Hydrochory, the dispersal of propagules by water, is widely recognized as a major engine of plant invasions in riparian landscapes. Rivers act as highways for seeds, carrying them downstream and depositing them on bars, benches, and floodplains where recurrent disturbance and abundant resources create ideal conditions for germination. For invasive species, this secondary transport can extend dispersal distances far beyond what wind, gravity, or animals could achieve alone, linking distant populations and enabling rapid range expansion. Yet the precise seed traits that determine how long a diaspore stays afloat, and how those traits interact, have remained poorly understood for many invaders.

Echinocystis lobata offered researchers an ideal model to probe these questions. The vigorous annual climber, a member of the cucumber family whose name derives from the Greek words for hedgehog and bladder in reference to its spiny, inflated fruits, was introduced to Europe in the late nineteenth and early twentieth centuries as an ornamental plant. It soon escaped cultivation and spread rapidly, reaching from Central Europe to the Russian Pacific coast. In Poland, where the new study was conducted, the vine now forms dense, monospecific stands along riverbanks and wetlands, particularly in the valleys of the Bug and Liwiec rivers, where regular spring flooding shapes the landscape.

What makes the species especially intriguing is its production of two functionally distinct seed types. As the fruits dry, the outer capsule ruptures and most seeds are released freely; researchers call these normal seeds. But roughly one third of fruits contain trapped seeds, held within the fibrous internal framework of the capsule and released only after the fruit decomposes or is broken apart by wind, ice, or animals. Previous work had shown that trapped seeds are less accessible to seed-eating rodents and that the buoyant, fibrous fruits themselves can float downstream before releasing their cargo. Whether trapped seeds differ from normal seeds in their own flotation capacity, however, was unknown.

To find out, the team collected mature fruits from six populations along the Bug and Liwiec rivers between October and December 2024, gathering equal numbers of fruits with trapped and normal seeds at each site. In total, 681 normal seeds and 681 trapped seeds were measured for length, width, thickness, and fresh mass, with surface area calculated from the ellipse formula. The buoyancy experiment, conducted outdoors between February and March 2025 to coincide with the natural flooding season, placed each seed individually in a container of unfiltered river water at temperatures between 1 and 7 degrees Celsius. Containers were gently shaken once a day to simulate turbulence, and floating seeds were counted every 24 hours over a 14-day period.

The results revealed a complex, non-linear picture. Trapped seeds were generally smaller and lighter than normal ones, averaging 0.28 grams against 0.32 grams, and slightly more spherical in shape. They also sank faster: no trapped seed remained afloat beyond 11 days, while some normal seeds stayed buoyant for the full 14 days. Yet the proportions of floaters were modest in both groups, with 17.8 percent of trapped seeds and 12.3 percent of normal seeds floating initially, and only a small fraction lasting beyond the first day. A generalized linear mixed-effects model, which explained 43 percent of the variance in sinking probability, showed that buoyancy was governed not by any single trait but by interactions among mass, thickness, surface area, and trapping status.

Some of these interactions defied simple physical intuition. Among thin normal seeds, those measuring 0.30 centimeters or less in thickness, heavier seeds actually floated better: the predicted probability of sinking fell from 75 percent at a mass of 0.12 grams to just 5 percent at 0.52 grams. The researchers suggest that added mass may stabilize a thin seed’s orientation on the water surface, allowing it to exploit surface tension more effectively. Thick seeds, by contrast, sank regardless of mass, likely because their reduced surface-to-volume ratio undermines buoyant potential. This contradicts the common expectation that greater mass always accelerates sinking by increasing density, and it echoes earlier findings in other riparian invaders, such as Himalayan balsam, where seed-coat structures can offset mass-related sinking.

The most dramatic divergence between seed types emerged in the relationship between mass and sinking. In trapped seeds, heavier individuals sank more readily, with sinking probability climbing from 1 percent at 0.06 grams to 57 percent at 0.52 grams. In normal seeds the pattern ran in the opposite direction, with sinking probability falling from 82 percent at the lightest masses to zero at the heaviest. Surface area mattered too, but only in combination with other traits: larger trapped seeds sank more often, presumably because they absorb water faster and gain density, while surface area had little independent effect on normal seeds. The study site itself contributed only modestly to the observed variation, indicating that these patterns reflect seed biology rather than local population differences.

The authors interpret this functional divergence as a diversified dispersal strategy that serves the vine on two fronts. Normal seeds, with their flatter shape and superior flotation, are suited to long-distance hydrochorous transport, potentially drifting dozens of kilometers during floods, consistent with reports that alien diaspores on other rivers have drifted more than 150 kilometers under favorable flows. Trapped seeds, meanwhile, benefit from delayed release: even when their individual buoyancy is poor, the fibrous fruits that enclose them are buoyant and can carry seeds downstream before gradual liberation. This combination of immediate and delayed release, high fecundity, and trait variability generates a broad spectrum of dispersal outcomes, from local deposition near the parent plant to colonization of distant downstream habitats, and mirrors heteromorphic strategies documented in other invaders such as common ragweed.

The findings carry practical weight for invasion management. Because hydrochory amplified by seed dimorphism appears central to the vine’s spread, the researchers argue that removing reproductive plants near waterways before fruits mature is crucial to cutting off the propagule supply. Control efforts should also prioritize sites where floating seeds and fruits accumulate and release seeds gradually, creating dispersal hotspots along the river network. More broadly, the study demonstrates that understanding how trait interactions shape dispersal can sharpen invasion risk prediction, allowing managers to align interventions with hydrological connectivity and seasonal flood dynamics. Future work coupling trait data with hydrodynamic and landscape models, the authors suggest, could further improve forecasting and help identify priority zones for coordinated control of this and similar riparian invaders.

Subject of Research: Seed buoyancy and water-mediated dispersal traits in the invasive vine Echinocystis lobata

Article Title: Functional trait interactions drive seed buoyancy and dispersal strategies in Echinocystis lobata

Article References: Szulc, A., Czortek, P., & Marciniuk, P. (2025). Functional trait interactions drive seed buoyancy and dispersal strategies in Echinocystis lobata. NeoBiota, 104, 301-318. https://doi.org/10.3897/neobiota.104.162267

Image Credits: AI Generated

DOI: 10.3897/neobiota.104.162267

Keywords: Echinocystis lobata, hydrochory, seed buoyancy, invasive species, riparian ecosystems, functional traits, seed dimorphism, dispersal ecology, river corridors, invasion biology, wild cucumber, NeoBiota

The research team investigated the leaf-level functional traits of five native mangrove species alongside the introduced S. apetala in six representative sites along the Beibu Gulf. By measuring seventeen distinct leaf traits, including morphological dimensions, structural investment, and physiological markers, the scientists moved beyond traditional single-trait analyses. They employed a functional trait network (FTN) approach, a sophisticated method that visualizes the relationships among traits as a complex web of nodes and edges. This framework allows for a comprehensive understanding of how multiple traits coordinate to drive ecological strategies, offering a more nuanced view of plant adaptation than standard dimensionality reduction techniques.

The analysis revealed a fundamental divergence in the network topology between the native and introduced species. The native mangroves exhibited a “dispersed-cooperative” strategy, characterized by higher modularity and greater system redundancy. Their trait networks were partitioned into three distinct functional modules, allowing for independent regulation of different physiological processes. This modular structure enhances adaptability and stability, particularly in dynamic and stress-prone environments where conditions fluctuate due to tidal changes and seasonal variations. The native species rely on conservative traits, such as lower specific leaf area, to maintain long-term community stability and ecological resilience.

In contrast, S. apetala displayed a “centralized-efficient” strategy. Its leaf trait network was less modular, consisting of only two functional communities, but it exhibited significantly higher connectivity and centralization. The edge density of the S. apetala network was higher than that of the native species, indicating tighter coordination among its traits. This structure facilitates rapid resource acquisition and growth in resource-abundant environments. The efficiency of this system is based on high chlorophyll content, elevated nitrogen concentration, and specific leaf shape factors, which allow the plant to optimize photosynthesis and nutrient uptake over short timescales.

The study further examined the node-level parameters within these networks to identify the key traits driving these strategies. For native species, traits such as leaf length, leaf area, and leaf circumference showed high degree and closeness centrality, reflecting their importance in long-term ecological adaptation. These stable morphological traits optimize photosynthetic performance and water-use efficiency across evolutionary timescales. Additionally, leaf dry matter content acted as a critical bridge trait in native networks, linking different functional modules and contributing to overall system robustness.

