Geoscience Reference
In-Depth Information
outside of protected areas (see Figure 2.6) (Biggs et al. 2011). For example, wildlife tourists may
prefer high densities of elephants in open landscapes that are good for game viewing. Farmers
cultivating crops, or people depending on trees for fuel wood, might prefer more dense tree
cover and fewer elephants. Therefore negotiating TPCs depends on integrating diverse strands
of knowledge, from both scientific and social perspectives.
The controversy and emotion surrounding elephant conservation is unlikely to be easily
resolved, but what is becoming clear is that without reliable estimates of the variability and
resilience of savannas, we are likely to keep making poor decisions based on subjective
assessments of how savanna landscapes should look. The palaeo-work from Tsavo and Kru-
ger provides insights into the resilience and variability of savanna tree cover, while the mod-
elling work shows what the future might hold (Gillson 2004a, b, Ekblom and Gillson 2010b, c,
Staver et al. 2011a, b, Staver et al. 2011b, Higgins and Scheiter 2012, Scheiter and Higgins 2012).
Both strands are essential tools, alongside ecological and social studies, in making conserva-
tion decisions that reflect ecological reality while accommodating the aesthetic, cultural and
economic concerns that make up the conservation ecosystem. Modelling of palaeo-data in
the light of future environmental and socioeconomic scenarios might help to bridge the gap
between past, present and future.
Savanna vegetation is dynamic, and tree cover responds to changing rainfall, fire, herbivory,
and nutrients. There are few long-term records of long-term changes in elephant habitat,
however, because written records only date back a century for most of Africa and it is difficult
to find well-preserved pollen in the semiarid savanna ecosystems, so the historic and prehis-
toric ranges of variability are seldom known. Many protected areas were established in excep-
tional times, when decades of overhunting and disease had disrupted local ecology; elephant
populations were dramatically reduced by hunting for ivory trade through the eighteenth and
nineteenth centuries, while rinderpest outbreaks in the late nineteenth and early twentieth
century devastated ungulate populations (Dublin et al. 1990, Carruthers 1995, du Toit et al.
2003, Gillson and Duffin 2007). For example, when the Kruger National Park was founded,
elephants had been completely removed by hunting, and fire was then suppressed, so it is
likely that the Park's early days were characterized by anomalously high tree densities. Colo-
nization and modernization also disrupted traditional systems of pastoralism that were well
adapted to variable environments (see Chapter 7), for example through restricting transhu-
mance (the movement between wet season and dry season grazing areas) and access to trad-
itional water and grazing resources, thereby initiating a shift towards sedentary cultivation
and cash crops that is continuing through to the present day (Marchant and Lane 2013).
There is no doubt that elephants impact on their environment, but savannas are dynamic
systems in which tree density fluctuates widely in response to myriad drivers, including rain-
fall, nutrient availability, and fire. As savannas are spatially heterogeneous and temporally
variable, static conservation targets like a fixed population size for elephants and stable tree
density are not ecologically realistic. What is needed is an understanding of the range of
Search WWH ::
Custom Search