Southern African Landscapes and Environmental Change

Peter J. Holmes, John Boardman

• Publisher: Routledge
• Year: 2018
• Print ISBN: 9781138688957
• eBook ISBN: 9781134972395
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Ecology

This volume provides a textbook and reference work on the physical and biotic landscapes of Southern Africa. It examines the links between these environments and the ways in which they have been, are and will likely be subject to change. It covers the geomorphology, soils, vegetation and land use across a range of landscapes, including mountains, coasts, savannah, drylands and wetlands, and identifies the impacts of current and potential climate change and other factors on these environments.

The geographical focus is on the region defined by Namibia, South Africa, Botswana, Mozambique, Zimbabwe, Lesotho and Swaziland. Illustrated throughout in full colour, the book will serve as a reference volume for researchers and environmental professionals internationally, as well as a textbook for senior undergraduate and graduate-level students of geography, ecology and environmental studies in Southern Africa.

1
Introduction

Peter J. Holmes and John Boardman

The aim of this book is to bring together recent work on southern Africa’s biophysical landscapes in as much as landscapes both influence, and are influenced by, environmental change. The book comprises, between its Introduction and Conclusion, thirteen chapters by a number of southern African and United Kingdom authors, all of whom are research-active in the subcontinent. The authors present their work which, as will become apparent to the reader, covers a number of disciplines in the natural and social sciences. This is done in such a way as to present the reader with an accessible, appropriately illustrated synthesis of the associations between southern African biophysical landscapes and environmental change. Further details on the work may be found in the reference lists included with each chapter. The region of southern Africa is defined as covering Botswana, Lesotho, Mozambique, South Africa, Namibia, Swaziland and Zimbabwe.

As editors, we identified an area in the recent literature on southern African environmental change which lent itself to further elaboration and discussion. We would both describe ourselves first and foremost as geomorphologists with a particular interest in natural and anthropogenically induced landscape change. The rationale behind this volume is a better understanding of present and future landscapes (here we use the term in a broad sense, to cover the whole of the biophysical environment) in the southern African region. By way of background, two fairly recent volumes (Holmes and Meadows, 2012; Grab and Knight, 2015) dealt with the geomorphology of southern and South Africa respectively. These volumes largely superseded the volume from Moon and Dardis (1988) which was published thirty years ago. While the volume edited by Holmes and Meadows (2012) focused on recent trends and new directions in geomorphological research in southern Africa, Grab and Knight (2015) point out that published work around the geology and geomorphology of the subcontinent is focusing increasingly on current issues such as landscape sensitivity, sustainable resource management and, of course, environmental change. Their volume was complemented by the publication of Knight and Grab (2016) which examines what the title suggests, namely Quaternary environmental change in southern Africa.

Two additional volumes with regard to southern African biophysical environments must be mentioned. These are Soils of South Africa (Fey, 2010) and Vegetation of Southern Africa (Cowling et al., 2004). The titles are self-explanatory. Notwithstanding the significant volume of research across the full range of disciplines focusing on southern Africa’s biophysical environments, we felt that a reasonably concise volume, looking at southern Africa’s biophysical environments in the context of recent environmental change, could be useful to a broad readership mentioned below.

The current work is, therefore, different from the volumes mentioned above in that it examines a spectrum of topical and pressing environment issues from a broader biophysical perspective. These range from what might be regarded as baseline fundamentals, such as the geomorphic evolution of the subcontinent, its soils and its natural vegetation, to critical management issues around resources such as water, and human activities such as farming which depend on the inherent characteristics of specific southern African biophysical environments. As such, the book purports to be of value to a wide readership, ranging from academia to those in managerial and decision making roles in both government and corporate positions where aspects of the biophysical environment are relevant. The volume may also appeal to a broader public readership with an interest in recent environmental change.

What is this volume not about? First, it is not a volume on climate change. We assume, a priori, that climate, along with all other components of the Earth-atmosphere system, changes over time (see Chapter 14 in this regard). The debates around the magnitude, rate and relevance of climate change are well known, and frequently controversial. We have no wish to be drawn into these debates, preferring to invite our contributing authors to focus on effects, rather than causes, of environmental change within their individual areas of expertise. Secondly, it is not a volume on Quaternary environmental change per se. Finally, the volume does not attempt to review or synthesise the current literature around either the evolution of southern Africa’s biophysical environments or their association with environmental change. As such, it does not, for example, claim to parallel Holmes and Meadows (2012).