For S. apetala, the central nodes were dominated by physiological traits, specifically chlorophyll content and leaf nitrogen content. These traits served as hubs that integrated distinct functional modules, enabling the plant to rapidly adjust to varying light conditions and resource availability. The high betweenness centrality of these traits in S. apetala suggests a flexible, opportunistic strategy that allows for quick exploitation of ecological niches. However, this flexibility comes with a trade-off; the study found that the betweenness centrality of S. apetala was significantly negatively related to trait stability, indicating that these key traits are more sensitive to environmental fluctuations.

The implications of these network structures for ecosystem stability are profound. The native mangroves’ dispersed-cooperative strategy provides a buffer against environmental shocks, as the redundancy among traits ensures that if one function is compromised, others can compensate. This aligns with the metabolic-ecological stability theory, which posits that trait redundancy and interdependence confer systemic resilience. The introduced species, while efficient, lacks this regulatory flexibility. Its centralized-efficient strategy, while advantageous for rapid expansion, may lead to systemic collapse if critical trait nodes are disrupted by extreme environmental events, such as the frost events observed in previous years where S. apetala suffered significant leaf necrosis compared to native species.

From a management perspective, these findings suggest that the large-scale planting of S. apetala should be approached with caution. While it offers short-term benefits in revegetation, its long-term impact on native functional diversity poses a significant risk. The study recommends that restoration designs prioritize native mangrove species to safeguard ecosystem resilience. Where S. apetala is used, it should be restricted to carefully managed, spatially isolated sites with clear containment objectives to prevent its spread into intact native stands. In areas where dense stands of S. apetala have already formed, targeted thinning or gradual replacement with native species may help relieve competitive pressure and promote a more balanced community structure.

This research highlights the importance of considering the network structure of functional traits when assessing the invasive potential of introduced species. By framing species differences in terms of trait network topology, the study provides mechanistic insight into how S. apetala attained competitive dominance and how that dominance could alter the ecosystem’s functional structure. Future work should link these network patterns to demographic performance and site-level environmental gradients to further refine management guidance. Understanding the multidimensional adaptive strategies of mangroves is crucial for developing evidence-based restoration practices that balance immediate recovery needs with long-term ecological sustainability.

Subject of Research: Functional trait network analysis of invasive Sonneratia apetala versus native mangrove species in Guangxi, China

Article Title: Leaf trait network structure drives the invasion success of Sonneratia apetala in Guangxi mangroves

Article References: Pan, Y., Qiu, S., Tan, X., Su, Z., Pan, L., Qiu, G., & Fan, H. (2026). Leaf trait network structure drives the invasion success of Sonneratia apetala in Guangxi mangroves. NeoBiota, 106, 29-50. https://doi.org/10.3897/neobiota.106.177660

Image Credits: AI Generated

DOI: 10.3897/neobiota.106.177660

Keywords: mangrove ecology, invasive species, functional traits, network analysis, Sonneratia apetala, ecosystem restoration, biodiversity, plant physiology, coastal ecosystems, trait plasticity, Leaf, trait

The scale of the confusion is easy to quantify. A search for the term on Google Scholar returned more than 7.4 million results, with over 322,000 more in Web of Science, reflecting both enormous scientific interest and a sprawling, inconsistent literature. The concept traces back to 1913, when agricultural scientists Briggs and Shantz defined the water requirements of plants as the ratio of dry matter produced to water lost through transpiration. Since then, the term has been adopted by physiologists, isotope geochemists, ecosystem ecologists, remote sensing specialists, and Earth system modelers, each community shaping it to fit its own instruments and questions. The result is a metric whose numerical value can change dramatically depending not on the vegetation being measured, but on who is doing the measuring and how.

At the leaf level, the two most common formulations already diverge in meaning. Instantaneous water use efficiency is the ratio of net carbon assimilation to transpiration, while intrinsic water use efficiency divides assimilation by stomatal conductance to water vapor. The distinction matters because transpiration depends strongly on the vapor pressure deficit of the surrounding air, the physical driver of evaporation, whereas stomatal conductance does not. Intrinsic water use efficiency therefore strips out atmospheric demand and isolates the plant’s own regulatory behavior, which is why it can be reconstructed from carbon isotope discrimination in tree rings and used to track century-scale changes in forest physiology. But the two are not interchangeable, and the review stresses that even the familiar equivalence between intrinsic water use efficiency and the ratio of intercellular to atmospheric CO2 concentrations holds only under specific gas-exchange assumptions, such as a negligible cuticular conductance. Recent recalculations of photosynthesis measurement systems have shown that incorporating cuticular conductance and more complete transport physics can alter estimated stomatal conductance and intercellular CO2 while leaving measured fluxes unchanged, undermining naive conversions between formulations.

Perhaps the most conceptually important distinction in the review separates ratio-based metrics from optimality-based ones. Ratios like assimilation divided by transpiration describe realized carbon-water exchange, but they respond strongly to environmental conditions and say little about strategy. By contrast, the marginal water cost of carbon gain, denoted lambda and defined as the partial derivative of transpiration with respect to assimilation, emerges from the Cowan-Farquhar optimality framework, which assumes plants regulate their stomata to maximize carbon gain per unit water risk. Liang and colleagues showed that these quantities capture genuinely different aspects of plant water use, and Bonan and colleagues demonstrated that stomatal optimization schemes built on different objective functions produce different predictions of how conductance and assimilation respond to atmospheric demand. In other words, the choice of water use efficiency formulation is not a neutral act of bookkeeping; it encodes a hypothesis about how plants balance carbon against water.

This leads to an uncomfortable question: is water use efficiency even a functional trait? Following the influential definition by Violle and colleagues, a functional trait should be measurable without reference to the environment. Most water use efficiency formulations fail this test. Assimilation-to-conductance and assimilation-to-transpiration ratios shift with vapor pressure deficit, irradiance, temperature, atmospheric CO2, and soil moisture, even when the underlying plant strategy is unchanged. A rise in the metric during drought, for example, may simply reflect stomatal closure reducing water loss faster than carbon gain, without indicating improved drought tolerance or higher productivity. The authors therefore recommend treating water use efficiency as a process metric whose interpretation is always conditional on context, rather than as an environment-independent property of an organism.

The problems compound as measurements move up the hierarchy of biological organization. Ecosystem-scale water use efficiency is typically computed from gross primary productivity divided by evapotranspiration, but evapotranspiration includes soil evaporation and canopy interception alongside transpiration. Because these non-transpirational components do not respond to CO2-driven stomatal closure the way transpiration does, evapotranspiration-based ecosystem metrics tend to overestimate the sensitivity of water use efficiency to rising CO2 relative to leaf-scale intrinsic measures. Separately, because evapotranspiration exceeds transpiration, using it in the denominator deflates the absolute magnitude of the ratio. These two effects operate in opposite directions and are frequently conflated, the review warns, making explicit partitioning of transpiration from total evapotranspiration essential for sound interpretation. Where partitioning is unavailable, the evapotranspiration-based formulation remains the appropriate empirical choice, but its values cannot be compared directly with transpiration-based ones without correction.

Units and variable choices add further traps. Stomatal conductance is conventionally reported on a water vapor basis, but isotope-based and optimality-derived formulations often use a CO2 basis, related by a diffusivity factor of 1.6; mixing the two without conversion introduces a systematic 60 percent error in intrinsic water use efficiency. Denominators may be transpiration or evapotranspiration, numerators may be leaf assimilation, gross or net primary productivity, or biomass, and fluxes may be instantaneous rates or seasonal sums. Even vapor pressure deficit normalization is contested: the widely used underlying water use efficiency formulation assumes a fixed optimality exponent of 0.5, yet recent work shows this exponent varies dynamically with soil water content, atmospheric drought, and species-specific hydraulic strategies, suggesting that fixed corrections may oversimplify carbon-water coupling in water-limited ecosystems.

The methodological provenance of an estimate matters as much as its formula. Empirical measurements from gas exchange, isotopes, and eddy covariance are constrained by instrument accuracy and site conditions. Model-derived estimates depend on process representations, parameterization, and assumptions about canopy structure and physiology. Satellite products such as those from MODIS offer global coverage but infer, rather than measure, the underlying fluxes. Optimality-based approaches derive efficiency from assumed principles of plant regulation rather than observed fluxes. The review provides a comparability matrix showing which pairs of metrics can be converted directly, which require caution, and which quantify fundamentally different quantities, along with a supplementary conversion guide detailing the assumptions each translation requires.

