Sally Archibald
Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

David J. Augustine
Rangeland Resources Research Unit, US Department of Agriculture – Agricultural Research Service, Fort Collins, CO, USA

Eduardo Barbosa
Departamento Botânica, Universidade de Brasília, Brasília, Distrito Federal, Brazil

Jean‐Francois Barczi
CIRAD, UMR AMAP, Montpellier, France

Brian Beckage
Departments of Plant Biology and Computer Science, University of Vermont, Burlington, VT, USA

William J. Bond
South African Environmental Observation Network, National Research Foundation, Cape Town, South Africa

Fabian Borghetti
Departamento Botânica, Universidade de Brasília, Brasília, Distrito Federal, Brazil

Gabriela Bucini
Departments of Plant Biology and Computer Science, University of Vermont, Burlington, VT, USA

Simon Chamaillé‐Jammes
Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Montpellier, France

Tristan Charles‐Dominique
Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, China

Daryl Codron
Department of Zoology and Entomology, University of the Free State, Bloemfontein, South Africa

Corli Coetsee
SANParks, Scientific Services, Skukuza, South Africa and School of Natural Resource Management, Nelson Mandela University, George, South Africa

Garry D. Cook
CSIRO Land and Water, Darwin, Northern Territory, Australia

Joris Cromsigt
Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden and Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela University, Port Elizabeth, South Africa

Dave J. Druce
Ezemvelo KZN Wildlife, Hluhluwe‐iMfolozi Park, Hluhluwe, South Africa

Caroline Farrior
Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA

Edmund C. February
Department of Biological Sciences, University of Cape Town, Cape Town, South Africa

Dario Fornara
Agri‐food and Biosciences Institute, Belfast, UK

Norma L. Fowler
Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA

Juan H. Gowda
INIBIOMA, CONICET/Universidad Nacional del Comahue, Bariloche, Río Negro, Argentina

Louis J. Gross
National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, USA

Gareth P. Hempson
Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
and
South African Environmental Observation Network (SAEON), Ndlovu Node, Kruger National Park, Phalaborwa, South Africa

Steven I. Higgins
Department of Botany, University of Otago, Dunedin, New Zealand

William Hoffmann
Department of Plant Biology, North Carolina State University, Raleigh, NC, USA

Grant Joseph
Percy FitzPatrick Institute of African Ornithology, Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa and Centre for Invasion Biology, School of Mathematical & Natural Sciences, University of Venda, Thohoyandou, South Africa

Gregory Kiker
Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL, USA and School of Mathematics, Statistics and Computer Science, University of KwaZulu‐Natal, Pietermaritzburg, South Africa

Caroline Lehmann
School of GeoSciences, University of Edinburgh, Edinburgh, UK

Norman Owen‐Smith
Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

Bruce Page
School of Life Sciences, University of KwaZulu‐Natal, Westville, South Africa

William J. Platt
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA

Jayashree Ratnam
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India

José Felipe Ribeiro
Núcleo de Recursos Naturais, Embrapa Cerrados, Planaltina, Distrito Federal, Brazil

Leandro Ribeiro
Departamento Botânica, Universidade de Brasília, Brasília, Distrito Federal, Brazil and Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Fortaleza, Ceará, Brazil

Mahesh Sankaran
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India and School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK

Melissa H. Schmitt
South African Environmental Observation Network (SAEON), Ndlovu Node, Kruger National Park, Phalaborwa, South Africa

Peter Frank Scogings
School of Life Sciences, University of KwaZulu‐Natal, Pietermaritzburg, South Africa

Colleen Seymour
South African National Biodiversity Institute, Claremont, South Africa and Percy FitzPatrick Institute of African Ornithology, Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa

Chintan Sheth
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India

Adrian M. Shrader
Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa

Matthew G. Slocum
Department of Biological Sciences, Louisiana State University,Baton Rouge, LA, USA

Carla Staver
Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA

Nicola Stevens
Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, South Africa and School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

