Book contents
- Only in Africa
- Only in Africa
- Copyright page
- Dedication
- Contents
- Foreword
- Preface
- Abbreviations
- Part I The Physical Cradle: Land Forms, Geology, Climate, Hydrology and Soils
- Part II The Savanna Garden: Grassy Vegetation and Plant Dynamics
- Chapter 6 Forms of Savanna: From Woodland to Grassland
- Chapter 7 How Trees and Grasses Grow and Compete
- Chapter 8 Plant Demography and Dynamics: Fire Traps
- Chapter 9 Paleo-savannas: Expanding Grasslands
- Part II Synthesis: Savanna Structure and Dynamics
- Part III The Big Mammal Menagerie: Herbivores, Carnivores and Their Ecosystem Impacts
- Part IV Evolutionary Transitions: From Primate Ancestors to Modern Humans
- Appendix Scientific Names of Extant Animal and Plant Species Mentioned in the Book Chapters (Ecologically Conservative with Regard to Species Recognition)
- Index
- References
Chapter 6 - Forms of Savanna: From Woodland to Grassland
from Part II - The Savanna Garden: Grassy Vegetation and Plant Dynamics
Published online by Cambridge University Press: 09 September 2021
Book contents
- Only in Africa
- Only in Africa
- Copyright page
- Dedication
- Contents
- Foreword
- Preface
- Abbreviations
- Part I The Physical Cradle: Land Forms, Geology, Climate, Hydrology and Soils
- Part II The Savanna Garden: Grassy Vegetation and Plant Dynamics
- Chapter 6 Forms of Savanna: From Woodland to Grassland
- Chapter 7 How Trees and Grasses Grow and Compete
- Chapter 8 Plant Demography and Dynamics: Fire Traps
- Chapter 9 Paleo-savannas: Expanding Grasslands
- Part II Synthesis: Savanna Structure and Dynamics
- Part III The Big Mammal Menagerie: Herbivores, Carnivores and Their Ecosystem Impacts
- Part IV Evolutionary Transitions: From Primate Ancestors to Modern Humans
- Appendix Scientific Names of Extant Animal and Plant Species Mentioned in the Book Chapters (Ecologically Conservative with Regard to Species Recognition)
- Index
- References
Summary
This chapter covers factors governing the prevalence of savanna and grassland formations. Savannas are climatically defined by the duration and intensity of the dry season. The tree canopy potentially closes above 650 mm in mean annual rainfall, but is widely variable. Above 1000 mm either a savanna woodland or a forest/grassland mosaic may prevail. Soil fertility based on bedrock geology coupled with rainfall underlies a division between arid/eutrophic and mesic/dystrophic savanna forms, not represented on other continents. Corresponding vegetation distinctions exist between fine-leaved and broad-leaved savannas. Water redistribution within landscapes contributes to local variation in tree canopy cover. Several factors contribute to the lack of tree cover in grasslands, but especially soils. The savanna biome is more widespread in Africa than in other continents. Characteristic tree and grass species are described in an appendix.