The stakes extend well beyond academic tidiness. Water use efficiency is embedded in United Nations Sustainable Development Goal Target 6.4 and its Indicator 6.4.1, with the Food and Agriculture Organization as custodian, tying the metric directly to global water management and food security. Under climate change, rising CO2, warming temperatures, and intensifying drought are altering plant carbon-water dynamics across every biome, and recent studies suggest that increases in intrinsic water use efficiency do not necessarily translate into higher productivity, because the relationship depends on hydroclimatic constraints and hydraulic limitations. The authors propose standardized reporting practices, including stating the exact formula, the temporal and spatial scales, the units, whether vapor pressure deficit normalization was applied, and the transpiration fraction of evapotranspiration. Their glossary assigns unique names and abbreviations to each of the fourteen metrics, reserving prefixes and suffixes to signal conductance basis, scale, and provenance. The goal, they emphasize, is not to eliminate methodological diversity but to make it explicit, traceable, and scientifically interpretable, so that a number labeled water use efficiency finally means the same thing to the physiologist, the modeler, and the policymaker reading it.

Subject of Research: Reconciling divergent definitions and formulations of water use efficiency in plant and ecosystem science

Article Title: One Metric, Many Meanings: Reconciling Water Use Efficiency Definitions

Article References: Puchi, P. F., Saurer, M., & Collalti, A. (2026). One Metric, Many Meanings: Reconciling Water Use Efficiency Definitions. Current Climate Change Reports, 12(1), Article 3. https://doi.org/10.1007/s40641-026-00210-z

Image Credits: AI Generated

DOI: 10.1007/s40641-026-00210-z

Keywords: water use efficiency, intrinsic water use efficiency, stomatal conductance, transpiration, evapotranspiration, carbon-water coupling, stable isotopes, eddy covariance, stomatal optimization, vapor pressure deficit, functional traits, climate change

The study area, a region of fine-grained sediment known as a mud depocenter, sits in water depths of roughly 7 to 51 meters and has recently been identified as a hotspot for carbon burial, with burial efficiency reported to be about twice the global average. Such depocenters form where hydrodynamic conditions trap and retain fine particles delivered by rivers, allowing organic matter to accumulate rapidly. While the geochemistry of these deposits has attracted considerable attention, the biological side of the equation has remained poorly resolved. The new research addresses that gap by asking how the composition, traits, and diversity of bottom-dwelling invertebrates vary across the depocenter and how those variations translate into ecosystem functions tied to carbon cycling.

Sampling was carried out in July 2023 aboard the research vessel Heincke, using a van Veen grab at each of the 50 stations. The team identified 31,086 individual animals spanning 9 phyla and 89 families, ranging from brittle stars and heart urchins to bivalves and bristle worms. Biomass across the stations varied more than twentyfold, from less than 0.4 grams to more than 10 grams of ash-free dry mass per square tenth of a meter. When the researchers clustered the communities by their biomass composition, four distinct assemblages emerged, arranged in a striking east-west pattern: two clusters dominated the deeper western reaches of the study area, while the other two occupied the shallower eastern zone, with all four overlapping in a transitional band between 20 and 30 meters of water depth.

Statistical modeling revealed that this spatial structure was not random. A distance-based redundancy analysis showed that environmental variables explained 44.1 percent of the variation in community composition, with sediment sorting, skewness, kurtosis, median grain size, bottom salinity, and bottom shear stress all emerging as significant predictors. The deeper communities were associated with higher salinity and calmer bottom waters, whereas the shallower communities endured stronger tidal shear stress and fresher, more variable conditions. In effect, the seafloor fauna of the depocenter is sorted along two intersecting gradients: one physical, driven by the friction of currents on the bed, and one chemical, driven by the mixing of saline North Sea water with freshwater runoff from the coast.

The functional contrast between deep and shallow assemblages proved even more telling than the taxonomic one. In the deeper clusters, biomass was dominated by mobile biodiffusors and subsurface filter feeders, most notably the brittle star Amphiura filiformis, which alone accounted for nearly 59 percent of total macrofaunal biomass in those communities on average. Laboratory studies cited by the authors show that this species can mix sediments at rates of roughly 35 square centimeters per year, actively transporting particles both downward to its mouth and upward to the surface. In the shallower clusters, by contrast, the fauna was dominated by less mobile, surface-modifying bivalves such as Abra species and tube-dwelling polychaetes, organisms that redistribute particles only at the sediment surface and ventilate their burrows infrequently.

These trait differences translated directly into divergent ecosystem functions. The team calculated four functions for each community: bioturbation potential, bioirrigation potential, secondary production, and respiration. Bioturbation and bioirrigation, the processes by which animals rework sediment particles and pump oxygenated water into their burrows, were roughly two to two and a half times higher in the deep clusters than in the shallow ones, with mean bioturbation potential of 284.0 versus 151.2 and mean bioirrigation potential of 223.2 versus 86.6. Both differences were highly significant statistically. The pattern reversed for energy-related functions: community respiration averaged 505.9 milligrams of carbon per square meter per day in the shallow clusters against 347.6 in the deep ones, a significant difference, while secondary production showed the same trend at 135.9 versus 107.5 milligrams of carbon per square meter per day.

The biodiversity-functioning relationships that emerged were, in places, counterintuitive. Secondary production and respiration both increased with taxonomic and functional richness, with correlation coefficients around 0.54, consistent with the idea that a greater variety of species brings a greater variety of trait combinations and enhances niche complementarity. But bioturbation and bioirrigation potentials were negatively correlated with Shannon diversity, Simpson diversity, and community evenness, with the strongest negative correlation, r equal to minus 0.55, linking evenness to bioturbation. The explanation, the authors argue, lies in a selection effect: sediment reworking in this system is disproportionately driven by a few highly efficient key species, above all Amphiura filiformis, rather than by the collective action of a diverse community. Where one dominant bioturbator reigns, evenness falls and reworking potential soars.

Crucially, the study shows that these biodiversity-functioning relationships are not fixed but bend along environmental gradients. Interaction regressions and simple slope analyses revealed that bottom shear stress and salinity significantly modulated the sign and strength of the correlations. In the deeper, high-salinity, low-shear habitats, the negative relationships between bioturbation or bioirrigation and diversity were pronounced; in the shallower, high-shear, low-salinity zone, they weakened or even turned slightly positive, though not significantly. The relationship between functional redundancy and energy-related functions was likewise modulated by shear stress, salinity, and sediment kurtosis, a measure of the peakedness of the grain-size distribution that the authors suggest may serve as a proxy for habitat stability. In stable, high-kurtosis sediments, functionally redundant communities appeared to prioritize persistence over peak performance, hinting at a trade-off between resilience and functioning efficiency.

The implications extend beyond the German Bight. Because bioturbation and bioirrigation control the delivery of oxygen and electron acceptors such as nitrate into deeper sediment layers, they regulate the microbial processes that determine whether organic matter is remineralized to carbon dioxide or preserved in the deposit. The finding that deeper communities combine high biomass with intense reworking suggests that carbon and nutrient cycling in the heart of the depocenter is strongly biologically driven, whereas in the shallower, physically disturbed margins, carbon dynamics are governed more by hydrodynamic forces than by fauna. As the authors note, a direct measurement linking macrofaunal communities to carbon sequestration is still missing, and closing that gap will be essential for predicting how these systems respond to change.

What the study delivers, meanwhile, is a clear warning wrapped in an opportunity. Biodiversity loss in shelf seas may not simply erode ecosystem functions uniformly; it may rewire them, suppressing some pathways while leaving others intact, depending on which species disappear and where. Preserving functional diversity, and in particular the keystone bioturbators that dominate the deep muds, appears essential for sustaining the benthic machinery that allows coastal depocenters to act as carbon reservoirs. As climate policy increasingly looks to natural carbon sinks, this work makes the case that the humble invertebrates of the seafloor, from brittle stars to burrowing clams, deserve a seat at the table alongside forests and wetlands in the accounting of the planet’s carbon budget.