With the above in mind, here follows a brief overview of the thirteen chapters which make up this volume. We have attempted to place the chapters within two broad, but overlapping divisions. Chapters 2 to 5 are by way of background. Each chapter contains a descriptive and explanatory component with regard to the particular component of the biophysical environment addressed in the chapter. This is followed, where appropriate, by a discussion around issues of vulnerability for that particular component. By way of example, certain southern African soils have inherent properties which make them susceptible to degradation under certain environmental conditions.

Turning to the content of this volume, in Chapter 1 Holmes and Boardman, the book’s editors, provide a brief rationale for the volume, and outline the content of the book in terms of its two broad subdivisions and chapter structure.

In Chapter 2, Knight and Grab discuss the main evidence for and controls on long-term landscape evolution in southern Africa. The authors point out that the conventional view on southern Africa as distinct, uplifted and largely unchanged peneplanes is problematic and the concept of landscape as a palimpsest is preferable. This implies the overprinting effect of recent processes on older landscapes thus modifying them. The process continued in the Quaternary (the last ~2 million years) with the considerable impact of alternating warm and cool climates at a regional scale.

Soils, to a greater or lesser extent, reflect aspects and properties of the landscape in which they develop. In Chapter 3, Du Preez, Kotzé and van Huyssteen describe the nature and properties of southern African soils, and introduce an important theme of the book, that of human impacts on the physical environment. These impacts are further elaborated on in the second part of the book.

In Chapter 4, Turton looks at southern African rivers in their capacity as a fresh water resource. This is done within the temporal context of the Anthropocene. By way of example, the author focuses on the mining and industrial heartland of South Africa, primarily the Vaal River catchment, as well as the Limpopo River. Each river has a unique biophysical characteristic, defined by the flood pulse and conversion of rainfall to streamflow and hence providing the fresh water resource on which all life depends.

Chapter 5, by Esler and Archer, introduces vegetation as the fourth key component (following geomorphology, fresh water and soils) of the biophysical landscape. The chapter comprises a systematic overview of the different biomes of southern Africa. While the chapter is, by design, primarily descriptive, it provides essential background for a fuller appreciation of, in particular, Chapters 6, 10 and 12.

The second part of the book commences with Chapter 6. Following on the inventory of southern African biomes in Chapter 5, Hoffman describes the extent to which different land use practices in southern Africa have influenced the vegetation of the region. The historical period, from the time of colonial settlement to the present, and especially the last 100 years, provides the temporal context for the chapter. Several case studies highlight the impact that land use has had on land cover, while the main trajectories of vegetation change reported within each of the major biomes of southern Africa are described.

Fluvial erosion has played a dominant role in shaping and modifying the landscapes of southern Africa during both geological times, and more recently. In Chapter 7, Rowntree, van der Waal and Smith-Adao discuss fluvial erosion, erosive mechanisms, and the consequences thereof. The authors focus on environmental change through modern time, which they consider to have begun with the spread of European settlement through South Africa from the mid-1800s.

Depending on exactly how these are defined, up to 50% of southern Africa could arguably be considered to comprise drylands, or dryland margins. Chapter 8, by Knight and Holmes, examines the unique challenges associated with these environments. Given the general aridity of the entire western half of the subcontinent, such challenges are important. Given too the unpredictable nature of environmental change over southern Africa and possible further aridification, the chapter is significant.

In Chapter 9, by Grab and Knight, the spotlight falls on what might be regarded as the opposite extreme, namely montane environments and their wetlands. In the case of southern Africa, the highlands and mountains of the eastern escarpment not only comprise unique landscapes and ecosystems but play a vital role in terms of water discharge and water storage. Management issues around southern Africa’s montane environments are discussed in this chapter.

The savannah biome covers a large area of southern Africa (see Figure 5.1). Unlike drylands and dryland margins, these savannahs support, in places, relatively dense human settlement and both subsistence and commercial agriculture. In Chapter 10, Mukwada elaborates on savannahs as distinctive ecosystems. The climatic conditions that prevail in southern African savannas and their ecological importance are described, and the ecological processes responsible for shaping the savannahs are outlined. The drivers behind these processes, including those induced by both natural and anthropogenic phenomena, are examined. The latter are intricately interwoven with human needs.

