The study, published in Nature Plants, brings together results from 19 CO₂-enrichment experiments conducted in glasshouses, growth chambers and field environments. The experiments included plant communities ranging from grass-dominated ecosystems to multispecies assemblages. By comparing plants grown alone with plants grown in mixtures, the researchers examined a question that has often been overlooked in climate-change experiments: does elevated CO₂ help all species equally, or does competition determine which plants are able to use the additional carbon?

The contrast was striking. When plants grew without neighbours, most species responded positively to elevated CO₂, or eCO₂. This response is biologically plausible because CO₂ is the raw material plants use during photosynthesis. Inside leaves, carbon dioxide is fixed into sugars through the Calvin cycle, providing the carbon skeletons needed to build new tissues. Higher atmospheric CO₂ can also reduce the amount of water plants lose while taking up carbon, because leaf pores known as stomata may not need to remain as open. Under controlled conditions, these effects can translate into faster growth and greater biomass.

Yet those benefits often disappeared when plants had to share their environment. More than half of the species examined showed neutral or negative responses to eCO₂ when growing in mixtures. In other words, a plant that grew better under elevated CO₂ by itself was not necessarily able to capitalize on the same conditions when surrounded by other species. The finding challenges the tendency to use single-species experiments as a guide to how natural plant communities will respond to a carbon-rich atmosphere.

Competition can block the conversion of extra carbon into additional growth in several ways. Plants may compete for sunlight, water, nitrogen and phosphorus, all of which are required to turn photosynthetic products into leaves, stems, roots and seeds. A plant may absorb more CO₂ and produce more sugars, but if nutrients are scarce, it may be unable to construct the proteins and tissues needed to use that carbon. Similarly, a taller or faster-growing neighbour may capture the available light before a smaller species can benefit, creating a physical barrier between elevated CO₂ and actual plant growth.

The community-level result was more subtle than a simple collapse in productivity. Although many individual species experienced neutral or negative responses, dominant species often drove modest increases in total mixture biomass under eCO₂. This means a plant community can appear to benefit from elevated CO₂ even while many of its members do not. A rise in total biomass therefore does not necessarily indicate that growth has been shared evenly, or that the community has become more productive in a way that benefits all species.

That distinction could have major implications for biodiversity. If elevated CO₂ consistently favours species that are already dominant, they may capture an even larger share of light, nutrients and space. Subdominant species could then face stronger suppression, reducing their growth and potentially altering the composition of plant communities over time. The result may be a greener-looking ecosystem with fewer species, rather than a uniformly healthier or more productive one.

The researchers’ trait analysis offers a clue about why some plants succeed while others fall behind. Acquisitive strategies, associated broadly with rapid resource capture and fast growth, were better predictors of performance under competition than a species’ intrinsic sensitivity to CO₂ alone. This suggests that the key question is not simply whether a plant can respond physiologically to elevated carbon dioxide. It is whether the plant can acquire enough light, water and nutrients quickly enough to turn that response into a competitive advantage.

The findings also expose a limitation in how climate models and ecological forecasts often treat CO₂ fertilization. If models assume that species respond independently, they may overestimate the benefits that rising CO₂ will deliver to plant communities. Real ecosystems are networks of interactions, and the outcome for one species depends partly on the traits and abundance of its neighbours. The same atmospheric change can therefore stimulate growth in an isolated plant, suppress a subordinate competitor and produce only a small increase in total community biomass.

As atmospheric CO₂ continues to rise, understanding this uneven distribution of benefits will become increasingly important. The new synthesis does not suggest that elevated CO₂ has no effect on vegetation. Instead, it shows that its effects are filtered through competition. Dominant plants may gain enough to lift overall biomass, while many less competitive species receive little benefit or even lose ground. The future of plant communities may therefore be shaped not by a universal CO₂ boost, but by an intensified struggle over which species can claim it.

Subject of Research: The effects of elevated carbon dioxide on plant growth and competition in multispecies communities.

Article Title: Interspecific competition negates CO₂ benefits for most plant species.

Article References: Raubenheimer, S.L., Simpson, K.J., Ripley, B.S. et al. “Interspecific competition negates CO₂ benefits for most plant species.” Nature Plants (2026). https://doi.org/10.1038/s41477-026-02360-2

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41477-026-02360-2

Keywords: Elevated CO₂, climate change, plant competition, biodiversity, plant communities, ecosystem productivity, dominant species, subdominant species, CO₂ fertilization, plant traits

The notion of plants communicating through underground fungal networks, commonly referred to as the ‘wood wide web,’ has generated much interest in recent years. This intricate system arises from symbiotic relationships between mycorrhizal fungi and plant roots, wherein plants receive essential nutrients while fungi benefit from the carbon produced by photosynthesis. Researchers have long been aware of the capacity for resource and information transfer via these mycorrhizal networks. However, whether plants actively signal each other during distress has remained an open question, riddled with theoretical difficulties.

