Soil holds more carbon than the atmosphere and all living vegetation combined, yet not all of that carbon is equally stable. Researchers distinguish broadly between mineral-associated organic matter, abbreviated MAOM, which clings to the reactive surfaces of clay and silt particles and can persist for decades to millennia, and particulate organic matter, or POM, which consists of recognizable fragments of plant and microbial debris. POM can be further divided into free POM, which sits loosely between soil aggregates and is readily decomposed, and occluded POM, which has become physically trapped inside aggregates where it enjoys a degree of shelter from microbes and their enzymes. Which of these pools a soil accumulates, and in what proportions, determines whether that soil behaves as a long-term carbon vault or a short-term holding pen.

The research team hypothesized that the two fractions respond to different mineral controls. For mineral-associated organic matter, the key variable should be the total reactive surface area offered by the dominant clay mineral. Clays vary enormously in this respect: kaolinite, a low-activity 1:1 clay, presents relatively little surface, illite offers an intermediate area, and montmorillonite, a swelling 2:1 clay with expansive interlayer spaces, provides by far the most reactive real estate. For particulate organic matter, by contrast, the hypothesis centered on pore architecture rather than surface chemistry. The researchers predicted that substrates dominated by illite, which maintain comparatively larger pores, would promote the storage of POM, particularly the occluded fraction protected within those pore spaces, whereas the fine-textured montmorillonite and kaolinite substrates would offer less such physical refuge.

To test these ideas, the team grew two plant species with contrasting traits, the grass Festuca rubra and the leguminous herb Lotus corniculatus, in three soil-forming substrates dominated respectively by kaolinite, illite and montmorillonite. Crucially, the design separated the influence of plant roots from direct contact with clay by employing two exposure modes. In one, plants grew in pots filled entirely with a single clay substrate, so roots permeated the mineral matrix directly. In the other, plants grew in larger pots of sand into which the clay substrates were buried in mesh bags, allowing roots and their exudates to reach the clay by growing through the mesh without the substrate dispersing. This elegant manipulation meant the researchers could ask whether clay effects depend on intimate root-mineral contact or operate regardless of physical arrangement.

The results were strikingly consistent. Across both exposure modes and both plant species, the largest carbon storage occurred in the montmorillonite-dominated substrates, followed by illite and then kaolinite, exactly the ranking predicted by increasing mineral surface area. The accumulation of mineral-associated organic matter followed the same pattern, confirming that the reactive surface area of clay minerals is a decisive control on this slow-cycling, chemically protected carbon pool. Whether carbon arrived as root litter, rhizodeposition or microbial necromass, the abundant surfaces of montmorillonite simply offered more sites on which organic molecules could bind and be withdrawn from circulation by decomposers.

The story changed, however, when the researchers turned to particulate fractions. Free POM, the most labile pool, showed no significant response to clay mineral identity at all, suggesting that once carbon escapes mineral surfaces it decomposes at a rate governed by factors other than the dominant clay type. Occluded POM, on the other hand, peaked in the illite-dominated substrates, significantly exceeding levels in both kaolinite and montmorillonite. This outcome matched the pore-size hypothesis: the coarser pore network of illite-rich material appears to provide physical niches large enough to encase organic particles within stable aggregates, shielding them from decomposition, while the very fine or very dense fabrics of the other two minerals offer fewer such refuges.

Together these findings sharpen a conceptual model that soil scientists have been assembling for decades, in which mineral-associated and particulate carbon are governed by distinct protective mechanisms. Surface area controls adsorption and hence MAOM accumulation; pore size distribution controls physical exclusion and hence occluded POM accumulation. Neither mechanism substitutes for the other, and a soil can be rich in one fraction while poor in the other depending on its mineralogy and structure. This decoupling matters because the two pools respond differently to disturbance: POM tends to be lost quickly when soils are tilled or aggregate structures collapse, whereas MAOM persists until surfaces saturate or chemistry shifts. Global carbon models that lump all soil organic matter into a single pool may therefore misjudge how different soils will respond to land-use change and warming.

