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Human-modified landscapes: patterns of fine-scale woody vegetation structure in communal savannah rangelands

Published online by Cambridge University Press:  29 November 2011

J. T. FISHER ,
E.T.F. WITKOWSKI ,
B.F.N. ERASMUS ,
J. VAN AARDT ,
G. P. ASNER ,
K. J. WESSELS  and
R. MATHIEU
J. T. FISHER*
Affiliation:
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg 2050, South Africa Ecosystems Earth Observation, Natural Resource and Environment, Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa
E.T.F. WITKOWSKI
Affiliation:
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg 2050, South Africa
B.F.N. ERASMUS
Affiliation:
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg 2050, South Africa
J. VAN AARDT
Affiliation:
Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, New York 14623, USA
G. P. ASNER
Affiliation:
Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford CA 94305, USA
K. J. WESSELS
Affiliation:
Remote Sensing Research Unit, Council for Scientific and Industrial Research (CSIR)-Meraka Institute, PO Box 395, Pretoria 0001, South Africa
R. MATHIEU
Affiliation:
Ecosystems Earth Observation, Natural Resource and Environment, Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa
*
*Correspondence: J.T. Fisher Tel: +27 11 717 6408 Fax: +27 11 717 6494 e-mail: [email protected]
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Summary

Despite electrification, over 90% of rural households in certain areas of South Africa continue to depend on fuelwood, and this affects woody vegetation structure, with associated cascading effects on biodiversity within adjacent lands. To promote sustainable use, the interactions between anthropogenic and environmental factors affecting vegetation structure in savannahs need to be understood. Airborne light detection and ranging (LiDAR) data collected over 4758 ha were used to examine woody vegetation structure in five communal rangelands around 12 settlements in Bushbuckridge, a municipality in the Kruger to Canyons Biosphere Reserve (South Africa). The importance of underlying abiotic factors was evaluated by measuring size class distributions across catenas and using canonical correspondence analysis. Landscape position was significant in determining structure, indicating the importance of underlying biophysical factors. Differences in structure were settlement-specific, related to mean annual precipitation at one site, and human population density and intensity of use at the other four sites. Size class distributions of woody vegetation revealed human disturbance gradients around settlements. Intensity of use affected the amplitude, not the shape, of the size class distribution, suggesting the same height classes were being harvested across settlements, but amount harvested varied between settlements. Highly used rangelands result in a disappearance of disturbance gradients, leading to homogeneous patches of low woody cover around settlements with limited rehabilitation options. Reductions in disturbance gradients can serve as early warning indicators of woodland degradation, a useful tool in planning for conservation and sustainable development.

Keywords

Carnegie Airborne Observatorycommunal rangelandsLiDARresource gradientssize structureSouth Africasustainable resource use
Type
Papers
Information
Environmental Conservation , Volume 39 , Issue 1 , March 2012 , pp. 72 - 82
Copyright
Copyright © Foundation for Environmental Conservation 2011

