Defaunation Effects on Tropical Forest Ecosystems

Defaunation—the decline or loss of animal species from ecological communities—has emerged as a pressing challenge in tropical forests worldwide. Driven principally by hunting, habitat fragmentation and human disturbance, the disappearance of large-bodied mammals, primates and birds disrupts key processes such as seed dispersal, predation and nutrient cycling. These alterations cascade through trophic networks, diminishing forest regeneration, modifying species composition and undermining aboveground carbon storage. The loss of frugivores, for instance, reduces the recruitment of large-seeded tree species that contribute disproportionately to biomass accumulation, while extirpation of predators can prompt herbivore overabundance and consequent vegetation degradation. Moreover, behavioural shifts in residual fauna—such as heightened nocturnality—further reshape food-web interactions. As tropical forests perform vital roles in global carbon sequestration, hydrological regulation and biodiversity maintenance, defaunation poses profound threats to ecosystem resilience and climate mitigation objectives. Holistic conservation strategies that integrate wildlife protection with sustainable forest management and economic incentives are therefore crucial to safeguard these complex, interdependent systems and uphold the services they deliver at local and planetary scales.

Research from Nature Portfolio

Recent studies have documented behavioural adaptations and ecosystem consequences of defaunation across diverse tropical landscapes. A comparative analysis of camera-trap networks in Southeast Asia reveals that wildlife communities in disturbed sites shift peak activity towards dawn and dusk, altering diel overlaps among predators and prey without necessarily changing net interaction rates. A foundational pan-tropical assessment demonstrates that simulated losses of large-seeded, animal-dispersed trees yield contrasting impacts on aboveground carbon stocks: considerable carbon declines in African, American and South Asian forests compared with marginal effects in Southeast Asia and Australia due to regional differences in dispersal mode and tree size relationships. Complementing these findings, a global meta-analysis shows that hunting and fragmentation-driven vertebrate defaunation consistently reduces forest regeneration, with primates and birds playing outsized roles in maintaining seedling recruitment and long-term carbon storage.

Defaunation Effects on Tropical Forest Ecosystems publication trend

The graph below shows the total number of articles in defaunation effects on tropical forest ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Defaunation: The reduction or local extinction of animal species from ecological communities due to anthropogenic pressures.

Faunal degradation: The process of incremental loss of species or populations within an ecosystem, often preceding complete defaunation.

Seed dispersal: The movement of seeds away from parent plants by animals, crucial for forest regeneration and the maintenance of tree species diversity.

Aboveground carbon storage: The accumulation of carbon in living plant biomass, primarily in woody tissues, which contributes to climate regulation.

Functional diversity: The range and distribution of species’ ecological traits within a community, reflecting resilience and ecosystem functioning.

References

1. Effects of human disturbances on wildlife behaviour and consequences for predator-prey overlap in Southeast Asia. Nature Communications (2024).
2. Contrasting effects of defaunation on aboveground carbon storage across the global tropics. Nature Communications (2016).
3. Quantifying the impacts of defaunation on natural forest regeneration in a global meta-analysis. Nature Communications (2019).
4. Situating defaunation in an operational framework to advance biodiversity conservation. BioScience (2023).
5. To avoid carbon degradation in tropical forests, conserve wildlife. PLOS Biology (2023).