Subject of Research: Benthic macrofaunal biodiversity and its role in carbon cycling ecosystem functions in a North Sea mud depocenter

Article Title: Linking marine benthic biodiversity and ecosystem functions related to carbon cycling in a continental mud depocenter

Article References: Tung, C.-C., Holtappels, M., Wrede, A., Köster, M., Sander, L., Beermann, J., Sidorenko, V., & Gutow, L. (2026). Linking marine benthic biodiversity and ecosystem functions related to carbon cycling in a continental mud depocenter. Biogeosciences, 23(19), 7129-7150. https://doi.org/10.5194/bg-23-7129-2026

Image Credits: AI Generated

DOI: 10.5194/bg-23-7129-2026

Keywords: benthic macrofauna, biodiversity, carbon cycling, bioturbation, bioirrigation, North Sea, mud depocenter, ecosystem functioning, sediment biogeochemistry, functional traits, carbon sequestration, shelf sea

A team led by Ying Liu of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Potsdam turned to sedimentary ancient DNA, or sedaDNA, extracted from lake sediment cores collected at nine sites across northeastern Siberia and Alaska. Because this region remained largely free of ice sheets during the last glacial period, its lakes preserve an unusually continuous archive of the vegetation that surrounded them. The researchers analysed 369 samples yielding more than 78 million DNA sequence reads, representing 625 plant amplicon sequence variants, all verified against a customised regional reference database. The technique targets the P6 loop of the chloroplast trnL (UAA) intron, a barcode region that offers far finer taxonomic resolution than traditional pollen analysis.

The raw genetic signal told a familiar story of post-glacial change. Before about 14,000 calibrated years before present, during the depths of the last ice age, the plant communities were dominated by herbaceous taxa. Forbs made up roughly 60 percent of total plant abundance, while cushion plants and grass-like graminoids each accounted for less than 10 percent. Woody taxa were scarce, contributing less than 30 percent of the community. Then, as temperatures climbed through the Bølling–Allerød Interstadial between 14,000 and 12,000 years ago, the balance shifted. Willows rose moderately, other shrubs expanded rapidly to peak at 31 percent at the onset of the Holocene around 10,000 years ago, and trees crept up to about 9 percent. Meanwhile, forbs crashed to a minimum of 30 percent and cushion plants and graminoids fell below 5 percent.

Crucially, the team did not stop at documenting which plants lived where. Their central question was how those plants treated one another, and answering it required disentangling genuine biological interactions from the many other forces that make species appear together or apart. Species can co-occur because they favour the same climate, because they disperse similarly, or simply by chance. To isolate the biological signal, the researchers built species distribution models trained on modern occurrence data from the Global Biodiversity Information Facility, using mean annual and mean July temperatures as the key predictors. These models predicted which species the climate alone would allow at each lake through time.

From there, the team applied environmentally constrained null models, a mathematical framework previously used on modern vegetation surveys in the Swiss Alps but never before on palaeoecological data. The approach compares a co-occurrence statistic called the C-score, calculated from the actual sedaDNA records, against the distribution of that statistic in thousands of simulated communities in which species are placed according to climate suitability rather than biology. Species pairs that were significantly more segregated than the climate-only expectation were scored as negative interactions, likely competition, while pairs more aggregated than expected were scored as positive interactions, such as facilitation. Dispersal limitation was ruled out separately by testing whether species pairs had overlapping geographic ranges and aligned distribution centroids. The resulting interaction networks showed a significant overlap of about 26 percent with the Globi database of documented plant interactions, far exceeding what random pairings would produce, which supports the reliability of the inference.

The temporal pattern that emerged is striking. During the glacial period, positive interactions dominated, peaking around the Last Glacial Maximum between 20,000 and 18,000 years ago, when taxa such as Saxifraga oppositifolia, Saxifraga tricuspidata and Dryas were heavily involved in facilitative links. Cushion plants, the classic nurse species of harsh environments, showed a median of roughly 60 percent positive interactions across all time slices, consistent with modern field observations of these mat-forming plants trapping heat, stabilising soil and sheltering seedlings within their crowns. Then, beginning around 14,000 years ago, negative interactions climbed steadily, reaching equilibrium with positive ones at the dawn of the Holocene and becoming predominant thereafter. Woody taxa, including trees and shrubs, were overwhelmingly embedded in negative links, which made up 70 to 95 percent of their connections, exemplified by larch, Larix, in the Holocene networks.

The mechanism behind this behavioural shift appears to lie in plant functional traits. Using trait databases including the Tundra Trait Team, TRY 5.0 and Global Root Trait compilations, the researchers calculated community-weighted averages of plant height and maximum root length across time. As woody taxa encroached, community-weighted height surged from glacial levels to nearly 3 metres between about 16,000 and 14,000 years ago and peaked at approximately 4 metres in the early Holocene, while community-weighted root length climbed to around 0.47 metres and stayed elevated. Taller canopies preempt light and shade out low-growing herbs, potentially causing etiolation or outright exclusion of shade-intolerant species, while longer, long-lived root systems intensify belowground competition for water, nutrients and space, and foster mycorrhizal partnerships that further boost resource uptake.

A structural equation model built from 1,200 observations, spanning 100 resampling iterations across 12 two-thousand-year time slices, confirmed the causal chain. Rising temperature drove the expansion of woody taxa and the associated increase in community height and root length, and it was these trait shifts, modelled as a latent variable, that directly increased the proportion of negative interactions. In other words, climate acted as an external trigger that opened the door for woody expansion, but the internal dynamics of competition then took over and amplified the transformation. The pattern also fits the Stress Gradient Hypothesis, which predicts that facilitation dominates under harsh conditions while competition prevails in benign ones. Intriguingly, some shrubs such as Cassiope tetragona and Empetrum nigrum appear to have switched roles, acting as nurse plants that sheltered neighbours during glacial millennia but becoming competitors once the climate eased, a flexibility that likely helped them persist across both worlds.

The consequences ripple outward through entire communities. During the glacial period, widespread facilitation helped species expand their ranges, kept regional beta diversity low and buffered plants against extinction despite the cold. In the Holocene, intensified competition constrained the establishment of new taxa, suppressed range expansion of residents and contributed to a higher than expected loss of plant taxa, with herbaceous species of short stature and shallow roots especially vulnerable to local extirpation. Yet competition also fostered divergent community assemblies across sites, enhancing regional beta diversity even as local diversity declined. For the present day, the analogy with contemporary Arctic greening is direct: as shrubs and trees advance under rapid warming, species distribution models that consider only climate may badly overestimate the futures of low-competitive native herbs, which could vanish through competitive exclusion before warming ever exceeds their physiological tolerances. The Arctic’s botanical future, this 24,000-year record suggests, will be decided not just by who can tolerate the cold, but by who can win the fight for light and soil.

Subject of Research: Long-term shifts in Arctic plant interactions during post-glacial woody encroachment reconstructed from sedimentary ancient DNA

Article Title: Woody plant encroachment enhanced negative interactions in Arctic plant communities over the last 24,000 years

Article References: Liu, Y., Jia, W., Liu, S., Lisovski, S., Stoof-Leichsenring, K. R., Farkas, L. Z., & Herzschuh, U. (2026). Woody plant encroachment enhanced negative interactions in Arctic plant communities over the last 24,000 years. Nature Communications, 17(1), Article 10083. https://doi.org/10.1038/s41467-026-77801-9

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77801-9

Keywords: Arctic, woody plant encroachment, sedimentary ancient DNA, plant interactions, competition, facilitation, paleoecology, Arctic greening, functional traits, Holocene, biodiversity, Siberia

The central concept at work is the efficiency-safety trade-off, a long-standing principle in plant physiology. Plants that move water quickly through their xylem, the vascular tissue that carries water from roots to leaves, gain an advantage: high hydraulic conductivity supports high stomatal conductance, which in turn allows photosynthesis to run at full throttle. But fast, wide, or highly conductive xylem comes at a cost. Under drought, the negative pressures that pull water upward can exceed critical thresholds, causing air bubbles to nucleate and block the conduits in a process called cavitation or embolism. Plants with safer hydraulic architecture, by contrast, feature narrower conduits, denser wood, and stronger embolism resistance, allowing them to keep their vascular systems intact as soils dry, but at the price of slower water delivery and reduced photosynthetic capacity when water is plentiful.

What makes the new study remarkable is its scale and its focus on herbaceous plants, the dominant life form of dryland ecosystems that has often been overshadowed in hydraulic research by trees and shrubs. By sampling herbaceous communities systematically across the Mongolian Plateau, the researchers were able to aggregate individual species traits up to the community level and ask whether the efficiency-safety trade-off operates as an organizing axis for whole ecosystems. The answer, they report, is a clear yes: a community-wide trade-off between hydraulic efficiency and safety fundamentally structures ecosystem function across the region.

