Please read the abstract in the section 09summary of this document / Thesis (PhD (Sustainable Ecological Management))--University of Pretoria, 2007. / Animal and Wildlife Sciences / unrestricted

Land degradation is a serious problem in communal district of Alfred Nzo, Eastern Cape in South Africa. The root causes of land degradation and soil erosion differ. The causes of land degradation in Alfred Nzo district communal areas are due to soil erosion by wind, water and poor agricultural practices. Rainfall is one of the most important climatic factor that contributed a lot in land degradation in the Alfred Nzo District. Other main factors contributing to land degradation include: Socio-economic factors related to historical land policies and inappropriate land uses, Poor land use planning, Drought and rainfall variability .Land use and management and sand mining. This study tried to pay more focus on the assessment of government policies which aimed at combating land degradation in South Africa in their nature but the area of focus will be Ntabankulu Local Municipality area in the project called Ematolweni Agricultural Co-operative Project. The reason to focus in this project is because they are currently practising crop production under electrified irrigation system but the main obstacle in this project are the dongas which are seemed to be a serious threat to the project site. During rainy seasons the project site is not easily accessible, that hampers access to market. There is also direct and serious effect of land degradation which is food insecurity which is emanating from loss of biodiversity and ground cover, loss of soil productivity, loss of income, decreased yield, and decline in economic productivity and national development. Lastly it is wisely recommended that to reduce the effect of land degradation in Alfred Nzo enlarge, government should strengthen the intervention programmes and provide more support to the LandCare programme which was the concept introduced in Australian and adopted in South Africa in 2001. This programme is assisting at restoring sustainability and productivity to land and water management in both rural and urban areas. It is holistic in nature, encompassing integrated sustainable natural resource management.

Land degradation in most communal parts of the Keiskamma catchment has reached alarming proportions. The Keiskamma catchment is particularly predisposed to severe land degradation associated with soil erosion, thicket degradation and deteriorating riparian vegetation. There is a close coupling between land use/cover dynamics and degradation trends witnessed in the catchment. Soil erosion is prevalent in most of the communal areas in the catchment. The principal aim of this study was to investigate land use/cover trends, model the spatial patterns of soil loss and predict future land use/cover scenarios as a means of assessing land degradation in the Keiskamma catchment. Multi-temporal Landsat satellite imagery from 1972 to 2006 was used for land use/cover change analyses using object-oriented post-classification comparison. Fragmentation analysis was performed by computing and analyzing landscape metrics in the riparian and adjacent hillslope areas to determine the land cover structural changes that have occurred since 1972. The landscape function analysis was used to validate the current rangeland conditions in the communal areas and the former commercial farms. The current condition of the riparian zones and proximal hillslopes was assessed using the Rapid Appraisal of Riparian Condition and future land use/cover scenarios were simulated using the Markovcellular automata model. Spatial patterns of soil loss in the Keiskamma catchment were determined using the Sediment Assessment Tool for Effective Erosion Control (SATEEC), which is a GIS based RUSLE model that integrates sediment delivery ratios. Object oriented classification was used to map soil erosion surfaces and valley infill in ephemeral stream channels as a means of demonstrating the major sediment transfer processes operating in the Keiskamma catchment. The Mahalanobis distance method was used to compute the topographic thresholds for gully erosion. To understand the effect of soil characteristics in severe forms of erosion, laboratory analyses were undertaken to determine the physico-chemical soil properties. iv The temporal land use/cover analysis done using the post-classification change detection indicated that intact vegetation has undergone a significant decline from 1972 to 2006. The temporal changes within the intermediate years are characterized by cyclic transitions of decline and recovery of intact vegetation. An overall decline in intact vegetation cover, an increase in degraded vegetation and bare eroded soil was noted. Fragmentation analyses done in the communal villages of the central Keiskamma catchment indicated increasing vegetation fragmentation manifested by an increase in smaller and less connected vegetation patches, and a subsequent increase of bare and degraded soil patches which are much bigger and more connected. The Landscape Organisation Index revealed very low vegetation connectivity in the communal rangelands that have weak local traditional institutions. Fragmentation analyses in the riparian and proximal hillslopes revealed evidence of increasing vegetation fragmentation from 1972 to 2006. The Markov Cellular Automata simulation predicted a decline in intact vegetation and an increase in bare and degraded soil in 2019. The Keiskamma catchment was noted as experiencing high rates of soil loss that are above provincial and national averages. The classification of erosion features and valley infill showcased the vegetation enrichment in the ephemeral streams which is occurring at the expense of high soil losses from severe gully erosion on the hillslopes. This in turn has led to an inversion of grazing patterns within the catchment, such that grazing is now concentrated within the ephemeral stream channels. Soil chemical analyses revealed a high sodium content and low soluble salt concentration, which promote soil dispersion, piping and gully erosion. The presence of high amounts of illite-smectite in the catchment also accounts for the highly dispersive nature of the soil even at low SAR values. Significant amounts of swelling 2:1 silicate clays such as smectites cause cracking and contribute to the development of piping and gullying in the catchment. Given the worsening degradation trends in the communal areas, a systematic re-allocation of state land in sections of the catchment that belonged to the former commercial farms is recommended to alleviate anthropogenic pressure. Strengthening local institutions that effectively monitor and manage natural resources will be required in order to maintain v optimum flow regimes in rivers and curb thicket degradation. Measures to curb environmental degradation in the Keiskamma catchment should encompass suitable ecological interventions that are sensitive to the socio-economic challenges facing the people in communal areas.

