The Zagros is Iran’s largest mountain range, stretching from the northwest to the south of the country with many peaks exceeding 3,500 meters above sea level. It lies within the Irano-Turanian phytogeographic region and has been recognized as an area of endemism inside the Irano-Anatolian global biodiversity hotspot, a designation reserved for regions with high numbers of endemic species and heavy impacts from human activity. Although alpine ecosystems cover only about 1 percent of Iran’s land surface, they harbor 4 percent of the country’s non-endemic flora and 7 percent of its endemic flora. Many mountains within the Zagros remain poorly explored because of their vast extent and inaccessibility, and the high-elevation flora of Fereydunshahr had never been systematically documented before this study.

The study area encompasses several significant peaks, including Mount Zardigari at 3,700 meters in the northwest, Mount Didtseri at 3,620 meters in the north, Mount Tatara at 3,520 meters in the south, Mount Tsikhe at 3,320 meters in the west, and Mount Kalabis kobi at 3,000 meters in the northeast. The region’s geomorphology is shaped by the Zagros Fault, which divides the area into the Elevated Zagros to the west and the Sanandaj-Sirjan zone to the east. Diverse limestone formations and soils consisting mainly of Inceptisols and Entisols create a mosaic of microclimates that support distinct vegetation types and ecological zones. The climate is Mediterranean in regime, with cold, wet winters and dry, warm summers; the mean annual temperature is 11.65 degrees Celsius and annual precipitation totals 540 millimeters.

Fieldwork was carried out during the growing season from April to September across three years, with sampling conducted randomly from mountain slopes to summits within an elevation range of 2,500 to 3,700 meters. Each of the more than 1,000 collected specimens was tagged with detailed location, elevation, and habitat information, then identified using Flora Iranica and Flora of Iran and deposited in the Herbarium of the University of Isfahan. The researchers assigned species to major vegetation types, elevation zones, and chorotypes based on field observations, literature studies, and the reference floras. Life forms were classified using Raunkiaer’s system, which groups plants into chamaephytes, geophytes, hemicryptophytes, phanerophytes, and therophytes according to where their buds sit relative to the ground surface.

The largest plant families recorded were Asteraceae with 44 species, Fabaceae with 32, Brassicaceae with 29, Lamiaceae with 27, Apiaceae with 20, and Poaceae with 18, an ordering similar to the entire flora of the Zagros range. At the genus level, Astragalus was by far the richest with 23 species, followed by Allium with seven, Scorzonera with six, and Nepeta and Stachys with five each. Astragalus is the biggest genus in Iran with approximately 885 species, roughly 589 of them endemic, and it dominates the study area with 14 species endemic to Iran and six to the Zagros. Interestingly, Cousinia, the second biggest genus of Iran with about 300 species and roughly 80 percent endemism, was represented by only four species in the study area, a pattern the authors attribute to the genus being poorly represented in the alpine zone of Iran overall.

Life form analysis revealed that hemicryptophytes, plants whose buds lie at or just below the ground surface, dominate the flora at 53 percent of species. This is consistent with alpine habitats worldwide, where hemicryptophytes succeed because their protected buds shield them from frost and desiccation while their low-growing structures reduce wind exposure and retain heat. Therophytes, the annual plants that complete their life cycle within a single growing season, accounted for 49 species, but only three of these are specifically subalpine or alpine; the rest belong to lower elevation zones. The short growing season at high elevations makes this strategy largely untenable there, and therophytes comprise only about 2.5 percent of Iran’s alpine flora. Geophytes made up 7 percent of the subalpine and alpine species, in line with the 6 percent recorded for Iran’s alpine flora, while phanerophytes, mainly shrubs of the genera Amygdalus, Cerasus, Cotoneaster, Rosa, and Daphne, were concentrated in the montane zone. Juniperus excelsa, which forms treeline woodlands in parts of the Alborz and Zagros, has become very scarce in the study area, most likely due to human activities.