Crucially, the team found that aridity acts as the master variable steering this trade-off. As conditions become drier along the precipitation gradient, the composition of herbaceous communities shifts strategically from efficiency-oriented traits toward safety-oriented traits. In wetter parts of the plateau, communities are dominated by species whose leaves can move water rapidly, fueling fast growth and high carbon uptake. In the driest reaches, the flora tilts toward species engineered to survive hydraulic failure, sacrificing peak productivity for the assurance that their water transport pathways will not collapse during the frequent and severe droughts that characterize the region.

This strategic shift does not merely describe which plants live where; it propagates directly into ecosystem-level properties that matter for pastoral livelihoods, carbon cycling, and land management. The researchers quantified three core functions: aboveground biomass, water-use efficiency, and ecosystem stability. Hydraulic efficiency, they found, enhances aboveground biomass by supporting greater photosynthetic carbon assimilation, but it simultaneously reduces water-use efficiency and undermines ecosystem stability. Safety traits produce exactly the opposite pattern. Communities built for hydraulic security fix less carbon per unit of leaf area and accumulate less biomass, but they use the water they do take up more sparingly and their productivity fluctuates less through time, a hallmark of stability in variable environments.

The quantitative strength of the framework is one of its most striking features. By combining community-aggregated hydraulic traits into a predictive model, the authors explain 43 percent of the variance in aboveground biomass, 40 percent of the variance in water-use efficiency, and fully 60 percent of the variance in ecosystem stability across the 306 study sites. In ecology, where field data are notoriously noisy and single variables rarely explain more than a modest fraction of observed variation, these are substantial effect sizes. They suggest that a relatively simple axis, the position of a community along the efficiency-safety spectrum, captures much of the functional character of these grasslands.

The implications extend well beyond the Mongolian Plateau. Drylands cover roughly 40 percent of the terrestrial land surface and support hundreds of millions of people, many of whom depend on herbaceous vegetation for grazing livestock. As climate change intensifies aridity across much of Central Asia and other dryland regions, the trait composition of these communities is expected to shift further toward the safety end of the spectrum. The study’s findings imply that such a shift would likely come with declining biomass production and altered water-use patterns, even as stability characteristics change in complex ways. Understanding this coupling between plant hydraulics and ecosystem function provides a mechanistic basis for anticipating how grassland productivity and resilience will respond to ongoing drying.

The work also carries direct lessons for resilience-focused ecosystem management. Grassland restoration and grazing management decisions are often guided by aboveground indicators such as biomass or species cover, which can be misleading proxies for underlying functional capacity. The trait-based framework developed here suggests that monitoring or targeting hydraulic trait composition could offer a more predictive handle on how a given grassland will behave under drought. Communities dominated by efficiency-oriented species may deliver high forage production in favorable years but risk instability when drought strikes, whereas safety-oriented communities trade some productivity for steadier performance. Managers seeking to balance livestock production against long-term ecosystem resilience could, in principle, use this trade-off as a diagnostic lens.

Methodologically, the study exemplifies a growing trend in ecosystem ecology: moving from single-species measurements to community-wide, trait-based approaches that link organismal physiology to landscape-scale function. Rather than treating drought response as an emergent mystery, the researchers traced it through an explicit causal chain, from the hydraulic architecture of leaves, through stomatal behavior and carbon assimilation, to biomass accumulation, water-use efficiency, and temporal stability of the ecosystem. Each link in that chain was quantified across hundreds of field sites, giving the framework empirical grounding that laboratory studies alone cannot provide.

The research, published open access in Communications Earth & Environment with contributions from ecologists at Inner Mongolia University, Lanzhou University, the Inner Mongolia Institute of Meteorological Sciences, Inner Mongolia Normal University, and the Institute of Water Resources for Pastoral Areas, arrives at a moment when the world’s drylands face mounting pressure from warming temperatures, shifting precipitation regimes, and intensifying land use. By demonstrating that a single, measurable trade-off in leaf hydraulics can explain large fractions of variation in the functions that sustain grassland ecosystems, the study offers both a warning and a tool: a warning that increasing aridity will push these systems toward safer but less productive configurations, and a tool in the form of a quantified, predictive framework that can help scientists and managers anticipate and perhaps buffer those changes before they unfold.

Subject of Research: Leaf hydraulic trait trade-offs and their effects on ecosystem function in Mongolian Plateau grasslands

Article Title: Herbaceous leaf hydraulic trade-offs shape ecosystem function across the Mongolian Plateau

Article References: Guo, X., Wang, X., Jia, C., Liu, T., Li, Z., Liu, H., Wang, L., Wang, Y., Dong, L., Liang, C., & Zhang, J. (2026). Herbaceous leaf hydraulic trade-offs shape ecosystem function across the Mongolian Plateau. Communications Earth & Environment. https://doi.org/10.1038/s43247-026-04121-7

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04121-7

Keywords: plant hydraulics, leaf traits, efficiency-safety trade-off, Mongolian Plateau, grassland ecology, drought, aridity gradient, ecosystem stability, water-use efficiency, aboveground biomass, functional traits, drylands

The authors trace the problem through three generations of biodiversity metrics. Species-based indices describe community composition with precision but offer no mechanism for prediction. Functional-diversity indices, which characterise the distribution of traits such as body size, feeding mode or dispersal ability within a community, still depend on inventories of species that have already been recorded. Habitat-based metrics, the third generation, replace laborious species surveys with habitat classification, dramatically improving scalability, and they now underpin global policy. The Kunming–Montreal Global Biodiversity Framework, adopted at COP15 in December 2022, formalises habitat-based measures in its monitoring targets for 2030. England’s mandatory Biodiversity Net Gain requirement, in force since 2024 under the Environment Act 2021, calculates standardised biodiversity units from habitat distinctiveness and condition. Yet the evidence for these proxies is sobering: studies show the English metric is associated with measurable gains in plant biodiversity but not in birds or butterflies, and it predicts invertebrate biodiversity poorly.

The deeper issue, the authors contend, is that all three metric generations measure patterns rather than the processes that generate them. Even the ambitious European Biodiversity Observation Network roadmap, with its 84 Essential Biodiversity Variables spanning genes to ecosystems, remains observational by design. Such systems can standardise how biodiversity state and change are measured, but they cannot supply the causal prediction needed to evaluate an individual management decision. Correlative models fitted to observed occurrences project associations between recorded species and recorded conditions, with the projected species pool bounded by the region and period used for fitting. They output expected occurrence, not the conditions required for persistence, and they cannot identify which ecological constraint prevents a management response. The distinction the authors draw is not between description and prediction, but between observation-anchored prediction and mechanistic prediction.

The empirical motivation for FTC comes from a stubborn and poorly explained pattern in two decades of agri-environment research: the same intervention produces different, sometimes opposite, biodiversity responses in different landscape contexts. Meta-analyses indicate that organic farming increases species richness by roughly 30 percent on average relative to conventional management, yet 16 percent of studies report negative effects. Benefits tend to be greater in intensively managed, structurally homogeneous landscapes than in heterogeneous ones. A global analysis of 60 crops across six continents confirmed that ecological benefits were greatest in intensive agricultural landscapes, while the same landscape variable could have contrasting effects on different sustainability outcomes. Agri-environment schemes show the same context dependence: a landmark five-country study found substantial variation among countries, taxa and scheme types, with common species benefiting more than species of conservation concern, and a subsequent meta-analysis showed that species richness increased in simple cropland landscapes but not in complex ones.

Spatially explicit modelling offers independent support for a capacity-based interpretation. Across 611 simulated landscapes, landscape structure explained 84 percent of variation in mean beetle density and 70 percent of variation in pesticide impact, with mitigation effects also strongly landscape dependent. The authors argue that these variable outcomes are unlikely to be failures of intervention design. Instead, an intervention acts on biodiversity capacity, a property generated by the landscape as a system, whereas evaluation usually records species occurrence at particular places and times. A predictive metric must represent the processes that generate capacity, not only the patterns those processes have already produced.

So what exactly is Functional Trait Capacity? The authors define it as the range of viable functional-trait combinations that a landscape can sustain, given specified landscape configuration, management regime and assessment horizon. The object of measurement shifts from the community currently observed to the breadth of ecological strategies and life-history solutions for which the landscape provides viable conditions. A wider trait space can support a greater range of species and functional groups, because landscapes act on the resources, disturbance regimes and environmental constraints that filter trait combinations; species composition is one historically contingent outcome of that filtering. The concept builds on Hutchinson’s classic n-dimensional hypervolume and on modern functional-trait ecology, joining them by asking which trait combinations a landscape can sustain rather than which happen to be present.

