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Being a Node in Arid Lands

By Joh Henschel, Arid Lands Node

The Oxford English Dictionary defines a node as “a point in a network at which lines intersect or branch”.

In the case of the Arid Lands Node, our lines stretch far… half-way across South Africa, and we have a branch as distant as Prince Albert is from Kimberley.

Rarely does this node become nodular, but this occurred between 21–24 January when nearly all members of the Arid Lands team gathered in Kimberley to feel what it is like to be a team as expressed in the pictures below, and in several articles in this issue of SAEON eNews.

Team Arid Lands, bolstered by National Office. L-R: Johan Pauw, Elvirena Coetzee, Mthokozisi Moyo, Casper Crous, Helga van der Merwe, Betsie Milne, Hana Petersen, Gina Arena, Maletsatsi Mohapi, Tim O’Connor, Juan Swanepoel, Marco Pauw, Joh Henschel. Tshililo Ramaswiela (inset) was unfortunately unable to participate (Photo: Leazill Peenze)

NRF Corporate Executives Kedirang Oagile (HR and Finance), Clifford Nxomani (National Facilities) and Phethiwe Matutu (Strategy Planning and Partnerships) were joined by Theo Jongwana and Johan Pauw in the field, guided by Marco Pauw, as part of a diverse demonstrative programme presented by the Arid Lands team on 22 January (Photo: Joh Henschel) This artwork composed by members of the Arid Lands team during Teamweek, demonstrates a wide diversity of perceptions and styles, which unite coherently in the Xhaeruh, the original name of the Karoo standing for ‘dry and hard’, or perhaps expressing XHAERUH: Xeric, Hot, Aesthetic and Extreme, Rainfall Unleashes Happiness (Photo: Mthokozisi Moyo)

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Hot-spot Tierberg

By Joh Henschel, Arid Lands Node

Tierberg is a hot-spot of research in the Karoo in more ways than one. Not only are there more scientific papers published from research here than from anywhere else in the Karoo (see Arena et al., 2018), but this site is experiencing the highest temperatures in its 31-year history as research site.

On 7 February 2019, the temperature rocketed from a cool 19 ^oC at sunrise to 45.6 ^oC in late afternoon – on seven occasions during the month preceding that event, maximum daily temperatures exceeded 40 ^oC (Figure 1).

Figure 1: Temperature record during early February 2019 (above) and four weeks preceding the record event

The trend of increasing temperatures is not new at Tierberg as the thirty-year record shows (Figure 2).

Figure 2: At Tierberg-LTER, mean daily maximum and minimum temperatures have been steadily increasing over 30 years. Days above 40oC have strongly increased, while events below freezing have decreased.

How much can plants and animals withstand before conditions go beyond their physiologically maximum tolerance levels? Similar questions also pertain at ecosystem level, not only because of heat stress, but also dehydration promoted by escalating evapotranspiration.

Tierberg research promises to be hotter than ever in more ways than one.

Further reading  

• Arena, G., van der Merwe, H., Todd, S.W., Pauw, M.J., Milton, S.J., Dean, W.R.J., Henschel, J.R. (2018) Reflections, applications and future directions of Long-Term Ecological Research at Tierberg. African Journal of Range & Forage Science 35: 257-265. DOI: 10.2989/10220119.2018.151307

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