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References

Archibald, S., Roy, D.P., van Wilgen, B.W. & Scholes, R.J. (2009) What limits fire? An examination of drivers of burnt area in Southern Africa. Global Change Biology 15: 613–630.CrossRefGoogle Scholar
Asner, G.P., Knapp, D.E., Kennedy-Bowdoin, T., Jones, M.O., Martin, R.E., Boardman, J. & Field, C.B. (2007) Carnegie Airborne Observatory: in-flight fusion of hyperspectral imaging and waveform light detection and ranging (wLiDAR) for three-dimensional studies of ecosystems. Journal of Applied Remote Sensing 1: 013536.CrossRefGoogle Scholar
Asner, G.P., Hughes, R.F., Vitousek, P.M., Knapp, D.E., Kennedy-Bowdoin, T., Boardman, J., Martin, R.E., Eastwood, M. & Green, R.O. (2008) Invasive plants transform the three-dimensional structure of rain forests. Proceedings of the National Academy of Science USA 105: 4519–4523.CrossRefGoogle ScholarPubMed
Asner, G.P., Levick, S.R., Kennedy-Bowdoin, T., Knapp, D.E., Emerson, R., Jacobson, J., Colgan, M.S. & Martin, R.E. (2009) Large-scale impacts of herbivores on the structural diversity of African savannas. Proceedings of the National Academy of Science USA 12: 261–278.Google Scholar
Banks, D.I., Griffin, N.J., Shackleton, C.M., Shackleton, S.E. & Mavrandonis, J.M. (1996) Wood supply and demand around two rural settlements in a semi-arid savanna, South Africa. Biomass Bioenergy 11: 319–331.CrossRefGoogle Scholar
Bock, M., Bohner, J., Conrad, O., Kothe, R. & Ringeler, A. (2007) Methods for creating functional soil databases and applying digital soil mapping with SAGA GIS. In: Status and Prospect of Soil Information in South-Eastern Europe: Soil Databases, Projects and Applications, ed. Hengl, T., Panagos, P., Jones, A & Toth, G., pp. 149–163, Italy: European Commission.Google Scholar
Botha, J., Witkowski, E.T.F. & Shackleton, C.M. (2004) The impact of commercial harvesting on Warburgia salutaris (‘pepper-bark tree’) in Mpumalanga, South Africa. Biodiversity and Conservation 13: 1675–1698.CrossRefGoogle Scholar
Coetzer, K.L., Erasmus, B.F.N., Witkowski, E.T.F. & Bachoo, A.K. (2010) Land cover change in the Kruger to Canyons Biosphere Reserve (1993–2006): a first step towards creating a conservation plan for the subregion. South African Journal of Science 106: 26–35.CrossRefGoogle Scholar
Dovie, D.B.K., Shackleton, C.M. & Witkowski, E.T.F. (2002) Direct-use values of woodland resources consumed and traded in a South African village. International Journal of Sustainable Development and World Ecology 9: 269–283.CrossRefGoogle Scholar
Esri (2009) ArcMap. Redlands, USA: Esri Inc.Google Scholar
Freitag-Ronaldson, S. & Foxcroft, L.C. (2003) Anthropogenic influences at the ecosystem level. In: The Kruger Experience: Ecology and Management of Savanna Heterogeneity, ed. Du Toit, J.T., Rogers, K.H., & Biggs, H.C., pp. 3–21. Washington, DC, USA: Island Press.Google Scholar
Giannecchini, M., Twine, W. & Vogel, C. (2007) Land-cover change and human-environment interactions in a rural cultural landscape in South Africa. The Geographical Journal 173: 26–42.CrossRefGoogle Scholar
Gillson, L. (2004) Evidence of hierarchical patch dynamics in an east African savanna? Landscape Ecology 19: 883–894.CrossRefGoogle Scholar
Helm, C., Wilson, G., Midgley, J., Kruger, L. & Witkowski, E.T.F. (2011) Investigating the vulnerability of an African savanna tree (Sclerocarya birrea ssp. caffra) to fire and herbivory. Austral Ecology doi: 10.1111/j.1442-9993.2010.02232.x (in press).CrossRefGoogle Scholar
Higgins, S.I., Shackleton, C.M. and Robinson, E.R. (1999) Changes in woody community structure and composition under contrasting landuse systems in a semi-arid savanna, South Africa. Journal of Biogeography 26: 619–627.CrossRefGoogle Scholar