Anthony Swemmer
South African Environmental Observation Network, National Research Foundation, Phalaborwa, South Africa

Gabriella Teren
Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

Wayne Twine
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

Marion Valeix
Laboratoire de Biométrie et Biologie Evolutive, CNRS, Villeurbanne, France

Antoinette Veldtman
Cape Nature, Jonkershoek, Stellenbosch, South Africa

Bruno Machado Teles Walter
Herbário CEN, Embrapa Recursos Genéticos e Biotecnologia, Brasília, Distrito Federal, Brazil

David Ward
Department of Biological Sciences, Kent State University, Kent, OH, USA

Benjamin Wigley
School of Natural Resource Management, Nelson Mandela University, George, South Africa and National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India

Richard J. Williams
CSIRO Land and Water, Darwin, Northern Territory, Australia

“Savanna” has different meanings for different people, and the term has continued to elude a widely agreed definition (Lehmann and Parr 2016). “Savanna” continues to be used extensively to label any vegetation comprising a continuous herbaceous layer and a discontinuous woody layer of variable density and height (e.g. Furley 2016). However, in the past decade, it has become increasingly recognized that savannas are synonymous with “C₄ grassy biomes” or “tropical grassy biomes” (e.g. Bond et al. 2008; Parr et al. 2014), i.e. biomes containing herbaceous vegetation dominated by graminoids using the C₄ photosynthetic pathway. As such, savannas are largely tropical and sub‐tropical ecosystems, but are also found within warm temperate climates of North America and Asia (see Edwards et al. 2010). Although reference is occasionally made in this book to savannas where C₃ grasses dominate the herbaceous layer, and to savannas that are seasonally flooded grasslands, the scope of this book is the majority of global savannas, which are C₄ grassy ecosystems with a woody component.

The specific focus of this book is on the ecology of woody plants and associated herbivores in savannas. Advancement of the understanding of interactions between woody plants and browsing mammals in savannas, and the application thereof in models for savanna management, whether for biodiversity conservation or animal production purposes, has been neglected for far too long. Rather, to put it bluntly, it has been commonly assumed that all browsing mammals behave the same and all woody species respond in the same way to browsing, and that forage intake is inhibited by the same factors in both grasses and woody plants. For various reasons, books on savannas have tended to not include anything substantial about the interactions between woody plants and browsing mammals, except for the impacts of elephants on vegetation and how browsing affects the woody–grass interaction. One of these reasons is that, for a long time, the vast majority of understanding of browse–browser interactions was developed in other biomes, for example, boreal forests (Rooke et al. 2004). Hence, books on large herbivore ecology have also tended to contain very little information on browsing in savannas. This is a noteworthy omission from the literature, given the rich diversity of woody species and the abundance of large herbivores, whether domestic or wild, in savannas of the world.

This book is intended to complement, rather than compete with, other contemporary books on either savanna ecology or large herbivore ecology. The feature that distinguishes this book from others is its focus on the woody component of savanna ecosystems and, in particular, the woody plant–large herbivore interactions in savannas. A further defining feature of this book is the contrasts made among different systems: savannas within continents, savannas on different continents, and, to some extent, savannas compared with other biomes where woody plants and browsing mammals occur. As such, lead authors were encouraged to (i) collaborate across continents to develop global perspectives; (ii) consider how development of concepts in other woody biomes could contribute to developing the understanding of savanna functioning; (iii) consider the roles of soils and climate (traditionally seen as the main determinants); and (iv) consider possible impacts of climate change. Inevitably, the extent to which these “terms of reference” where adhered varies from chapter to chapter; most chapters emphasize some aspects more than others.