Chorological analysis showed that 52 percent of the identified species are Irano-Turanian elements, with the remainder belonging to combinations of the Irano-Turanian, Euro-Siberian, Mediterranean, and Saharo-Sindian regions. Notably, the floristic affinity with the Euro-Siberian region proved stronger than with the Mediterranean region, the reverse of the pattern for the entire Zagros flora. The authors suggest this reflects the study area’s high elevation, since higher precipitation and lower temperatures at altitude favor Euro-Siberian affinities, and the fact that the Alborz and Zagros have historically acted as migration corridors between Central Asia and the European mountains. Affinity with the dry Saharo-Sindian region was very poor, as expected given the region’s arid climate. Approximately 19 percent of the identified species are endemic to Iran and 7 percent are endemic to the Zagros, and previous work has ranked the mountains of Fereydunshahr among the top 10 percent richest endemic hotspots on the Iranian Plateau.

Species distribution across elevation zones followed a pattern seen in mountains worldwide, with richness declining as elevation increases, driven by reductions in both surface area and temperature. A third of the species occupy both montane and subalpine zones, 20 percent are subalpine, and only 9 percent are true alpine species, reflecting the small extent of genuine alpine habitat below the 3,700-meter summit. Yet the endemism rate climbs steeply with altitude: 57 percent of the alpine species are endemic to Iran, compared with 38 percent in the subalpine zone and just 20 percent in the montane zone. This trend matches global studies showing that endemism increases along elevation gradients, a phenomenon attributed to increasing isolation that raises allopatric speciation rates. The high-elevation flora thus represents the region’s most irreplaceable biological heritage.

Vegetation type analysis placed 24 percent of species in subalpine and alpine thorn-cushion grasslands, the vegetation type with the greatest gamma diversity in the study area. These communities, dominated in the subalpine zone by Acantholimon hohenackeri, Astragalus brachycalyx, and Bromus tomentellus and above 3,500 meters by Astragalus murinus, A. raswendicus, and Cousinia multiloba, thrive on windswept slopes where snow cover is brief and the growing season correspondingly long. Cushion plants function as foundation species: their tightly packed apical meristems and dense layers of stems and dead leaves buffer environmental extremes, creating micro-refugia that facilitate less stress-tolerant species and boost the alpha, gamma, and phylogenetic diversity of their communities. Montane steppe shrublands, characterized by Astragalus microcephalus and shrubs of Amygdalus, Cotoneaster, and Cerasus, contained 19 percent of species. The tall-umbelliferous vegetation of steep scree slopes, dominated by Apiaceae such as Prangos ferulacea and Ferulago angulata, held only 5 percent of species but a striking 56 percent endemism rate, followed by chasmophytic rock-dwelling vegetation with 43 percent endemism, consistent with global patterns of high endemicity in scree and cliff habitats.

The study concludes that the region’s rich flora faces severe pressure from anthropogenic activities, above all overgrazing. Paleobotanical evidence shows the Zagros vegetation has been shaped by human activity for five millennia, and genetic studies indicate goats were domesticated in the Zagros roughly 10,000 years ago. Today, the abundance of poisonous and thorny overgrazing indicators such as Euphorbia, Cirsium, and Cousinia in the Fereydunshahr highlands signals heavy livestock pressure, which drives soil erosion and community degradation. Illegal harvesting of rare plants, agricultural expansion, and infrastructure projects including roads, dams, and mines further fragment habitats, while climate change threatens to shift vegetation zones across all alpine ecosystems. Because no protected area currently exists in this recognized center of endemism, the researchers strongly recommend establishing one, alongside strict land-use regulation and community engagement, to preserve the unique ecological value of these mountains before their endemic flora is lost.

