Ecological connectivity – the ability of species, water, and nutrients to move freely, often across large landscapes – is essential for maintaining healthy and resilient ecosystems. In the Amazon basin, this connectivity links the Andes mountains to the lowland rainforests, supporting biodiversity, climate regulation, and the livelihoods of millions.
Unfortunately, these connections are increasingly fragmented by expanding roads, dams, and deforestation. Networks of protected areas can help maintain connectivity, but the effectiveness of these networks often depends on the mix of land types they include. While many studies show that incorporating Indigenous Territories and Protected Areas (ITPAs) into conservation networks can slow deforestation, much less is known about how well these areas preserve the broader ecological linkages that sustain the Amazon as a whole.
Duarte Ritter, C., Muñoz, J., Fabrício Machado, A., Albert, J.S., Ribas, C.C., Carnaval, A.C., Ulloa Ulloa, C., Carrillo, J.D., Tuomisto, H., Armenteras, D. and Guayasamin, J.M. 2025. Indigenous territories and protected areas are crucial for ecosystem connectivity in the Amazon basin. Proceedings of the National Academy of Sciences 122(31): e2418189122.
A new study addresses this gap by mapping ecosystem connectivity across the entire Amazon basin. The authors analyzed the spatial overlap of six major human impacts (deforestation, fire, mining, oil and gas extraction, dam construction, and roads) across four landscape types: the Amazonian Andes, lowland forests, wetlands, and rivers.
They used a resistance-based modeling approach, where intact areas had low resistance and areas with greater human disturbance had higher resistance, indicating reduced connectivity. They then combined remote-sensing data and spatial analyses to calculate connectivity for each ecosystem and compared results inside and outside ITPAs.
The findings reveal that about one-quarter of the Amazon basin’s ecosystems show signs of major disturbance. In unprotected areas, 38% of land is affected by at least one human activity, compared to only 14-16% within ITPAs. Across all three major ecosystems (terrestrial, wetland, and riverine), connectivity is significantly higher inside ITPAs.
The most heavily degraded regions occur in the southern and eastern Amazon, where deforestation, mining, and fire have caused extensive fragmentation. River connectivity is particularly at risk: most Andean headwaters are now blocked or degraded by dams and illegal in-stream mining, leaving only a handful of free-flowing rivers such as the Napo, Putumayo, and Japurá. Wetlands and floodplain systems also show declining connectivity due to altered hydrology, though they remain relatively intact within ITPAs.
Beyond their legal protection, the strength of ITPAs lies in the stewardship of Indigenous peoples and local communities, who help maintain ecological functions through traditional land-use practices like rotational farming, controlled burning, and sustainable fishing. These areas serve not only as biodiversity reserves but also as vital corridors that allow ecosystems to function and adapt under climate and land-use change.
For conservation planners, this research demonstrates that maintaining connectivity requires reinforcing ITPA governance, restoring degraded buffer zones, and formally recognizing Indigenous territories that remain unprotected. Protecting key transboundary corridors and free-flowing rivers could safeguard the ecological link between the Andes and the Amazon lowlands. By centering Indigenous stewardship and connectivity in future management plans, conservation efforts can better preserve the ecological integrity of the world’s largest tropical forest.
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