The Importance of Animals in the Forest

Abstract

Most species in tropical forests are animals and most of these animals are invertebrates, particularly insects. Vertebrates are much less diverse, but dominate some key ecological roles. Almost all plants in tropical lowland forests are pollinated by animals, with bees, followed by beetles and flies, most important. Most seeds are also dispersed by animals, except in the upper canopy, with birds, fruit bats, primates, and a variety of terrestrial mammals most important. Maximum routine movement distances for both pollen and seeds are most often in the range 100–1000 m. Seeds are predated before dispersal by colobine monkeys, squirrels, birds, and insects and after dispersal by rodents, birds, ants, and other insects. After germination, the dominant herbivores are insects, and insects also dominate the consumption of dead plant material. Carnivorous animals have indirect impacts on plants through their effects on the abundances and behaviors of other animals. Few forest animals survive deforestation, while hunting is the major threat to vertebrates in intact and logged forests. Failures of seed dispersal are currently the most obvious impacts of animal losses, but more subtle impacts would be easily overlooked. Restoration of seed dispersal services is potentially one of the most effective ways of enhancing forest recovery after logging and increasing resilience to climate change.