Subject of Research: Vascular plant diversity, life forms, chorology, and vegetation types of the subalpine and alpine zones of the Fereydunshahr mountains, Central Zagros, Iran

Article Title: Vascular plant diversity of the high mountains of Fereydunshahr, Central Zagros, Iran

Article References: Yaselyani, M., Bagheri, A., Saeidi, H., & Noroozi, J. (2024). Vascular plant diversity of the high mountains of Fereydunshahr, Central Zagros, Iran. Vegetation Classification and Survey, 5, 329-346. https://doi.org/10.3897/vcs.110546

Image Credits: AI Generated

DOI: 10.3897/VCS.110546

Keywords: plant biodiversity, Zagros mountains, endemism, alpine flora, Iran, conservation, Astragalus, overgrazing, Vascular, plant, diversity, high

The research team, publishing in the journal Caucasiana, examined plant community structure along an elevation gradient spanning 1,884 to 2,685 metres above sea level, covering montane, subalpine, and alpine vegetation zones. They compared 36 ski piste plots — 18 on standard tracks and 18 on eroded sections crossed by maintenance roads — with 25 adjacent undisturbed control plots. In total, 211 plant species were recorded across the 62 sampled plots, with 103 species occurring in at least five plots retained for multivariate analysis. The study area has a long and layered history of human use: alpine skiing has been practised on this mountain since 1932, and before that the terrain served as summer pasture, a grazing tradition that continues today with cattle and sheep transferred to the mountain from late May until September.

The statistical architecture of the study was rigorous. Principal Component Analysis (PCA) in between-group mode revealed that the first component, explaining 66.91% of total variation, was strongly associated with bare soil surface (negatively) and with soil depth, species richness, and aboveground biomass (positively). In other words, the dominant axis of variation in the data was not elevation or slope — the natural environmental variables that dominated the second component — but a gradient of human impact intensity. A subsequent Canonical Correspondence Analysis (CCA), using the PCA components as composite environmental variables and based on Bray–Curtis dissimilarity, confirmed that species distributions closely tracked this impact gradient. Both CCA axes were highly significant (p < 0.001, 999 permutations), with the first axis accounting for 68.62% of constrained variation and clearly separating control plots from disturbed ones.

Hierarchical cluster analysis, using Jaccard distances and Ward’s minimum-variance linkage, identified four floristically distinct groups whose membership was significantly associated with plot category (χ² = 21.10, simulated p = 0.0005). The first cluster was dominated by control plots, representing undisturbed habitats; the second contained predominantly eroded and track plots, reflecting moderate-to-high disturbance; the third was compositionally heterogeneous, corresponding to transitional communities at higher elevations where harsh abiotic conditions exert a strong compositional filter; and the fourth was small and predominantly control-associated. Together, the clusters confirmed that disturbance is a primary determinant of compositional differentiation, with natural environmental variation playing a secondary role, particularly at extreme elevations where control and track plots showed greater similarity — possibly because extensive artificial snowmaking at lower elevations shortens the growing season and reduces diversity there.

Indicator Species Analysis (ISA), performed with the IndVal.g association measure and 999 permutations, revealed clear floristic signatures for each condition. Undisturbed control plots were characterised by typical alpine meadow species: Gentiana septemfida (IndVal 0.683), Bromus variegatus (0.670), Veratrum lobelianum (0.636), Bistorta carnea (0.628), and Silene saxatilis (0.585). Eroded plots were associated with disturbance-tolerant taxa — Draba hispida (0.451) and Arctium lappa (0.427) — while track plots were most strongly characterised by Calamagrostis pseudophragmites (0.430), a compaction-tolerant grass that thrives in compressed soils and along drainage channels. Notably, two species — Rhinanthus major var. apterus (0.722) and Anthoxanthum odoratum (0.690) — were shared indicators of control and track plots, suggesting that moderate piste disturbance does not eliminate all meadow-adapted species. Rhinanthus, a summer annual, is less affected by winter mechanical stress, and the vegetation gaps created by disturbance may actually facilitate its seed germination.