The rhizosphere focus of the study adds further weight to its conclusions. Roots are the principal conduit through which fresh carbon enters soil, and the two plant species used here differ in litter chemistry and root traits, yet the mineral-driven patterns held for both. That generality suggests clay mineral properties impose a first-order constraint on rhizosphere carbon storage that overrides moderate differences in vegetation, at least over the timescales of a pot experiment. It also implies that restoring or managing soils for carbon sequestration may benefit from attention to texture and mineralogy: amending sandy, kaolinite-poor soils with high-surface-area clays could raise their ceiling for mineral carbon protection, while preserving aggregate structure in illite-bearing soils could safeguard the physically occluded fraction.

As climate policy increasingly looks to soils as a natural climate solution, studies like this one provide the mechanistic ground truth on which realistic sequestration targets must rest. By demonstrating, in a controlled setting, that surface area and pore size exert opposing and fraction-specific influences on organic matter accumulation, the Prague-led team has given modelers a clearer rulebook and given land managers a more discriminating lens. The carbon beneath our feet, it turns out, is not stored in one great reservoir but in compartments with different locks, and the keys are written in the geometry of clay.

Subject of Research: The contrasting effects of clay mineral surface area and pore size on the accumulation of mineral-associated and particulate soil organic matter fractions in the rhizosphere.

Article Title: Clay mineral surface area and pore size have contrasting effect on accumulation of soil organic matter fractions in the rhizosphere

Article References: Irshad, S., Soukup, K., Setničková, K., & Frouz, J. (2026). Clay mineral surface area and pore size have contrasting effect on accumulation of soil organic matter fractions in the rhizosphere. Biogeochemistry. https://doi.org/10.1007/s10533-026-01370-8

Image Credits: AI Generated

DOI: 10.1007/s10533-026-01370-8

Keywords: clay minerals, soil organic matter, mineral-associated organic matter, particulate organic matter, rhizosphere, pore size, surface area, carbon storage, kaolinite, illite, montmorillonite, soil biogeochemistry

The insight emerges from a global synthesis, described in a companion study by Chao Wang and colleagues, that paired estimates of microbial energy demand with measurements of the energy contained in the substrate carbon itself. Microbes are not passive recipients of carbon; they are energetic organisms that must harvest usable chemical energy from organic molecules to power their metabolisms, maintain cellular machinery and synthesize new biomass. Two substrates that contain identical amounts of carbon can differ dramatically in the energy they yield when oxidized. A reduced, energy-rich compound such as a lipid or a lignin monomer releases far more free energy upon microbial oxidation than a highly oxidized compound such as oxalate, even if both carry the same carbon atoms. By treating soil organic matter as an energy currency rather than merely a carbon reservoir, the new framework quantifies how much of that energy is available to the microbial community and how much of it is reinvested in growth.

This energetic perspective has deep roots in ecology. Raymond Lindeman’s classic 1942 paper on trophic dynamics introduced the idea that ecosystems can be understood as chains of energy transfer, with inefficiency at each link constraining the biomass that higher levels can support. Max Kleiber’s work on animal metabolism in the 1940s established quantitative relationships between body size and energy use that still underpin metabolic theory. The new analysis extends this energy-budget logic downward to the smallest and most consequential trophic level in terrestrial ecosystems: the heterotrophic microbial community that decomposes plant litter and, in doing so, decides whether organic carbon is respired to the atmosphere or stabilized in soil. When microbial demand for usable energy exceeds the supply of energetically favorable substrates, the community slows its growth, produces less residue biomass, and ultimately contributes less carbon to the stable soil pool regardless of how much raw carbon is present.

The technical heart of the argument lies in the distinction between carbon use efficiency and energy use efficiency. Carbon use efficiency, a metric that has dominated microbial ecology for the past decade, describes the fraction of assimilated carbon that microbes allocate to biomass production rather than to respiration. It has been widely used as a lever in Earth system models to tune how much plant carbon is retained in soils. Yet as the new analysis makes clear, carbon use efficiency treats all carbon atoms as equivalent, ignoring the fact that microbial metabolism is fundamentally governed by thermodynamics. Energy use efficiency, by contrast, tracks the fraction of harvested chemical energy converted into growth, and it varies with the redox state and molecular composition of the substrate. A community feeding on energy-dense reduced compounds can achieve high growth yields; a community stuck processing energy-poor oxidized substrates must respire more of its intake simply to break even, releasing carbon dioxide and leaving little biomass behind.

