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Contrasting Effects of Defaunation on Aboveground Carbon Storage Across the Global Tropics

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Fungi and Insects Compensate for Lost Vertebrate Seed Predation in an Experimentally Defaunated Tropical Forest

Background

Defaunation disrupts key plant-animal interactions such as seed dispersal and seed predation, triggering cascading effects on plant regeneration, species composition, and carbon storage. While past studies emphasize the negative consequences of losing vertebrate seed dispersers and predators, it remains unclear whether other organisms like fungi and insects can compensate for these losses. This study investigates whether non-vertebrate predators offset the decline of large vertebrate seed predators in a tropical rainforest.

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Size-Related Differential Seed Predation in a Heavily Defaunated Neotropical Rain Forest

Background

Defaunation, driven by hunting and habitat loss, disproportionately affects medium and large mammals, often leaving behind a residual community dominated by small rodents. This shift in mammal communities can alter seed predation dynamics and impact forest regeneration. In heavily defaunated areas like Los Tuxtlas, Mexico, small rodents have become the primary seed predators. This study investigates whether seed predation patterns differ based on seed size in a highly defaunated forest. Specifically, it examines whether small rodents preferentially consume small seeds while large-seeded species escape predation, potentially influencing seed germination and plant recruitment.

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Seed dispersal strategies and the threat of defaunation in a Congo forest

Background

Seed dispersal plays a critical role in shaping plant communities and maintaining biodiversity in tropical forests. In the Congo Basin, most tree species depend on animals (zoochory) to disperse their seeds, with large vertebrates such as forest elephants and bonobos serving as key dispersers. However, hunting and poaching threaten these animals, potentially triggering cascading effects on forest structure and plant regeneration. This study investigates the extent of animal-mediated seed dispersal in the LuiKotale forest in the Democratic Republic of the Congo (DRC) and evaluates how hunting pressure on frugivores may influence tree community composition.

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Defaunation of Large-Bodied Frugivores Reduces Carbon Storage in a Tropical Forest of Southeast Asia

Background

Tropical forests are vital for carbon storage, but recent studies suggest that defaunation—the loss of large-bodied seed dispersers due to hunting and habitat fragmentation—can significantly impact this function. While previous research has shown reductions in above-ground carbon storage due to defaunation in South America and Africa, its effects on Southeast Asian forests remain debated. Some scientists argue that the dominance of wind-dispersed Dipterocarpaceae trees in the region buffers against carbon losses from defaunation. This study examines the extent to which defaunation influences carbon storage in a tropical forest in Thailand, where large frugivores such as primates, hornbills, and terrestrial mammals still persist.

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Drivers and spatial patterns of avian defaunation in tropical forests

Background

Tropical forests harbor an immense diversity of bird species, but hunting and wildlife trade are driving widespread declines in bird populations. Unlike habitat loss, hunting often occurs in seemingly intact forests, making its impact more difficult to detect. Birds are harvested for both subsistence (food) and commercial purposes (pet trade), but the spatial extent and drivers of avian defaunation remain poorly understood. This study aims to assess the factors influencing bird population declines and map defaunation patterns across tropical forests.

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Using Janzen–Connell to predict the consequences of defaunation and other disturbances of tropical forests

Background

The Janzen–Connell (J–C) model describes how seed dispersal and mortality shape tropical forest diversity. According to the model, seeds that fall close to their parent trees suffer high mortality due to host-specific predators, pathogens, and herbivores. In contrast, seeds dispersed farther away have a better chance of survival. Defaunation, particularly the loss of large-bodied seed dispersers, disrupts this balance by reducing seed dispersal distances. This study applies the J–C model to predict how defaunation and other disturbances affect tree recruitment and forest composition.

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Cascading effects of contemporaneous defaunation on tropical forest communities

Background

Defaunation, caused by hunting and habitat fragmentation, is a major threat to biodiversity in tropical forests. It disproportionately affects large-bodied vertebrates, which play key roles as seed dispersers, seed predators, and herbivores. The loss of these animals can have cascading effects on plant populations, altering species composition, seed dispersal, and plant recruitment. This study reviews empirical evidence from 42 studies to understand how defaunation influences plant-animal interactions, plant demography, and overall community diversity.

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Defaunation affects carbon storage in tropical forests

Background

Tropical forests play a critical role in global carbon storage, holding approximately 40% of the Earth's terrestrial carbon. While deforestation, logging, and climate change are well-documented threats to these forests, the impact of defaunation (the loss of large frugivorous animals due to hunting and habitat loss) has been largely overlooked. Many large-seeded hardwood trees rely on large vertebrates for seed dispersal, and their decline could significantly affect forest composition and carbon storage.

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The social and ecological costs of reforestation. Territorialization and industrialization of land use accompany forest transitions in Southeast Asia

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