The framework distinguishes three capacity states. Theoretical FTC is the capacity expected from a site’s physical characteristics and natural ecological trajectory in the absence of deliberate management, a declared reference rather than an absolute biophysical maximum. Management-determined FTC is the capacity produced by a specified land-use and management regime, and it is not necessarily lower than the reference: management can create conditions absent from the natural trajectory, for example by maintaining open habitat where woodland would otherwise develop. Realised biodiversity is the community currently present after historical filtering, the state measured by existing metrics. The gaps between these states represent biodiversity debts or opportunities, separating capacity lost or created through management from capacity that is viable but not yet realised. Crucially, FTC is designed to complement, not replace, observational systems: monitoring tracks realised state and trend, while FTC asks the adjacent causal question of what functional capacity specified conditions should produce.

To show the concept is calculable, the team built a deterministic demonstration using 80 virtual strategies generated from 16 archetypes defined by trophic role, fast–slow life history and disturbance response. Four traits determine viability: spatial access, temporal resource requirement, disturbance tolerance and biotic dependency, with rules for phenological overlap and acyclic food-web structure excluding biologically arbitrary combinations. Four 50-by-50-cell agricultural landscapes varied field configuration and non-crop area in a two-by-two design. The striking result: the researchers selected the same 32-strategy realised community in all four landscapes, yet full assessment of all 80 admissible strategies gave FTC values of 46, 67, 44 and 65. Identical observed richness concealed a difference of up to 23 viable strategies, strategies that occur in none of the observations and therefore could never be recovered by a model fitted only to them. When the same intervention, converting 5 percent of cropped cells to semi-natural habitat along field edges, was applied everywhere, FTC rose by 14 strategies in one landscape, four in another, and not at all in the remaining two, even though mean viable area increased in every case.

Robustness analyses suggest the pattern is not an artefact. Across 60 combinations of persistence thresholds, conversion intensities and placement rules, the high-non-crop landscape always had greater FTC than its low-non-crop counterpart, and intervention effects differed among landscapes in 50 of 60 combinations. In sensitivity ensembles varying the sampled strategies and seasonal resource profiles, baseline FTC differed among landscapes in every replicate, and the intervention response differed among landscapes in all 20 combined replicates. The authors are careful about what this proves: the demonstration shows FTC can be calculated, not that it is empirically valid. Observations remain essential to parameterise resource use, movement and disturbance responses, to test predicted viability and to estimate uncertainty. Their role changes rather than disappears, informing and testing the ecological processes that the model then uses to predict viable strategies under conditions not yet observed.

The path to operational use runs through existing infrastructure. The authors envisage a process-based estimation layer supplying maps, scenario contrasts, limiting-factor diagnoses and uncertainty-bounded indicators to advisers, conservation managers and policy analysts, who would never need to run the underlying model. Inputs correspond to established data streams: Integrated Administration and Control System records for cropping, remote sensing and habitat inventories for configuration, and open trait compilations. Spatially explicit platforms such as the Animal Landscape and Man Simulation System, already applied in eleven European countries, could serve as the mechanistic engine. Practical constraints remain, including restricted access to management records in some member states and incomplete representation of pesticide mixtures and habitat condition. But the conceptual stakes are high. As the EU Nature Restoration Regulation and nature-related financial disclosure frameworks demand choices about future outcomes rather than statements of present state, FTC offers something monitoring alone never can: a falsifiable, scenario-conditioned estimate of what our landscapes could sustain if we managed them differently.

Subject of Research: A computational framework for predicting landscape biodiversity capacity from functional traits and management scenarios

Article Title: Functional Trait Capacity: from observing biodiversity to predicting landscape capacity

Article References: Topping, C. J., Dalgaard, T., Rasmussen, C., & Dupont, Y. L. (2026). Functional Trait Capacity: from observing biodiversity to predicting landscape capacity. npj Sustainable Agriculture, 4(1), Article 79. https://doi.org/10.1038/s44264-026-00190-5

Image Credits: AI Generated

DOI: 10.1038/s44264-026-00190-5

Keywords: biodiversity, functional traits, agriculture, landscape ecology, ecological modelling, agri-environment schemes, conservation policy, Kunming-Montreal Global Biodiversity Framework, sustainable farming, ecosystem management, ALMaSS, biodiversity metrics

Long-term phenology datasets from tropical rainforests are notoriously scarce, particularly in the Oceania region, because they demand enormous investments of time and sustained funding. The Skyrail Rainforest Cableway offered an unusual solution. From a maintenance gondola travelling above the closed-canopy vine forest, the observer scored the presence or absence of open flowers and fruits across 320 subplots spanning roughly 80 hectares. Species identities were verified against ground-collected botanical samples using the Australian Rainforest Key. Because the gondola moved continuously at about five metres per second, the team recorded occupancy rather than intensity, but the spatial scale and weekly resolution more than compensated, yielding a dataset of unusual breadth for the region.

The community-level results are strikingly seasonal. Flowering across the forest peaked during the wet season, which runs from December to May, with abiotically dispersed species, those whose seeds travel by wind, water, or gravity, peaking earliest, around December. Biotically dispersed species, whose seeds are carried by animals in fleshy fruits, flowered later, with a primary peak in March. Fruiting told a different story: seasonality was weaker, and activity concentrated in the dry season from June to November, with the abiotic group peaking in July and the biotic group in August. The researchers suggest that in wet forests, light rather than water may limit fruiting, as trees retain access to soil moisture during drier months while benefiting from higher solar irradiance.

At the species level, the picture became far more complex. Most species showed significant seasonality in flowering, with 87.5 percent of analysable species displaying strong seasonal signals, but only about half did so for fruiting. Crucially, the mean flowering and fruiting dates of individual species were scattered across the entire year, meaning that although the community as a whole pulses with the seasons, some species are always reproductive. This temporal partitioning ensures that fleshy fruits, the currency of the forest’s frugivores, were available year-round, a pattern consistent with selection for complementary fruiting among animal-dispersed trees.

The study also uncovered a fundamental asymmetry in reproductive cycles. Flowering was dominated by annual patterns, with 57.5 percent of species flowering once per year, whereas fruiting was predominantly supra-annual, with roughly half of all species fruiting only in some years. Using Fourier transform analysis to detect periodicities in the time series, the team classified cycles as sub-annual, annual, or supra-annual, and found that supra-annual fruiting was common in both dispersal groups but showed little synchrony among species. Intriguingly, among the 42 annually flowering species, 38 percent nevertheless fruited supra-annually, suggesting that the resources needed for fruit development, or perhaps intermittent pollination success, are available less often than those required for flowering.

Functional traits emerged as powerful predictors of these patterns. Supra-annual flowering was significantly more likely in biotically dispersed species, while supra-annual fruiting was best predicted by seed size, with larger-seeded species more likely to skip years. The authors attribute this to the considerable energetic cost of producing large seeds, which may require longer intervals to accumulate reserves, and to the potential benefits of synchronised fruiting in satiating seed predators. A marginal relationship with carbon isotope signatures also hinted that supra-annual fruiters tend to have lower intrinsic water-use efficiency, possibly depending on years of high resource availability to reproduce at all.

The long-term analysis revealed that reproductive timing is not standing still. Of the species with sufficient data, 27.1 percent had advanced their flowering over the study period and 14.6 percent had delayed it, while for fruiting, 43.3 percent advanced and 13.3 percent delayed. Changes in fruiting timing were significantly more common among biotically dispersed species than abiotically dispersed ones. Most tellingly, the interval between peak flowering and peak fruiting shrank over time in the biotic group but not in the abiotic group, driven primarily by earlier fruiting rather than shifts in flowering. Whether this reflects shorter fruit development periods, altered pollinator activity, or changing plant-frugivore interactions remains an open question, but among the species showing fruiting shifts, several are known to be dispersed by the endangered southern cassowary, underscoring the conservation stakes.