The biomass data were equally dramatic. Mean aboveground biomass on control plots reached 2,526 kg per hectare — 2.1 to 3.0 times higher than on track plots (1,175 kg ha⁻¹) and eroded plots (833 kg ha⁻¹). Vegetation cover on control plots averaged 85%, with maximum herbaceous height of 68 cm, compared with just 45% cover and 44 cm maximum height on piste plots, where minimum cover occasionally dropped as low as 15%. A further PCA of functional-group biomasses showed that the first component (74.1% of variation) was positively associated with soil depth and the biomasses of all three functional groups, especially graminoids, indicating that deeper soils sustain higher productivity. Graminoid biomass on control plots was 2.5 times higher than on track plots and 3.5 times higher than on eroded plots; forb biomass was three times higher than on track and four times higher than on eroded plots.

Perhaps the most intriguing finding concerns legumes. Unlike graminoids and forbs, which declined sharply under disturbance (both differing significantly among land-use types, p < 0.001), legume biomass was statistically indistinguishable among land-use types (p = 0.515) and increased strongly over time across all categories (p < 0.001). The researchers attribute this resilience to nitrogen fixation, which gives legumes a competitive advantage in the nutrient-poor soils characteristic of high-altitude environments. Nitrogen limitation is a prominent feature of such soils, and legumes are frequently among the first colonisers of degraded alpine substrates. The elevated legume biomass on piste plots could also partly reflect deliberate sowing during restoration, as practised in some European ski areas. This contrasts with findings from the Pyrenees, where very intense mechanical disturbance reduced even legume cover — suggesting that the degree of impact, soil phosphorus levels, and mechanical disturbance are interdependent limiting factors.

Temporal monitoring from 2020 to 2023 painted a sobering picture of recovery capacity. Control plots showed stable or increasing biomass, with forb biomass increasing significantly between 2020 and 2021 (p = 0.0019), likely reflecting natural inter-annual variation. Eroded plots showed no significant temporal changes at all (p > 0.3), indicating persistent environmental stress and essentially no recovery. Track plots exhibited a modest increase in graminoid biomass between 2020 and 2021 (p = 0.044) that did not persist into 2023 — brief episodes of partial recovery that were insufficient for sustained restoration. Linear mixed-effects models, with year and land-use type as fixed effects and plot as a random effect, confirmed these patterns. The absence of any significant change on eroded plots over the study period points to ongoing environmental stress, and the short-lived graminoid increase on track plots suggests that recovery trajectories, where they occur at all, are multi-year processes consistent with experimental restoration studies in the Alps.

The context makes these findings urgent. Tourism is central to Georgia’s economy: in 2025 the country received over 5.5 million international visitors, nearly twice its resident population, and mountain and ski resorts recorded a 340% increase in visitor numbers between 2010 and 2017. The National Tourism Strategic Plan explicitly provides for the expansion of ski piste infrastructure. Bakuriani, among the most visited ski resorts in Georgia, hosted the freestyle ski and snowboarding world championships in 2023, events that further intensify impacts on piste vegetation. The resort sits within the Borjomi Municipality, adjacent to the Borjomi-Kharagauli National Park — one of the most extensively protected regions in the Caucasus — and is recognised as one of the most thoroughly documented floristic localities in the country. Yet no study had previously assessed the condition of vegetation on its pistes, nor on any piste in the South Caucasus.

The study’s authors recommend that future piste development minimise soil disturbance, prioritise ecological restoration of eroded sections using locally sourced seed mixtures, and incorporate long-term vegetation monitoring as a standard component of ski resort management. They also note limitations: control plots were situated 50–100 metres from the piste boundary, so indirect effects extending beyond that distance cannot be completely excluded, and the relatively short monitoring period limits the ability to distinguish persistent recovery trends from interannual climatic variability. Grazing, which occurs on and adjacent to the pistes throughout summer, likely interacts synergistically with skiing impacts — piste vegetation already weakened by soil compaction and erosion is particularly vulnerable to herbivory and trampling. The semi-natural grasslands of the Caucasus have been shaped by thousands of years of pastoral management, support exceptional plant diversity, and form a distinctive element of the mountain landscape. Reconciling the economic importance of ski tourism with the conservation of this unique heritage, the researchers conclude, requires careful ecological assessment and adaptive management — measures essential for protecting the Caucasus mountain biodiversity that draws visitors to these slopes in the first place.