The global pattern reported by Wang and colleagues reveals that this energy bottleneck operates at continental to planetary scales. Energetically favorable substrates are unevenly distributed across biomes, shaped by climate, vegetation type, mineralogy and the long history of decomposition that any given soil has undergone. In ecosystems where easily metabolized, energy-rich inputs are scarce, microbial communities operate close to their thermodynamic limits, and additional carbon inputs fail to translate into additional carbon storage. This helps explain a stubborn puzzle in carbon cycle science: manipulative experiments that add litter or exudates to soils often produce far less persistent soil organic carbon than models predict. The carbon arrives, but the energy needed to transform it into microbial residues and organomineral associations does not, and the surplus is rapidly respired away.

The framework also revitalizes the microbial efficiency-matrix stabilization hypothesis advanced by Chao Liang, Joshua Schimel and Julie Jastrow in 2017, which proposed that microbial residues, not recalcitrant plant molecules, form the dominant precursor of stable soil organic carbon. If persistent soil carbon is built largely from microbial necromass, then anything that constrains microbial growth constrains carbon sequestration directly. Energy limitation is precisely such a constraint. Microbes facing an energy deficit produce less biomass, and the living and dead microbial tissues that would otherwise bind to mineral surfaces or aggregate into stable soil structures never accumulate. The energy bottleneck thus acts as a gatekeeper between the flood of plant carbon entering the soil and the much smaller stream of carbon that survives on decadal to millennial timescales.

For Earth system models, the implications are immediate and uncomfortable. Most land surface models still represent soil carbon as a set of carbon mass pools linked by first-order decay constants, with temperature and moisture modulating the rates. Such schemes are blind to substrate quality in energetic terms and to the thermodynamic cost of microbial metabolism. Incorporating microbial energy demand requires modelers to track the oxidation state of organic inputs, the efficiency with which microbial communities convert energy to biomass, and the feedbacks between community composition and substrate availability. Recent work by Lei He, Nicolas Viovy and Xiaofeng Xu has begun to embed microbial energetics in global biogeochemical schemes, and the new global analysis provides the empirical anchor those efforts have lacked. Models that ignore energy constraints may systematically overestimate how much carbon soils can sequester under elevated carbon dioxide or enhanced vegetation growth, a bias with direct consequences for climate projections and carbon accounting.

The findings also reshape the conversation around natural climate solutions. Regenerative agriculture, reforestation and soil carbon markets all rest on the assumption that increasing carbon inputs to soils will increase carbon storage. If microbial energy availability is the binding constraint, interventions must be evaluated not just by the tonnage of carbon they add but by the energetic quality of that carbon. Inputs rich in reduced, energy-dense compounds, or management practices that sustain microbial communities with adequate energy budgets, are more likely to yield durable storage than practices that deliver large fluxes of energy-poor material. Experimental evidence from individual studies, including work on microbial bioenergetics published in biotechnology journals, supports the idea that growth yields track the thermodynamic favorability of the substrate, giving the global synthesis a firm mechanistic footing.

As with any paradigm shift, open questions remain. Measuring energy use efficiency directly in field soils is difficult, because the free energy of complex organic matter mixtures is not easily determined and microbial communities are taxonomically and functionally diverse. The global analysis relies on proxies and synthesis across heterogeneous datasets, and its conclusions will need validation through targeted experiments that manipulate substrate energetics while tracking microbial growth, respiration and residue formation. Nevertheless, the message is clear and consequential: the amount of carbon entering a soil is only half the story. The other half is written in the language of thermodynamics, in the free energy that microbes can harvest to build the residues on which long-term carbon storage depends. Recognizing the energy bottleneck in soil carbon reframes one of the planet’s most important carbon reservoirs not as a passive vault waiting to be filled, but as an energetic economy in which the currency, not the raw material, sets the limits of accumulation.

Subject of Research: Microbial energy limitation as the primary control on soil organic carbon sequestration

Article Title: Energy bottleneck in soil carbon

Article References: Xu, X. (2026). Energy bottleneck in soil carbon. Nature Geoscience, 19(9), 1006-1007. https://doi.org/10.1038/s41561-026-02066-2

Image Credits: AI Generated

DOI: 10.1038/s41561-026-02066-2

Keywords: soil organic carbon, microbial energetics, carbon use efficiency, energy use efficiency, carbon sequestration, microbial residues, soil biogeochemistry, carbon cycle, thermodynamics, Earth system models, microbial ecology, climate change

The work focuses on two Annex I habitat groups: inland peat-forming wetlands (Group 7: “Raised bogs, mires and fens”) and coastal lagoons (habitat type 1150). By translating complex ecology into actionable monitoring concepts, the report is designed to inform condition assessments under the Habitats Directive, the Water Framework Directive, and the Nature Restoration Regulation.

