Drought, climate change and vegetation response in the succulent karoo, South Africa

Hoffman, Margaret; Carrick, Peter J.; Gillson, Lindsey; West, Adam G.

doi:10.4102/sajs.v105i1/2.40

Cited by 87 publications

(60 citation statements)

References 23 publications

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“…The results do not show any intensification of the drought index during the time period investigated. The study is in agreement with Hoffman et al (2009) andNel (2009) who showed that there are no negative trends in annual rainfall over the southwestern parts of South Africa and no increased intensity of droughts from 1900 to 2000. Kruger and Shongwe (2004) and Lyon (2009) indicated significant temperature increase in southern Africa using 1960 to 2000 data.…”

Section: Wrsi For 120-day Maize Planted In Januarysupporting

confidence: 92%

Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa

Moeletsi

Walker

2011

Theor Appl Climatol

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Water Requirement Satisfaction Index (WRSI) at three different probability levels (20%, 50%, and 80%) was used to quantify drought affecting rain-fed maize production in the Free State Province of South Africa based on climate data from 227 weather stations. Results showed high spatial variability in the suitability of different areas: the southern and southwestern localities are unsuitable due to high drought incidences; the northern, central, and western regions are marginally suitable; the eastern, northerneastern areas and a few patches in the northwest are highly suitable with relatively low drought severity. Proper choice of maize varieties to suit conditions at different localities is crucial. The Mann-Kendall test and coefficient of variation were further used to determine trends and temporal variability, respectively, in the WRSI, seasonal rainfall, and seasonal maize water requirements. Results of this analysis revealed no significant positive trends in the WRSI, no significant negative trends in seasonal rainfall, and no significant positive trends in maize water requirements, contradicting previous findings of increased drought severity. Seasonal rainfall and the WRSI showed high interseasonal variability, while seasonal maize water requirements showed low variability. In view of these observations, it is apparent that realignment of management practices is an overdue prerequisite for sustainable maize production.

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Section: Wrsi For 120-day Maize Planted In Januarysupporting

confidence: 92%

Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa

Moeletsi

Walker

2011

Theor Appl Climatol

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“…However, climate change scenarios predict that the Karoo will get increasingly hot and dry over the next 100 years (Midgley et al, 2001), which could affect species distribution, threatening their survival (Erasmus et al, 2002;Hoffman et al, 2009;Korstjens et al, 2010). Korstjens et al (2010) propose that a 2 C increase in ambient temperature will demand an increase in "enforced" resting time (i.e., for thermoregulation) which will significantly constrain the time available for other important behaviors such as feeding and socializing.…”

Section: Discussionmentioning

confidence: 99%

“…This in turn is expected to have a significant impact on species survival and distribution (Erasmus et al, 2002;Hoffman et al, 2009;Korstjens et al, 2010). Here, we explore direct climatic effects on the on activity of wild vervet monkeys (Chlorocebus pygerythrus), during both the nonmating and mating seasons, as a means of assessing how animals prioritize behavior and whether they possess sufficient behavioral flexibility to adjust their activity budget in response to competing demands.…”

mentioning

confidence: 99%

Behavioral flexibility of vervet monkeys in response to climatic and social variability

McFarland

Barrett

Boner

et al. 2014

American J Phys Anthropol

100

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Responses to environmental variability sheds light on how individuals are able to survive in a particular habitat and provides an indication of the scope and limits of its niche. To understand whether climate has a direct impact on activity, and determine whether vervet monkeys have the behavioral flexibility to respond to environmental change, we examined whether the amount of time spent resting and feeding in the nonmating and mating seasons were predicted by the thermal and energetic constraints of ambient temperature. Our results show that high temperatures during the nonmating season were associated with an increase in time spent resting, at the expense of feeding. Cold temperatures during the nonmating season were associated with an increase in time spent feeding, at the expense of resting. In contrast, both feeding and resting time during the mating season were independent of temperature, suggesting that animals were not adjusting their activity in relation to temperature during this period. Our data indicate that climate has a direct effect on animal activity, and that animals may be thermally and energetically compromised in the mating season. Our study animals appear to have the behavioral flexibility to tolerate current environmental variability. However, future climate change scenarios predict that the time an animal has available for behaviors critical for survival will be constrained by temperature. Further investigations, aimed at determining the degree of behavioral and physiological flexibility displayed by primates, are needed if we are to fully understand the consequences of environmental change on their distribution and survival.

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“…Such dwarf succulents are thought to be amongst the most resilient of plant species in the biome to environmental change. By contrast both therophytes and geophytes show increased sensitivity to both drought and temperature extremes (Hoffman et al, 2009). Both emission scenarios examined in this study predict changes in the bioclimatic envelope for members of the genus.…”

Section: Discussionmentioning

confidence: 99%

“…While the inherent richness in floral diversity, especially amongst succulents, is one of the defining elements of the region, such diversity makes the prediction of responses to environmental change (e.g., increasing aridity and thermal stress) challenging. For example, the variability amongst the flora of these biomes in terms of drought tolerance is thought to be especially significant (e.g., Hoffman et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

Biodiversity and climate change: Risks to dwarf succulents in Southern Africa

Young

Guo

Desmet³

et al. 2016

Journal of Arid Environments

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The aim of this study was to explore the effects of anthropogenic climate change on the dwarf succulent genus Conophytum (Aizoaceae) within areas recognised for their floral biodiversity, namely the Succulent Karoo, Fynbos, Desert and Nama Karoo biomes of South Africa and Namibia. Niche-based modelling was used to identify the key climatic and geological variables influencing the distribution of members of the genus Conophytum. The distribution of the genus is primarily controlled by a small number of environmental variables, notably winter and summer rainfall levels, together with geology. Assuming a zero-dispersal model, the predicted effect of both the A1B and A2 climatic emission scenarios was a severe contraction in the area satisfying the bioclimatic envelope for the genus coupled with significant range dislocation. Reductions of >90% in suitable habitat for 10 of the 16 taxonomic Sections that comprise the genus and represent >80% of taxa under the A2 scenario are predicted. Under A1B the projected effects are ameliorated, but reductions of >50% of habitat can be seen in a majority of Sections. Significant projected reductions in the habitable bioclimatic envelope are very likely to increase risk of extinction of ~80% of taxa even under a partly mitigated emissions scenario.

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Drought, climate change and vegetation response in the succulent karoo, South Africa

Cited by 87 publications

References 23 publications

Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa

Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa

Behavioral flexibility of vervet monkeys in response to climatic and social variability

Biodiversity and climate change: Risks to dwarf succulents in Southern Africa

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