Skip to main content Accessibility help
Hostname: page-component-747cfc64b6-cssqh Total loading time: 0.202 Render date: 2021-06-16T08:59:38.232Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true }

Soil clay content and fire frequency affect clustering in trees in South African savannas

Published online by Cambridge University Press:  01 May 2008

Thomas A. Groen
Resource Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen, The Netherlands International Institute for Geo-Information Science and Earth Observation, PO Box 6, 7500 AA, Enschede, the Netherlands
Frank van Langevelde
Resource Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen, The Netherlands
Claudius A.D.M. van de Vijver
Plant Production Systems, Wageningen University, Haarweg 333, 6709 RZ Wageningen, The Netherlands
Navashni Govender
South African National Parks, Scientific Services, Private Bag X402, Skukuza, 1350, Republic of South Africa
Herbert H.T. Prins
Resource Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen, The Netherlands
E-mail address:


In this paper, we investigate which factors determine tree clustering in Southern African savannas. This was tested by measuring clustering of trees using the T-squared sampling method in plots of the Kruger National Park experimental burning programme in South Africa. Fire return interval is the main treatment in these plots, but also several auxiliary determining parameters like clay content in the soil, diameter of tree canopies, understorey composition, tree species diversity and average annual rainfall were measured while sampling. In the Kruger National Park 48 plots distributed over four different landscape types and with three different burning treatments (never, once every 3 y and annually) were sampled. First, we related the clustering of trees to these environmental variables. When looking at the most abundant species in each plot, the analysis revealed that clustering is mainly correlated with clay content in the soil. This analysis also showed that fire frequency had a positive effect on the clustering of tree species that are not very abundant. We suggest that less abundant species might be less resistant to fire and therefore adopt a mechanism of clustering to exclude grass fires under their canopy. Finally, we tested the effect of clustering on the impact of fire on trees by analysing the relationship between the distance of a tree to its nearest neighbour and its canopy diameter. We found that clustering reduces the damaging effect of fire on trees. Our study contributes to understanding of savanna functioning by showing which processes are relevant in the distribution of savanna trees.

Research Article
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below.


