Ecosystems have an afterlife, where dead help shape the living, research finds

In nature, what’s left behind isn’t just the past — it’s a powerful force shaping the future, according to new FIU research.

The study, published in Science Advances, reveals that the physical remains of foundation species — plants and animals that shape entire ecosystems — continue to influence the environment long after death. This includes the iconic mangroves that help shape the Florida Everglades. The research is especially important as extreme events like hurricanes, heatwaves, wildfires, and droughts often leave substantial amounts of dead material in their wake.

“We found that the material that remains from dead plants and animals can assist in the resilience and adaptations of individuals from the same and similar species,” said FIU biologist John Kominoski, principal investigator of the Florida Coastal Everglades Long-Term Ecological Research Program in the FIU Institute of Environment and co-author of the study.

Researchers analyzed long-term data from 10 ecosystems across the United States and French Polynesia, ranging from mangrove forests in South Florida to grasslands out west, oyster reefs on the east coast and the coral reefs of Moorea. In nearly every case, the remains of dead organisms played a significant role in how well new life grew, survived or recovered from environmental challenges.

Sometimes, those remains acted as a boost. For example, dead oyster shells provided a surface for new oysters to grow. Fallen trees helped young plants establish. In the case of the Everglades, dead and damaged mangroves helped living mangroves grow more roots following hurricanes. The scientists suggest this may be a result of the dead plant material adding nutrients back into the ground.

The findings highlight a concept scientists call “ecological memory.” This is the idea that ecosystems are shaped not just by what is alive today but also by what came before. Until now, the role of dead material in that process has been largely overlooked, Kominoski said. Only one of the 10 ecosystems studied — the kelp forests off the coast of California — exhibited no significant impact from dead material.

The research team, led by ecologist Kai L. Kopecky from the University of Colorado Boulder, found the post-death effects for the other nine sites were not subtle. In some cases, dead material increased growth 12-fold.

“The most striking takeaway is not the effect of any particular dead organism within its respective ecosystem, but how commonly and strongly the dead influence the living,” Kopecky said. “This demonstrates that dead organisms are not necessarily passive debris within their environments, but can be active components that shape how and whether ecosystems recover.”

The effects were not all positive. In some cases, dead materials hindered growth or recovery — blocking sunlight, damaging new growth or giving an advantage to competing species.

Just like the loss of species can have enduring effects on how ecosystems function and recover, so too can the loss of a species’ decomposing remains, the researchers said. With increasing frequency and intensity of extreme events, the scientists say it is likely that species will experience higher rates of mortality. Because of this, they say it is critically important to improve understanding of how their decomposition impacts different ecosystems.

“As disturbances become more frequent and severe, we’re going to see more of these legacy effects,” Kominoski said. “Understanding them could help us better manage and restore ecosystems.”

All the U.S. sites in the study are part of the U.S. Long Term Ecological Research Network (LTER) — an investment by the U.S. National Science Foundation to understand the long-term dynamics of ecosystems. FIU is home to the Florida Coastal Everglades LTER and is a partnering university with the Luquillo LTER in Puerto Rico.