Keywords
- Type
- Chapter
- Information
- Only in AfricaThe Ecology of Human Evolution, pp. 69 - 96Publisher: Cambridge University PressPrint publication year: 2021
References
Suggested Further Reading
Bond, WJ. (2019) Open Ecosystems. Ecology and Evolution Beyond the Forest Edge. Oxford University Press, Oxford.Google Scholar
Huntley, BJ; Walker, BH. (1982) Ecology of Tropical Savannas. Springer, Berlin.CrossRefGoogle Scholar
Lehmann, CER, et al. (2011) Deciphering the distribution of the savanna biome. New Phytologist 191:1970209.CrossRefGoogle ScholarPubMed
McClenahan, TR; Young, TP. (1996) East African Ecosystems and their Conservation. Oxford University Press, Oxford.Google Scholar
References
Pratt, DJ; Gwynne, M. (1977) Rangeland Management and Ecology in East Africa. Hodder and Stoughton, London.Google Scholar
Grunblatt, J, et al. (1989) A hierarchical approach to vegetation classification in Kenya. African Journal of Ecology 27:45–51.Google Scholar
Mucina, L; Rutherford, M. (2006) The Vegetation of South Africa, Lesotho and Swaziland. South African National Biodiversity Institute, Pretoria.Google Scholar
Lehmann, CER, et al. (2011) Deciphering the distribution of the savanna biome. New Phytologist 191:197–209.CrossRefGoogle ScholarPubMed
Good, SP; Caylor, KK. (2011) Climatological determinants of woody cover in Africa. Proceedings of the National Academy of Sciences of the United States of America 108:4902–4907.Google Scholar
Sankaran, M, et al. (2005) Determinants of woody cover in African savannas. Nature 438:846–849.Google Scholar
Sankaran, M, et al. (2008) Woody cover in African savannas: the role of resources, fire and herbivory. Global Ecology and Biogeography 17:236–245.Google Scholar
Staver, AC, et al. (2011) History matters: tree establishment variability and species turnover in an African savanna. Ecosphere 2:1–12.CrossRefGoogle Scholar
Charles-Dominique, T, et al. (2018) Steal the light: shade vs fire adapted vegetation in forest–savanna mosaics. New Phytologist 218:1419–1429.CrossRefGoogle ScholarPubMed
Huntley, BJ. (1982) Southern African savannas. In Huntley, BJ; Walker, B (eds) Ecology of Tropical Savannas. Springer, Berlin, pp. 101–119.CrossRefGoogle Scholar
Ellery, FN. (1995) The distribution of sweetveld and sourveld in South Africa’s grassland biome in relation to environmental factors. African Journal of Range and Forage Science 12:38–45.CrossRefGoogle Scholar
Scholes, R, et al. (2002) Trends in savanna structure and composition along an aridity gradient in the Kalahari. Journal of Vegetation Science 13:419–428.CrossRefGoogle Scholar
Crowther, TW, et al. (2019) The global soil community and its influence on biogeochemistry. Science 365:eaav0550.Google Scholar
Augustine, DJ. (2003) Long-term, livestock-mediated redistribution of nitrogen and phosphorus in an East African savanna. Journal of Applied Ecology 40:137–149.Google Scholar
Hogberg, P. (1986) Nitrogen-fixation and nutrient relations in savanna woodland trees (Tanzania). Journal of Applied Ecology 23:675–688.CrossRefGoogle Scholar
Childes, SL; Walker, BH. (1987) Ecology and dynamics of the woody vegetation on the Kalahari sands in Hwange National Park, Zimbabwe. Vegetatio 72:111–128.Google Scholar
Spinage, CA. (1988) First steps in the ecology of the Bamingui‐Bangoran National Park, Central African Republic. African Journal of Ecology 26:73–88.Google Scholar
February, EC, et al. (2019) Physiological traits of savanna woody species: adaptations to resource availability. In Scogings, PF; Sankaran, M (eds) Savanna Woody Plants and Large Herbivores. Wiley, Oxford, pp. 309–329.Google Scholar
Blackmore, AC, et al. (1990) The origin and extent of nutrient-enriched patches within a nutrient-poor savanna in South-Africa. Journal of Biogeography 17:463–470.CrossRefGoogle Scholar
Bond, WJ, et al.(2017) Demographic bottlenecks and savanna tree abundance. In Cromsigt, JPG, et al. (eds) Conserving Africa’s Mega-Diversity in the Anthropocene. Cambridge University Press, Cambridge, pp. 161–188.Google Scholar