Europe’s wetland story, however, is one of dramatic contraction. An estimated 80% of wetland area present a century ago no longer exists, and more than half of remaining peatlands have been drained. Despite their limited geographic footprint, peatlands store nearly one-third of global soil carbon, while coastal lagoons—covering roughly 13% of the global coastline—support disproportionately high biodiversity and biological productivity.

At the center of the report is a unifying conclusion: hydrology is the principal determinant of ecosystem condition. In peatlands, persistently high and stable water tables maintain anoxic conditions that suppress decomposition, enabling peat to accumulate. When drainage lowers the water table, peat oxidizes, subsides, and compacts, vegetation and microbial communities shift, and wildfire risk rises.

Crucially, structural changes to peat can be effectively irreversible. What begins as hydrological disruption can also flip a long-term carbon sink into a net source of greenhouse gases. Coastal lagoons face a different hydrological challenge: freshwater–marine exchange. There, circulation patterns, sediment transport, nutrient availability, and physico-chemical gradients shape community structure and productivity—often with strong natural variability unrelated to direct human pressure.

The report also emphasizes that degradation rarely comes from a single culprit. Drainage, land-use conversion, nutrient enrichment, peat extraction, contaminant inputs, coastal development, and climate change interact in reinforcing, sometimes non-linear ways. This pressure stacking can make ecological decline difficult to detect, attribute, and reverse.

To improve monitoring, the authors argue that no single indicator can capture ecosystem health. Instead, they propose tiered indicator frameworks separating essential from complementary variables across hydrological, physico-chemical, biological, and functional dimensions. Natural spatial and temporal variability—and ecological succession—must be explicitly accounted for, or monitoring may confuse intrinsic dynamics with human impact.

The report further calls for integrating Earth Observation with in-situ measurements. Remote sensing is best suited for hydrology and vegetation-linked metrics, but it must be field-calibrated and validated to maintain scientific reliability. Finally, it outlines a transition toward an integrated observation architecture combining Earth Observation, ground data, numerical modelling, and digital twin approaches.

This roadmap includes a dual monitoring strategy: standardized routine surveillance to capture heterogeneity and adaptive event-based monitoring for extremes and unexpected impacts. The authors frame the approach as a scientific foundation for a future EU Wetland Watch service, while identifying the next critical step—habitat-specific condition thresholds calibrated across Member States.

Subject of Research: Ecological characterisation of European peatlands and coastal lagoons for EU wetland assessment, monitoring, and restoration.
Article Title: Ecological characterisation of peatlands and coastal lagoons in Europe
News Publication Date: 2026
Web References: https://publications.jrc.ec.europa.eu/repository/handle/JRC146927
References: Cetinic, K.A., Pérez-Ruzafa, Á., Boix, D., Cravo-Laureau, C., Klimkowska, A., et al, Ecological characterisation of peatlands and coastal lagoons in Europe, Blasi, M., Korcheva, A., Vasilakopoulos, P. and Velasco Gomez, D.M. (editors), Publications Office of the European Union, Luxembourg, 2026, JRC146927.
Image Credits: Not provided.

Keywords: peatlands; coastal lagoons; hydrology; wetland loss; Habitats Directive; Water Framework Directive; Earth Observation; ecological indicators; biodiversity; carbon storage

The study opens with a revealing characterization of global riverine DOC concentrations, which exhibit an extraordinary three-orders-of-magnitude variability worldwide, averaging about 6.6 mg C per liter. Notably, rivers draining permafrost-influenced and densely forested catchments exhibit the highest DOC levels, attributable to abundant terrestrial organic matter and extensive soil carbon stocks. In stark contrast, glacially fed rivers register markedly low DOC concentrations due to minimal organic input. Model predictions generated by the research team elucidate that more than half of the river systems globally have DOC concentrations below 5 mg C per liter. Interestingly, DOC distributions demonstrate pronounced latitudinal patterns, with Arctic and boreal rivers exhibiting concentration peaks, whereas tropical rivers maintain lower baseline values. The extensive span of δ^13C-DOC isotopic values, ranging from –43.8‰ to –12.1‰, reflects a mosaic of source contributions and biogeochemical alteration processes across biomes. Tropical systems predominantly receive carbon from C3-type terrestrial vegetation, whereas temperate rivers show mixed sources including in situ primary production.

