Ecological consequences of forest elephant declines for Afrotropical forests

Abstract

Poaching is rapidly extirpating African forest elephants (Loxodonta cyclotis) from most of their historical range, leaving vast areas of elephant-free tropical forest. Elephants are ecological engineers that create and maintain forest habitat; thus, their loss will have large consequences for the composition and structure of Afrotropical forests. Through a comprehensive literature review, we evaluated the roles of forest elephants in seed dispersal, nutrient recycling, and herbivory and physical damage to predict the cascading ecological effects of their population declines. Loss of seed dispersal by elephants will favor tree species dispersed abiotically and by smaller dispersal agents, and tree species composition will depend on the downstream effects of changes in elephant nutrient cycling and browsing. Loss of trampling and herbivory of seedlings and saplings will result in high tree density with release from browsing pressures. Diminished seed dispersal by elephants and high stem density are likely to reduce the recruitment of large trees and thus increase homogeneity of forest structure and decrease carbon stocks. The loss of ecological services by forest elephants likely means Central African forests will be more like Neotropical forests, from which megafauna were extirpated thousands of years ago. Without intervention, as much as 96% of Central African forests will have modified species composition and structure as elephants are compressed into remaining protected areas. Stopping elephant poaching is an urgent first step to mitigating these effects, but long-term conservation will require land-use planning that incorporates elephant habitat into forested landscapes that are being rapidly transformed by industrial agriculture and logging.

Global analysis reveals complex demographic responses of mammals to climate change

“…Mammals are key ecosystem engineers, frequent apex predators, and providers of important ecosystem services e.g., 31,32 . Future dynamics of mammal populations can therefore determine overall ecosystem change 33 .…”

Movement patterns of forest elephants (Loxodonta cyclotis Matschie, 1900) in the Odzala‐Kokoua National Park, Republic of Congo

“…Despite our low sample size, the present study produced some interesting results. Previous studies found that unprotected roads have a barrier effect in elephant displacements, but not in the case of roads located inside protected areas (Blake et al, ; Kolowski et al, ; Poulsen et al, ; Schuttler et al, ). Given that our road is a protected road inside a National Park, our results are consistent with these previous studies.…”

“…Forest elephant ( Loxodonta cyclotis Matschie, 1900) movement and feeding behaviour (pollarding, peeling and trampling) modify forest structure, controlling the availability of resources for other organisms (Poulsen et al, ) and maintaining habitats with open canopy such as bais—forest clearings—(Fishlock, ; Metsio Sienne, Buchwald, & Wittemyer, ; Turkalo, ). A reduction in the abundance of forest elephants can alter plant communities and ecosystem function (Poulsen et al, ), which may have implications for the entire ecosystem due to cascading effects.…”

“…Forest elephant ( Loxodonta cyclotis Matschie, 1900) movement and feeding behaviour (pollarding, peeling and trampling) modify forest structure, controlling the availability of resources for other organisms (Poulsen et al, ) and maintaining habitats with open canopy such as bais—forest clearings—(Fishlock, ; Metsio Sienne, Buchwald, & Wittemyer, ; Turkalo, ). A reduction in the abundance of forest elephants can alter plant communities and ecosystem function (Poulsen et al, ), which may have implications for the entire ecosystem due to cascading effects. Central Africa holds the main part of African forest elephant populations, although they are currently enduring a pronounced increase in poaching activities, particularly in Gabon and Congo, where the bulk of the entire population exist (Breuer, Maisels, & Fishlock, ; Gobush, Mutayoba, & Wasser, ; Maisels et al, ; Poulsen et al, ), but also in eastern Democratic Republic of Congo, south‐eastern Cameroon and south‐western Central African Republic (Wasser et al, ).…”

Ranging behaviour of Uganda’s elephants

“…Maisels et al (2013) showed that the forest elephant declined by 62% in Central Africa between 2002 and 2011 and now occupies less than 25% of its potential range. This decline is concerning, as elephants are not only conservation flagships but also keystone species and ecosystem engineers (Buechner & Dawkins, 1961;Laws, Parker, & Johnson, 1975;Poulsen et al, 2017).…”