Previously conducted studies indicated that when a plant experiences an attack from herbivores or pathogens, neighboring plants connected through the same underground networks often activate their defense mechanisms. Yet, the specifics surrounding the existence and purpose of these signaling behaviors were unclear. It posed an intriguing dilemma: if plants were to signal their distress, how would it be evolutionarily advantageous to do so, particularly when plants often compete for sunlight and nutrients?

In addressing these queries, the research group led by Dr. Thomas Scott from the University of Oxford utilized mathematical modeling to explore the potential scenarios under which plants might choose to warn one another about threats. The results were striking; they found that situational contexts in which evolutionary selection would favor altruistic signaling among plants were incredibly rare. Thus, they proposed a more competitive view of plant interactions, one where signaling behaviors might at times be deceptive rather than genuinely supportive.

The model demonstrated that under competitive pressures, a plant could gain an advantage by signaling a false alarm, tricking neighboring plants into wasting valuable resources on defense when no threat exists. This opportunistic behavior could contribute to the overall survival of the signaling plant by reducing the defenses of its competitors, thus giving it a better chance of securing the scarce resources its survival depends on.

In this light, Dr. Scott emphasized the novel understanding that plants might indeed be more inclined to capitalize on dishonest signaling, rather than advance the welfare of their neighbors. The research underscores a significant deviation from the common perception of plant altruism, positing that plants might act more like cunning strategists rather than cooperative allies.

Furthermore, the study introduces an alternative hypothesis regarding the mechanisms through which signals may be transmitted among plants in these underground networks. Rather than plants actively communicating their distress, it is possible that the mycorrhizal fungi themselves could be the facilitators of signaling. Fungi have evolved to maintain their relationships with host plants, gaining carbohydrates in exchange for water and nutrients. Thus, if fungi are able to detect when a specific plant is under threat, they might relay this information to other plants, effectively acting as a conduit within their interconnected web.

Intriguingly, this concept echoes similar dynamics seen in social behaviors across various species, including humans. Just as human beings often share critical information in social settings, the potential for fungi to share information about plant health introduces a layer of complexity previously unconsidered in plant ecology. This suggests a multifaceted relationship in which fungi may not only support their plant partners but may also possess a vested interest in keeping the entire network resilient against threats.

Professor Toby Kiers, a co-author of the study, supports this narrative, suggesting that the dynamics of eavesdropping and monitoring may indeed mirror human-like behaviors in nature. She likens the interaction between plants to that of gossiping neighbors, where one plant may pick up on cues emitted by another, thereby catalyzing a broader response among the network without explicit communication between the plants themselves.

The implications of these findings broaden our understanding of ecological networks and challenge the conventional wisdom that assumed altruistic interactions among plants. This study valorizes the significance of competition in shaping communication strategies within the ecosystem, pushing researchers to rethink the evolutionary trajectories of these relationships.

As we uncover the layers of complexity involved in the interactions of plants with each other and their fungal allies, the study leaves us with more questions than answers. What other mechanisms of interaction are at play within the underground networks? How far do these competitive behaviors stretch? And what do such behaviors tell us about the broad tapestry of life that flourishes beneath our feet? The researchers’ work undeniably lays the groundwork for further investigation into plant behavior, signaling, and the role of mycorrhizal networks in maintaining ecosystem stability.

This investigation opens up exciting avenues for future research. Understanding how plants respond to threats not only enhances our appreciation of plant ecology but could also have practical applications in agriculture and land management. By examining the interconnections between flowering plants and fungi, researchers could potentially develop innovative strategies for crop resilience and sustainability. In a world increasingly impacted by climate change, such insights will be invaluable in ensuring food security and preserving biodiversity.

This study not only reshapes our understanding of plant communication but also exemplifies the intricate dance of life that occurs beneath the surface, a reminder of the complexity and interdependence that pervades the natural world. The revelations discussed in this research advance a compelling argument: that in the realm of the natural world, competition, deception, and survival often trump altruism.

Subject of Research: The evolution of signaling and monitoring in plant–fungal networks
Article Title: The evolution of signaling and monitoring in plant–fungal networks
News Publication Date: Wednesday, January 22, 2025
Web References: doi.org
References: Proceedings of the National Academy of Sciences
Image Credits: Mateo Barrenengoa
Keywords: Plant signaling, Mycorrhizal fungi, Competition, Eavesdropping, Ecosystem dynamics, Evolutionary biology, Plant behavior, Fungal networks, Plant defense mechanisms, Altruism in nature.