ARCHIBALD, S., BOND, W. J., STOCK, W. D. & FAIRBANKS, D. H. K. 2004. Shaping the landscape: fire–grazer interactions in an African savanna. Ecological Applications 15:96109.CrossRefGoogle Scholar
BAROT, S., GIGNOUX, J. & MENAUT, J. C. 1999. Demography of a savanna palm tree: predictions from comprehensive spatial pattern analyses. Ecology 80:19872005.CrossRefGoogle Scholar
BERJAK, S. G. & HEARNE, J. W. 2002. An improved cellular automaton model for simulating fire in a spatially heterogeneous savanna system. Ecological Modelling 148:133151.CrossRefGoogle Scholar
BIGGS, R., BIGGS, H. C., DUNNE, T. T., GOVENDER, N. & POTGIETER, A. L. F. 2003. Experimental burn plot trial in the Kruger National Park: history, experimental design and suggestions for data analysis. Koedoe 46:115.CrossRefGoogle Scholar
BYRAM, G. M. 1959. Combustion of forest fuels. Pp. 155182 in Davies, K. P. (ed.). Forest fire: control and use. McGraw-Hill, New York.Google Scholar
CAYLOR, K. K., SHUGART, H. H., DOWTY, P. R. & SMITH, T. M. 2003. Tree spacing along the Kalahari transect in Southern Africa. Journal of Arid Environments 54:281296.CrossRefGoogle Scholar
CARRICK, P. J. 2003. Competitive and facilitative relationships among tree shrub species and the role of browsing intensity and rooting depth in the succulent Karoo, South Africa. Journal of Vegetation Science 14:761772.CrossRefGoogle Scholar
DE RIDDER, N. & VAN KEULEN, H. 1995. Estimating biomass through transfer functions based on simulation model results: a case study for the Sahel. Agricultural Water Management 28:5771.CrossRefGoogle Scholar
DE RONDE, C., TROLLOPE, W. S. W., PARR, C. L., BROCKETT, B. H. & GELDENHUYS, C. J. 2004. Fire effects on flora and fauna. Pp. 6087 in Goldhammer, J. G. & De Ronde, C. (eds.). Wildland fire management: handbook for Sub-Sahara Africa. Global Fire Monitoring Centre, Freiburg.Google Scholar
DIGGLE, P. J. 2003. Statistical analysis of spatial point patterns. Oxford University Press, Oxford. 159 pp.Google Scholar
EUROCONSULT 1989. Agricultural compendium for rural development in the tropics and subtropics. Elsevier, Amsterdam. 740 pp.Google Scholar
GERTENBACH, W. P. D. 1983. Landscapes of the Kruger National Park. Koedoe 26:9121.CrossRefGoogle Scholar
GIBBS RUSSEL, G. E., WATSON, L., KOEKEMOER, M., SMOOK, L., BARKER, N. P., ANDERSON, H. M. & DALLWITZ, M. J. 1990. Grasses of Southern Africa. National Botanic Gardens/Botanical Research Institute, South Africa. 437 pp.Google Scholar
GIGNOUX, J., NOBLE, I. R. & MENAUT, J. C. 1995. Modelling tree community dynamics in savannas: effects of competition with grasses and impact of disturbance. Pp. 219230 in Bellan-Santini, D., Bonin, G. & Emig, C. (eds.). Functioning and dynamics of natural and perturbed ecosystems. Intercept Ltd, Paris.Google Scholar
GIGNOUX, J., MENAUT, J. C., NOBLE, I. R. & DAVIES, I. D. 1998. A spatial model of savanna function and dynamics: model description and preliminary results. Pp. 361383 in Newbery, D. M., Prins, H. H. T. & Brown, N. (eds.). Dynamics of tropical communities. Blackwell, Oxford. 635 pp.Google Scholar
GOHEEN, J. R., YOUNG, T. P., KEESING, F. & PALMER, T. M. 2007. Consequences of herbivory by native ungulates for the reproduction of a savanna tree. Journal of Ecology 95:129138.CrossRefGoogle Scholar
GOVENDER, N., TROLLOPE, W. S. W. & VAN WILGEN, B. W. 2006. The effect of fire season, fire frequency, rainfall and management on fire intensity in savanna vegetation in South Africa. Journal of Applied Ecology 43:748758.CrossRefGoogle Scholar
GRICE, T. C. & SLATTER, S. M. 1996. Fire in the management of Northern Australian pastoral lands. Tropical Grassland Society of Australia. Occasional publication No. 8.Google Scholar
HINES, W. G. S. & HINES, R. J. O. 1979. The Eberhardt statistic and the detection of nonrandomness of spatial point distributions. Biometrika 66:7379.CrossRefGoogle Scholar
HOWARD, T. 2000. Introduced grasses, poor master, but useful servant. Land Management. Scholar
JELTSCH, F., MILTON, S. J., DEAN, W. R. J. & ROOYEN, N. 1996. Tree spacing and coexistence in semiarid savannas. Journal of Ecology 84:583595.CrossRefGoogle Scholar
JELTSCH, F., MILTON, S. J., DEAN, W. R. J., VAN ROOYEN, N. & MOLONEY, K. A. 1998. Modelling the impact of small-scale heterogeneities on tree-grass coexistence in semi-arid savannas. Journal of Ecology 86:780793.CrossRefGoogle Scholar
