The spatial and temporal ecology of the large mammal populations and vegetation of Ngorongoro Crater, Tanzania

Oates, L

Abstract

Ngorongoro Crater in Tanzania is a World Heritage Site and Biosphere Reserve and is
home to tens of thousands of large mammals. This study documents the historical ecology of
the crater from 1892 to 2012 based on an analysis of the published literature and it
investigates the potential effects of vegetation change on the dynamics of large mammal
populations using remote sensing and GIS techniques.
Primary drivers of changes in the crater appear to be disease, vegetation change and
poaching. Wildebeest (Connochaetes taurinus) have declined and been replaced by buffalo
(Syncerus coffer) as the dominant herbivore in terms of biomass primarily due to vegetation
change, while black rhinoceros (Diceros bicornis) have reduced to population-threatening
numbers due to poaching.
Satellite imagery indicates that the woody shrub Gutenbergia cordifolia covered a
large portion of the crater's grasslands in 2001, however by 2008 the species had almost
disappeared. There is no evidence that the distributions of five large herbivore species
(wildebeest, zebra (Equus burchellii), Grant's gazelle (Nanger granti), Thomson's gazelle
(Eudorcas thomsonii) and warthog (Phacochoerus aethiopicus}} are negatively affected by
the presence of G. cordifolia and the species may therefore not be a significant threat to the
large mammal community, in spite of anecdotal evidence to the contrary. The Lerai Forest, a
previously important black rhinoceros calving refuge, has declined in area since the 1970s.
However, in recent years the loss of trees has slowed and some regeneration appears to be
occurring.
In the future the most important driver of change in the crater is likely to be climate
change due to its potential negative effect on the availability of fresh water in the crater.

• Thesis Type: Thesis
• Deposit Date: Jul 30, 2021
• Award Date: Oct 1, 2012