Due to its geographical position, southern Africa has a long, geomorphologically diverse coastline, bordering the Indian Ocean in the case of South Africa and Mozambique, and the Atlantic Ocean in the case of South Africa and Namibia. In Chapter 11, Carr and Smith examine both the physical nature of this coastline, as well as relevant management issues within the coastal zone. The authors review the underlying geomorphic processes and dynamics impacting on the southern African coastal zone and seek to illustrate the key processes shaping this coastline over a range of spatial and temporal scales.

In Chapter 12, van Huyssteen, Du Preez and Holmes discuss southern African agriculture and a changing biophysical environment. Possibly more than any other human activity relying on and intimately bound up with the biophysical environment, agriculture is subject to prevailing social, economic and political conditions which differ from country to country, and even region to region. These conditions can have just as great an impact as biophysical conditions. They therefore receive attention as part of this chapter.

In Chapter 13, Foster and Boardman return to the theme of land degradation and its impacts on the biophysical landscape (see also Chapters 6 and 7). They remind the reader that the notion of land degradation, once started, being regarded as unstoppable is not necessarily true. They use South African (the Swartland of the Western Cape), Namibian and Botswanan examples.

In the penultimate chapter of the volume, Chapter 14, Meadows and Holmes emphasise that the term environmental change is used to describe any changes to, typically, the physical or natural environment, regardless of spatial scale. They examine the many challenges of dating the spatially varied impacts of climate across southern Africa within both summer and winter rainfall zones. The imprint of these patterns of changing temperature and precipitation are still not entirely clear, which contributes to the challenge of predicting future scenarios for environmental change.

The volume concludes by way of a brief summary and observations by Holmes and Boardman. Looking at the volume as a whole, there are a number of issues which run like a thread through, especially, the second part of the book. We identify these, and comment on them in the Conclusion.

References

Cowling RM, Richardson D.M. and Pierce S.M. 2004. Vegetation of Southern Africa. Cambridge University Press, Cambridge.

Fey M.V.. 2010. Soils of South Africa. Cambridge University Press, Cape Town.

Grab S.W. and Knight J.. (eds.) 2015. Landscapes and Landforms of South Africa. Springer, Basel.

Holmes P.J. and Meadows M.E.. (eds.) 2012. Southern African Geomorphology: Recent Trends and New Directions. SUN, Bloemfontein.

Knight J. and Grab S.W.. (eds.) 2016. Quaternary Environmental Change in Southern Africa: Physical and Human Dimensions. Cambridge University Press, Cambridge.

Moon B.P. and Dardis G.F.. (eds.) 1988. The Geomorphology of Southern Africa. Southern, Johannesburg.

2
The geomorphic evolution of southern Africa during the Cenozoic

Jasper Knight and Stefan W. Grab

Introduction

The long-term landscape evolution of southern Africa has been a concern of geologists, geomorphologists, palaeontologists and ecologists since early studies on macroscale patterns of metalliferous rock types and topography, summarized by du Toit (1954) and King (1962). These early workers showed that (1) there is a close relationship between geology, topography and geomorphology in southern Africa, and (2) that different landscape elements are of different ages. From this, it can be inferred that the southern African landscape has evolved in different ways, in different places, and at different times, and that there is no single ‘narrative’ of landscape evolution ...

Table of contents

• Cover
• Title
• Copyright
• Contents
• List of illustrations
• List of contributors
• Acknowledgements
• 1 Introduction
• 2 The geomorphic evolution of southern Africa during the Cenozoic
• 3 Southern African soils and their susceptibility to degradation
• 4 Southern African rivers and fresh water resources within the context of the Anthropocene
• 5 Southern African biomes
• 6 Land use, land cover and vegetation change in southern Africa
• 7 Fluvial system response to environmental change
• 8 Southern African drylands and their unique challenges
• 9 Southern African montane environments
• 10 Savanna ecosystems of southern Africa
• 11 Landscape dynamics within the southern African coastal zone
• 12 Agriculture and a changing biophysical environment
• 13 Monitoring and assessing land degradation: New approaches
• 14 Quaternary environmental change
• 15 Conclusion
• Index