Termite Mounds Increase Functional Diversity of Woody Plants in African Savannas
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Fine-scale spatial heterogeneity influences biodiversity and ecosystem productivity at many scales. In savanna systems, Macrotermes termites, through forming spatially explicit mounds with unique woody plant assemblages, emerge as important sources of such heterogeneity. Despite a growing consensus regarding the importance of functional diversity (FD) to ecosystem processes, no study has quantified how termite mounds affect woody plant FD. We address whether termite mounds alter the distribution of functional traits, and increase FD of woody plant communities within Africa’s largest savanna woodland, the 2.7 million km2 miombo system. Using plant traits that change according to soil resources (for example, water and nutrients), and disturbance (for example, fire and elephant herbivory), we identified response functional groups and compared relative representation of these groups between mound and matrix habitats. We also asked whether mound and matrix habitats differed in their contribution to FD within the system. Although species representing most functional groups were found in both mound and matrix habitats, relative abundance of functional groups differed between mound and matrix. Mound plant assemblages had greater response diversity to soil resources than matrix plots, but there was no difference in response diversity to disturbance. High trait values on mounds included tree height, leaf nitrogen, phosphorus, and palatability. Species with root ectomycorrhizae dominated the matrix. In conclusion, these small patches of nutrient-enriched substrate emerge as drivers of FD in above-ground woody plant communities.
Key words:disturbances of herbivory and fire functional diversity functional groups Macrotermes resource patches soil resources spatial heterogeneity
This research was funded by an NRF-SADC collaborative grant and the DST/NRF Centre of Excellence at the University of Cape Town. The Director General of the Zimbabwe National Parks and Wildlife Management Authority (ZNPWMA) granted permission to carry out this research under the auspices of a memorandum of understanding between the ZNPWMA and the Tropical Resource Ecology Programme (TREP) at the University of Zimbabwe. Chris Chapano and Anthony Mapaura, and Christien Bredenkamp of the National Herbaria of Harare and Pretoria, respectively, offered assistance and guidance in building a database of functional traits.
- Clarke KR, Warwick RM. 1994. Change in marine communities: an approach to statistical analysis and interpretation. Natural Environment Research Council. Plymouth: Hutchings & Mason Ltd. 144 pp.Google Scholar
- Coates Palgrave K, Coates Palgrave M. 2002. Palgrave’s trees of southern Africa. Cape Town: Struik Publishers.Google Scholar
- FAO/IIASA/ISRIC/ISS-CAS/JRC. 2012. Harmonized World Soil Database (version 1.2). FAO Rome, Italy and IIASA, Laxenburg, Austria. http://webarchive.iiasa.ac.at/Research/LUC/External-World-soil-database/HTML/. Accessed 3 Nov 2012.
- Frost P. 1996. The ecology of miombo woodlands. In: Campbell B, Ed. The miombo in transition: woodlands and welfare in Africa. Bogor: Center for International Forestry Research (CIFOR). p 11–58.Google Scholar
- Higgins SI, Bond WJ, February EC, Bronn A, Euston-Brown DIW, Enslin B, Govender N, Rademan L, O’ Regan S, Potgieter ALF, Scheiter S, Sowry R, Trollope L, Trollope WSW. 2007. Effects of four decades of fire manipulation on woody vegetation structure in savanna. Ecology 88:1119–25.PubMedCrossRefGoogle Scholar
- Holdo RM, McDowell LR. 2004. Termite mounds as nutrient-rich food patches for elephants. Biotropica 36:231–9.Google Scholar
- Laliberté E, Shipley B. 2011. FD: measuring functional diversity from multiple traits, and other tools for functional ecology. R package 1.0–11.Google Scholar
- Lineham S. 1965. Rainfall in Rhodesia. In: Collins MO, Ed. Rhodesia: its natural resources and economic development. p. 26–7.Google Scholar
- Oksanen J, Blanchet FG, Roeland Kindt, Legendre P, Minchin PR, O’Hara RB, Simpson GL, Solymos P, Stevens MHH, Wagner H. 2013. Vegan: Community Ecology Package. R package version 2.0-7. http://cran.r-project.org/package=vegan. Accessed 5 May 2013.
- Podgaiski LR, Joner F, Lavorel S, Moretti M, Ibanez S, Mendonça MDS, Pillar VD. 2013. Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands. PloS one 8:e60207. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3610671&tool=pmcentrez&rendertype=abstract. Accessed 20 May 2013.
- R Development Core Team. 2011. R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, http://www.R-project.org/. Accessed 4 March 2011.
- SADC Food Security Programme. 1991. Draft soil map of Zimbabwe http://eusoils.jrc.ec.europa.eu/esdb_archive/eudasm/africa/maps/afr_zw2015_so.html. Accessed 20 June 2012.
- Sankaran M, Hanan NP, Scholes RJ, Ratnam J, Augustine DJ, Cade BS, Gignoux J, Higgins SI, Le Roux X, Ludwig F, Ardo J, Banyikwa F, Bronn A, Bucini G, Caylor KK, Coughenour MB, Diouf A, Ekaya W, Feral CJ, February EC, Frost PGH, Hiernaux P, Worden J, Zambatis N. 2005. Determinants of woody cover in African savannas. Nature 438:8–11.CrossRefGoogle Scholar
- Torrance JD. 1965. The temperature of Rhodesia. In: Collins MO, editor. Rhodesia: its natural resources and economic development. pp 28–9.Google Scholar
- Walker BH. 1980. A review of browse and its role in livestock production in southern African savannas. Proc Grassland Soc of southern Africa 11:125–130.Google Scholar
- Webb CO, Ackerly DD, McPeek MA, Donoghue MJ. 2002. Phylogenies and community ecology. Ann Rev Ecol Syst 33:475–505.Google Scholar
- White F. 1983. The vegetation of Africa: a descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa, p. 356. UNESCO, Paris.Google Scholar