JOQUET, P., TAVERNIER, V., ABBADIE, L. & LEPAGE, M. 2005. Nests of subterranean fungus-growing termites (Isoptera, Macrotermitinae) as nutrient patches for grasses in savannah ecosystems. African Journal of Ecology 43:191196.CrossRefGoogle Scholar
KENNEDY, A. D. & POTGIETER, A. L. F. 2003. Fire season affects size and architecture of Colophospermum mopane in southern African savannas. Plant Ecology 167:179193.CrossRefGoogle Scholar
KONATÉ, S., LE ROUX, X., TESSIER, D. & LEPAGE, M. 1999. Influence of large termitaria on soil characteristics, soil water regime, and tree leaf shedding pattern in a West African savanna. Plant and Soil 206:4760.CrossRefGoogle Scholar
MARION, G., SWAIN, D. L. & HUTCHINGS, M. R. 2004. Understanding foraging behaviour in spatially heterogeneous environments. Journal of Theoretical Biology 292:127142.Google Scholar
NDIAYE, D., LENSI, R., LEPAGE, M. & BRAUMAN, A. 2004. The effect of the soil-feeding termite Cubitermes niokoloensis on soil microbial activity in a semi-arid savanna in West Africa. Plant and Soil 259:277286.CrossRefGoogle Scholar
PACALA, S. W. & LEVIN, S. A. 1997. Biologically generated spatial pattern and the coexistence of competing species. Pp. 204232 in Tilman, D. & Kareiva, P. (eds.). Spatial ecology: the role of space in population dynamics and interspecific interactions. Princeton University Press, Princeton.Google Scholar
PICARD, N., KOUYATÉ, A. M. & DESSARD, H. 2005. Tree density estimation using a distance method in Mali Savanna. Forest Science 51:718.Google Scholar
PRINS, H. H. T. & VAN DER JEUGD, H. P. 1993. Herbivore population crashes and woodland structure in East Africa. Journal of Ecology 81:305314.CrossRefGoogle Scholar
RIETKERK, M., BOERLIJST, M. C., VAN LANGEVELDE, F., HILLERISLAMBERS, R., VAN DE KOPPEL, J., KUMAR, L., PRINS, H. H. T. & DE ROOS, A. M. 2002. Self organisation of vegetation in arid ecosystems. American Naturalist 160:524530.Google ScholarPubMed
SCHOLES, R. J. & ARCHER, S. R. 1997. Tree-grass interactions in savannas. Annual Reviews of Ecological Systems 28:517544.CrossRefGoogle Scholar
SHEA, R. W., SHEA, B. W., KAUFFMAN, J. B., WARD, D. E., HASKINS, C. I. & SCHOLES, M. C. 1996. Fuel biomass and consumption factors associated with fires in savanna ecosystems of South Africa and Zambia. Journal of Geophysical Research 101:2355123568.CrossRefGoogle Scholar
SKARPE, C. 1991. Spatial patterns end dynamics of woody vegetation in an arid savanna. Journal of Vegetation Science 2:565572.CrossRefGoogle Scholar
SMITH, T. M. & GOODMAN, P. S. 1986. The effect of competition on the structure and dynamics of Acacia savannas in Southern Africa. Journal of Ecology 74:10311044.CrossRefGoogle Scholar
TAINTON, N. M. 1999. Veld management in South Africa. University of Natal Press, Pietermaritzburg. 472 pp.Google Scholar
VAN DE VIJVER, C. A. D. M., FOLEY, C. A. & OLFF, H. 1999. Changes in the woody component of an East African savanna during 25 years. Journal of Tropical Ecology 15:545564.CrossRefGoogle Scholar
VAN LANGEVELDE, F., VAN DE VIJVER, C. A. D. M., KUMAR, L., VAN DE KOPPEL, J., DE RIDDER, N., VAN ANDEL, J., SKIDMORE, A. K., HEARNE, J. W., STROOSNIJDER, L., BOND, W. J., PRINS, H. H. T. & RIETKERK, M. 2003. Effects of fire and herbivory on the stability of savanna ecosystems. Ecology 84:337350.CrossRefGoogle Scholar
VAN NES, E. H. & SCHEFFER, M. 2005. Implications of spatial heterogeneity for catastrophic regime shifts in ecosystems. Ecology 86:17971807.CrossRefGoogle Scholar
WALKER, B. H. & NOY-MEIR, I. 1982. Aspects of the stability and resilience of savanna ecosystems. Pp. 556590 in Huntley, B. J. & Walker, B. H. (eds.). Ecology of tropical savannas. Springer Verlag, Berlin.CrossRefGoogle Scholar
WALLMER, M. 1994. Grass fuel build up over time on tropical hillslopes. Pp. 3033 in Van Cuyenberg, S. (ed.). Proceedings of the Fire Ecology Workshop. Parks and Wildlife Commission, Darwin.Google Scholar
ZAR, J. H. 1996. Biostatistical analysis. Prentice-Hall, Upper Saddle River. 931 pp.Google Scholar
Cited by

Send article to Kindle

To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Soil clay content and fire frequency affect clustering in trees in South African savannas
Available formats

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Soil clay content and fire frequency affect clustering in trees in South African savannas
Available formats

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Soil clay content and fire frequency affect clustering in trees in South African savannas
Available formats

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *