Ecological consequences of Late Quaternary extinctions of megafauna
Johnson, CN, Ecological consequences of Late Quaternary extinctions of megafauna, Royal Society of London. Proceedings. Biological Sciences, 276, (1667) pp. 2509-2519. ISSN 0962-8452 (2009) [Refereed Article]
Large herbivorous vertebrates have strong interactions with vegetation, affecting the structure, composition
and dynamics of plant communities in many ways. Living large herbivores are a small remnant of the
assemblages of giants that existed in most terrestrial ecosystems 50 000 years ago. The extinction of so many
large herbivores may well have triggered large changes in plant communities. In several parts of the world,
palaeoecological studies suggest that extinct megafauna once maintained vegetation openness, and in
wooded landscapes created mosaics of different structural types of vegetation with high habitat and species
diversity. Following megafaunal extinction, these habitats reverted to more dense and uniform formations.
Megafaunal extinction also led to changes in ﬁre regimes and increased ﬁre frequency due to accumulation
of uncropped plant material, but there is a great deal of variation in post-extinction changes in ﬁre. Plant
communities that once interacted with extinct large herbivores still contain many species with obsolete
defences against browsing and non-functional adaptations for seed dispersal. Such plants may be in decline,
and, as a result, many plant communities may be in various stages of a process of relaxation from
megafauna-conditioned to megafauna-naive states. Understanding the past role of giant herbivores provides
fundamental insight into the history, dynamics and conservation of contemporary plant communities.