Jager, T. (1982) Soils of the Serengeti woodlands, Tanzania. PhD thesis, Wageningen University, Wageningen.Google Scholar
Colgan, MS, et al. (2012) Topo-edaphic controls over woody plant biomass in South African savannas. Biogeosciences 9:1809–1821.Google Scholar
de Wit, HA. (1978) Soils and grassland types of the Serengeti Plains (Tanzania). PhD thesis, Wageningen University, Wageningen.Google Scholar
Holdo, RM, et al. (2020) Spatial transitions in tree cover are associated with soil hydrology, but not with grass biomass, fire frequency, or herbivore biomass in Serengeti savannahs. Journal of Ecology 108:586–597.CrossRefGoogle Scholar
Case, MF; Staver, AC. (2018) Soil texture mediates tree responses to rainfall intensity in African savannas. New Phytologist 219:1363–1372.Google Scholar
Tinley, K. (1982) The influence of soil moisture balance on ecosystem patterns in southern Africa. In Huntley, BJ; Walker, BH (eds) Ecology of Tropical Savannas. Springer, Berlin, pp. 175–192.CrossRefGoogle Scholar
O’Connor, TG; Bredenkamp, GJ. (1997) Grassland. In Cowling, RM, et al. (eds) Vegetation of Southern Africa. Cambridge University Press, Cambridge, pp. 215–257.Google Scholar
Sianga, K; Fynn, R. (2017) The vegetation and wildlife habitats of the Savuti–Mababe–Linyanti ecosystem, northern Botswana. Koedoe 59:1–16.Google Scholar
Knoop, WT; Walker, BH. (1985) Interactions of woody and herbaceous vegetation in a southern African savanna. The Journal of Ecology 73:235–253.Google Scholar
Archibald, S, et al. (2013) Defining pyromes and global syndromes of fire regimes. Proceedings of the National Academy of Sciences of the United States of America 110:6442–6447.Google Scholar
Eby, S, et al. (2015) Fire in the Serengeti ecosystem: history, drivers, and consequences. In Sinclair, ARE, et al. (eds) Serengeti IV: Sustaining Biodiversity in a Coupled Human–Natural System. University of Chicago Press, Chicago, pp. 73–103.Google Scholar
Probert, JR, et al. (2019) Anthropogenic modifications to fire regimes in the wider Serengeti–Mara ecosystem. Global Change Biology 25:3406–3423.Google Scholar
Higgins, SI, et al. (2007) Effects of four decades of fire manipulation on woody vegetation structure in savanna. Ecology 88:1119–1125.CrossRefGoogle ScholarPubMed
Govender, N, et al. (2006) The effect of fire season, fire frequency, rainfall and management on fire intensity in savanna vegetation in South Africa. Journal of Applied Ecology 43:748–758.Google Scholar
Browne, C; Bond, W. (2011) Firestorms in savanna and forest ecosytems: curse or cure? Veld & Flora 97:62–63.Google Scholar
Archibald, S, et al. (2012) Evolution of human-driven fire regimes in Africa. Proceedings of the National Academy of Sciences of the United States of America 109:847–852.Google Scholar
Trapnell, CG. (1959) Ecological results of woodland and burning experiments in Northern Rhodesia. The Journal of Ecology 47:129–168.Google Scholar
Titshali, LW, et al. (2000) Effect of long-term exclusion of fire and herbivory on the soils and vegetation of sour grassland. African Journal of Range and Forage Science 17:70–80.CrossRefGoogle Scholar
Oliveras, I; Malhi, Y. (2016) Many shades of green: the dynamic tropical forest–savannah transition zones. Philosophical Transactions of the Royal Society B – Biological Sciences 371.CrossRefGoogle ScholarPubMed
Walters, G. (2012) Customary fire regimes and vegetation structure in Gabon’s Bateke Plateaux. Human Ecology 40:943–955.Google Scholar
Stevens, N, et al. (2017) Savanna woody encroachment is widespread across three continents. Global Change Biology 23:235–244.CrossRefGoogle ScholarPubMed
Sinclair, ARE, et al. (2007) Long‐term ecosystem dynamics in the Serengeti: lessons for conservation. Conservation Biology 21:580–590.CrossRefGoogle ScholarPubMed
Bond, WJ; Midgley, GF. (2000) A proposed CO2‐controlled mechanism of woody plant invasion in grasslands and savannas. Global Change Biology 6:865–869.Google Scholar
Buitenwerf, R, et al. (2012) Increased tree densities in South African savannas: >50 years of data suggests CO2 as a driver. Global Change Biology 18:675–684.Google Scholar
