Ecology of Angola

Front matter

Ecology of Angola

Terrestrial Biomes and Ecoregions

A Springer

Foreword

Angola is globally recognised and envied for the richness of its biomes, ecoregions, fauna and flora. With habitats ranging from the rain forests of Cabinda to the ultra-desert of Namibe, Angola has a greater diversity of ecosystems than any other African country. In contrast to many other African nations, however, Angola has very few academic resources (textbooks, training manuals) to support students and young researchers studying the country’s living natural assets—its ‘life on land’. Furthermore, most of the books published on Angola’s biodiversity are not available in Portuguese. A critical challenge to students and researchers in Angola has been the reality that English is the international language of science.

This barrier to developing a new generation of motivated and skilled researchers and technicians, together with interested citizens, into the fields of biodiversity, conservation and sustainable development, has been recognised by academics both in Angola and Portugal. Encouraged and supported by the respective ministries of science, technology and higher education in both countries, several ambitious initiatives have recently been launched to address this language impediment. In this respect, CIBIO (the Research Centre in Biodiversity and Genetic Resources of the University of Porto) has made a major contribution.

CIBIO’s mission is to develop world-class research in the area of biodiversity, advancing knowledge on the origins and maintenance of biodiversity and applying this knowledge to address societal challenges related to climate and land use changes, environmental degradation, the loss and sustainable use of biodiversity and agrobiodiversity and the management, restoration and sustainable use of ecosystems and their services.

Over the past decade, the CIBIO initiatives in Africa have grown rapidly through several collaborative projects. These include the TwinLabs Programme, the UNESCO Chair Life on Land, and the evolution of CIBIO into a major Centre of Excellence—the BIOPOLIS Association—supported by the European Commission, the Portuguese Ministry of Science, through national and regional funding entities, the universities of Porto and Montpellier and multiple private sector investors.

vi Foreword

Throughout this phase of growth, CIBIO has worked closely with its Angolan partners to ensure a strong focus on the country’s priority needs in science, technology and higher education.

The first TwinLab was created in October 2012, in Angola, at the Higher Institute of Education Sciences (ISCED) of Lubango, Huila. Since then, the TwinLabs network has expanded through formal agreements with institutions of higher education in Mozambique, Namibia, South Africa, Zimbabwe and Botswana. Preparatory work is under way for the implementation, among others, of TwinLabs in São Tomé e Príncipe and Guinea-Bissau. The UNESCO Chair Life on Land was established in 2017 and the BIOPOLIS Association in 2021.

Results from these initiatives include an encouraging number of new publications, both generalist and technical, that can inspire students and encourage the general public to take an interest in and support the conservation of Angola's biodiversity. These include Biodiversity of Angola: A Modern Synthesis; South West Angola: A Portrait of Land and Life; 50 Birds of Angola: Rarity and Endemism; and the present volume, Biomes and Ecoregions of Angola: An Introduction to Terrestrial Ecology. Each of these authoritative books, published by CIBIO, is available in free-access ebook format, making them easily accessible to Angolan students. Further, through the UNESCO Chair Life on Land, two volumes of the UNESCO Biodiversity Learning Kits have been translated into Portuguese and published by CIBIO, in both hardcopy and e-book format. These richly illustrated volumes are of the highest technical quality and provide essential introductions to the biological sciences for secondary and tertiary-level students.

The strong collaboration between the Angolan and Portuguese ministries of science, technology and higher education has been fundamental to the success of these joint initiatives. With the evolution of CIBIO into the new BIOPOLIS Association, it is our firm expectation that our two countries will enjoy the benefits of a new generation of biodiversity scientists ready to meet the developmental needs of our countries. We therefore welcome the publication of the present volume, which will provide the basis for advanced courses in ecology, biodiversity and conservation at Angolan universities. We thank and congratulate CIBIO/BIOPOLIS on yet another outstanding contribution to Angolan biodiversity science and education.

