Dead organisms shape ecosystems

A large-scale study published in June in the journal Science Advances has highlighted the significant role dead organisms play in shaping and sustaining ecosystems. Researchers analyzed data from the long-term ecological research network of the National Science Foundation of the United States, examining ten ecosystems—half marine and half terrestrial—spanning from the tropics to the Arctic Circle.

Foundational species leave lasting impacts

The study focused on the remains of "foundational species," such as corals in reefs and trees in forests, which play a structuring role in their environments. Researchers found that the remains of these foundational species are not passive debris but active agents that can modify the structure, functioning, and resilience of ecosystems.

Dead trees and marine life support growth

For example, dead trees can promote the growth of shrubs by maintaining a favorable microclimate, while the accumulation of dead leaves in mangrove root networks after a hurricane boosts nutrient content, promoting new root formation. Similarly, burned black spruces in boreal forests release a large quantity of seeds into the soil, aiding forest recovery. In temperate forests in New England, dead trees also support shrub growth. At sea, dead organisms also support life.

Dead organisms provide food and shelter

The accumulation of dead mussel shells on mudflats provides a surface for young mussels to settle and grow. The study also noted that the carcass of a whale can provide food for deep-sea creatures equivalent to what normally reaches them from the surface over 100 to 200 years. Prior research has shown that dead organisms support life in various ways.

Not all effects are positive

In forests, 20 to 30 percent of insects depend directly or indirectly on dead or decaying wood. On beaches, algae and marine animal debris nourish plants, insects, and birds. However, the study also found that the influence of dead organisms is not always positive. In Moorea, French Polynesia, coral skeletons decimated by marine heatwaves provide a refuge for macroalgae that hinder the survival of juvenile corals, potentially transforming reefs into "ghost cities of dead skeletons."

Understanding ecological legacies

In a humid tropical forest in Puerto Rico, forest debris after a hurricane can block sunlight, slowing the growth of young shoots. The researchers emphasized the importance of understanding how species continue to transform their environment after death, especially in the context of increasing disturbances such as climate chaos, deforestation, megafires, and overfishing. They called for further studies and suggested that leaving decomposing trees, empty shells, and dead algae in ecosystems could provide opportunities for life to emerge.