Subject of Research: Ecological impacts of ski piste construction and maintenance on mountain grassland vegetation in the Lesser Caucasus, Georgia

Article Title: Vegetation of Ski Pistes in the Lesser Caucasus (Bakuriani, Georgia): Species Composition, Functional Traits, and Temporal Dynamics

Article References: Tedoradze, G., Bakhia, A., Jugeli, T., Khuskivadze, D., Megvinetukhutsesi, N., Mikeladze, G., Rasran, L., Sikharulidze, S., & Kikvidze, Z. (2026). Vegetation of Ski Pistes in the Lesser Caucasus (Bakuriani, Georgia): Species Composition, Functional Traits, and Temporal Dynamics. Caucasiana, 5, 147-166. https://doi.org/10.3897/caucasiana.5.e207119

Image Credits: AI Generated

DOI: 10.3897/caucasiana.5.e207119

Keywords: ski tourism, Lesser Caucasus, Bakuriani, plant biodiversity, biomass, restoration ecology, Vegetation, Pistes, Lesser, Caucasus, Georgia, Species

The research, led by former UC Santa Barbara postdoctoral researcher Courtney Reed, now at Princeton University, and published in the Proceedings of the National Academy of Sciences, combined measurements of soil chemistry, microbial communities, plant biodiversity and herbivore activity at elephant carcass sites. Senior author Deron Burkepile, a professor of ecology, evolution and marine biology at UC Santa Barbara, and senior author Dave Thompson, a biodiversity scientist at the South African Environmental Observation Network, guided the project as it grew from an opportunistic observation into one of the most holistic studies of terrestrial mega-carcasses conducted to date. The findings reveal a decomposition cascade that simultaneously energizes an ecosystem and reduces its diversity, an unusual combination that challenges assumptions about how large animal remains influence land-based food webs.

The project traces its origins to 2009, when one of Kruger National Park’s great tuskers, a large lone bull elephant named Alexander, died of natural causes near a main road. Thompson, who frequently traveled that route for another project, watched the carcass decompose over the course of a few months and became curious about what it was doing to the ground below. He shared his observations with Burkepile, and the two began developing hypotheses about effects on soil, knock-on consequences across the food web and how those effects might change over time. Early explorations quickly showed how dynamic carcass sites could be, and the pair soon enlisted Kruger’s rangers to help locate sites and applied for grants to study the phenomenon in earnest.

The immediate physical impact of an elephant’s death is dramatic. According to Reed, the carcass initially wipes out all the biomass at its center, leaving a large bare patch. The animal’s immense bulk flattens vegetation, and the traffic of scavengers scrapes the surrounding ground clean. Burkepile describes the effect as a reset of the plant community to zero. Co-author Izak Smit, a senior scientist at South African National Parks, admitted that his intuition had been the opposite of what the data showed. Because the carcass is physically present for only a relatively short period, he expected its ecological effect to be muted and transient. When the laboratory results came back, a very different picture emerged.

That picture centers on an extraordinary pulse of nutrients. Decomposing elephant remains percolate nitrogen and other compounds into the soil, altering soil chemistry and restructuring the microbial community. Reed had suspected nutrient levels would be elevated beneath a carcass, but the magnitude astonished her. At very fresh carcass sites, soil nitrogen concentrations can reach up to 3,000 times higher than surrounding levels, a figure she described as simply insane. Co-author Tercia Midzi, a senior manager in scientific services at Kruger National Park, remarked that that amount of ammonium was not on her bingo card. Counterintuitively, the initial spike does not stimulate regrowth. Rather than acting like spilled fertilizer, the influx of compounds such as ammonium creates nutrient toxicity that prevents plants from growing back at first.

Below ground, the nutrient flood transforms microbial life. Burkepile describes the microbes at an elephant carcass as sprinting, with their metabolism cranking. Activity rises sharply, but diversity falls, likely because a small number of fast-growing species come to dominate the site. Once the soil chemistry mellows somewhat, the plant community follows a similar trajectory. The researchers observed biodiversity coldspots dominated by just a handful of fast-growing species, a pattern that persisted for at least eight years after an elephant’s death. The same cascade that fuels microbial and plant vigor therefore actively suppresses the variety of life at the site, an outcome the team did not anticipate when the work began.