Minister of Higher Education, Science, Technology and Innovation, Angola

Minister of Science, Technology and Higher Education, Portugal

Dr. Rosario Bragança Sambo Minister of Higher Education, Science, Technology and Innovation, Angola

Prof. Manuel Frederico Heitor Minister of Higher Education, Science, Technology and Innovation, Portugal

Preface

The need for a Portuguese language textbook with a focus on Angolan ecosystems has been recognised by the country’s academics and conservation professionals for many years. The present book results from discussions held with Vladimir Russo, Amándio Gomes, Fernanda Lages, Seródio d' Almeida and Brian Huntley at the launch of Biodiversity of Angola in Luanda in April 2019. The event marked the launch of two major books on Angolan biodiversity and regional landscapes, products of the CIBIO TwinLabs and UNESCO Life on Land initiatives. A primary objective of these projects, conceived and hosted by CIBIO, has been to support the development of facilities and tools for biodiversity research and education in Angola and other Lusophone countries. As Director of CIBIO, I requested the coordinator of the Biodiversity of Angola project, Professor Brian Huntley, to prepare a synthesis on the terrestrial ecosystems of the country, as a ‘student primer’. This somewhat more comprehensive Ecology of Angola: Terrestrial Biomes and Ecoregions is a consequence of our discussions.

This book provides a detailed account of the distribution, structure and functioning of Angolan biomes, ecoregions and ecosystems and the interactions of plant and animal species with their environment. It will serve as a learning resource for use by Angolan students, from undergraduate to postgraduate levels. For the first time in Africa, an ecological textbook has been devoted to a single country, in the national language. The subject matter provides a strong African perspective, using examples of ecological concepts, principles and phenomena drawn from Angolan landscapes, ecosystems and species. Furthermore, the book aims to develop an understanding of the mechanisms determining the dynamics of ecosystems in response to natural and human-driven changes. Such an understanding is essential for the sustainable use and conservation of Angola’s natural resources. The book is thus designed to serve not only students and the interested public, but also the key leaders of land use management policy, planning and practice.

The author, Professor Brian Huntley, has been actively involved in the survey and conservation of Angola’s ecosystems since 1971. Over the past 50 years, he has been repeatedly called upon by Angolan authorities and academics and international development agencies for advice and mentorship. He has initiated and led several

Vii viii Preface training expeditions for young Angolan ecologists and, most recently, coordinated the compilation and publication of a comprehensive synthesis of knowledge on the country's biodiversity.

Prof. Nuno Ferrand de Almeida UNESCO Life on Land Chair Holder Director, CIBIO/Associacáo BIOPOLIS Porto, Portugal

Acknowledgements

In preparing a work for use by present and future Angolan ecologists, it was clear that guidance would be needed from colleagues across southern Africa, most especially from Angola. My friends of many years—Seródio d' Almeida, Vladimir Russo, Amándio Gomes, Pedro Vaz Pinto, Francisco Gongalves and Martim Melo—were generous in their advice. In developing the structure of the book, ecologists Pedro Beja, William Bond, Chris Hines, John Mendelsohn, Bob Scholes and Thomas Smith gave valuable suggestions.

The rapidly expanding literature on the terrestrial ecology of southern Africa has provided a rich resource on challenging concepts and fascinating evidence, too much to reduce to a single volume. In contrast, published research on Angolan ecosystems remains embryonic, necessitating use of examples of ecological processes and phenomena from neighbouring countries. Here the enthusiastic support from colleagues across the continent and beyond was a source of great encouragement. As the technical content of the chapters evolved, specific material was contributed and the presentations enriched by leading specialists in key fields of research. In particular, the support of the following scientists is greatly appreciated.

e Francois Engelbrecht, Eckhart Freyer, Jasper Knight, Antonio Martins, John Mendelsohn, Roger Swart, John Ward, Mike de Wit (Geology, Geomorphology, Soils, Climate);

e Tristan Charles-Dominique, Gareth Hempson, Marc Stalmans, Brian van Wilgen (Fire and Herbivores);

e William Bond, Chris Hines, Bob Scholes (Ecosystem Processes);

e Sally Archibald, Amándio Gomes, Francisco Gongalves, Andre de Kesel, Frangois Malaisse, Rasmus Revermann, Bryan Shorrocks, Izak Smit, Nicola Stevens, Pedro Vaz Pinto, Luis Veríssimo, Paulina Zigelski (Mesic and Arid Savannas);

x Acknowledgements e Patricia Craven, Joh Henschel, Norbert Juergens, Gert Kruger, Barry Lovegrove, Ernst van Jaarsveld (Namib Desert);

e Michel Morais, Carmen van Dunem, Kostadin Luchansky, Kellie Pendoley (Mangroves);

e Tertius Gous, for use of the photo of Monteiro's Bushshrike in the Frontispiece.

