DOI: 10.5061/dryad.bt21d
title: Data from: Synergistic effects of fire and elephants on arboreal animals in an African savannah

description: 1. Disturbance is a crucial determinant of animal abundance, distribution
 and community structure in many ecosystems, but the ways in which multiple
 disturbance types interact remain poorly understood. The effects of
 multiple-disturbance interactions can be additive, subadditive or
 super-additive (synergistic). Synergistic effects in particular can
 accelerate ecological change; thus, characterizing such synergies, the
 conditions under which they arise, and how long they persist has been
 identified as a major goal of ecology. 2. We factorially manipulated two
 principal sources of disturbance in African savannas, 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 savanna. 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 gecko
 density twofold 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 threefold within 4
 months of the experimental burn; this occurred because fire increased the
 incidence of elephant damage to trees, which in turn improved microhabitat
 quality for geckos. However, this synergistic positive effect of fire and
 elephants 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 dominant tree species
 (Acacia drepanolobium); this influenced gecko habitat selection but did
 not explain the synergistic effect of fire and elephants. However,
 fire-driven shifts in plant-ant occupancy may have indirectly mediated
 this effect by increasing trees' susceptibility to elephant damage.
 5. Our findings confirm the importance of fire × elephant interactions in
 structuring arboreal wildlife populations. Where habitat modification by
 megaherbivores facilitates co-occurring species, fire may amplify these
 effects in the short term by increasing the frequency or intensity of
 herbivory, leading to synergy. In the longer term, tree mortality due to
 both top kill by fire and toppling by large herbivores may reduce overall
 microhabitat availability, eliminating the synergy.
description: Patch-scale summary
 dataContains data for each
 900 square-meter patch (patches were the primary units of analysis in the
 study). These data are the basis of Figures 1 and 2, and Tables 1 and S1,
 in the paper. Data include the experimental treatment of each patch; gecko
 (lizard) abundances and densities in July 2013, March 2014, and July 2014;
 the number and density of trees per patch; mean tree height and basal
 circumference; abundance and length of insects (gecko prey) captured in
 sticky traps within each patch; number and density of elephant damaged
 trees in each patch; and number of trees in each patch occupied by four
 different symbiotic acacia-ant species (along with unoccupied trees and
 trees other than Acacia drepanolobium, which do not have
 ants).July 2013 gecko habitat
 selection dataContains attribute data
 for each of 559 unique Acacia drepanolobium trees surveyed in July 2013.
 These data are the basis for Tables 2 and S2 in the paper. Attributes
 included are: (A) presence/absence of geckos (0,1); (B) presence/absence
 of elephant damage (0,1); (C) species of symbiotic ant occupant
 (categorical, with 6 categories); and (D) tree basal
 circumference.