Orientadores: Carlos Roberto de Souza Filho, Juliano Alves de Senna / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T00:03:43Z (GMT). No. of bitstreams: 1 SoaresFilho_Adelsom_D.pdf: 18241807 bytes, checksum: f11fd992a9b6c4a961610919317e9db9 (MD5) Previous issue date: 2015 / Resumo: Análise de processos de transformação da paisagem com base em espectroscopia de reflectância e sensoriamento remoto multiespectral: Estudo de caso no núcleo de Gilbués, Piauí ¿ Brasil Processos de degradação da terra têm sido freqüentemente descritos no sudoeste do Piauí como um dos maiores casos de desequilíbrio ambiental do Brasil. Uma das áreas mais citadas é denominada de "Núcleo de Desertificação de Gilbués" (NDG). Inserido na faixa de transição entre o domínio dos cerrados do Brasil Central e o domínio do semiárido do nordeste brasileiro, essa área apresenta acentuada exposição de materiais de superfície relacionados à erosão do solo e degradação das terras. Nesse contexto, o principal objetivo desse trabalho é investigar a possível relação entre processos de degradação das terras, amplamente verificados no NDG, com variações na composição mineralógica dos solos e a compartimentação estrutural regional, visando demonstrar e debater potenciais efeitos causais, sejam eles naturais e/ou antrópicos, que possam ter funcionado como deflagradores ou maximizadores desses processos e seus efeitos. A metodologia abrangeu a determinação da composição físico-química do solo a partir de espectros de reflectância medidos em laboratório com um espectrorradiômetro portátil. Após a identificação das assembléias de minerais presentes em diferentes tipos de solos, suas similaridades foram avaliadas, o que favoreceu a escolha de endmembers representativos da área, os quais foram, em seguida, utilizados na classificação das imagens ASTER. Os intervalos espectrais na região do visível (520-690 nm), NIR (0.78-860 nm), SWIR (1.300-2.500 nm) e TIR (8.125-11.65 nm) foram investigados. Os resultados indicam que a caulinita corresponde ao material de topo e as esmectitas ao da base das vertentes. Os minerais mapeados foram distribuídos espacialmente na base de dados e de acordo com as características de declive, suscetibilidade erosiva do solo e uso da terra, e classificados segundo diferentes estágios de degradação. A exposição dos terrenos aparenta ser um processo predominantemente natural, com alguma contribuição antrópica. Os resultados obtidos podem contribuir para o entendimento de sistemas ambientais em avançados estágios de degradação da terra. O uso dos dados e métodos de sensoriamento remoto aqui experimentados com sucesso podem ser reaplicados em ambientes análogos visando atingir objetivos equivalentes / Abstract: Analysis of landscape transformation process based on reflectance spectroscopy and multispectral remote sensing: a case of study in the Gilbues Desertification Core, Piauí State, Brazil Land degradation processes have been described in southwest Piauí as a leading case of environmental imbalance in Brazil. One of the key studied areas is referred to as the "Gilbués Desertification Core" (GDC). Inserted in the transition zone between the central Brazilian Cerrado (savanna) terrains and the Northeastern Brazilian semi-arid terrains, the area has an ample exposure of surface materials related to soil erosion and land degradation. In this context, the main objective of this work is to investigate the possible relationship between land degradation processes, widely observed in the GDC, with variations in the mineralogical composition of the soils and regional structures. The notion is to demonstrate and discuss potential natural and/or anthropic causes, which may have worked as triggers or maximizers of the degradation processes and their effects. The method involved the determination of the physical-chemical composition of the soils from reflectance spectra measured in the laboratory with a portable spectrometer. Once mineral assemblages present in different types of soils were identified, their similarities were evaluated. This favored the choice of representative endmembers for specific sectors in the study area, which were used in the classification of ASTER images, considering Visible (520-690 nm), Near Infrared (780-860 nm), Shortwave Infrared (1.300-2.500 nm) and Thermal Infrared (8.125-11.650 nm) wavelengths. The results indicate that kaolinite dominates the top of the topographic highs, whereas smectite is commonly found along the slopes and in the pediplains. Mineral maps yielded from the ASTER data were merged with slope, soil erosion susceptibility and land use maps, and then classified according to different stages of degradation. The exposure of land and erosion appears to be a predominantly natural process, with minor anthropogenic contribution. The results yielded in the GDC may contribute to the understanding of environmental systems in advanced stages of land degradation. Remote sensing data and methods successfully tested here can be applied in comparable environments in order to reach similar goals / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutor em Ciências