These colleagues not only contributed original papers, figures and photos, but also reviewed many chapters. Where there are lapses or incorrect interpretations of evidence, the responsibility remains with me. My special thanks go to Nuno Ferrand for initiating the project, and to Christopher Hines and John Mendelsohn for regular discussion. Kenneth L Tinley's unique understanding of African landscapes has guided my approach to ecosystem ecology throughout my career. My wife, Merle, is thanked for her critical editorial support, and for sharing, supporting, enjoying and enduring a half-century of Angolaphilia.

Brian John Huntley CIBIO/Associagáo BIOPOLIS, Porto, Portugal

Editorial Notes

Definition of Terms: Important terms and concepts are indicated in bold at their first use, where a brief definition is given. A Glossary of Ecological Terms is provided. Vernacular terms (cacimbo, anhara, etc.) are indicated by the use of italics.

Common Names: Common names of mammals follow Beja et al. (2019), birds follow Mills & Melo (2013), and reptiles and amphibia follow Marques et al. (2018), where common names of animals or plants are used in a general sense (elephants, acacias), they are not capitalised.

Scientific Names: The scientific, English and Portuguese names of vertebrate species will be found in the above references and in the Appendix. Species names of plants follow Barbosa (1970) and Figueiredo & Smith (2008). The traditional taxonomy of Acacia is used rather than Vachellia (for species with capitate inflorescences and spinescent stipules) and Senegalia (for species with spicate flowers and non-spinescent stipules) (Kyalangalilwa et al. 2013).

Portuguese Terminology: Vegetation types follow Barbosa (1970), but with the use of Bioma de Florestas Hiimidas Guineo-Congolesas, Bioma de Florestas e Prados Afromontanos, Bioma de Savanas Mésicas and Bioma de Savanas Aridas for the main biomes and the terms prados, savanas, bosques, matos and florestas for the main physiognomic types.

Abbreviations: Frequently used abbreviations include Ma for Million Years Ago, C3, C4 and CAM for photosynthetic pathways, MAP for mean annual precipitation, MAT for mean annual temperature and ITCZ for intertropical convergence zone.

Photographs: Author credits are given in the captions of contributed photos. The remaining photos are by the author.

Graphics: The original author of graphics is cited in captions.

xi xii Editorial Notes

Barbosa, L. A. G. (1970). Carta Fitogeográfica de Angola. Instituto de Investigação Científica de Angola, Luanda.

Beja, P., Vaz Pinto, P, Verissimo, L. et al. (2019). The Mammals of Angola. In: Huntley, B. J., Russo, V., Lages, F., et al. (Eds.) Biodiversity of Angola. Science & Conservation: a Modern Synthesis (pp 357-444). Springer Nature.

Figueiredo, E. & Smith G. F. (2012). Common Names of Angolan Plants. Inhlamba Books, Pretoria.

Kyalangalilwa, B., Boatwright, J. S., Daru, B.H., et al. (2013). Phylogenetic position and revised classification of Acacia s.l. (Fabaceae; Mimosoideae) in Africa, including new combinations in Vachellia and Senegalia. Botanical Journal of the Linnean Society, 172, 500—523.

Marques, M. P., Ceriaco, L. M. P., Blackburn, D. C., et al. (2018). Diversity and Distribution of the Amphibians and Reptiles of Angola (p. 501). California Academy of Sciences, San Francisco.

Mills, M. S. L. & Melo, M. (2013). The Checklist of the Birds of Angola (p. 75). Associação Angolana para Aves e Natureza (AvesAngola), Luanda.

Contents

PartI An Introduction to Angola’s Biomes and Ecoregions

1 Opportunities in and Approaches to the Study of Angolan DOolüpt Lossdpi ss tessa deheiietandesinidienieieabe eel Eten 11 ‘The Seience.and Practice of Ecology isis ra ra

1.3 How to Use This Book: Interconnections and Recurrent MIGSSQERNS uspersqpRREXY a P PCUPRERIOIIERXARERURR CERERI NE BOIGIEBOES oio ciao ames cece o Abe eec ma RRs oes ore

Part II Determinants of Pattern: Conditions, Resources and Disturbance xiii N

5.8 Se rare ens SEED 118 |o ig M UMP a et ete tained, cc!

6.2 Development of Soil: Weat m Me Pelorna TED 6.3 Soil Water Relations . Sout janice UTERE VR 64 Soil — and Nutrient Status " ORTU 135