Broadly, the first section comprises general chapters that introduce readers to contemporary views and debates about what savannas are, where they are found, and why they are important to understand, while being attentive to the woody component. Among the chapters about each continent, readers will note that each chapter has a different angle or focus, depending on the main direction that research on each continent has taken due to different circumstances among continents. So, for example, the chapter on African and Asian savannas places emphasis on determinants of savannas, including herbivory; the chapter on Australian savannas has a focus on Late Pleistocene human impacts, megafauna extinctions and recent introductions of ungulates (see Williams et al. [2017] for details of climate, soils, and vegetation of Australian savannas); the chapter on South American savannas is detailed in its descriptions of floristic composition; and the chapter on North American savannas places emphasis on the roles of fire and herbivory in recent management of savannas. All the continent‐specific chapters deal with the roles of resources (soils and climate) and fire, as well as human impacts, to greater or lesser extent, but the role of extant native browsers is limited to the chapter on Africa and Asia.

The second section comprises chapters that update readers about the ecology and evolution of animals that are closely associated with woody plants in savannas. The third section comprises chapters that focus on the ecology and evolution of woody plants in relation to browsing mammals in savannas. There is no single chapter devoted to the evolution of woody plants in savannas, as this is touched on in many of the chapters. The final section consists of chapters on modeling savannas for management purposes, and a concluding synthesis. Thus, when taken together, there is scope for inferring impacts of introduced, wild or domestic, browsers on different continents, as well as inferring impacts of browser removal from savannas. Such information is useful for managing conservation programs, as well as managing domestic livestock farming or feral animal control programs.

The expected readership is international and primarily includes advanced students, researchers, and academics in fields such as plant ecology, animal ecology, rangeland ecology, wildlife biology, conservation biology, and natural resource management. General readers might include geographers, evolutionary biologists, and informed members of the general public. For the reader, this book provides comprehensive insights into recent advances in the understanding of global savannas, especially in areas of research that have been neglected in other books, or are emerging. For example, substantial advances have been made in understanding drivers at the boundaries of savannas (Accatino and de Michele 2013; Rosatto et al. 2013). The recognition that savannas on different continents function differently is a significant recent advance (Lehmann et al. 2014). Yet, similarities between savannas and forests in certain aspects of their functioning are also emerging (Scogings et al. 2013; Churski et al. 2017). The understanding of interactions between browsing mammals and woody plants in savannas is increasing. The important role of small‐ and medium‐sized mammal herbivores has recently been emphasized (Sankaran et al. 2013; O'Kane et al. 2014). Research into these interactions has started to follow new and exciting trajectories. For example, it has been recognized in recent years that better knowledge of the complex mixtures of secondary metabolites in woody plants, and their heritability, is needed to gain better understanding of such interactions (Wallis et al. 2012; de Gabriel et al. 2014). Understanding of the responses of plants to resources in savannas is also increasing (Tomlinson et al. 2013; Barbosa et al. 2014; Vadigi and Ward 2014). While updating the reader comprehensively, future directions for research are highlighted, as well as how concepts developed in one biome may be applicable in another, either as frameworks for future research, or in managing biomes for biodiversity conservation.

We are grateful for the efforts made by numerous reviewers who contributed to improving each chapter: Sally Archibald, David Augustine, Sumanta Bagchi, Daryl Codron, Garry Cook, Ben Cousins, Joris Cromsigt, Kevin Duffy, Johan du Toit, Augusto Franco, Hervé Fritz, Jake Goheen, Iain Gordon, Juan Gowda, Ricardo Holdo, Bill Hoffmann, Lindsay Hutley, Christine Janis, Felicia Keesing, Greg Kiker, Mike Lawes, Norman Owen‐Smith, Adam Pellegrini, Jayashree Ratnam, Christina Skarpe, Lisa Shipley, Julius Tjelele, Kyle Tomlinson, Joe Veldman, and Ben Wigley.

