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A ‘Special Issue’ about what’s special about the Karoo
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Twenty years ago, a milestone book appeared: The Karoo – ecological patterns and processes edited by Richard Dean and Sue Milton.
It is high time to extend and update this information with the next scientific compendium, doubling up as a Festschrift in honour of Sue and Richard as outstanding Karoo scientists.
Accordingly, the Grasslands Society of Southern Africa invited Joh Henschel (SAEON), Timm Hoffman (University of Cape Town) and Cherryl Walker (Stellenbosch University) to compile the “Karoo Special Issue – Trajectories of Change in the Anthropocene” in the African Journal of Range and Forage Science, Volume 35(3&4): 151-393.
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SAEON was not only involved in compiling this volume, but six of 11 associate editors were from SAEON (Casper Crous, Sue Milton, Tim O’Connor, Helga van der Merwe, Gretel and Noel van Rooyen), and 12 of the 22 papers in this issue were authored or co-authored by 16 SAEON staff, students and associates (Gina Arena, William Bond, Richard Dean, Justin du Toit, Joh Henschel, Sue Milton, Elelwani Nenzhelele, Tim O’Connor, Marco Pauw, Tshililo Ramaswiela, Rudi Swart, Simon Todd, Helga van der Merwe, Gretel and Noel van Rooyen, Stefan Goets).
Significant ecological and social transformations
This publication of research by natural and social scientists comes timely, as the Karoo is experiencing ecological and social transformations which are arguably as significant as any previously in its history.
The vast, dry, hot spaces of the Karoo cover a third of South Africa and fewer than 2% of South Africans live here. Its two biomes, the Succulent Karoo and the Nama-Karoo, are starkly different in terms of moisture regimes, land uses and biodiversity, with 8% of the Succulent Karoo formally protected, compared with only 2% of the Nama-Karoo.
Global change is shifting conditions of water, carbon and energy, with regional climate projected to become even hotter with more frequent extreme events, including more severe droughts, the current condition being a case in point. Furthermore, large-scale shifts in land use, such as renewable energy generation, electricity power corridors, mining and astronomy as well as intensification of agriculture and the drive to improve human well-being and welfare, are changing the Karoo’s ecosystems, economy and social fabric.
The lead article of the Karoo Special Issue reviews and discusses these changes. The article emphasises that the Karoo requires wise stewardship if its distinctive but vulnerable social-ecological systems are to survive the current transformation.
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Half a dozen papers outline how the Karoo has previously been subjected to significant changes, when prehistoric ecosystems as well as indigenous hunter-gatherers and herders were affected during colonial times by developments of towns, fences, boreholes and dams, roads, alien plants and numerous sheep, which degraded the veld, subsequently partly recovered, albeit accompanied by local economic contraction and emigration. Vulnerable to droughts, compounded by heat waves, farming is economically risky, which in turn inspires local entrepreneurship, not yet adequately recognised and supported by government.
Long-term ecological research
A good handful of papers concern long-term ecological research, leading off with long-term experiments at Tierberg-LTER and at Grootfontein, following through with three papers on Namaqualand. Karoo ecosystems are driven by long-term rainfall trends compounded by fluctuating rainfall events, closely tracked by populations of short-lived plant species and rare recruitment events of perennial plants, all of which can, in turn, drive boom and bust patterns of animal populations.
These papers on long-term ecological research and several other papers also reveal some effects of livestock farming, with intensive browsing reducing shrub cover and favouring other plant types, such as grass or annual plants, depending on rainfall. Intensive trampling decreases shrub cover, but the accompanying dunging stimulates shrub regeneration.
In one study, spiders served as example to illustrate how trampling of web spiders can furthermore have cascading effects on food webs and nutrient cycles, thus potentially driving broader ecosystem changes. Another paper analyses the persistent persecution of jackals and other meso-predators and how interference with their natural populations can have negative knock-on effects on ecosystems. This can also be said more generally of populations of other indigenous mammals, which are vulnerable to large-scale developments such as mining, including uranium and shale-gas.
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Ecosystem recovery is difficult and extremely slow in the Karoo, dependent on a range of ecosystem services such as those relating to the complex communities of biological soil crust. Where seedbanks are degraded, natural recovery may be impeded without ecological restoration and even then, floral communities do not recover as readily as does re-establishing vegetation cover, while arthropod communities reconstitute more quickly.
Informed decision-making
The range of papers in the Karoo Special Issue straddles not only natural and social sciences, but also basic and applied research and points the direction to future approaches for research to encompass the complexities of Earth systems and human societies in the Anthropocene. Research should thus contribute iteratively to informed decision-making so as to swing the balance between unprecedented destructive and creative human capabilities in favour of sustainable and equitable outcomes.
To achieve this, is a key challenge of environmental research in the Karoo.
