Abstract Anthropogenic nitrogen (N) deposition is a major driver of global change. However, its effects on the developmental plasticity of plant nutrient strategies remain poorly understood. This is particularly critical in phosphorus (P)‐limited subtropical forests, where N‐induced shifts in biogeochemical cycles may intensify P constraints. Using Moso bamboo ( Phyllostachys edulis ) as a model system, we investigated the response of root P acquisition strategies and leaf P fractions to different N addition (0, 30 and 60 kg N ha −1 year −1 ) at different developmental stages (young vs. mature). We identified a convergent shift in P acquisition pathways in response to N addition. Young bamboos transitioned from morphological strategies (specific root length and area) to exudation‐based strategies, whereas mature bamboos shifted from carboxylate‐dominated to phosphatase‐enhanced pathways. Ultimately, both stages converged on root phosphatase‐mediated organic P mobilization. This strategic unification was also observed in the leaves. N addition significantly reduced leaf inorganic P pools without altering lipid‐P, residual‐P and nucleic‐P, indicating a prioritization of P for growth under intensified limitation. Key drivers, including soil acidification, depletion of available P, accumulation of microbial biomass P, and increased root phosphatase activity, collectively influenced this root–leaf recalibration. Furthermore, responses in root P acquisition strategies and leaf P fractions saturated at the low N addition level, indicating a non‐linear threshold effect rather than a proportional dose–response. By integrating specific root pathways and internal P fraction dynamics, our study advances the conventional ‘Get–Save–Return’ framework and underscores developmental plasticity as a central mechanism in clonal plant responses to N deposition. These findings provide a new mechanistic insight into nutrient cycling in subtropical forests under global climate change. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Forests are one of the most important terrestrial carbon sinks, but are increasingly under pressure due to drought, heat and the occurrence of extreme events. There are opposing longer term trends for European forest growth reported, and severe drought and disturbance events additionally impact forest ecosystems, so that the overall trend of forest productivity is uncertain. Thirty years of harmonized forest monitoring at 18 forest sites along an altitudinal gradient in Switzerland provides a good basis for assessing the effects of climate change on forest conditions. We found a decreasing trend of forest productivity (basal area index and net carbon uptake by growth), particularly pronounced since 2015 across all altitudinal ranges, age classes and species, which could not solely be attributed to stand density and ageing of the forest, but also to soil water availability and nitrogen deposition. The growth rate of trees, as well as the ingrowth rate, were hereby the most important factors explaining the overall forest productivity. At a given stand density, forest productivity was lower in recent years compared to earlier decades. Overall, our results indicate a decreasing stand‐level growth trend irrespective of site conditions and stand structure. This 30‐year declining trend can be partly attributed to water and nitrogen availability, and points to a decreasing growth capacity of the forest sites that is the long‐term potential of a site to sustain tree growth. The pivotal role of water availability for sustainable forest production and the long‐term effect of drought years on forest vitality urges us to rethink the adaptability of forests in view of the increasing frequency of drought and heat periods predicted for the future. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Shrub encroachment into grasslands modifies ecosystem functions, species composition and soil properties. However, knowledge about its detailed below‐ground effects and specifically on concurrent changes in root traits and mycorrhizal associations is missing. We studied the effects of shrub encroachment on the herbaceous and the whole subalpine grassland community (i.e. including herbaceous and shrub species) in the Austrian Alps. We analysed changes in root traits and mycorrhizal associations, and their interactions, along two gradients of shrub cover, one dominated by deciduous and the other by evergreen dwarf shrubs. As shrub cover increased, in the herbaceous community root tissue density (RTD) increased, while specific root length (SRL), arbuscular mycorrhizal fungi (AMF) colonization and arbuscule abundance, where nutrient exchange occurs, all decreased. In the whole community, RTD unexpectedly decreased with shrub cover, as shrubs showed lower RTD than neighbouring herbaceous swards. The decrease in RTD, SRL, root diameter and AMF colonization was only compensated by a slight increase in the relative abundance of ericoid mycorrhizal fungi (ErM). Shrub encroachment in subalpine grasslands significantly modifies root traits and mycorrhizal associations. Herbaceous plants shift towards more conservative root strategies with increasing shrub cover. Concurrently, the whole community shows compensation between ErM and AMF colonization, while root resistance and soil exploration ability decrease. Our results suggest that changes along a gradient of shrub cover concern individual traits or trait–trait interactions, rather than following the ‘root economics space’ framework focused primarily on AMF. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Ecological communities are structured by a few common species, while most occur at low abundance. Understanding the drivers of this widespread pattern raises fundamental questions about community assembly rules and is important for applied ecology for identifying conservation targets. We used assemblages of phyllostomid bats to answer the following questions: (i) Does a higher divergence of morphological traits and functional hypervolume from the assemblage explain the prevalence of low‐abundance species? (ii) What is the relative importance of single functional traits and functional hypervolume divergence to explain such patterns? We sampled phyllostomid bats across an urban–rural landscape and estimated species abundance, measured key morphological traits, and calculated functional hypervolumes. We then applied a Bayesian causal inference framework to identify the drivers of abundance. The divergence of functional hypervolume, flight performance, and food acquisition traits had a negative impact on the abundance of the species. This pattern holds whether assessing aggregated species abundance or