Data from: Release of tree species diversity follows loss of elephants from evergreen tropical forests

Little is known about the impacts of megaherbivores in closed-canopy
tropical evergreen forests. We report on a decade of research on
megaherbivore impacts in such forests in Gabon and Malaysia, comparing
sites with (+) and without (-) elephants and documenting major differences
in forest structure, tree species composition, and tree species diversity.
In both regions, we compared sites supporting natural densities of
elephants with otherwise undisturbed sites from which elephants had been
absent for several decades. Elephant (+) sites supported low densities of
seedlings and saplings relative to elephant (-) sites. In Lope National
Park, Gabon, 88% of saplings and small trees (<20 cm dbh) were of
species avoided by elephants, implicating forest elephants as powerful
filters in tree recruitment. In Malaysia, Asian elephants showed strong
preferences for monocots over dicots, as we found through both indirect
and direct means. Loss of elephants from both Asian and African forests
releases diversity from top-down pressure, as preferred forage species
increase in abundance, leading to increased density of small stems and
increased tree species diversity. In contrast, loss of other major
functional groups of animals, including top carnivores, seed predators and
seed dispersers, often results in negative impacts on tree diversity.