Renosterveld Ecology, Evolution & Management

Lowland Renosterveld is a relatively fertile, shale-derived vegetation type found within the Fynbos Biome of South Africa. Due to the fact that Renosterveld tends to be dominated by a handful of small-leaved asteraceous shrub species, it creates the illusion that it is a homogeneous habitat with low levels of alpha diversity and species turnover. This is exacerbated by the widely accepted, although not proven, hypothesis that states that current-day Renosterveld is derived from a pristine C4 grassland and that the dominance of asteraceous shrubs is solely due to more than 300 years of mismanagement of fire and grazing.

It is crucial that we undertake more in-depth studies which examine how modern-day Renosterveld can be managed optimally, using the existing tools at hand (mostly fire and livestock grazing), in order to equip ourselves to provide the best possible advice to landowners.

Additionally, lowland Renosterveld has been extensively transformed for agricultural development, rendering it a Critically Endangered vegetation type, with an estimated 5% of the original extent remaining in a severely fragmented state.

The true measure of the extent of species losses does not lie in extensive Red Data listings, but rather in the extinction or reduction of ecological processes, which are often overlooked. Hence, we need to understand the real potential for a habitat type to become functionally extinct and therefore need to examine the processes that affect drive or influence these ecosystems. Studies involving Renosterveld pollination webs, pollination requirements and deficits, seed-set and other measures of ecosystem functioning would all be part of addressing these questions.

One of the primary core functions of the ORCT is to grow research capacity in the Overberg’s Renosterveld, through collaborative projects with the relevant research / tertiary education institutes and through providing the base from which students and collaborative scientists can work. The Renosterveld Research & Visitors Centre forms a hub for Renosterveld research and we aim to attract an increasing number of collaborative researchers and students to this ‘Renosterveld home’ every year. Please do contact the ORCT if you are a post-grad student looking for project ideas to inspire you!

Renosterveld Research themes

The following key research themes have been identified by the ORCT. These themes highlight what we consider our top priorities, but the ORCT welcomes any additional proposals or ideas. However, we do recommend that collaborators first consider this list of priorities and how their projects could fit into one of these themes.

1.  Understanding biodiversity & threatened species in renosterveld remnants

Examples include: diversity of invertebrates, plants, birds, mammals and other taxa at different scales (alpha, beta, gamma diversity), within different veld management practices and vegetation age (grazing, fire, etc.), as well as habitat use by important / keystone species.

The ORCT’s collaborative research project on Black Harriers falls within this theme, while we are developing small mammal studies with partnering collaborators at both UCT and NMU. We welcome additional initiatives on any taxa in the system, as most are poorly studied within renosterveld.

2.  Landscape ecology

Examples include: pollination webs; investigating evidence for the existence of extinction debts; implications for conservation planning and management of fragmented systems at the landscape level. Also under this theme is the crucial need to understand the impacts that managed honeybees are having on the indigenous pollinators (particularly solitary bees).

This is a top priority for the ORCT, as the complex web of pollinator-plant relationships is key to understanding if and how we can mitigate for the impacts of fragmentation that this system is no-doubt experiencing.

3.  Habitat management and restoration

Examples include: impacts of fire and grazing management on renosterveld; investigating alternative uses for old lands through partial restoration or planting of indigenous fodder plants (for adding grazing value to farms and creating corridors between fragments); restoration methods for degraded and ‘overgrazed’ virgin land (including holistic approach using heavy hoof action as a tool).

This research is critical for renosterveld management, but needs to be long-term (with, for example, multiple post-graduate studies contributing to a larger, long-term study). The major constraint here is that setting up experimental research of this nature is complex and costly, but sourcing the funds to support the set-up costs is a top priority for the ORCT. Results from such research will inform how the ORCT advises landowners on management, as well as how we manage our own reserves and easements.

4.  Watercourses in renosterveld: their role as corridors and their restoration potential

Examples include: investigating the role that watercourses play as corridors for larger vertebrates, as well as invertebrates with an emphasis on pollinators; experimental research on watercourse restoration; investigating the ranges of indigenous fish species and the impacts of invasive alien fish and surrounding land use practice on these threatened species; quantifying the impacts of farming-related chemical (fertilizer and pesticides) runoff from surrounding production lands into watercourses and the extent to which buffers (of varying widths) are able to protect these watercourses from these impacts.

Collaborating students and thesis titles:

B-Tech Students

Jamy Fredericks (CPUT with Prof Sjirk Geerts)

Thesis title: Renosterveld pollinators

Masters Students

1. Tabitha Coetzee (NMU with Dr Tineke Kraaij & CPUT with Prof Sjirk Geerts & ORCT with Dr Odette Curtis)

Thesis title: ‘Effects of landscape fragmentation on pollination systems in the Eastern Rûens Shale Renosterveld of the Overberg region.’

2. Simone Maier & Sina Hauber (CPUT with Prof Sjirk Geerts & Prof Mirijam Gaetner, Germany) (Germany)

Thesis title: Effects of habitat fragmentation on selected plant species and their pollination in Renosterveld, Overberg, South Africa.

3. Abigail Widdiger (UCT with Pippin Anderson) (SA))

Thesis title: Understanding renosterveld ecosystem function: the role of small mammals to inform ecological restoration.

4. Dylan Jacklin (SUN with Jan de Waal) (SA)

Thesis title: The potential use of plant species within Critically Endangered Renosterveld vegetation for the phytoremediation of glyphosate and fertilisers to conserve South African freshwater systems.

5. Sachin Doarsamy (UKZN with Prof Steve Johnson & Dr Bennie Bytebier) (SA))

Thesis title: Phylogenetic analysis of the genus Wurmbea in South Africa and chemistry of the floral compounds.

6. Brian du Preez (UCT with Prof Muthama Muasya) (SA)

Thesis title: Polhillia on the brink: Systematic revision, ecophysiology and conservation assessment of a highly threatened Cape legume genus.

7. Luke Gallant (UCT with Dr Samson Chimphango) (SA)

Thesis title: MSc project titled Characterizing native palatable legume and non-legume species in the rangelands of the Overberg Renosterveld.

8. Sanjo Rose (UCT with Dr Robert Thomson) (SA)

Thesis title: Land use and breeding ecology of a renosterveld endemic bird: the Agulhas Long-billed Lark Certhilauda brevirostris

PhD students

1. Daniel Zhigila (UCT with Prof Muthama Muasya & Anthony Verboom) (Nigeria)

Thesis title: Molecular phylogeny and climate change responsiveness of Thesium L. (Thesiaceae)

2. Oliver Cowan (UCT with Pippin Anderson) (SA)

Thesis title: Functional ecology of the critically endangered Rûens Shale Renosterveld of the Overberg with a view towards future restoration and management interventions.

3. Zoë Poulsen (UCT with Samson Chimphango, Timm Hoffman, Pippin Anderson, Muthama Muasya) (UK)

Thesis title: Conserving living landscapes and sustaining rural livelihoods: Investigating impacts of livestock grazing and assessing rangeland restoration potential in critically endangered Overberg Renosterveld.

4. Jan de Waal (SUN) (SA)

Thesis title: “Renosterveld Buffers in Remediation of Agricultural Pollutants.”

5. Ethan Newman (KZNU with Prof Steve Johnson) (SA)

Thesis title: The convergence and divergence of floral traits are driven by the heterogeneity of pollinator and plant communities.

6. Evan Eifler (University of Wisconsin-Madison with Prof Henry Allan Gleason and Dr Tom Givnish) (USA)

Thesis title: Geissorhiza: an evolutionary case study in the Cape Floristic Region.