References E E SDVAREEN A EENIEREDUEUDN UNDE 147

The jape er Role of Ene

8.1] The Evolution of African Mammalian Herbivores

8.3 Patterns of Impacts of Browsers and nisus. sautada taes reaa ES |i ns c A TE EE E banks E NEE

Contents

Part II Ecological Concepts and Ecosystem Processes

9.1 The Evolutionary Basis of Ecology sik a xedeta sexos reis

Lu species Richness, Evenness and Divent ——

ened EE De iis ci PTET NE

10 10. 1 10.2 10.3 10.4

10.5 10.6 10.7 n for Food i ina | Prods Environment big e | echanisms: Camouflage, Deceit, Mimicry,

ial Behaviour . "P ewe a E EE T E E EE EET

Part IV Ecological Features of — Biomes and Ecoregions sas Pe o PLU RM MM ERR XV

215 219 221 222

226 226 230

236 245 249 250 256 259

260 265 273

279 284

Cate 1a Concept, Termitaria

15.1 Angolan Mopane Woodlands (Eco oregion 1

16.1 The Age and Evolution of the Namib Deset VOXiqimcbensssnu. gibt

16.3 Climate: The South Atlantic Antieyelone, wel Benguela Current am Wind .. i ;

Contents

Part V Synopsis and Conclusions

19.1 The Big Picture: Global Tectonic and Ci atic Forces that Have Shaped Angola's Bio 19.2 Contemporary Drivers of | Ecosystem Structure

19.3 Ecological Patterns at African and Kagol Scales aisicc

193 Ecological Concepts and Theories Relevant to Conserving

Oe ee ee ee ee ee ee ee ee ee ee ae ee ee

19.6 DL Why pias An ii for bii References: v5 00005044 P he robes e utet ose ie iebe tas Appendix: Names of Vertebrate Species Mentioned in This Volume ....

383 394 396 398 403

407 408 410 414 415 418

419 420

423 435

About the Author

Brian John Huntley is an internationally respected conservationist with over 50 years of research and management experience in southern African countries.

Following ecological studies in the sub-Antarctic Prince Edward Islands in the 1960s and national park management planning across Angola in the early 1970s, Huntley coordinated biome research programmes across South Africa, before two decades as CEO of the South African National Biodiversity Institute. He has been active in many international conservation organisations. Ecology of Angola concludes a trilogy on the conservation history, biodiversity and terrestrial ecology of the country, written since retirement to a village between sea and mountains, near the southernmost tip of Africa. He is currently attached to the Research Centre for Biodiversity and Genetic Resources (CIBIO) at the University of Porto.

xix

Part I An Introduction to Angola’s Biomes and Ecoregions Context: Angola: An Ecologist’s ‘Continent in One Country’

Angola occupies only four percent of the terrestrial area of the African continent, yet it possesses the highest number of biomes of any African country. It is second in terms of the number of ecoregions represented within its borders. It has ecosystems as diverse as the rain forests of Maiombe of Cabinda, to the vegetationless dunes of Namibe, and the endless savannas and woodlands of the Cuando Cubango, to the tiny remnant forests of the highest valleys of Mount Moco in Huambo. It is the only home to the most magnificent mammal in the world—the Giant Sable Antelope.

João Manuel Gonçalves Lourenço: His Excellency the President of the Republic of Angola

In the opening paragraph of his Foreword to Biodiversity of Angola, President João Lourenço (2019) succinctly encapsulates the magic of Angola’s biological and ecological riches. Angola is truly an ecologist's ‘continent in one country’. It is the perfect living laboratory for research into the structure and functioning of African ecosystems, be they rain forests, deserts, savannas, montane grasslands or the mangroves that clothe the mouths of the Cuanza and Congo rivers. Nowhere else on the continent can one find such ecological diversity.

This introduction provides a brief outline of what awaits the inquisitive student. It is a snapshot of Angola's biodiversity and ecosystems, sufficient to stimulate interest but without attempting to answer the multitude of questions that arise when scanning the ever-changing landscape. A first step is to recognise the range of biomes that unfolds as one moves from Cabinda to the Cuando Cubango, or from the heights of Morro Moco to the coastal desert of Iona.

