Trees are not passive scenery; they are sophisticated social networks

Nature · Published 24 October 2026 Swipe more like this →

In short: We often view trees as static backdrops to our lives, but beneath the soil and within the bark lies a complex system of defense, communication, and cooperation. From sharing nutrients with struggling neighbors to actively defending against predators, trees operate as some of the planet's most sophisticated life forms.

While forests are often defined by their height or diameter, true 'old-growth' status is determined by a forest's history of being undisturbed by human activity. These climax ecosystems, which cover roughly one-third of the world's 4.06 billion hectares of forested land, provide unique ecosystem services that younger forests cannot replicate. They are characterized by complex stand structures featuring multiple canopy layers, native understory plants, and a significant amount of deadwood and woody debris. These primary forests are defined by the Food and Agriculture Organization as naturally regenerated native species showing no visible human impact. They provide social, cultural, and spiritual value that younger stands lack. The specific traits of a forest, such as maximum height or longevity, dictate its classification.

The internal mechanics of these forests reveal a hidden sociality. Trees communicate through underground fungal networks, which serve as conduits for sharing water and nutrients. In these systems, older 'mother trees' can actively support the survival of struggling saplings. Beyond cooperation, trees are also proactive defenders; they employ specific mechanisms to ward off herbivores and bark beetles while mangroves simultaneously act as coastal protectors and marine nurseries. Trees also serve as vital habitats for various animals like squirrels and countless insects. In tropical mangroves, the root systems create essential nurseries for marine life. These plants are active participants in reproduction cycles alongside their many partners.

Despite their importance, old-growth forests—particularly those in Brazil, Canada, and Russia—face severe threats from anthropogenic climate change, logging, and clear-cutting for agriculture. Protecting these areas is vital not just for the thousands of species they house, such as indris, owls, and cassowaries, but because their complex ecological processes are essential for global carbon storage and biodiversity resiliency. The Sierra Nevada mountains in California house ancient red giants that are the last of their kind. These isolated giants represent a unique remnant of the past. Conservation efforts aim to protect these specific sites from further degradation.

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