#02 2022

A fledgling environmental observation platform in the arid lands at the Square Kilometre Array

By Helga van der Merwe, Sue Milton, Richard Dean, Tim O’Connor and Joh Henschel, SAEON Arid Lands Node

The establishment of the Square Kilometre Array (SKA) presents an opportunity to promote and expand long-term environmental research in the drylands of the Karoo. The National Research Foundation (NRF) now owns about 135 000 ha of land where the highest concentration of the SKA radio astronomy infrastructure will be placed (Figure 1).

This land is located within an area declared as the Karoo Central Astronomy Advantage Area (KCAAA – Astronomy Geographic Advantage Act). Furthermore, the SKA property was declared as the Meerkat National Park in March 2020, managed by the South African National Parks (SANParks).

Livestock, predominantly sheep, were removed from the NRF property, resulting in a marked reduction in stocking pressure. The SKA infrastructure development will be accompanied by the removal of internal fencing, artificial water points and extensive stands of alien mesquite (Prosopis spp.) trees, and a gradual increase in wildlife numbers over time under the management of SANParks. Thus, the SKA property and neighbouring farmland can serve as a large-scale, long-term landscape-level experiment manipulating stocking rate, animal type, animal distribution and direct vegetation management.

This development is an excellent opportunity to investigate gradual natural or assisted rehabilitation of areas disturbed in the past or due to current developments. The reduction of the stocking rate and a switch from rotational domestic stock grazing systems for commercial purposes to a continuous grazing system for large-scale wildlife management by a conservation entity is a great opportunity to learn about the complex responses of ecosystems to changes in land management.

In planning to develop an environmental observation research platform, NRF-SAEON collated relevant information on the area in a comprehensive environmental baseline report (Milton et al. (2020). Using available information and possible future land-use scenarios, Van der Merwe et al. (2021) developed a conceptual model predicting trajectories of change under these scenarios and the factors influencing them (Figure 2).

NRF-SAEON aspires to investigate the changes taking place in the larger SKA landscape and invites collaboration with researchers already present in the landscape, for example the South African Radio Astronomy Observatory (SARAO) and SANParks, as well as researchers from a diversity of fields from other organisations wishing to contribute to our understanding of Karoo rangelands.

KCAAA, Karoo Central Astronomy Advantage Area25

Figure 1: The location of the Square Kilometre Array (SKA) area, Northern Cape, South Africa. National Research Foundation property boundaries are indicated in black.

Figure 2: Conceptual model of future land-use scenarios, predicted trajectories of change and factors that could influence the predicted trajectories. (Source: Van der Merwe et al., 2021)

Further reading

Milton SJ, Henschel JR, Van der Merwe H, Dean WRJ, Meyer-Milne E, Gerber H. Environmental baseline review of the core area and surrounds of the Square Kilometre Array (SKA). SAEON report and appendices. Pretoria: South African Environmental Observation Network (SAEON); 2021. https://doi.org/10.15493/saeon.arid.10000001

Van der Merwe H, Milton SJ, Dean WRJ, O’Connor TG, Henschel JR. Developing an environmental research platform in the Karoo at the Square Kilometre Array. S Afr J Sci. 2021;117(11/12), Art. #10511. https://doi.org/10.17159/sajs.2021/10511

The shrubby plains and inselbergs of the SKA region. (Photo: Helga van der Merwe)

Grassy patches on deeper sandy soils. (Photo: Helga van der Merwe)

Historically disturbed areas without active rehabilitation. (Photo: Helga van der Merwe)

Assessment of possible long-term monitoring sites. (Photo: Joh Henschel)