Hobbs, R.J., Arico, S., Aronson, J., Baron, J.S., Bridgewater, P., Cramer, V.A., Epstein, P.R., Ewel, J.J., Klink, C.A., Lugo, A.E., Norton, D., Ojima, D., Richardson, D.M., Sanderson, E.W., Valladares, F., Vila, M., Zamora, R. & Zobel, M. (2006) Novel ecosystems: theoretical and management aspects of the new ecological world order. Global Ecology and Biogeography 15: 1–7.CrossRefGoogle Scholar
ITT Vis (2009) ENVI, ITT Visual Information Solutions. Boulder, Colorado, USA: ITT CorporationGoogle Scholar
Joppa, L.N., Loarie, S.R. & Pimm, S.L. (2009) On population growth near protected areas. PLoS ONE 4: e4279.CrossRefGoogle ScholarPubMed
Kaschula, S.A., Twine, W.E. & Scholes, M.C. (2005) Coppice harvesting of fuelwood species on a South African common: utilizing scientific and indigenous knowledge in community based natural resource management. Human Ecology 33: 387–418.CrossRefGoogle Scholar
Leps, J. & Smilauer, P. (2003) Multivariate analysis of ecological data using CANOCO. Cambridge, UK: Cambridge University Press.CrossRefGoogle Scholar
Levick, S.R., Asner, G.P., Kennedy-Bowdoin, T. & Knapp, D.E. (2009) The relative influence of fire and herbivory on savanna three-dimensional vegetation structure. Biological Conservation 142: 1693–1700.CrossRefGoogle Scholar
Luoga, E.J., Witkowski, E.T.F & Balkwill, K. (2005) Land cover and use changes in relation to the institutional framework and tenure of land and resources in eastern Tanzania Miombo woodlands. Environment, Development and Sustainability 7: 71–93.CrossRefGoogle Scholar
Lykke, A.M. (1998) Assessment of species composition change in savanna vegetation by means of woody plants’ size class distributions and local information. Biodiversity and Conservation 7: 1261–1275.CrossRefGoogle Scholar
Manning, A.D., Fischer, J. & Lindenmayer, D.B. (2006) Scattered trees are keystone structures: implications for conservation. Biological Conservation 132: 311–321.CrossRefGoogle Scholar
Mwavu, E.N. & Witkowski, E.T.F. (2009) Population structure and regeneration of multiple-use tree species in a semi-deciduous African tropical rainforest: implications for primate conservation. Forest Ecology and Management 258: 840–849.CrossRefGoogle Scholar
Neke, K.S., Owen-Smith, N. & Witkowski, E.T.F. (2006) Comparative resprouting response of savanna woody plant species following harvesting: the value of persistence. Forest Ecology and Management 232: 114–123.CrossRefGoogle Scholar
Pollard, S., Shackleton, C. & Curruthers, J. (2003) Beyond the fence: people and the lowveld landscape. In: The Kruger Experience: Ecology and Management of Savanna Heterogeneity, ed. Du Toit, J.T., Rogers, K.H., & Biggs, H.C., pp. 422–446. Washington, DC, USA: Island Press.Google Scholar
Pysek, P. & Leps, J. (1991) Response of a weed community to nitrogen fertilization: a multivariate analysis. Journal of Vegetation Science 2: 237–244.CrossRefGoogle Scholar
Rutherford, M., Mucina, L., Lotter, M.C., Bredenkamp, G.J., Smit, J.H.L., Scott-Shaw, C.R., Hoare, D.B., Goodman, P.S., Bezuidenhout, H., Scott, L., Ellis, F., Powrie, L.W., Siebert, F., Mostert, T.H., Henning, B.J., Venter, C.E., Camp, K.G.T., Siebert, S.J., Matthews, W.S., Burrows, J.E., Dobson, L.N., Schmidt, E., Winter, P.J.D., Ward, R.A., Williamson, S. & Hurter, P.J. (2006) Savanna biome. In: The Vegetation of South Africa, Lesotho and Swaziland, ed. Mucina, L. & Rutherford, M.C., pp. 439–539. Strelitzia 19. Pretoria, South Africa: South African National Biodiversity Institute.Google Scholar
Sankaran, M., Hanan, N.P., Scholes, R.J., Ratnam, J., Augustine, D.J., Cade, B.S., Gignoux, J., Higgins, S.I., Xavier, , Ludwig, F., Ardo, J., Banyikwa, F., Bronn, A., Bucini, G., Caylor, K.K., Coughenour, M.B., Diouf, A., Ekaya, W., Feral, C.J., February, E.C., Frost, P.G.H., Hiernaux, P., Hrabar, H., Metzger, K., Prins, H., Rigrose, S., Sea, W., Tews, J., Worden, J. & Zambatis, N. (2005) Determinants of woody cover in African savannas. Nature 438: 8–11.CrossRefGoogle ScholarPubMed