Climate change and land degradation, which is defined as the decline in the productive capacity of the land, have profound implications for resource-based livelihoods and food security. In this dissertation, I use remote sensing to improve understanding of how climate variability affects the productivity of global pasturelands and to quantify the spatial and temporal patterns of land degradation in the Southern Cone region (SCR) of South America. In the first chapter, I characterize the sensitivity of global pastureland productivity to climate variability by analyzing the relationship between MODIS enhanced vegetation index and gridded precipitation data. Results show that pasturelands are least capable of withstanding precipitation deficits in Australia, while pasturelands in Latin America recover more slowly after drought compared to other regions. In the second chapter, I use Landsat observations to measure the magnitude, geography, and rate of change in the amount of bare ground, herbaceous and woody vegetation in the SCR since 1999. Paraguay experienced the highest proportional increase in herbaceous cover as a result of agricultural expansion and intensification, while Uruguay experienced the highest proportional increase in woody cover as a result of afforestation. Argentina, the largest and most heterogeneous country in the SCR, experienced widespread land cover changes from deforestation, reforestation, afforestation, and desertification, each of which varied in extent and magnitude by ecoregion. In the third chapter, I assess patterns of land degradation in the SCR using the United Nations Sustainable Development framework. My results show that 67.5% of the SCR experienced changes in land cover properties in the 21st century, with widespread improvement (i.e., increased productive capacity), along with substantial hotspots of degradation caused by expansion of agriculture and systematic decreases in precipitation. Monitoring degradation is necessary to assess ecosystem services, ensure food security, and develop land use policies designed to increase the resilience of land systems to the joint stresses imposed by climate change and a growing global population. The methods, datasets, and results from this dissertation provide an improved basis for creating such policies in some of the world’s most vulnerable and food insecure regions.

Student Number : 9511039F - MSc Dissertation - School of Animal, Plant and Environmental Sciences - Faculty of Science / An estimated 91 % of South Africa’s total land area is considered dryland and susceptible to desertification. In response, South Africa has prepared a National Action Programme to combat land degradation, and this requires assessment and monitoring to be conducted in a systematic, cost effective, objective, timely and geographically-accurate way. Despite a perception-based assessment of land degradation conducted in 1999, and a land-cover mapping exercise conducted for 2000/2001, there are few national scientifically rigorous degradation monitoring activities being undertaken, due largely to a lack of objective, quantitative methods for use in large-scale assessments. This study therefore tests a satellitederived index of degradation for the Limpopo Province in South Africa, which is perceived to be one of the most degraded provinces in the country. The long-term average maximum normalized difference vegetation index (NDVI), calculated from a time series (1985-2004) of NOAA AVHRR satellite images, as a proxy for vegetation productivity, was related to water balance datasets of mean annual precipitation (MAP) and growth days index (GDI), using both linear and non-linear functions. Although the linear regressions were highly significant (p<0.005), a non-linear four parameter Gompertz curve was shown to fit the data more accurately. The curve explained only a little of the variance in the data in the relationship between NDVI and GDI, and so GDI was excluded from further analysis. All pixels that fell below a range of threshold standard deviations less than the fitted curve were deemed to represent degraded areas, where productivity was less than the predicted value. The results were compared qualitatively to existing spatial datasets. A large proportion of the degraded areas that were mapped using the approach outlined above occurred on areas of untransformed savanna and dryland cultivation. However the optical properties of dark igneous derived soils with high proportions of smectitic minerals and therefore low reflectance, were shown to lower NDVI values substantially. Overall, there was an acceptable agreement between the mapped degradation and the validation datasets. While further refinement of the methodology is necessary, including a rigorous field-based resource condition assessment for validation purposes, and research into the biophysical effects on the NDVI values, the methodology shows promise for regional assessment in South Africa.

Many grasslands in arid and semi-arid regions are undergoing rapid changes in vegetation, including encroachment of woody plants and invasive grasses, which can alter the rates and patterns of fire and sediment transport in these landscapes. We investigated the spatial distribution of sediments at the scale of vegetated microsites for three years following a prescribed fire using a multiple rare earth element (REE) tracer-based approach in a shrub-grass transition zone in the northern Chihuahuan desert (New Mexico, USA). To this end, we applied REE tracers – holmium, europium, and ytterbium on shrub, grass, and bare microsites, respectively in March 2016. Soil samples were collected from both burned and control (not burned) sites before (March) and after (June) the annual windy season, from 2016 through 2018. Results indicate that although the horizontal mass flux (HMF) of wind-borne sediment increased approximately threefold in the first windy season following the fire, and the HMF of both plots were not significantly different after three windy seasons. Comparing REE concentrations in sediments from both plots over the three years and three annual windy seasons, we observed a post-fire shift in source and sink dynamics of sediments. The tracer analysis of wind-borne sediments indicated that the source of the HMF in the burned site was mostly derived from shrub microsites following the fire, whereas the bare microsites were the major contributors for aeolian sediment in control areas. The shift in sources and sinks, and the spatial homogenization of REEs indicate that the removal of shrub vegetation resulted in sediment redistribution to the bare microsites even three years after the prescribed fire. The findings of this study will improve our understanding of post-fire geomorphic processes at a microsite scale in a grassland ecosystem undergoing land degradation induced by shrub encroachment. / Geology

The objective of this dissertation is to establish the notion that art can serve to create and communicate an awareness of the interconnectedness between people and nature. This study debates the theoretical similarities and differences in attitudes toward the planet as interpreted in the artworks of pre-history shamans and traditional societies, 20th century land and urban artists and contemporary environmentally concerned artists. The comparative findings suggest that attitudes of anthropocentricism, greed and power and a denial of Pantheism associated with agriculture, industrial and technological developments, have changed the human-nature symbiosis found in early societies. The creative component of this study has employed the processes of etching and embossing, digital image manipulations and the juxtaposition and layering of images to establish visual metaphors that communicate interconnectedness. Sculptures, billboards, prints and photographs as artworks of the conscience intend to shift socially and personally constructed perceptions from human-centeredness toward a symbiotic worldview. / Art History, Visual Arts & Musicology / M.A. (Visual Arts)

