European forest policies aimed at increasing the amount of carbon stored in living trees have limited potential, because the most important factor for many forms of forest life is not living biomass, but the carbon contained in dead wood. This, in a nutshell, is the key finding of a study published in Nature Communications, led by Sapienza University of Rome within the COST Action “Bottoms-Up” and carried out in collaboration with numerous European universities and research centres, including the Institute for Research on Terrestrial Ecosystems of the National Research Council of Italy (CNR-IRET).
The research team harmonised data collected from forest sites across Europe, combining species richness data from six major taxonomic groups (vascular plants, mosses, lichens, fungi, deadwood-associated beetles and birds) with information on forest structure and carbon stocks. Using advanced statistical models, the researchers estimated how much each carbon pool contributes to biodiversity conservation across the different taxonomic groups.
The results challenge the idea of a consistently positive relationship between carbon and biodiversity. Carbon stored in living trees is not a reliable indicator of forest biodiversity: for most taxonomic groups, the relationship is weak or even negative. In particular, the species richness of vascular plants tends to decline as carbon in living trees increases, probably due to greater canopy cover, which reduces the amount of light reaching the forest understory. By contrast, carbon stored in dead wood—both standing and lying on the ground—is strongly associated with higher levels of diversity, especially for fungi, lichens and beetles. In some cases, even relatively small amounts of dead wood are enough to produce marked increases in species richness.
“Focusing only on carbon in living biomass,” explains Giovanni Trentanovi, researcher at CNR-IRET and co-author of the study, “is very limiting for biodiversity conservation. Dead wood, on the other hand, emerges as one of the most promising components for reconciling climate and conservation goals. It is a key element for ensuring structural complexity, stable microclimatic conditions and ecological continuity, which are essential for many taxonomic groups.”
The authors call for climate and biodiversity goals to be aligned through forest policies that go beyond the role of living trees, adopting an approach that systematically considers the different carbon components within forests. In particular, integrating dead wood into monitoring tools and carbon accounting is crucial to prevent climate mitigation measures from harming biodiversity, and to steer forest management towards outcomes that are beneficial on both fronts.
Link to the study:
https://www.nature.com/articles/s41467-026-68668-x
