Data from: Synergistic effects of fire and elephants on arboreal animals in an African savannah

1. Disturbance is a crucial determinant of animal abundance, distribution, and community structure in many ecosystems, but ways in which multiple disturbance types interact remain poorly understood. The effects of multiple-disturbance interactions can be additive, sub-additive, or super-additive (synergistic). Synergistic effects in particular can accelerate ecological change and trigger regime shifts; consequently, characterizing synergies, the conditions under which they arise, and how long they persist has been identified as a major goal of modern ecology. 2. We factorially manipulated two principal sources of disturbance in African savannahs, fire and elephants, and measured their independent and interactive effects on the numerically dominant vertebrate (the arboreal gekkonid lizard Lygodactylus keniensis) and invertebrate (a guild of symbiotic Acacia ants) animal species in a semi-arid Kenyan savannah. 3. Elephant-exclusion alone (minus fire) had negligible effects on gecko density. Fire alone (minus elephants) had negligible effects on gecko density after 4 months, but increased density by two-fold after 16 months, likely because the decay of fire-damaged woody biomass created refuges and nest sites for geckos. In the presence of elephants, fire increased gecko density nearly three-fold within 4 months of the experimental burn: fire increased the incidence of severe elephant damage to trees, which in turn improved microhabitat quality for geckos. However, this synergy attenuated over the ensuing year, such that only the main effect of fire was evident after 16 months. 4. Fire also altered the structure of symbiotic plant-ant assemblages occupying the locally dominant tree (Acacia drepanolobium); this influenced gecko habitat selection but did not explain the synergistic effect of fire and elephants. However, plant-ant occupancy may have indirectly mediated this effect on geckos by increasing trees’ susceptibility to damage by browsing elephants. 5. Our findings confirm the importance of fire×elephant interactions in structuring arboreal wildlife populations. Where habitat modification by elephants facilitates co-occurring species, fire may amplify these effects in the short term by locally increasing the frequency or severity of browsing, leading to synergy. In the longer term, tree mortality due to both top-kill and elephant toppling may reduce overall microhabitat availability, eliminating the synergy.