Given the central importance of the concepts of biomes and ecoregions in this volume, it is necessary to define these terms at this point.

* A biome is a large unit of structurally and functionally similar habitats which share climates, soils and disturbance factors.

* Biomes, such as equatorial rain forests, tropical savannas, temperate grasslands and deserts, occur on many continents, but often with very different floristic and

2 Part I: An Introduction to Angola's Biomes and Ecoregions faunistic compositions. They are the ecological units which one can recognise in satellite images.

* An ecoregion is a large unit of land or water that contains a distinct assemblage of species, habitats and processes and whose boundaries attempt to depict the original extent of natural communities before major land use change.

* Biomes and ecoregions in turn are assemblages of many ecosystems, themselves comprising multiple species.

The Congo Basin holds the second-largest area of equatorial rain forest on the planet, second only to the Amazon. On the southwestern margin of the Congo Basin lie the Maiombe forests of Cabinda, Gabon and the Republic of the Congo. The Angolan Maiombe has no fewer than 14 primate species, from Gorillas and Chimpanzees to the tiny Talapoin. It has several hundred species of birds and over two thousand species of plants. Antelope includes five species of forest duiker, plus the small, deer-like Chevrotain, Forest Buffalo and Forest Elephant. Its amphibians and reptiles await detailed survey, as do its rich butterfly and dragonfly faunas. Of its ecology, no studies have yet been undertaken. In terms of biological surveys, it is Angola's terra incognita.

Southwards from the Maiombe, and running from Cabinda to the Cunene, is the Angolan Escarpment. This major topographic buttress between the coastal lowlands, the Marginal Mountain Chain and the interior high plateau—the planalto—is of special ecological importance. Providing a steep gradient of landscapes and habitats between the arid coast and the moist interior plateau, the Escarpment Zone has long been recognised as a centre of evolution and speciation. With a dense mosaic of forests, thickets, woodlands, savannas and grasslands, the Escarpment has provided a refuge for species from the arid lowlands and moister plateau during the climatic changes of the Pleistocene—the ‘Ice Ages’ of the Northern Hemisphere that reached tropical Africa as alternating wetter and drier periods.

Rising above the Escarpment are Angola's high peaks—Moco, Mepo and Namba. Here the cooler, moist climate provides conditions for remnant patches of Afromontane forest. This distinctive phytogeographic division extends as an archipelago of forest patches from the Ethiopian Highlands, down the Eastern Arc Mountains of Kenya and Tanzania, along the escarpments of Malawi, Mozambique and South Africa to Cape Town. After a gap of 2000 km across Namibia, Afromontane forests appear again in the highlands of Huila, Huambo, Benguela and Bié provinces. These remote and highly threatened forest fragments are the habitat of many species of birds, reptiles, amphibia, invertebrates and plants that are endemic to Angola, or have close relatives in other Afromontane ecosystems in eastern, southern and western Africa. They represent what were much more extensive forests during the wetter periods of the Pleistocene. They are appropriately described as providing "fingerprints of the past’.

The greatest proportion of Angola, over two-thirds of its surface area, is occupied by mesic savannas and woodlands, known internationally as ‘miombo’. This biome covers most of the planalto and the great Congo and Zambezian peneplains—the gently undulating landscapes that extend from the highlands of Malange, Huambo,

Part I: An Introduction to Angola's Biomes and Ecoregions 3

Benguela and Bié to the Lundas, Moxico and Cuando Cubango. Rainfall is seasonal, falling in the hot summer, with from 650 to 1400 mm per year. Tall woodlands of deciduous trees, typically species of Brachystegia and Julbernardia, alternate with grassy valleys (mulolas) along the drainage lines, with occasional gallery forests (muxitos) that occupy moist but well-drained soils. The miombo has its own distinctive fauna, which includes species of antelope such as Giant Sable, Roan Antelope, Puku, Oribi and Lichtenstein’s Hartebeest. The soils are nutrient poor, and the grasses are of low quality for herbivores, so these mesic savannas support low mammal biomass. They are shaped by regular bush fires, the great consumer of African savannas.