The incorporation of radiocarbon data (Δ^14C) dramatically expands the insight into the temporal dynamics of riverine DOC, unveiling a remarkable spectrum ranging from modern carbon to ancient material exceeding 29,000 years in radiocarbon age. The mean Δ^14C signature corresponds to a radiocarbon age of roughly 221 years, highlighting that the vast majority of riverine DOC is relatively young, with nearly 60% of carbon bearing an age younger than a century. Nevertheless, distinct pockets of aged carbon persist prominently in high-latitude and high-altitude ecosystems, driven by processes such as permafrost thaw and glacial melt which remobilize carbon repositories sequestered for millennia. These findings underscore the critical influence of climate-sensitive biogeophysical mechanisms in modulating the age composition of dissolved organic matter entering aquatic systems.

To disentangle the sources of riverine DOC, the authors employed a sophisticated four-endmember isotope mixing model. This analytical approach enabled quantification of the contributions from petrogenic fossil carbon, modern terrestrial organic matter, in-stream autochthonous production, and Holocene-aged sedimentary carbon. The results indicate that fossil carbon constitutes a relatively minor fraction globally, averaging 6.7%, but can locally surge to upwards of 40% in Arctic and alpine rivers, where ancient sedimentary rocks and carbon deposits are exposed. In contrast, modern terrestrial organic carbon and in-stream primary production dominate the global DOC pool, delivering approximately 38% and 44%, respectively. Holocene sediment-derived DOC also represents a noteworthy 10.7%, particularly in floodplains subjected to permafrost degradation and sediment reworking. This nuanced compositional framework reveals competing spatial controls dictating the prevalence of carbon from distinct sources, reflecting landscape-scale variability and biogeochemical cycling histories.

Climatic variables emerge as pivotal regulators of Δ^14C in riverine DOC, with temperature and precipitation patterns exerting primary control on soil carbon turnover and subsequent leaching into aquatic systems. Warm, wet conditions accelerate microbial respiration and organic matter decomposition in soils, fostering the export of younger carbon, whereas cold or dry environments slow these processes, promoting the release of older carbon stocks. Hydrological transport pathways further modulate DOC age by facilitating the movement of both recently fixed carbon near the surface and older carbon from subsoil horizons through complex surface and subsurface flow networks. The close alignment of riverine Δ^14C-DOC with surface soil organic carbon signatures suggests that DOC primarily originates from topsoil layers rather than depths below. These interactions eloquently articulate how integrated climatic and hydrological forcings orchestrate carbon age and fluxes from terrestrial reservoirs into river systems.

Human impacts superimpose additional complexity onto natural controls of riverine DOC. Reservoir creation alters flow regimes and nutrient dynamics, often stimulating algal blooms and enhancing contributions of modern, ^14C-enriched DOC derived from aquatic autotrophs. Meanwhile, agricultural practices and urban expansion can elevate soil disturbance, erosion, and fossil carbon mobilization, effectively increasing the export of older carbon fractions to rivers. These anthropogenic influences compound the sensitivity of carbon cycling dynamics to land-use changes, underscoring the need to incorporate human perturbations into predictive models of carbon fluxes and ecosystem responses.

Comparative analysis with particulate organic carbon (POC) further dissects carbon dynamics in rivers by highlighting that POC is generally older than DOC, reflecting differential transport mechanisms and transformation processes. While DOC is primarily composed of “young” carbon derived from surface soils and contemporary biological production, POC includes more refractory organic matter, often deriving from eroded soil and sediment sources. This decoupling of DOC and POC age structures emphasizes the heterogeneous nature of terrestrial carbon inputs into riverine environments and their distinct biogeochemical fates.

This study represents a crucial advancement in bridging knowledge gaps between terrestrial carbon storage, mobilization, and aquatic processing at a global scale. By elucidating the dominant role of soil carbon residence times in controlling riverine DOC age and provenance, the research establishes a mechanistic foundation for anticipating how ongoing and future climate change may reshape organic carbon cycling along the terrestrial–aquatic continuum. Such insights will be pivotal for refining Earth system models and informing strategies aimed at mitigating greenhouse gas emissions and managing the carbon balance across critical ecosystems.

