Palaeoecology: how an understanding of ancient savannas helps inform elephant management

Despite their role as a conservation flagship species, elephants can be highly destructive to their natural environment. They play a huge role in the management of savanna ecosystems across Africa, but in some areas, the widespread damage they bring to vegetation and farmer’s land makes them a pest. Two main control methods have been suggested for elephants – culling or a hands-off approach of letting nature “do its thing”  (Gillson, 2015). But often the theory behind conservation targets is overshadowed by arguments over which management technique is best. This post will cover how conservation targets are set, when they are appropriate, and how this affects elephants in African savannas.

African bush elephant - Wikipedia
Cheeky African bush elephant pic, couldn’t be avoided. Source: wikipedia.org

Equilibrium Theory

Historically, static habitat states were used to define conservation targets, without any consideration of fluctuations in the ecosystem. For example, managers in Kruger National Park limited elephant population to the arbitrary value of 7000 individuals (Gillson, 2015), without considering the long-term dynamics of the species, nor how it would be affected by external influences such as climate or fire. Setting firm baselines is risky as they are not often correct for the habitat: for example a target vegetation level was set for Kruger National park which turned out to be far too high, as a rinderpest outbreak had recently devastated wild animal populations and lead to an abnormally high level of vegetation (Gillson, 2004). The “ideal” state for conservation also depends on how far into the past you look, a problem known as “shifting baselines”.

Instead of this approach, equilibrium theory presents the idea that species and their habitats are in a fluctuating equilibrium (balance), and that any human interaction disturbs this natural relationship between predators and prey. Ecosystems are in constant flux, with natural variability integral to habitat health. This approach is supported by findings of variability in savanna habitats: for example, a savanna-woodland cyclicity of around 250-500 years occurs in Tsavo National Park in Kenya, as identified by paleoecological data (Gillson, 2004).

Savanna - Simple English Wikipedia, the free encyclopedia
Savanna habitat is characterised by a mixed woodland-grassland ecosystem with widely spaced trees. Source: wikipedia.org

Paleoecological data is important for understanding the limits of natural variability and influencing flexible management. By providing long-term perspectives on climate history, precipitation levels, fire frequency and vegetation abundance (through fossilised pollen and charcoal) (Gillson, 2004), insights can be made into arid ecosystem health prior to human interference, as well as the effectiveness of previous management practices. For example, changes in fire frequency identified in Kruger National Park indicated early fire suppression, used to manage vegetation across the site and therefore elephant populations (Gillson & Marchant, 2014). Historical records also show how elephant population varied during periods of culling; in Addo Elephant National Park, culling was used in response to elephants destroying farmers land, due to lack of boundaries between territories (Whitehouse & Kerley, 2002). Reactive approaches such as this are now being replaced with more proactive approaches which better align with the natural elephant population variability

Adaptive management

Adaptive management focuses on maintaining the resilience and natural fluxes in population density of elephants across Africa (Gillson & Marchant, 2014). In Kruger National Park, instead of setting a defined population limit for the elephants at the site, losses in vegetation are permitted to fluctuate at around 80% locally or 30% across the park (Gillson, 2015). This gives a wider scope of acceptability for the habitat, and reduces the need to focus on culling for the sake of culling. Another example of proactive management is by using controlled water points across a national park in Zimbabwe to reduce local elephant density (Chamaille-Jammes, 2007). Such equilibrium-based approaches are founded on evidence of the importance of natural disturbance, variability and fluxes in the savanna ecosystem.

In summary, paleoecological information is vital to managing elephant populations because it helps define a more flexible range of acceptable habitat for savannas. This understanding can be used to develop more appropriate and efficient management targets, such as through adaptive management. Improving the effectiveness of habitat management will reduce the strain on conservation funds, whilst reducing the need for culling of unsustainable elephant populations. Improving the theory behind setting conservation targets is the first step towards developing a sustainable approach to the management of one of the world’s most charismatic animals.

Read more about…

Palaeoecology and fire

How did humans get here?

Pleistocene rewilding

References

ChamailléJammes,S., Valeix, M. & Fritz, H. (2007) Managing heterogeneity in elephant distribution: interactions between elephant population density and surface‐water availability. Journal of Applied Ecology44(3), pp.625-633

Gillson, L. (2015) Biodiversity conservation and environmental change: using palaeoecology to manage dynamic landscapes in the Anthropocene. OUP Oxford.

Gillson, L. (2004) Evidence of hierarchical patch dynamics in an East African savanna?. Landscape Ecology19(8), pp.883-894

Gillson, L. (2004) Testing non-equilibrium theories in savannas: 1400 years of vegetation change in Tsavo National Park, Kenya. Ecological Complexity1(4), pp.281-298

Gillson, L. & Marchant, R. (2014) From myopia to clarity: sharpening the focus of ecosystem management through the lens of palaeoecology. Trends in Ecology & Evolution29(6), pp.317-325

Whitehouse, A.M. & Kerley, G.I. (2002) Retrospective assessment of long-term conservation management of elephants in Addo Elephant National Park, South Africa. Oryx36(3), pp.243-248

Published by avleveri

Hi! I'm Anna, an environmental science graduate from the UK. My main interests (if you can't already tell from my blog posts) are sustainability, consumption, conservation, nutrition, fitness and food! Lots of food.

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