How Invasive Jackfruit Trees Reshape Forest Ecosystems and Impact Amphibian Life

The jackfruit tree (Artocarpus heterophyllus), native to Southeast Asia, is increasingly recognized not just as a source of food, but as an invasive species with significant ecological consequences. A recent study in Brazil’s Atlantic Forest reveals how the spread of jackfruit alters forest floor habitats, impacting the diversity and abundance of amphibians.

Jackfruit’s Invasion and its Effects on Forest Structure

Originally introduced to Brazil in the 1800s, jackfruit now densely colonizes areas like Tijuca National Park and the Duas Bocas Biological Reserve [1]. Researchers have found that jackfruit’s proliferation leads to a simplification of the forest floor environment. Specifically, dense jackfruit populations result in a thinner layer of leaf litter and a reduction in the density of arthropods – small invertebrates crucial to the forest food web [1].

Differential Impacts on Amphibian Species

The study focused on three leaf-dwelling amphibian species with varying ecological strategies to understand how these habitat changes affect them: Rhinella crucifer, Haddadus binotatus, and Proceratophrys schirchi [1]. The findings revealed distinct responses:

• Rhinella crucifer: This widespread and adaptable species showed a positive correlation with jackfruit density, suggesting it benefits from the altered habitat.
• Haddadus binotatus: This species, reliant on moist leaf litter, exhibited a negative correlation with jackfruit density, indicating a decline in areas with high jackfruit populations.
• Proceratophrys schirchi: Occupancy of this species was positively correlated with deeper leaf litter and higher arthropod diversity, meaning it thrives in undisturbed microhabitats.

Cascading Effects and Ecological Mechanisms

Structural equation modeling (SEM) clarified the pathways through which jackfruit impacts amphibian occupancy. Jackfruit density directly reduces leaf litter depth and arthropod density. These changes then affect amphibian populations, either directly or indirectly [1]. The research highlights a process of “biotic homogenization,” where invasive species favor tolerant species like Rhinella crucifer while disadvantaging those with specialized habitat requirements, like Haddadus binotatus and Proceratophrys schirchi.

Implications for Conservation

This research underscores the importance of considering not only direct competition between invasive plants and native flora, but also the cascading effects on animal communities and ecosystem processes. Controlling the spread of invasive trees like jackfruit within protected areas is crucial. Conservation efforts should also prioritize maintaining leaf litter quality and the complexity of the forest floor to support the biodiversity of amphibians and other species dependent on these habitats [1].

Identifying and mitigating these indirect invasion pathways is critical to protecting amphibian diversity and maintaining the ecological resilience of tropical forests in the face of increasing invasion pressure.