Contradictory findings among scientific studies that address a particular issue may impede
the conversion of science to management implementation. A systematic review of peerreviewed
studies to generate a single outcome may overcome this problem. The contentious
topic of the impact that a megaherbivore such as the savanna elephant have for other
species and their environment can benefit from such an approach. After some 68 years, 367
peer-reviewed papers covered the topic and 51 of these papers provided sufficient data to
be included in a meta-analysis. We separated the direct impact that elephants had on trees
and herbs from the indirect effects on other vertebrates, invertebrates, and soil properties.
Elephants have an impact on tree structure and abundance but no overall negative cascading
effects for species that share space with them. Primary productivity explained a small
amount of variation of elephant impact on vegetation. Elephant numbers (density), study
duration, rainfall, tree cover, and the presence of artificial water and fences failed to describe
patterns of impact. We conclude that published information do not support the calls made
for artificially manipulating elephant numbers to ameliorate elephant impact, and call for the
management of space use by elephants to maintain savanna heterogeneity.
S1 Appendix. The PRISMA flow diagram.
S2 Appendix. R code for the analyses.
S3 Appendix. Complete list of scholarly papers on elephant impact.
S1 Fig. The number of papers published each year since 1947 on the effect that elephant
had on the environment.
S2 Fig. Frequency distributions of the individual elephant effects (k) on soil properties.
S1 Table. Type, description, and source of the variables included in the generalized linear
mixed-effects models to explain elephant impact.
S2 Table. Selection parameters of the candidate generalized linear mixed-effects models
that describe the variation in direct effects.
S3 Table. Selection parameters of the candidate generalized linear mixed-effects models
that describe the variation in indirect effects.