Phylogenetic analysis added an evolutionary dimension to the findings. Supra-annual fruiting showed a weak but significant phylogenetic signal, with species exhibiting multi-year fruiting cycles concentrated within the orders Laurales and Proteales, whereas supra-annual flowering showed no such structure. The authors note this is compatible with regional evidence of phylogenetic clustering in sex systems and fruit types, and perhaps with the region’s palaeoclimatic history, as large parts of the Wet Tropics were more seasonal during the last glacial maximum. Climate triggers such as the El Niño-Southern Oscillation may also contribute to inter-annual variation, a possibility the authors flag for future investigation in the bioregion.

Beyond its scientific insights, the study delivers a practical gift: the first comprehensive phenological calendar for 81 tree species of the Wet Tropics, summarising each species’ reproductive pattern, dispersal mode, season of activity, mean activity dates, and any detected shifts in timing. Because much of the Wet Tropics rainforest is fragmented, reforestation plantings are being implemented to restore connectivity and resilience, and successful restoration depends on knowing when seeds can be collected and when plantings will thrive. The calendars are designed to ensure that seed sourcing and planting schedules follow ecological principles rather than logistical convenience alone.

The work also stands as a tribute. The weekly observations were collected single-handedly by the late Tore Linde of Skyrail, who passed away before the manuscript was conceived; the authors dedicate the paper to his memory. His foresight transformed a scenic cableway into a scientific observatory, and the resulting dataset now provides the baseline that ecologists in the region have long lacked. As climate change accelerates across the tropics, datasets of this depth are the only reliable yardstick for detecting phenological change, anticipating consequences for plant-animal interactions, and guiding the restoration of one of Australia’s most biodiverse landscapes. The message from fifteen years above the canopy is clear: tropical forests operate on rhythms both seasonal and multi-year, and only patient, long-term observation can hope to read them.

Subject of Research: Long-term reproductive phenology of tropical rainforest trees in the Australian Wet Tropics

Article Title: Seasonal and long-term patterns of reproductive phenology in the Wet Tropics rainforests of Australia

Article References: Vogado, N. O., Engert, J. E., & Liddell, M. J. (2026). Seasonal and long-term patterns of reproductive phenology in the Wet Tropics rainforests of Australia. Web Ecology, 26(2), 175-192. https://doi.org/10.5194/we-26-175-2026

Image Credits: AI Generated

DOI: 10.5194/we-26-175-2026

Keywords: phenology, tropical rainforest, Wet Tropics, flowering, fruiting, seed dispersal, functional traits, climate change, canopy observations, supra-annual cycles, ecological restoration, circular statistics

The team designed an elegant experiment around five varieties of pepper, Capsicum annuum: two wild ancestors and three modern elite cultivars. Each variety was grown either alone in monoculture or intercropped with maize, Zea mays, one of the world’s most dominant cereal crops. Crucially, the researchers ran the whole experiment twice over, once under normal moisture conditions and once under drought, creating a full factorial design that allowed them to separate the effects of domestication history, cropping system, and water availability. This mattered because the outcome of any plant interaction is not fixed; the stress-gradient hypothesis in ecology holds that neighbors that harm each other under benign conditions can switch to helping each other when the environment turns harsh, as shade from one plant conserves soil moisture for another.

The results confirmed that moisture dramatically rewires the pepper-maize relationship. Under normal watering, intercropping actually suppressed pepper growth, with maize presumably winning the contest for light and resources. Under drought, however, the picture flipped: pepper responses became predominantly neutral or even facilitative, and every wild and modern pepper-maize combination achieved overyielding, meaning the relative yield total exceeded one. In practical terms, the mixed stands produced more combined biomass per unit area than the two species grown separately would have. For a world facing growing water scarcity, especially in major agricultural regions of China where this work was conducted, the finding that drought can transform a competitive interaction into a productive partnership is genuinely striking.

Yet the study’s most provocative insight concerns domestication. Wild pepper varieties showed higher log response ratios, a standard metric of how a plant’s performance changes between monoculture and mixture, and intercrops involving wild varieties achieved higher relative yield totals than those with modern cultivars. In other words, the wild plants were better at turning a neighbor’s presence into an advantage. Interestingly, this relative superiority of wild peppers did not vary significantly with moisture, suggesting that the domestication penalty is baked into the plants themselves rather than being an artifact of any particular watering regime. Modern breeding, optimized for high yields in monoculture fields with ample inputs, may have inadvertently selected against traits that make crops good teammates.

To understand the mechanism, the researchers measured seventeen functional traits spanning leaves and roots, the biological machinery that determines how a plant acquires light, water, and nutrients. Under normal moisture, modern pepper varieties displayed a distinctive combination in monoculture: acquisitive leaf traits, the fast-growth leaf economics typical of bred crops, paired with conservative root traits. More tellingly, modern varieties showed greater intercropping-induced variability in root traits than wild ancestors when water was plentiful. The team quantified this plasticity using multidimensional hypervolumes, a modern ecological technique that treats a plant’s suite of traits as a cloud of points in multi-dimensional space and measures how that cloud expands or shifts when conditions change.

Drought told a different story. When water became scarce, intercropped modern peppers showed reduced variation in root chemical and morphological traits compared with their well-watered counterparts. This contraction of the root trait space suggests that modern cultivars lose part of their capacity to reconfigure their underground foraging strategy precisely when reconfiguration matters most. Roots are the hidden half of intercropping success; complementary root depths, architectures, and nutrient-acquisition strategies are among the main drivers of overyielding in cereal-legume and cereal-vegetable mixtures worldwide. If domestication has narrowed the plasticity of root-acquisition traits, modern peppers may simply be less able to negotiate a division of labor with maize below ground.

The study fits into a growing body of evidence that crop domestication disrupts biodiversity effects. Previous work has shown that domestication erodes beneficial interactions in barley-faba bean mixtures, shifts competitive ability in durum wheat, and alters root trait syndromes across many crop types. What makes the new pepper-maize study distinctive is its explicit focus on how moisture modulates these domestication effects through the lens of functional trait plasticity. Plasticity, the ability of a single genotype to express different phenotypes in different environments, is a double-edged trait: it is advantageous when environments vary predictably and costly when they do not. The authors argue that domestication was associated with trait-specific changes in moisture-dependent plasticity, particularly in root-acquisition traits, and that this may constrain how modern varieties respond to the simultaneous pressures of competition and facilitation.

The implications for breeding are tantalizing. If the wild ancestors of pepper carry alleles that promote beneficial root plasticity and facilitative interactions, those traits could theoretically be reintroduced into elite germplasm, either through conventional crossing with wild relatives or through genomic selection. The authors explicitly suggest that reintroducing beneficial wild traits may improve crop performance in intercropping systems under variable environments. This is part of a broader conversation in agroecology about back-crossing to the wild, a strategy that has been proposed for restoring lost genetic diversity in everything from disease resistance to drought tolerance. The pepper study adds a new dimension to that debate: what is being lost may not only be stress tolerance itself, but the behavioral flexibility that allows crops to cooperate with their neighbors.

There are, of course, caveats. The experiment involved a single partner crop, maize, and a handful of pepper varieties, and biomass responses in a controlled setting do not always translate directly to grain or fruit yield in farmers’ fields. The relative advantages of wild varieties also did not shift with moisture in the statistical tests, hinting that the domestication effect is robust but perhaps not moisture-specific in the way the trait data alone might suggest. Still, the combination of trait measurements, hypervolume analysis, and yield metrics makes this one of the most mechanistically complete examinations of domestication’s cost to intercropping to date, and it arrives at a moment when intercropping is being promoted as a pillar of sustainable intensification from smallholder farms in Asia and Africa to experimental systems in Europe and North America.

For now, the message for growers and breeders alike is nuanced but clear. Intercropping pepper with maize remains a promising strategy, especially under water-limited conditions where every combination tested achieved overyielding. But the full potential of these ancient partnerships may be locked behind traits that modern breeding left behind in the wild. As climate change makes rainfall less predictable and water scarcity more common, the plants best suited to the fields of the future may be those that have not forgotten how to share. Reconnecting modern crops with their wild heritage, the study suggests, could be the key to unlocking it.

