[en] Savannas cover one-fifth of the Earth's surface, harbour substantial biodiversity, and provide a broad range of ecosystem services to hundreds of millions of people. The community composition of trees in tropical moist forests varies with climate, but whether the same processes structure communities in disturbance-driven savannas remains relatively unknown. We investigate how biodiversity is structured over large environmental and disturbance gradients in woodlands of eastern and southern Africa. We use tree inventory data from the Socio-Ecological Observatory for Studying African Woodlands (SEOSAW) network, covering 755 ha in a total of 6780 plots across nine countries of eastern and southern Africa, to investigate how alpha, beta, and phylogenetic diversity varies across environmental and disturbance gradients. We find strong climate-richness patterns, with precipitation playing a primary role in determining patterns of tree richness and high turnover across these savannas. Savannas with greater rainfall contain more tree species, suggesting that low water availability places distributional limits on species, creating the observed climate-richness patterns. Both fire and herbivory have minimal effects on tree diversity, despite their role in determining savanna distribution and structure. High turnover of tree species, genera, and families is similar to turnover in seasonally dry tropical forests of the Americas, suggesting this is a feature of semiarid tree floras. The greater richness and phylogenetic diversity of wetter plots shows that broad-scale ecological patterns apply to disturbance-driven savanna systems. High taxonomic turnover suggests that savannas from across the regional rainfall gradient should be protected if we are to maximise the conservation of unique tree communities.
Davies, Robert W. ; Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, United Kingdom
Ryan, Casey M.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Harrison, Rhett D.; World Agroforestry, Lusaka, Zambia
Dexter, Kyle G.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom ; Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom
Ahrends, Antje; Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom
te Beest, Mariska; Copernicus Institute for Sustainable Development, Utrecht University, Netherlands ; Centre for African Conservation Ecology, Nelson Mandela University, Port Elizabeth, South Africa
Benitez, Lorena; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Brade, Thom K.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Carreiras, Joao M. B.; National Centre for Earth Observation (NCEO), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, United Kingdom
Druce, Dave J.; Ecological Advice, Ezemvelo KZN Wildlife, Hluhluwe-iMfolozi Park, South Africa ; School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Fayolle, Adeline ; Université de Liège - ULiège > TERRA Research Centre > Gestion des ressources forestières
Finckh, Manfred; Biodiversity, Evolution and Ecology of Plants, Institute of Plant Sciences and Microbiology, University of Hamburg, Hamburg, Germany
Godlee, John L.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Gonclaves, Francisco M.; Herbarium of Lubango, ISCED Huíla, Lubango, Angola
Grundy, Isla M.; Department of Biological Sciences, University of Zimbabwe, Harare, Zimbabwe
Hoche, T.; Biodiversity, Evolution and Ecology of Plants, Institute of Plant Sciences and Microbiology, University of Hamburg, Hamburg, Germany
Holdo, Ricardo M.; Odum School of Ecology, University of Georgia, Athens, United States
Makungwa, Steve; Lilongwe University of Agriculture and Natural Resources (LUANAR), Lilongwe, Malawi
McNicol, Iain M.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Mograbi, Penelope J.; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom ; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
Muchawona, Anderson; Forest Research Centre, Harare, Zimbabwe
Muhate, Aristidies; Ministry of Land, Environment and Rural Development Mozambique, Maputo, Mozambique
Muledi, Jonathan; Ecologie, Restauration Ecologique et Paysage, Faculté des Sciences Agronomiques, Université de Lubumbashi, Democratic Republic Congo
Pritchard, Rose; Global Development Institute, School of Environment, Education and Development, University of Manchester, Manchester, United Kingdom
Revermann, Rasmus ; Biodiversity, Evolution and Ecology of Plants, Institute of Plant Sciences and Microbiology, University of Hamburg, Hamburg, Germany ; Faculty of Natural Resources and Spatial Sciences, Namibia University of Science and Technology, Windhoek, Namibia
Ribeiro, Natasha S.; Department of Forest Engineering, Faculty of Agronomy and Forest Engineering, Universidade Eduardo Mondlane, Maputo, Mozambique
Siampale, Abel; Ministry of Lands and Natural Resources, Cairo Road, Lusaka, Zambia
Carla Staver, A.; Department of Ecology and Evolutionary Biology, Yale University, New Haven, United States
Syampungani, Stephen; ORTARChI Chair Environment and Development, Department of Environmental and Plant Sciences, Copperbelt University, Kitwe, Zambia ; Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
Williams, Mathew; School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
Swemmer, Anthony M.; South African Environment Observation Network (SAEON), Phalaborwa, South Africa
Edwards, David P.; Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, United Kingdom
Precipitation gradients drive high tree species turnover in the woodlands of eastern and southern Africa
Publication date :
2023
Journal title :
Ecography
ISSN :
0906-7590
eISSN :
1600-0587
Publisher :
John Wiley and Sons Inc
Volume :
2023
Issue :
10
Peer reviewed :
Peer Reviewed verified by ORBi
Tags :
ForestIsLife
Funders :
NERC - Natural Environment Research Council NCEO - National Centre for Earth Observation
Funding text :
– DPE and RDH were supported by the UK Natural Environment Research council (NERC; grant no.: NE/W003708/1). JMBC was supported by the UK Natural Environment Research Council (NERC), through agreement no. PR140015 between NERC and the National Centre for Earth Observation.
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