In the southwest, northwards along the hot, low coastal belt, arid savannas, woodlands and thickets dominate. Here rainfall is highly erratic, ranging from 250 to 650 mm per year. A typical community is that of the tree Colophospermum mopane (mutiati) that occurs on rich soils of Cunene, Namibe and Benguela provinces. Along the coast, many hardy, drought-resistant woody species of Acacia, Combretum, Commiphora, Euphorbia and Sterculia are conspicuous. Throughout the arid savannas, from the Cunene to Cabinda, the baobab (imbondeiro) Adansonia digitata, is the most prominent tree. The shrubs and grasses of arid savannas, occurring on rich soils, are highly nutritious and in past centuries supported large herds of herbivores such as wildebeest, buffalo, zebra, kudu, eland, impala, elephant and black rhino. These herds have been severely reduced, and the herbivore niche has now been filled by cattle and goats.

The ultimate extreme of harsh environmental conditions is to be found in the Namib Desert. From the Namibian border at Foz do Cunene, the Angolan component of this ancient desert extends northwards as a narrow belt, never more than 80 km in breadth, to the Carunjamba River just south of Lucira. While geographers define a desert as an area receiving less than 250 mm rainfall per year, the Namib generally receives less than 150 mm rainfall per year. It is best characterised by plant and animal species and their adaptations for life in hyper-arid conditions, rather than being defined by the rainfall it receives. The gravel plains, calcrete pavements and rocky hills of the Namib are the habitat of Welwitschia mirabilis, penetrating inland in places with slightly higher rainfall. Intermontane basins, carrying grasslands and shrub savannas, are occupied by Gemsbok, Springbok and Hartmann’s Zebra, with Kirk’s Dik-dik, Greater Kudu and rarely, Savanna Elephant and Black Rhino (now extinct) in the wooded hills below the Escarpment. The antelope moves from one area to another according to rainfall patterns, often moving farther inland as food resources are depleted during dry periods. The desert is also home to many specialised reptiles and invertebrates. All species of animal and plants make good use of the fog that moves inland from the cold Benguela Current, in places adding more than five times the moisture received from rainfall, which is often less than 30 mm per year.

Against this background of biome and ecosystem diversity, one can expect high species richness. The Angolan inventory of vascular plants now stands at over 6850 species. Mammals number 291 species, birds 940, reptiles 278 and amphibians 111. Of invertebrate groups, only butterflies (792 species) and dragonflies (260 species) have been surveyed in any detail. Much has still to be learned of the diversity of

4 Part I: An Introduction to Angola’s Biomes and Ecoregions some taxa, especially invertebrates, but even reptiles and amphibia have species new to science described every year.

While good progress is being made on the inventory of Angola’s biodiversity, very few studies, beyond those on Giant Sable and vegetation surveys, have been initiated on the ecology of individual species or ecosystems and nothing on ecosystem processes such as primary production, consumption and decomposition, or on energy, water and nutrient transfers. The opportunities for research are diverse, exciting and ready for action. It is in the new generation of Angolan ecologists that expectations are vested.

Reference

Lourengo, J. (2019). Foreword. In: Huntley, B. J., Russo, V., Lages, F., et al. (Eds). Biodiversity of Angola. Science & Conservation: A Modern Synthesis (p. 549). Springer Nature.

Chapter 1 A) Opportunities in and Approaches get to the Study of Angolan Ecology e The critical role of an ecological understanding in achieving the sustainable use of the biosphere.

e What we understand by the term ecology, its interdisciplinary scope and the need for an African perspective.

e Why spatial and temporal scales and the integration of successive levels of biological organisation need to be studied.

e The importance of understanding the processes of evolution and adaptation in shaping the composition of communities.

Why the ecological whole is greater than the sum of its parts. The basis of research—the scientific method—and its application in ecological studies.

The structure of this book in phased steps of a learning process.

e How to use this book in developing knowledge, understanding and a career in ecology.

Context: Why Ecology? Human-Environment Interactions

This book has a pragmatic purpose. It has been written for Angolan students, young and old, to help them to get to know, understand and value the amazing natural life and landscapes of the country. This book aims to introduce the student to the science and practice of ecology by describing examples of key features and concepts which relate to Angola's terrestrial ecosystems, their structure and functioning. The focus is on providing an enduring understanding of what is special about Angolan ecosystems, in succinct chapters illustrated with easily accessible examples.

Why is an understanding of ecology critical to Angola's sustainable development? The answer is easy to predict if one recognises that Angola's human population has increased from 6.5 million at independence in 1975, to 32.8 million in 2022. At its current rate of growth, the population will surpass 50 million by 2035. At Independence, over 80% of the human population comprised rural communities of

© The Author(s) 2023 5 B. J. Huntley, Ecology of Angola, https://doi.org/10.1007/978-3-031-18923-4 1 subsistence farmers, but today 67% of the population lives in cities and towns and only 33% in rural areas. These dramatic demographic changes have had significant and often negative impacts on the natural environment. In urban situations, pollution through injudicious solid waste disposal and erosion through poor storm-water management, are serious problems. In rural areas, the loss of forest and woodland cover (to provide charcoal as the primary domestic energy resource for urban families), extinction of mammal populations (through the bushmeat trade), accelerating soil erosion (through mining operations and unsustainable farming practices) and the transformation of plant communities due to clearance for agriculture or repeated, extensive and uncontrolled bush fires, plus the impacts of invasive plants, accounts for severe loss of the productive potential of landscapes. To these impacts must be added that of global dynamics, most especially the impacts of climate changes. These human-environment interactions are described in a series of Boxes at the end of chapters, demonstrating why an ecological understanding of the structure, functioning and vulnerabilities of the country's ecosystems is so critical to achieving the sustained wellbeing of Angola's people.

1.4 The Science and Practice of Ecology

An ecologist is a person imbued with an insatiable curiosity about the workings of all living things. The great nineteenth-century European explorer-naturalists— Alexander von Humboldt (1769-1859), Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913)— were passionate seekers of knowledge, but specifically of explanations as to why certain species were found only in specific regions of the globe and not in others. They were the pioneers of ecology. The term ‘ecology’ was first described as the study of ‘the economy of nature’ (Haeckel, 1866) and ecology is today defined as ‘the scientific study of the distribution and abundance of organisms and the interactions that determine their distribution and abundance'.

An Interdisciplinary Science

In the two centuries of its gestation and development, ecology has become a multiand interdisciplinary science, being undertaken by researchers in fields as diverse as the biochemical reactions within nitrogen-fixing bacteria—to the feeding habits of elephant—to the influence of the Earth's tilted axis on the passage of seasons. Both curiosity-driven and applied interests stimulate ecological studies. The workings of insect pollinators in the fertilization of tropical orchids are as fascinating to one ecologist as the resilience of socio-economic systems to the impacts of global climate change is to another.

Ecology has its early nineteenth century roots in the tropics—through the revolutionary thinking of Humboldt, Darwin and Wallace. The theory of evolution through natural selection is a cornerstone of ecology. Humboldt sought explanations for the distribution of vegetation formations across altitude and climate. Darwin sought understanding by studying smaller and smaller pieces of life's puzzle in a world

1.1 The Science and Practice of Ecology 7 driven by competition and selection at the species level. Wallace explored life at a planetary scale, in which the world is a web of interdependencies (Flannery, 2010).

Presenting an African Perspective

These broad perspectives were evolved further into specific ecological concepts in the northern temperate latitudes by Andreas Schimper (1856-1901), Arthur Tansley (1871-1955) and Frederick Clements (1874-1945) and others in the early twentieth century. From the 1950s, the science accelerated rapidly in North America and Europe, from where the great majority of concepts and examples quoted in standard textbooks on ecology are drawn. Some concepts developed in temperate latitudes are of limited relevance to tropical African ecosystems, so this volume presents a deliberately African perspective. In recent decades there has been a blossoming of ecological research in South and Central America, Australasia and southern Africa. In Angola, important contributions were made by the pioneers of Angolan biodiversity research—Welwitsch (Swinscow, 1972), Anchieta (Andrade, 1985), Gossweiler (Gossweiler & Mendonga, 1939), Jessen (1936), Barbosa (1970), Monteiro (1970) and Machado (1995). Today there is increasing investment in ecological research across Africa, as scientists and governments recognise the important relationship between biodiversity, environmental health and socio-economic development and sustainability.

Scales in Space and Times

Ecology is an integrative science, working at multiple spatial and temporal scales, from the individual organism to the biosphere. At the level of the individual plant or animal, ecologists examine how features of morphology, physiology and behaviour determine an individual’s ability to survive, grow and reproduce. Successive levels of organization—individual, population, community, ecosystem, landscape, ecoregion, biome, biosphere—all work at different spatial and temporal scales, but are closely linked through positive and negative interactions that determine their dynamics.