Subject of Research: Effects of crop domestication on functional trait plasticity and intercropping performance of pepper with maize under varying moisture conditions

Article Title: Impaired intercropping effect of domesticated pepper with maize under variable moisture conditions: a functional trait perspective

Article References: Ye, J., Liu, Y., Yi, W., Zhao, L., Liu, Y., Guo, L., Tang, J., Hu, L., & Chen, X. (2026). Impaired intercropping effect of domesticated pepper with maize under variable moisture conditions: a functional trait perspective. Plant and Soil. https://doi.org/10.1007/s11104-026-09086-2

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09086-2

Keywords: crop domestication, intercropping, pepper, maize, drought stress, functional traits, phenotypic plasticity, root traits, overyielding, relative yield total, agroecology, plant breeding

The research addresses one of the most perplexing puzzles in marine science, known as the ‘missing plastic’ paradox. Ocean-input models predict far more microplastic floating at the sea surface than scientists actually find there, suggesting that most plastic sinks. Marine sediments are now recognized as the principal global sink, potentially sequestering 70 to 90 percent of all plastic entering the ocean. Dense polymers such as polyethylene terephthalate and polyvinyl chloride sink directly, while buoyant polymers like polyethylene and polypropylene are dragged down after biofouling — the accumulation of microbial films — increases their density. Yet the seafloor is not a dead end. Once particles arrive, the fate of burial, resuspension, or transfer up the food chain is governed by the organisms living in the sediment, and that is where nematodes take center stage.

To probe this hidden role, a team led by Flávia Juliana Lobato de França and Giovanni Amadeu Paiva dos Santos of the Universidade Federal de Pernambuco in Brazil, together with Anna-Maria Vafeiadou and Tom Moens of Ghent University in Belgium, ran two independent microcosm experiments using sediment from Cupe Beach in Ipojuca, Pernambuco, Brazil. Each experiment used glass beakers holding 400 grams of sediment — a blend of natural live sediment and defaunated sediment that had been frozen and thawed to remove animals while preserving much of the native microbial community. The worms were exposed to fluorescent polystyrene microspheres just one micrometer in diameter, a size chosen to mimic the bacterial prey that many deposit-feeding nematodes naturally consume. Exposure densities spanned 10³, 10⁵, and 10⁷ particles per milliliter of sediment, with the lowest reflecting levels found in moderately polluted coastal sediments and the higher tiers representing plausible future scenarios. One experiment ran for nine days, with sampling at days three, six, and nine; the other stretched to thirty days, with sampling at days fifteen and thirty.

The results were strikingly conditional. Ingestion was detected exclusively in the highest-density treatment. In the short-term experiment, a total of 4,452 particles were quantified across 13 of the 52 nematode genera identified, and the community’s gut burden nearly doubled between day three and day nine, rising from an average of 294 to 581 particles. Most particles accumulated in the intestine rather than the pharynx, with the posterior gut holding significantly more than the anterior region — a pattern consistent with the posterior intestine serving as the principal site of retention and transit. In the long-term experiment, total uptake was far lower, just 571 particles across ten genera, and did not increase significantly with exposure time, hinting at a dynamic equilibrium in which particles are rapidly ingested and egested rather than stored indefinitely.

Even more revealing was who was doing the eating. In the short-term experiment, a single genus, Daptonema — which made up more than 87 percent of the community’s relative abundance — accounted for 89.9 percent of all ingested particles, averaging roughly ten particles per individual. Other genera such as Rhynchonema, Marylynnia, Viscosia, and Theristus collectively contributed about eight percent. Daptonema is a non-selective deposit-feeder with an opportunistic, r-selected life strategy, classified as a colonizer-persister group 2 organism, and its dominance of the sequestration function perfectly matched the researchers’ hypothesis that fast-living, indiscriminate feeders with wide buccal cavities would be the main gateways for microplastic entry into the benthic food web. In the long-term experiment, where the starting community was structurally very different and Daptonema was nearly absent, the sequestration role shifted to a consortium of four genera — Rhynchonema, Latronema, Marylynnia, and Theristus — which together carried over 91 percent of ingested particles. These were functionally more diverse taxa, dominated by more K-selected, persistent life strategies, yet all shared fairly wide buccal cavities.

That anatomical detail appears to be a fundamental constraint. Selective deposit-feeders, which possess tiny or absent buccal cavities, showed minimal to no ingestion, and previous work has demonstrated that microplastic uptake is only possible when the buccal cavity exceeds the particle diameter by a factor of roughly 1.3. Body size mattered too: across both experiments, the researchers found significant positive correlations between individual and community biomass and the number of ingested particles, suggesting that larger worms, with higher feeding rates and larger gut volumes, are more efficient sequestrators. In the short-term trial, Daptonema’s individual biomass correlated strongly with its particle load, while in the long-term trial total community biomass correlated with total ingestion, indicating that the sequestration function had become distributed across the community’s collective biological mass rather than concentrated in one taxon.

The most counter-intuitive finding, however, concerned harm rather than uptake. The most severe community-level impacts — reduced nematode density and biomass — occurred at the lowest and intermediate plastic densities, precisely where no ingestion was detected. In the 10³ particles per milliliter treatment, Daptonema’s abundance collapsed to less than 17 percent of the community by day three, and nematode densities remained significantly below control levels throughout the short-term experiment. The researchers propose several possible explanations, including a behavioral avoidance response that exhausts the animals metabolically, a hormetic stress reaction in which low doses trigger stronger effects than high ones, or adverse effects mediated by direct physical contact with particles — polystyrene microspheres have previously been shown to inhibit nematode reproduction even without detectable ingestion. At the highest density, by contrast, Daptonema persisted at control-like abundances while simultaneously functioning as the community’s principal biological sink, a striking decoupling of the sequestration function from direct ecological harm.

Long-term exposure told a different story again. Chronic exposure consistently lowered nematode density across all treatments, and the community lost 16 of its 37 genera between days fifteen and thirty, although much of that loss occurred in the control microcosms as well, pointing to experimental bottling effects. The dominance structure shifted transiently: at day fifteen, the control was dominated by Chromadorella, while the highest-density treatment was co-dominated by Rhynchonema, Latronema, and Theristus. Crucially, in the long-term experiment the researchers found a complete decoupling between community structure and sequestration function — none of the standard diversity metrics correlated with total ingestion, suggesting that under chronic exposure, the identity and traits of the taxa present, rather than their abundance or diversity, determine how much plastic the community processes.

So how much does any of this matter for the ocean’s plastic budget? The team ran a back-of-the-envelope calculation assuming a realistic intertidal community of about 1,000 nematodes per 10 square centimeters, all non-selective deposit-feeders carrying roughly ten particles each, all eventually eaten by predators. In a sediment volume containing 10⁷ particles per milliliter, such a community would transfer about 1.1 × 10⁴ particles to higher trophic levels out of a total sediment load of 2 × 10⁸ — less than one percent. The quantitative importance of nematode gut storage for trophic transfer therefore appears very limited. But the authors caution against complacency. Gut loads at any instant are a minute fraction of total throughput, since many nematodes pass gut contents in minutes to hours, and if gut enzymes dislodge or modify pollutants adsorbed to plastic surfaces, the cumulative pollutant exposure could exceed what gut loads suggest by one or two orders of magnitude.

The study paints the seafloor not as a passive graveyard for plastic but as an active biological processing zone, where the smallest and most abundant animals continuously encounter, ingest, and transform microplastic particles. The sequestration function is conditional, dependent on a high-contamination threshold well beyond most currently recorded sediment loads, and its identity shifts over time from opportunistic specialists to a more diverse, persistent consortium. The authors acknowledge the limitations of using a single polymer type and particle size in simplified microcosms, and they call for validation under natural conditions, experimental tests of trophic transfer and its consequences for carbon assimilation in higher consumers, and assessments of how different polymer shapes and sizes alter these pathways. As plastic production continues and coastal sediments near urban and industrial zones already approach the densities tested here, the humble nematode may prove to be a small but telling barometer of how the ocean’s largest waste problem plays out at its smallest scale.

Subject of Research: Microplastic sequestration and community-level effects of microplastic exposure in marine nematodes

Article Title: Community dynamics and functional traits drive microplastic sequestration by marine nematodes

Article References: de França, F. J. L., Silva, R. B. D., França, D. A. D. A., Frasson, I. D., Silva, G. A. X. D., Rodrigues, M. E. L., Pessoa, G. L., Vafeiadou, A.-M., Moens, T., & dos Santos, G. A. P. (2026). Community dynamics and functional traits drive microplastic sequestration by marine nematodes. Discover Oceans, 3(1), Article 16. https://doi.org/10.1007/s44289-026-00125-5

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00125-5

Keywords: marine nematodes, microplastics, benthic sediments, meiofauna, functional traits, missing plastic paradox, polystyrene microspheres, buccal cavity morphology, trophic transfer, community ecology, Daptonema, ocean plastic pollution