Above ground, however, the story is one of attraction rather than avoidance. Grasses colonizing carcass sites are exceptionally nutritious, based on the team’s assays of grass leaves. Burkepile compares the transformation to turning grasses from watery iceberg lettuce into juicy romaine. Those plants probably grow faster, but herbivores mow them down eagerly because they want access to the nutrient-rich forage. Grazers continued to revisit carcass sites for years after death, and their manure further enriched the soil, creating a feedback loop that keeps nutrient levels elevated. To disentangle grazing from intrinsic regrowth, the team installed fenced exclosures that keep herbivores out of some carcass sites, and they hope to publish the results of that experiment within the coming year.

Burkepile believes savannas may occupy a Goldilocks zone in which carcasses exert particularly strong influence. In more dynamic ecosystems such as forests or wetlands, heavy rainfall may leach nutrients out of the topsoil and wash them away, shortening the effect. Deserts, by contrast, may be too water-limited for microbes and plants to exploit the nutrients a carcass provides. The team is seeking collaborators across sub-Saharan Africa to test these hypotheses and intends to keep surveying Kruger’s carcass sites to build a longitudinal time series. They also plan to examine how extreme weather shapes these processes. Kruger experienced exceptionally high rainfall in the past year, and the 2026–27 El Niño is expected to dry the region considerably. Floods and drought can each redirect where nutrients end up, whether percolating into the ground, washing away or preventing growth altogether.

The researchers draw a natural comparison to whale falls, the sunken remains of giant whales that trigger explosions of activity and productivity on the seafloor. Burkepile initially expected elephant carcasses to operate similarly, creating unique islands of ecosystem processes and biodiversity. But the abyssal plain is not the savanna. The deep sea is essentially a food desert, so nutrient-poor and energy-poor that whale carcasses attract organisms from far and wide. Kruger, by contrast, is reasonably fertile, so the nutrient dump from an elephant creates a hotspot so intense that it suppresses microbial and plant diversity rather than enhancing it. Speed differs too. While parts of a whale carcass can persist for decades, even a huge animal like an elephant can lose its meat and bones within a couple of weeks under the African sun. Whale falls have been studied since the late 1970s, but research on terrestrial mega-carcasses is young, with most studies published in the past five years and none previously examining the impacts as comprehensively.

The endurance of the signal surprised the team most. Even around eight years after death, the signature remained detectable in soil and vegetation, and herbivores still preferentially visited those areas. Grazing intensity and nitrogen levels in grasses showed no decline at the oldest sites the researchers surveyed, and the reduced microbial and plant diversity had not rebounded. Smit called it a powerful reminder that what we see in nature is often shaped by legacies from the past, even when their causes have long since disappeared from view. The implications extend deep into history. Elephants and their relatives ranged across most continents until a few millennia ago, living and dying alongside other megafauna. This study shows that what has been lost is not only the influence of living giants but also their posthumous effects. As Smit notes, researchers can only speculate about ecosystems where these mega-herbivores are now missing, but the Kruger findings make those questions far more pressing. What began as two curious scientists with clipboards has become an interdisciplinary effort spanning microbes, soils, plants, herbivores, predators and whole ecosystems, supported by rangers who record elephant mortalities and even creative collaborators producing a documentary, ensuring that the hidden legacy of dead elephants reaches both science and the public.

Subject of Research: Ecological legacy effects of elephant carcasses on savanna soil chemistry, microbial and plant communities, and herbivore grazing in Kruger National Park

Article Title: Elephants continue to shape the savanna even after death

Article References: Elephants continue to shape the savanna even after death. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: elephants, savanna ecology, nutrient hotspots, carcass decomposition, soil microbiome, Kruger National Park, plant biodiversity, herbivore grazing, whale falls, megafauna, nitrogen cycling, PNAS

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