The collaborative endeavor underpinning this research harnessed expertise from multiple institutions worldwide, demonstrating the power of international cooperation in addressing major environmental challenges. Co-first authors Zhaohui Liu and Professor Gerard Rocher-Ros contributed significantly to data synthesis and model development, while senior co-authors including Professors Joshua F. Dean, Jack J. Middelburg, and Pierre Regnier provided critical interpretation and contextualization within broader biogeochemical frameworks. The study benefited from funding support by the National Natural Science Foundation of China and the Chinese Academy of Sciences, ensuring the integration of cutting-edge analytical methodologies and comprehensive environmental datasets.

Ultimately, this pioneering global atlas of riverine DOC isotopic characteristics not only refines our fundamental understanding of carbon biogeochemistry but also serves as an invaluable resource for scientists and policymakers seeking to address the complex feedback loops between the biosphere, hydrosphere, and atmosphere. By revealing how terrestrial processes govern the age spectra of organic carbon exported to rivers, the study signals new directions for research into ecosystem resilience, carbon sequestration potential, and the impacts of anthropogenic change on freshwater carbon fluxes worldwide.

Subject of Research: Riverine dissolved organic carbon (DOC) concentration, isotopic characterization, and controls on carbon age and cycling in global rivers.

Article Title: Soil carbon residence time regulates the age of dissolved organic matter in global rivers

Web References:
DOI: 10.1093/nsr/nwag237

Image Credits: ©Science China Press

Keywords: riverine dissolved organic carbon, DOC, radiocarbon dating, Δ^14C, δ^13C, soil carbon residence time, river carbon cycling, permafrost carbon, biogeochemistry, carbon isotopes, terrestrial-aquatic carbon flux, global carbon cycle

Ectomycorrhizal fungi form symbiotic associations with roughly a quarter of all terrestrial vegetation worldwide, a partnership that fuels critical biochemical cycles. Their underground hyphal networks not only ferry essential nutrients like nitrogen and phosphorus to plants but also sequester vast amounts of carbon by transporting it into deep soil layers. Estimates suggest these fungi are responsible for the annual drawdown of more than nine billion tons of atmospheric CO₂, equating to over 25% of global fossil fuel emissions—a staggering ecosystem service that underscores their climate relevance. Despite this, our catalog of described fungal species remains woefully incomplete. Current estimates indicate only about 155,000 fungal species have been formally described, a fraction of the 2 to 3 million species believed to inhabit the Earth.

The primary obstacle to understanding this subterranean biodiversity lies in the prevalence of “dark taxa,” fungal groups identifiable only through sequences of environmental DNA (eDNA) extracted from soil and root samples. Modern sequencing technologies allow scientists to detect these DNA fragments shed by organisms into their surroundings, but the process of linking DNA sequences to known species depends on existing reference databases. Unfortunately, the majority of fungal eDNA sequences lack corresponding, named species in these databases. As a result, researchers encounter strings of nucleotides—As, Ts, Cs, and Gs—that betray an organism’s existence but provide no avenue for classical taxonomic classification.

Lead author Laura van Galen, a microbial ecologist associated with the Society for the Protection of Underground Networks (SPUN) and ETH University in Switzerland, captures the dilemma succinctly: “Environmental DNA has enormous potential as a research tool to detect fungal species, but we can’t include unnamed species in conservation initiatives. How can you protect something that hasn’t yet been named?” This paradox illuminates a critical gap in biodiversity protection—undocumented species that underpin fundamental ecosystem processes remain invisible to policymakers and conservation frameworks predicated on formal taxonomic recognition.

The biogeography of these dark taxa is equally revealing. The review identifies discrete global hotspots where unknown ectomycorrhizal species cluster, specifically tropical forests in Southeast Asia, Central and South America, as well as tropical shrublands in central Africa. Additional hotspots include the montane conifer forests of the Sayan Mountains above Mongolia and other understudied mid-latitude and southern-hemisphere regions. These findings disrupt the traditional ecological paradigm that has disproportionately focused on temperate northern ecosystems. There is an urgent need to redistribute scientific resources and funding to these biodiverse, yet neglected, regions where fungal diversity—and thus ecosystem resilience—may be most vulnerable.