Scholes, R.J. & Walker, B.H. (1993) An African Savanna. Synthesis of the Nylsvley Study. Cambridge, UK: Cambridge University Press.CrossRefGoogle Scholar
Scholes, R.J. & Archer, S.R. (1997) Tree-grass interactions in savannas. Annual Review of Ecology and Systematics 28: 517–544.CrossRefGoogle Scholar
Scholes, R.J. (2009) Syndromes of dryland degradation in southern Africa. African Journal of Range and Forest Science 26: 113–125.CrossRefGoogle Scholar
Shackleton, C.M., Griffin, N.J., Banks, D.I., Mavrandonis, J.M. & Shackleton, S.E. (1994) Community structure and species composition along a disturbance gradient in a communally managed South African savanna. Vegetatio 115: 157–167.CrossRefGoogle Scholar
Shackleton, C.M., Shackleton, S.E., Buiten, E. & Bird, N. (2007) The importance of dry woodlands and forests in rural livelihoods and poverty alleviation in South Africa. Forest Policy and Economics 9: 558–577.CrossRefGoogle Scholar
Smit, I.P.J., Asner, G.P., Govender, N., Kennedy-Bowdoin, T., Knapp, D.E. & Jacobson, J. (2010) Effects of fire on woody vegetation structure in African savanna. Ecological Applications 20: 1865–1875.CrossRefGoogle ScholarPubMed
ter Braak, C.J.F. & Smilauer, P. (2002) CANOCO Reference Manual and CanoDraw for Windows User's Guide: Software for Canonical Community Ordination (Version 4.5). Ithaca, New York, USA: Microcomputer Power.Google Scholar
Twine, W., Moshe, D., Netshiluvhi, T. & Siphugu, V. (2003) Consumption and direct-use values of savanna bio-resources used by rural households in Mametja, a semi-arid area of Limpopo province, South Africa. South African Journal of Science 99: 467–473.Google Scholar
Twine, W.C. (2005) Socio-economic transitions influence vegetation change in the communal rangelands of the South African lowveld. African Journal of Range and Forest Science 22: 93–99.CrossRefGoogle Scholar
UNESCO (1996) Biosphere Reserves: The Seville Strategy and the Statutory Framework of the World Network. Paris, France: UNESCO.Google Scholar
van Aardt, J.A.N., Wynne, R.H. & Oderwald, R.G. (2006) Forest volume and biomass estimation using small-footprint LiDAR-distributional parameters on a per-segment basis. Forest Science 52: 636–649.Google Scholar
Venter, F.J., Scholes, R.J. & Eckhardt, H.C. (2003) The abiotic template and its associated vegetation pattern. In: The Kruger Experience: Ecology and Management of Savanna Heterogeneity, ed. Du Toit, J.T., Rogers, K.H. & Biggs, H.C., pp. 83–129. Washington, DC, USA: Island Press.Google Scholar
Wehr, A. & Lohr, U. (1999) Airborne laser scanning - an introduction and overview. ISPRS Journal of Photogrammetry and Remote Sensing 54: 68–82.CrossRefGoogle Scholar
Wessels, K.J., Mathieu, R., Erasmus, B.F.N., Asner, G.P., Smit, I.P.J., van Aardt, J., Main, R., Fisher, J., Marais, W., Kennedy-Bowdoin, T., Knapp, D.E., Emerson, R. & Jacobson, J. (2011) Impact of contrasting land use on woody vegetation structure in the Lowveld savannas of South Africa. Forest Ecology and Management 261: 19–29.CrossRefGoogle Scholar
Wilson, B.G. & Witkowski, E.T.F. (2003) Seed banks, bark thickness and change in age and size structure (1978–1999) of the African savanna tree, Burkea africana. Plant Ecology 167: 151–162.CrossRefGoogle Scholar
Witkowski, E.T.F. & O'Connor, T.G. (1996) Topo-edaphic, floristic and physiognomic gradients of woody plants in a semi-arid African savanna woodland. Vegetatio 124: 9–23.CrossRefGoogle Scholar
Zar, J.H. (1999) Biostatistical Analysis. Fourth edition. Upper Saddle River, USA: Pearson Education.Google Scholar
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