References

1. Accatino, F. and de Michele, C. (2013). Humid savanna–forest dynamics: a matrix model with vegetation–fire interactions and seasonality. Ecological Modelling 265: 170–179.
2. Barbosa, E.R.M., van Langevelde, F., Tomlinson, K.W. et al. (2014). Tree species from different functional groups respond differently to environmental changes during establishment. Oecologia 174: 1345–1357.
3. Bond, W.J., Silander, J.A., Ranaivonasy, J., and Ratsirarson, J. (2008). The antiquity of Madagascar's grasslands and the rise of C₄ grassy biomes. Journal of Biogeography 35: 1743–1758.
4. Churski, M., Bubnicki, J.W., Jęzdrzejewska, B. et al. (2017). Brown world forests: increased ungulate browsing keeps temperate trees in recruitment bottlenecks in resource hotspots. New Phytologist 214: 158–168.
5. De Gabriel, J.L., Moore, B.D., Felton, A.M. et al. (2014). Translating nutritional ecology from the laboratory to the field: milestones in linking plant chemistry to population regulation in mammalian browsers. Oikos 123: 298–308.
6. Edwards, E.J., Osborne, C.P., Strömberg, C.A.E. et al. (2010). The origins of C₄ grasslands: integrating evolutionary and ecosystem science. Science 328: 587–591.
7. Furley, P.A. (2016). Savannas: A Very Short Introduction. Oxford: Oxford University Press.
8. Lehmann, C.E.R., Anderson, T.M., Sankaran, M. et al. (2014). Savanna vegetation‐fire‐climate relationships differ among continents. Science 343: 548–552.
9. Lehmann, C.E.R. and Parr, C.L. (2016). Tropical grassy biomes: linking ecology, human use and conservation. Philosophical Transactions of the Royal Society B 371: 20160329.
10. O'Kane, C.A.J., Duffy, K.J., Page, B.R., and Macdonald, D.W. (2014). Model highlights likely long‐term influences of mesobrowsers versus those of elephants on woodland dynamics. African Journal of Ecology 52: 192–208.
11. Parr, C.L., Lehmann, C.E.R., Bond, W.J. et al. (2014). Tropical grassy biomes: misunderstood, neglected, and under threat. Trends in Ecology and Evolution 29: 205–213.
12. Rooke, T., Danell, K., Bergström, R. et al. (2004). Defensive traits of savanna trees – the role of shoot exposure to browsers. Oikos 107: 161–171.
13. Rosatto, D.R., Hoffmann, W.A., de Carvalho Ramos Silva, L. et al. (2013). Seasonal variation in leaf traits between congeneric savanna and forest trees in central Brazil: implications for forest expansion into savanna. Trees 27: 1139–1150.
14. Sankaran, M., Augustine, D., and Ratnam, J. (2013). Native ungulates of diverse body sizes collectively regulate long‐term woody plant demography and structure of a semi‐arid savanna. Journal of Ecology 101: 1389–1399.
15. Scogings, P.F., Hjältén, J., and Skarpe, C. (2013). Does large herbivore removal affect secondary metabolites, nutrients and growth in woody species in semi‐arid savannas? Journal of Arid Environments 88: 4–8.
16. Tomlinson, K.W., Poorter, L., Sterck, F.J. et al. (2013). Leaf adaptations of evergreen and deciduous trees of semi‐arid and humid savannas on three continents. Journal of Ecology 101: 430–440.
17. Vadigi, S. and Ward, D. (2014). Herbivory effects on saplings are influenced by nutrients and grass competition in a humid South African savanna. Perspectives in Plant Ecology, Evolution and Systematics 16: 11–20.
18. Wallis, I.R., Edwards, M.J., Windley, H. et al. (2012). Food for folivores: nutritional explanations linking diets to population density. Oecologia 169: 281–291.
19. Williams, R.J., Cook, G.D., Liedloff, A.C., and Bond, W.J. (2017). Australia's tropical savannas: vast, ancient and rich landscapes. In: Australian Vegetation (ed. D. Keith), 368–388. Cambridge: Cambridge University Press.