Trees, grasses, corals, and oysters are foundational to the structure of an ecosystem while they are alive. But new research led by the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder shows that when they die — due to extreme events like storms, wildfires, or marine heatwaves — the physical remains of these species continue shaping the ecosystem.
The study, published today in Science Advances, focuses on "foundation species," those that create habitats, protect against environmental stress, and control biodiversity. Researchers analyzed and combined datasets on foundation species from 10 diverse ecosystems, ranging from subarctic forests to tallgrass prairies and coral reefs.
"We found that dead organisms have these strong, enduring influences that are much more common than previously thought across a wide range of otherwise really different ecosystems," said Kai Kopecky, CIRES postdoctoral researcher and lead author of the paper. "It really illustrates the role that death plays in shaping life."
The team found that the remains of five foundation species promoted recovery. Layers of old oyster shells provide the surfaces young oysters need to settle and grow on tidal flats. Standing dead hemlock trees in temperate forests support the establishment of new saplings. Leaf debris from dead or damaged mangrove trees in the subtropics increases nutrient availability, stimulating new root growth. In subarctic forests, standing burned trees release seeds that help regenerate the forest.
In contrast, four of the cases showed dead organisms slowed or prevented recovery. Thick layers of grass litter can block sunlight and delay prairie grasses from sprouting from underground biomass. In tropical forests, fallen canopy debris can limit light and space, preventing seedling survival. Floating marine debris in salt marshes can smother live marsh grasses, and dead, branching coral skeletons can provide habitat for competing organisms that hinder the growth of living coral. One ecosystem, a kelp forest, showed a neutral response.
"As disturbances become more frequent and severe, we're going to see more of these legacy effects," said co-author Florida International University biologist John Kominoski. "Understanding them could help us better manage and restore ecosystems."
Letting nature recover on its own — when dead organisms promote regrowth — can reduce the need for expensive interventions, while targeted action can prevent long-term damage when legacies are harmful.
