proposed future development is planned for some of the highest biodiversity sites. This synthesis and the subsequent identification of the gaps in our understanding and research themes will allow a purposeful and informed advancement of the science of urban ecology in South Africa and the contribution thereof towards advancing urban ecology globally. In addition, the history of urbanization affects contemporary vegetation assemblages in urban areas indicating potential extinction debts. Moreover, the significant decreases in indigenous species richness of woody and grassland sites have important consequences for urban grassland conservation in South Africa. Subsequently, the knowledge and the identification of research gaps allow decision makers in Potchefstroom to plan for sustainable future solutions and for this city to emerge as a leading role player in the South African urban ecological context. The results of this thesis could be a substantial practical aid in policy and management strategies furthering decision makers in the pursuit of the elusive goal of developing sustainable cities. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

As rural populations decrease and cities expand, the importance of urban ecological research becomes globally significant. Urban ecology seeks to understand the complex relationships between human settlements and their ecological contexts in an attempt to ensure sustainable futures. The discipline of urban ecology is at the forefront of the conflict between human perceptions, economy, and politics. Despite numerous studies conducted in urban areas in South Africa, no one city has yet synthesized all the amassed research conducted within its city limits. A shortage of detailed ecological data, therefore, led to an extensive study of urban open spaces in some cities of the North-West Province encompassing multiple disciplines. Consequently, this study attempts to consolidate and evaluate all the existing urban ecological research in South Africa and specifically, in the city of Potchefstroom. Firstly, a comprehensive overview of South African urban ecological literature discussing the early development, research themes and the future of urban ecology in South Africa was carried out. Three hundred and fourteen publications were reviewed and categorized into the following research themes: physical environment, biodiversity, management, conservation, planning, human needs, sustainability, public participation, ecosystem services, and resilience. Secondly, as researchers have long been interested in studying and explaining patterns of biodiversity in natural and anthropogenic landscapes, many theories have been proposed on the drivers of these patterns and numerous studies compare current land-use effects with biotic assemblages. However, a much-neglected perspective in urban ecological research is the impact of the history of the landscape. Consequently, the second paper investigated the possible time lags in the response of temperate natural grasslands to urbanization and the factors driving these changes. Thirdly, a study of the temporal vegetation dynamics of urban grasslands in Potchefstroom over a 17-year period was carried out. Open grasslands, woody vegetation sites, and vacant lots were resurveyed within the city limits. The potential change in species richness and abundance of species, and the differences in species composition between these three habitat types were compared. Lastly, the fourth paper synthesizes all the relevant existing interdisciplinary research carried out of urban open spaces in Potchefstroom. This is evaluated against municipal governance and management strategies, environmental law, public opinion and the steep spatially organized socio-economic gradient found in Potchefstroom, informing the progress towards a sustainable, liveable city. The results of the literature study indicated that there were various gaps within each theme that need to be addressed in future. In the study on the effects of urbanization history on observed vegetation patterns, the woody vegetation showed important time lags in the response of indigenous species richness to urbanization. The measures altitude and the road network density of natural areas were the most frequent predictors of species richness. Results of the temporal vegetation dynamics of urban grasslands indicated that in the relatively short 17 year period most vegetation diversity indices changed significantly, specifically a significant decrease in indigenous species richness of both grasslands and woody communities were noted. The synthesis of all the studies carried out in Potchefstroom revealed an impressive number of studies carried out, however most of the biodiversity groups were represented by a single investigation only. Evaluating the results with the IDP revealed than much of the known ecological information in Potchefstroom remains undiscovered by municipal policymakers. Moreover, proposed future development is planned for some of the highest biodiversity sites. This synthesis and the subsequent identification of the gaps in our understanding and research themes will allow a purposeful and informed advancement of the science of urban ecology in South Africa and the contribution thereof towards advancing urban ecology globally. In addition, the history of urbanization affects contemporary vegetation assemblages in urban areas indicating potential extinction debts. Moreover, the significant decreases in indigenous species richness of woody and grassland sites have important consequences for urban grassland conservation in South Africa. Subsequently, the knowledge and the identification of research gaps allow decision makers in Potchefstroom to plan for sustainable future solutions and for this city to emerge as a leading role player in the South African urban ecological context. The results of this thesis could be a substantial practical aid in policy and management strategies furthering decision makers in the pursuit of the elusive goal of developing sustainable cities. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