The ramifications for conservation are profound. Many of the plants dependent on ectomycorrhizal fungi are themselves categorized as endangered, a sobering reminder of the interconnectedness of life. The potential loss of host plants inevitably jeopardizes their fungal partners, many of which are essential to soil health, nutrient cycling, and carbon sequestration. Van Galen warns, “If we lose these host plants, we might also be losing really important fungal communities that we don’t know anything about yet.” This cascade effect underscores the intrinsic value of fungi in maintaining biodiversity and ecosystem services.

Addressing this invisible fungal frontier requires innovative approaches. The researchers advocate for increased collection, morphological study, and genomic sequencing of mushrooms and fungal specimens. Co-author Camille Truong of SPUN and the Royal Botanic Gardens Victoria highlights a low-hanging fruit: “There are mushrooms that have been sitting for decades in collections of botanical gardens. These should be urgently sequenced so that we can, hopefully, start matching them up with some of these dark taxa.” This strategy offers a rapid, cost-effective pathway to expand fungal reference databases that can transform unidentified eDNA into named entities, a cornerstone for integrating fungi into conservation policies.

The technological tools underpinning this effort are mature and accessible. High-throughput DNA sequencing, advanced bioinformatics pipelines, and global data-sharing platforms provide an unprecedented capacity to profile soil fungal communities in situ. Yet, despite these advancements, fungi remain conspicuously overlooked in global conservation and climate agendas. The call to action is clear: elevate fungal biodiversity to the same level of importance as plants and animals in ecological research, environmental monitoring, and policy making.

SPUN’s mission exemplifies this paradigm shift. The non-profit scientific organization aims to map and safeguard Earth’s fungal networks in collaboration with local researchers and communities, focusing especially on regions harboring high concentrations of undocumented fungi. Through these partnerships, SPUN seeks to fill critical knowledge gaps and advocate for the inclusion of fungi in climate and conservation strategies worldwide. Their work highlights the ecological significance of subterranean biodiversity and the urgent need to protect these cryptic yet essential life forms.

In synthesizing this review’s insights, it becomes evident that naming and documenting fungal species is not merely a taxonomic exercise; it is foundational to preserving ecosystem functions that sustain human and planetary health. Without clear identification and understanding, conservation efforts risk overlooking key organisms that stabilize soils, promote plant growth, and mitigate climate change through carbon sequestration. The invisibility of dark taxa thus represents both a scientific frontier and a critical conservation blind spot demanding immediate attention.

The discovery of global hotspots teeming with undescribed ectomycorrhizal fungi also reframes our understanding of biodiversity patterns. Tropical forests and understudied montane regions emerge as reservoirs of fungal diversity that could harbor novel species, metabolic pathways, and ecological interactions. Unveiling these hidden communities could yield breakthroughs not only in ecology but also in biotechnology, medicine, and agriculture.

As the scientific community advances toward a more comprehensive catalog of Earth’s fungi, the review underscores a vital principle: conservation is necessarily tied to knowledge. Protecting fungi without their formal recognition is practically and legally challenging; thus, expanding the fungal species’ registry becomes an ethical imperative. Bridging the knowledge gap will require cross-disciplinary collaboration, enhanced funding, and inclusive capacity-building among scientists in the Global South, where fungal diversity is richest but research infrastructure often lags.

In conclusion, the review published in Current Biology charts a new trajectory for mycology and conservation science. It reveals that a vast majority of Earth’s ectomycorrhizal fungi remain hidden in the shadows of taxonomy, detected only through environmental DNA signatures without formal names or descriptions. This “dark taxa” phenomenon not only complicates biodiversity assessments but threatens to exclude fungi from much-needed conservation policies despite their ecological indispensability. Bringing these organisms into the light through strategic sequencing, taxonomy, and global collaboration is essential for safeguarding Earth’s climate, biodiversity, and the health of ecosystems that humanity depends upon.

Subject of Research: Not applicable

Article Title: The biogeography and conservation of Earth’s ‘dark’ ectomycorrhizal fungi

News Publication Date: 9-Jun-2025

Web References:
https://spun.earth/
http://dx.doi.org/10.1016/j.cub.2025.03.079

Image Credits: Adriana Corrales/SPUN

Keywords:
Mycorrhizal fungi, Mycology, Ecology, Applied ecology, Biodiversity, Conservation ecology