Sani Pass Elevation Gradient Project

Investigating patterns and drivers of diversity

About this Project

This study aims to investigate patterns and drivers of diversity across an elevation gradient.

An elevation gradient from sea level to almost 3400 m above sea level in the Maloti-Drakensberg Mountains provides an excellent opportunity to investigate the effects of climate on animal and plant diversity.  The Sani Pass provides road access to the steepest part of this elevation gradient, and this region is where most of our effort has been invested.  Ground dwelling arthropods (insects, spiders, millipedes) are sampled twice per year in eight 300 m elevation bands from 900 m to 3000 m.  The focus of the study has been on ant diversity, but specimens of other groups, including spiders, wasps and beetles that have been sampled in pitfall traps have been shared with various collaborators.  As the gradient provides an ideal means of examining the influence of climate on invasive species, several studies on alien plant diversity have been conducted.

An undergraduate field course is an important part of our activities in this area. Click here for more about this course.

Summer field work

The elevation gradient from sea level to almost 3400 m above sea level sampling locations.

Biodiversity Gallery

Click here to view a biodiversity gallery of the area

Sani Pass Elevation Gradient Project Publication List

Publications

Publications

Elevation-diversity patterns through space and time: ant communities of the Maloti-Drakensberg Mountains of southern Africa.

Bishop, T., Robertson, M.P., van Rensburg, B.J., Parr, C.L. 2014. Elevation-diversity patterns through space and time: ant communities of the Maloti-Drakensberg Mountains of southern Africa. Journal of Biogeography. 41: 2256-2268. doi:10.1111/jbi.12368


Contrasting species and functional beta diversity in montane ant communities.

Bishop, T., Robertson, M.P., van Rensburg, B.J., Parr, C.L. 2015. Contrasting species and functional beta diversity in montane ant communities. Journal of Biogeography. 42, 1776–1786.  doi:10.1111/jbi.12537


Ant assemblages have darker and larger members in cold environments.

Bishop, T.R., Robertson, M.P., Gibb, H., van Rensburg, B.J., Braschler, B.,  Chown, S.L., Foord, S., Munyai, C., Okey, I., Tshivhandekano, P., Werenkraut, V., Parr, C. 2016. Ant assemblages have darker and larger members in cold environments. Global Ecology and Biogeography. 25: 1489-1499.  doi:10.1111/geb.12516


Coping with the cold: minimum temperatures and thermal tolerances dominate the ecology of mountain ants.

Bishop, T.R., Robertson, M.P., van Rensburg, B.J. and Parr, C.L. 2017. Coping with the cold: minimum temperatures and thermal tolerances dominate the ecology of mountain ants. Ecological Entomology. 42: 105–114.  doi:10.1111/een.12364


Thermoregulatory traits combine with range shifts to alter the future of montane ant assemblages.

Bishop, T.R., Parr, C.L., Gibb, H. van Rensburg, B.J., Braschler, B., Chown, S.L., Foord, S.H., Lamy, K., Munyai, T.C., Okey, I., Tshivhandekano, P.G., Werenkraut, V. and Robertson, M.P. 2019. Thermoregulatory traits combine with range shifts to alter the future of montane ant assemblages. Global Change Biology. 25:2162–2173. doi:10.1111/gcb.14622


Invasion of grasslands by silver wattle, Acacia dealbata (Mimosaceae) alters beetle (Coleoptera) assemblage structure.

Coetzee, B.W.T., van Rensburg, B.J., Robertson M.P. 2007. Invasion of grasslands by silver wattle, Acacia dealbata (Mimosaceae) alters beetle (Coleoptera) assemblage structure. African Entomology. 15: 328-339.  doi:10.4001/1021-3589-15.2.328


Low levels of intraspecific trait variation in a keystone invertebrate group.

Gaudard, C. Robertson, M.P. Bishop, T.R. 2019. Low levels of intraspecific trait variation in a keystone invertebrate group. Oecologia.  190: 725–735.  doi:10.1007/s00442-019-04426-9


Human activity facilitates altitudinal expansion of exotic plants along a road in montane grassland, South Africa.

Kalwij, J.M., Robertson, M.P., van Rensburg, B.J. 2008. Human activity facilitates altitudinal expansion of exotic plants along a road in montane grassland, South Africa. Applied Vegetation Science. 11: 491-498.  doi:10.3170/2008-7-18555


Annual monitoring reveals rapid upward movement of exotic plants in a montane ecosystem.

Kalwij, J., Robertson, M.P., van Rensburg, B.J. 2015. Annual monitoring reveals rapid upward movement of exotic plants in a montane ecosystem. Biological Invasions. 17: 3517–3529.  doi:10.1007/s10530-015-0975-3


Plant species that invade high elevations are generalists: support for the directional ecological filtering hypothesis.

Steyn, C., Greve, M., Robertson, M.P., Kalwij, J.M., le Roux, P.C. 2017. Plant species that invade high elevations are generalists: support for the directional ecological filtering hypothesis. Journal of Vegetation Science. 28: 337–346.  doi:10.1111/jvs.1247

Student Theses

Assessing the intraspecific variation in the ants of Sani Pass in response to temporal changes.

Engelbrecht, E. 2019. Assessing the intraspecific variation in the ants of Sani Pass in response to temporal changes. Honours project, University of Pretoria.


Taxonomic and functional diversity of ants across environmental gradients.

Newman, S.A. 2018. Taxonomic and functional diversity of ants across environmental gradients. MSc thesis, University of Pretoria.


Intraspecific variation in ants: Testing a central paradigm of functional trait ecology.

Gaudard, C. A. 2018. Intraspecific variation in ants: Testing a central paradigm of functional trait ecology. Honours project, University of Pretoria.


Taxonomic and functional ecology of montane ants.

Bishop, T.R. 2016. Taxonomic and functional ecology of montane ants. PhD thesis, University of Liverpool.


A comparison of ant diversity between natural and disturbed montane grasslands in South Africa.

de Jong, G. 2016. A comparison of ant diversity between natural and disturbed montane grasslands in South Africa. Honours project, University of Pretoria.


What makes for a successful alpine alien ascender? Identifying the drivers of upslope range expansion by alien plants.

Steyn, C. 2014. What makes for a successful alpine alien ascender? Identifying the drivers of upslope range expansion by alien plants. Honours project, University of Pretoria.


Invertebrate species turnover and body size patterns across an altitudinal gradient.

Jansen, W. 2013. Invertebrate species turnover and body size patterns across an altitudinal gradient. MSc thesis, University of Pretoria.


Invasion of grasslands by silver wattle, Acacia dealbata alters beetle assemblage structure.

Coetzee, B.W.T. 2006. Invasion of grasslands by silver wattle, Acacia dealbata alters beetle assemblage structure. Honours project, University of Pretoria.


Environmental effects on Coleoptera diversity in the Maloti-Drakensberg region.

Reynolds, B.N. 2006. Environmental effects on Coleoptera diversity in the Maloti-Drakensberg region. Honours project, University of Pretoria.


The impact of silver wattle (Acacia dealbata) on small mammal assemblages in the Sani Pass region of the Drakensberg.

Van der Merwe, J. 2005. The impact of silver wattle (Acacia dealbata) on small mammal assemblages in the Sani Pass region of the Drakensberg. Honours project, University of Pretoria.


Funders and Partners