The antelope jackrabbit (Lepus alleni) inhabits the seasonal landscape of the subtropical Sonoran savanna grassland in southern Arizona. Basic ecological information on this understudied lagomorph is lacking beyond historical responses to rangeland conditions. This is the first study to utilize radio collars to assess space use of antelope jackrabbits. In the semidesert grassland of Buenos Aires National Wildlife Refuge, Arizona, we estimated antelope jackrabbit home range size, seasonal ranges, and movement patterns. Home range estimates were comparable to other Lepus species, however, seasonal range sizes did not differ. We analyzed antelope jackrabbit habitat structure, measured vegetation characteristics, and determined whether there was a spatial association between antelope jackrabbits and the endangered Pima pineapple cactus (Coryphantha scheeri var. robustispina). Antelope jackrabbits selected vegetation structure and characteristics similarly to available areas on the refuge. We did not detect a spatial association between antelope jackrabbits and Pima pineapple cacti, however given the importance of understanding endangered species relationships, further investigation is warranted. Our results add to the limited ecological information known about antelope jackrabbits and provide baseline data for future studies. Knowledge about spatial ecology and habitat selection helps managers and biologists make informed recommendations for land and wildlife management.

The evaluation of the state of grass species composition was conducted as an attempt to confirm the survey conducted by the United Nations Convention to Combat Desertification (UNCCD), where the Zeerust District was identified as an area with serious degradation problems. Quantitative data was obtained through botanical surveys (April 2001-February 2002) and verified by household surveys (March 2001-April 2002). Study sites included Braklaagte, Dinokana, Doomlaagte, Serake and Supingstad, with benchmark sites in Madikwe Grune Reserve. Between 6-12 survey points per site were selected after consultation with local Agricultural Extension Officers and communities. Survey points included the range of veld condition between bush encroached and severely denuded and eroded areas. The results indicate 12.3 % to 45.1 % loss of vegetal cover. Resistance above 2 000 ohms, base saturation exceeding 100 % and pH values below 5.5 are evidence of soil degradation. The general profile of the fanning household is that of an aging adult community, with however, a relatively good knowledge of fanning practices. 52 % of the respondents depend on the government pension fund as a source of income. 60 % of the respondents use crop fanning products strictly for household purposes. Poor economic return from fanning activities has resulted in overutilization of the herbaceous layer with consequent changes of grass species composition towards retrogression and the establishment of woody species. This environmental degradation is a serious risk to long-term sustainable development. It is therefore, recommended that environmental education programmes and ecological restoration projects be started in degraded areas. The government should set up and enforce land-use policies. Community participation should be encouraged in all land care activities. Land degradation is a real social problem that must be tackled before many people's aspirations of a better life are met. / Thesis (M.Sc. (Biology) North-West University, Mafikeng Campus, 2003

The best way of dealing with the restoration of chalk grassland encroached by scrub is unclear and the subject of many debates. The traditional method is to clear the scrub primarily by manual methods of cutting the scrub and after clearance the land is left to regenerate naturally. More recently the development of using livestock to browse and gradually reduce the scrub is thought to be an alternative. However the effectiveness of either of these methods (Manual clearance or Livestock browsing) is questioned by many and some believe that once scrub has encroached, the soils beneath this will become too enriched to be able to support a chalk grassland flora. This thesis aimed to provide a better understanding by undertaking a five year investigative trial of the two restoration methods and comparing and examining the ability of these to successfully restore a chalk grassland habitat. To undertake this both methods were trailed on scrub invaded chalk grassland and changes in vascular plants and invertebrates were monitored throughout trial period. Areas of nonintervention scrub were also included to act as controls. Successful restoration was assessed by comparing the results from the trials with measurable vascular plant restoration targets that were identified and set from known chalk grasslands in favourable condition. Soil fertility within the trial area was also examined to determine if the soils were considered to fertile to support a chalk grassland flora and costs and practicalities of using ether method were recorded throughout enabling these to be taken into account. The results showed that differences in both the species richness and composition of vascular plants and spider and beetles invertebrate species occurred. Soil fertility was found to suitable to support chalk grassland plants and vascular plants species were identified as moving away from those associated with scrub into those associated with chalk grasslands. It was observed however that on the areas trailed using Manual clearance, an initial flush of ruderal species occurred after clearance, it was therefore concluded that for Manual clearance to be successful continued restoration management is required if these species are to be controlled. It was also observed that the areas trailed using Manual clearance were moving towards successful restoration quicker those trailed using Livestock browsing thus indicating that the rate of change is more gradual using Livestock browsing. This rate of change was also found to occur within the invertebrate beetles and spider communities. Species richness within the spider communities however decreased on the areas manually cleared. Costs of using the restoration methods showed that the use of Livestock browsing was five times more costly that using Manual clearance. However it was found that majority of Livestock browsing costs incurred through welfare and husbandry of the stock. Restoration using Manual clearance also involved using livestock once scrub had been cleared however the costs of these were born by a local grazier and thus did not show as a cost of restoration. It was concluded that if a grazier is not found then these costs would be incurred. Overall it is concluded that both Livestock browsing and Manual clearance have the ability to successfully restore a chalk grassland community but that this must be viewed as a long term objective. Restoration management is critical to continue after clearance until restoration targets have been met.