Smit, IP; Archibald, S. (2019) Herbivore culling influences spatio‐temporal patterns of fire in a semiarid savanna. Journal of Applied Ecology 56:711–721.Google Scholar
Rountree, M, et al. (2000) Landscape state change in the semi-arid Sabie River, Kruger National Park, in response to flood and drought. South African Geographical Journal 82:173–181.CrossRefGoogle Scholar
Ratnam, J, et al. (2016) Savannahs of Asia: antiquity, biogeography, and an uncertain future. Philosophical Transactions of the Royal Society B – Biological Sciences 371.Google Scholar
Lehmann, CER, et al. (2014) Savanna vegetation–fire–climate relationships differ among continents. Science 343:548–552.Google Scholar
Eiten, G. (1982) Brazilian ‘savannas’. In Huntley, BJ; Walker, BH (eds), Ecology of Tropical Savannas. Springer, Berlin, pp. 25–47.Google Scholar
Sarmiento, G. (1984) The Ecology of Neotropical Savannas. Harvard University Press, Cambridge, MA.Google Scholar
Borghetti, F. (2020) South American savannas. In Scogings, PF; Sankaran, M (eds) Savanna Woody Plants and Large Herbivores. Wiley, Oxford.Google Scholar
Medina, E; Silva, JF. (1990) Savannas of northern South America: a steady state regulated by water–fire interactions on a background of low nutrient availability. Journal of Biogeography 17:403–413.CrossRefGoogle Scholar
Bucher, EH. (1982) Chaco and Caatinga – South American arid savannas, woodlands and thickets. In Huntley, BJ; Walker, BH (eds) Ecology of Tropical Savannas. Springer, Berlin, pp. 48–79.CrossRefGoogle Scholar
Fensham, RJ, et al. (2005) Rainfall, land use and woody vegetation cover change in semi-arid Australian savanna. Journal of Ecology 93:596–606.Google Scholar
Williams, RJ, et al. (1997) Leaf phenology of woody species in a North Australian tropical savanna. Ecology 78:2542–2558.Google Scholar
References
Staver, AC, et al. (2012) Top‐down determinants of niche structure and adaptation among African acacias. Ecology Letters 15:673–679.Google Scholar
Smith, P; Allen, Q. (2004) Field Guide to the Trees and Shrubs of the Miombo Woodlands. Royal Botanic Gardens Kew, Richmond, pp. 132–133. Includes a picture.Google Scholar
McNaughton, SJ. (1983) Serengeti grassland ecology – the role of composite environmental factors and contingency in community organization. Ecological Monographs 53:291–320.Google Scholar
Augustine, DJ. (2003) Spatial heterogeneity in the herbaceous layer of a semi-arid savanna ecosystem. Plant Ecology 167:319–332.Google Scholar
Hempson, GP, et al. (2019) Alternate grassy ecosystem states are determined by palatability–flammability trade-offs. Trends in Ecology & Evolution 34:286–290.Google Scholar
Archibald, S, et al. (2019) A unified framework for plant life-history strategies shaped by fire and herbivory. New Phytologist 224:1490–1503.Google Scholar
Fynn, R, et al. (2011) Trait–environment relations for dominant grasses in South African mesic grassland support a general leaf economic model. Journal of Vegetation Science 22:528–540.Google Scholar
Cromsigt, J, et al. (2017) The functional ecology of grazing lawns – how grazers, termites, people, and fire shape HiP’s savanna grassland mosaic. In Cromsigt, JPG, et al. (eds) Conserving Africa’s Mega-diversity in the Anthropocene: the Hluhluwe-iMfolozi Park Story. Cambridge University Press, Cambridge, pp. 135–160.Google Scholar
Linder, HP, et al. (2018) Global grass (Poaceae) success underpinned by traits facilitating colonization, persistence and habitat transformation. Biological Reviews 93:1125–1144.Google Scholar
Wigley, BJ, et al. (2009) Sapling survival in a frequently burnt savanna: mobilisation of carbon reserves in Acacia karroo. Plant Ecology 203:1.Google Scholar
Maurin, O, et al. (2014) Savanna fire and the origins of the ‘underground forests’ of Africa. New Phytologist 204:201–214.Google Scholar
February, EC, et al. (2019) Physiological traits of savanna woody species: adaptations to resource availability. In Scogings, PF; Sankaran, M (eds) Savanna Woody Plants and Large Herbivores. John Wiley & Sons, Oxford, pp. 309–329.Google Scholar