Today's arid and semi-arid zones of the Mediterranean are affected by desertification, resulting from various factors, including climatic variations and human activities such as overcultivation, overgrazing and deforestation. Afforestation programs are one of the most effective means in preventing desertification. For many years Libya has had afforestation programs in order to restore degraded land and in response to rapid desert encroachment in the north east of Libya, in the area called the Jabal Akhdar (Green Mountain), which has been investigated in this study. The purpose of this research was to investigate the relative roles of exotic compared to native tree species in preventing desertification and enhancing degraded land restoration in the Jabal Akhdar. The effect of environmental factors on exotic compared to native tree species have been assessed by observations on growth and reproductive success of the species, including variables of stocking rate, trunk diameter, tree height, crown diameter, tree coverage, natural mortality, felling and seedling regeneration, as well as calculated variables, derived from these measurements. The effects of methods and age of afforestation on the promotion of biological diversity have been investigated using the Shannon-Wiener diversity index. The effects of tree species on soil depth have also been investigated. Multivariate statistical analyses of site, species and environmental data, using both cluster analyses and factor analyses have been performed, with the aim of determining what is influencing the species, crops or differentiating between the sites, based on soil depth, angle of slope, altitude, rainfall and air temperature values. Pinus halepensis showed success in its growth and regeneration, particularly at higher altitudes and steeper slopes. Cupressus sempervirens was successful in growth and regeneration in the mountains. The exotic Eucalyptus gomphocephala was very successful in its growth, but did not regenerate well, while the exotic Acacia cyanophylla trees had a failure of both growth and regeneration. E. gomphocephala species appeared to favour relativley the flatter (non-mountain) sites, while A. Cyanophylla appeared to favour relativly the mountain sites. All the species responded positively to greater rainfall and deep soil, but they differed in where they were most likely to be successful. Environmental factors such as climate, terrain and soil are the main determinants of species distribution in the study area, in addition to their impact on the growth of the main trees. There appeared not to be any relationship between biodiversity and whether the main trees were native or exotic, and only P. halepensis showed any negative effect on the abundance of shrubs. There was greater diversity of trees and shrubs generally at the younger sites than the old sites. The present study emphasises the current mismanagement of planted forests, particularly with overgrazing contributing to desertification, through preventing tree growth and eliminating most sapling regeneration. This study concludes by making recommendations for more effective choice of tree species to plant, and for subsequent management to improve afforestation programmes in the Jabal Akhdar area.

abstract: Use of off-highway vehicles (OHV) in natural landscapes is a popular outdoor activity around the world. Rapid-growing OHV activity causes impacts on vegetation and land cover within these landscapes and can be an important factor in land degradation and ecosystem change. The Algodones Dunes in southeastern California is one of the largest inland sand dune complexes in the United States and hosts many endangered species. This study examines changes in land cover and OHV activity within two OHV active sites in comparison to an adjoined protected area. The study also investigates potential associations between land cover changes, climate trends, and OHV activity over recent decades. Time-series analysis was used to investigate the spatial-temporal changes and trends in the land cover in the Algodones Dunes from 2001 to 2016. In addition, high-resolution aerial photographs were analyzed to determine spatial patterns of OHV usage in comparison to visitor estimation collected by the Bureau of Land Management and observed changes in land cover composition between the control site and OHVs areas. A decreasing trend in Normalized Difference Vegetation Index over time indicates a decline in the amount of vegetation cover, which corresponds with an increasing trend in albedo and land surface temperature. Results also show a substantial difference in land cover between the control site and OHVs areas, which typically have a lower amount of vegetation cover, higher exposed sand surface, and increased anthropogenic features. Both climatic variations and OHV activity are statistically associated with land cover change in the dune field, although distinct causal mechanisms for the observed declines in vegetation cover could not be separated. The persistence of drought could inhibit vegetation growth and germination that, in turn, would hinder vegetation recovery in OHV areas. Meanwhile, repeated OHV driving has direct physical impacts on vegetation and landscape morphology, such as canopy destruction, root exposure, and increased aeolian sand transport. Active ecosystem protection and restoration is recommended to mitigate the response of declining vegetation cover and habitat loss to the impacts of OHV activity and climatic variability and allow natural recovery of re-establishement of nebkha dune ecosystems in the Algodones Dunes. / Dissertation/Thesis / Masters Thesis Geography 2018