Fine‐scale habitat heterogeneity influences browsing damage by elephant and giraffe

Kimuyu, Duncan M.; Kenfack, David; Musili, Paul M.; Ang’ila, Robert O.

doi:10.1111/btp.12848

Cited by 9 publications

(11 citation statements)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These typical scars have also been identified in other studies (e.g. Nelleman et al, 2002;Holdo, 2003;Staub et al, 2013;Kimuyu et al, 2020). We are therefore confident that most elephant impacts were not confounded with the impacts of other herbivores.…”

Section: Vegetation Structure Composition and Elephant Impactssupporting

confidence: 82%

Long‐term high densities of African elephants clear the understorey and promote a new stable savanna woodland community

Ferry

Dray

Fritz

et al. 2021

J Vegetation Science

View full text Add to dashboard Cite

Questions Species defined as ecosystem engineers (e.g. elephant) are able to strongly shape their habitat. In African savannas, elephants have often been shown to reduce woody‐plant abundance and diversity. However, recent studies highlight more complex elephant‐induced effects on vegetation. Here, we assessed if long‐term high elephant densities (>2 km−2) in a large open landscape resulted in the depletion of savanna woodland woody communities or if it led to a new alternative equilibrium. Location Woodland savanna of Hwange National Park, Zimbabwe. Elephant densities at the study site have remained high for the past two decades (>2 km−²). Methods We measured long‐term (>15 years) elephant utilisation of woody‐plant communities and their effects on vegetation structure, species composition and functional traits (e.g. N leaf concentration, specific leaf area) in 12 vegetation plots. Results We observed opportunistic foraging behaviour by elephants with only a slight temporal shift in species composition, mainly explained by changes in rare species. Further, we did not observe any modification in mean functional trait values, overall height, and stem diameters of the woody‐plant communities. However, we found differential changes in woody‐plant abundance according to the height layer (decrease in the number of tall plants [>200 cm] and increase in the number of short plants [<50 cm]) and a strong reduction in crown diameter for plants in the 50–200 cm height class. Conclusion Our study strongly suggests that long‐term high elephant densities have led to a stable state in savanna woodland vegetation in terms of plant community composition and their functional traits. However, high elephant densities did affect vegetation structure, which would have several important indirect effects on this ecosystem (e.g. predator–prey interactions). We hope that this study stimulates more work on the long‐term effects of ecosystem engineers in large and open ecosystems.

show abstract

Section: Vegetation Structure Composition and Elephant Impactssupporting

confidence: 82%

Long‐term high densities of African elephants clear the understorey and promote a new stable savanna woodland community

Ferry

Dray

Fritz

et al. 2021

J Vegetation Science

View full text Add to dashboard Cite

show abstract

“…The predominant effect of megaherbivores also suggests that wild herbivore communities are unlikely to resist invasions as effectively if megaherbivores are absent. Topographical features that deter megaherbivore activity, such as steep terrain, could therefore act as refugia for the cacti, as is the case for native woody flora (Freeman et al, 2022; Kimuyu et al, 2021). Alternatively, it is also possible that the megaherbivore exclusion effect is influenced by domestic camels, which are known to consume Opuntia (pers.…”

Section: Discussionmentioning

confidence: 99%

Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna

et al. 2022

Self Cite

View full text Add to dashboard Cite

1. Whether wild herbivores confer biotic resistance to invasion by exotic plants remains a key question in ecology. There is evidence that wild herbivores can impede invasion by exotic plants, but it is unclear whether and how this generalises across ecosystems with varying wild herbivore diversity and functional groups of plants, particularly over long-term (decadal) time frames.2. Using data from three long-term (13-to 26-year) exclosure experiments in central Kenya, we tested the effects of wild herbivores on the density of exotic invasive cacti, Opuntia stricta and O. ficus-indica (collectively, Opuntia), which are among the worst invasive species globally. We also examined relationships between wild herbivore richness and elephant occurrence probability with the probability of O. stricta presence at the landscape level (6150 km 2 ).3. Opuntia densities were 74% to 99% lower in almost all plots accessible to wild herbivores compared to exclosure plots. Opuntia densities also increased more rapidly across time in plots excluding wild herbivores. These effects were largely driven by megaherbivores (≥1000 kg), particularly elephants. 4. At the landscape level, modelled Opuntia stricta occurrence probability was negatively correlated with estimated species richness of wild herbivores and

show abstract

“…KLEE is situated in a relatively homogeneous community, both biologically and topographically. A broader, more topographically diverse landscape may harbour local refuges from large mammal herbivory [ 40 , 50 , 51 ].…”

Section: Discussionmentioning

confidence: 99%

Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland

et al. 2021

Self Cite

View full text Add to dashboard Cite

Excluding large native mammals is an inverse test of rewilding. A 25-year exclosure experiment in an African savanna rangeland offers insight into the potentials and pitfalls of the rewilding endeavor as they relate to the native plant community. A broad theme that has emerged from this research is that entire plant communities, as well as individual plants, adjust to the absence of herbivores in ways that can ill-prepare them for the return of these herbivores. Three lines of evidence suggest that these “naïve” individuals, populations, and communities are likely to initially suffer from herbivore rewilding. First, plots protected from wild herbivores for the past 25 years have developed rich diversity of woody plants that are absent from unfenced plots, and presumably would disappear upon rewilding. Second, individuals of the dominant tree in this system, Acacia drepanolobium, greatly reduce their defences in the absence of browsers, and the sudden arrival of these herbivores (in this case, through a temporary fence break), resulted in far greater elephant damage than for their conspecifics in adjacent plots that had been continually exposed to herbivory. Third, the removal of herbivores favoured the most palatable grass species, and a large number of rarer species, which presumably would be at risk from herbivore re-introduction. In summary, the native communities that we observe in defaunated landscapes may be very different from their pre-defaunation states, and we are likely to see some large changes to these plant communities upon rewilding with large herbivores, including potential reductions in plant diversity. Lastly, our experimental manipulation of cattle represents an additional test of the role of livestock in rewilding. Cattle are in many ways ecologically dissimilar to wildlife (in particular their greater densities), but in other ways they may serve as ecological surrogates for wildlife, which could buffer ecosystems from some of the ecological costs of rewilding. More fundamentally, African savannah ecosystems represent a challenge to traditional Western definitions of “wilderness” as ecosystems free of human impacts. We support the suggestion that as we “rewild” our biodiversity landscapes, we redefine “wildness” in the 21st Century to be inclusive of (low impact, and sometimes traditional) human practices that are compatible with the sustainability of native (and re-introduced) biodiversity.

show abstract

Fine‐scale habitat heterogeneity influences browsing damage by elephant and giraffe

Cited by 9 publications

References 75 publications

Long‐term high densities of African elephants clear the understorey and promote a new stable savanna woodland community

Long‐term high densities of African elephants clear the understorey and promote a new stable savanna woodland community

Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna

Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland

Contact Info

Product

Resources

About