when considering spatiotemporal variation in assemblage structure, implying that low‐abundance species had functional hypervolumes and morphological traits more divergent from the assemblage average. Species ranked at the quantile intervals 0%–25% and 25%–50% of abundance occupied hypervolumes 45.9% and 46.8% more divergent compared to species ranked at Q 75%–100%. Similarly, the species at Q 0%–25% and 25%–50% exhibited a 59.5% greater divergence in morphological traits compared to common species. Such divergence on specific traits and intraspecific functional space from the assemblage centroid can result in a substantial reduction (13%–57%) in species abundance. Our results indicate that low‐abundance species are linked to their trait and hypervolume functional divergence. We propose that the position of the species in the functional space and the divergence of sensory‐ and vagility‐related traits are factors that determine the structure of bat communities, which denotes niche axes that have likely been narrowed at the current human‐dominated habitat. Our findings emphasize the importance of low‐abundance species, as they occupy unique ecological niches and likely contribute to specific ecosystem processes. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Seed dispersal plays a central role in plant ecology and evolution, and understanding its variation is key to predicting species demography and range dynamics. However, dispersal is difficult to measure, and most modelling and field studies assume uniform dispersal within species, ignoring individual variation. Yet dispersal potential can differ strongly among individuals within species. More empirical data at the individual level are therefore needed to quantify the magnitude of intraspecific variation and its ecological underpinnings. We developed a wind dispersal trial to capture full individual seed dispersal distributions for 107 Arabidopsis thaliana genotypes originating across the species' European range. We used these data to (1) assess variation in seed dispersal patterns via dispersal kernel, (2) estimate dispersal kernel heritability, (3) identify how strong and widespread are the major phenotypic drivers of intraspecific variation in dispersal kernel, including (4) the relative contribution of intra‐individual versus inter‐individual phenotypic variation and (5) test whether spatial, demographic or environmental factors structure dispersal traits. Dispersal kernel properties, mean distance, skewness, kurtosis and standard deviation, varied significantly across genotypes and showed considerable heritability. These components were not uniformly controlled by the same set of traits. Mean distance, skewness and kurtosis that reflect aspects of average and longer distance dispersal were primarily driven by a few tightly linked traits, especially plant height and fecundity. In contrast, standard deviation (SD), which captures the variability in dispersal distance, was influenced by a broader and more complex set of predictors, including within‐individual variation in seed roundness and seed size. We found no clear geographic or demographic structure of dispersal kernel properties. However, SD, which is related to post‐dispersal sibling distance, was significantly associated with environmental unpredictability, suggesting it may represent an environmentally responsive and potentially adaptive strategy. Our findings reveal that, even within a single species and dispersal mode, dispersal varies substantially and is shaped by distinct trait dimensions. We highlight the need to account for intraspecific variation in seed dispersal potential and suggest that incorporating variation in kernel properties or the underlying trait complexity could improve predictions of species spread, persistence and adaptive capacity in changing environments. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Ecological communities are stressed by rapid and complex anthropogenic changes, threatening the persistence of biotic interactions and ecosystem functioning. Plant–pollinator communities, for instance, undergo structural transformations as a result of land‐use change, species invasion and climate change. By experimentally investigating changes of interaction networks over time, caused by anthropogenic disturbances, we will be able to better understand the underlying ecology and predict our impact on communities. Here, we used a long‐term community field experiment involving nitrogen (N) addition to investigate the impacts of anthropogenic N enrichment on seasonal dynamics of a N‐limited, fast‐changing ecosystem: alpine meadows on the Tibetan Plateau. Given the brief flowering season and pollinators' phenophase of alpine meadows, we were particularly interested in understanding how N‐induced changes in flowering communities alter plant–pollinator interactions assembly and disassembly over the season, which ultimately shapes network structure and defines ecological resilience of communities. We found that N‐induced declines in floral abundance and richness resulted in an increase in pollinator species turnover over the season. This, in turn, affected natural interaction rewiring processes among temporally persistent species, suggesting a markedly lower seasonal connectivity and persistence of plant–pollinator interactions in meadows with high N input. Importantly, we found that the effects of N on interaction dynamics were particularly strong late in the season, suggesting heightened vulnerability of plant–pollinator interactions to N enrichment during this period. N‐induced changes in plant–pollinator interaction dynamics further disrupted the structure of pollination networks in natural alpine meadows through reduced specialization and modularity, which suggests that pollinators interact with plants more opportunistically over time, resulting in more simplified and homogenized communities under high N input. By considering temporal dimension, our study demonstrates that anthropogenic N enrichment can interrupt seasonal connectivity and stability of plant–pollinator networks, providing novel insights into how and why anthropogenic environmental change affects multi‐trophic interactions in vulnerable alpine ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Plant‐ and microbial‐derived residues constitute the primary sources of soil organic carbon (SOC) in grassland ecosystems. However, their differential responses to chronic nitrogen (N) enrichment and the depth‐dependent mechanisms governing their accumulation remain poorly characterized, particularly for water‐limited grassland systems. Based on a 13‐year field experiment in a semiarid grassland, we quantified the effects of long‐term N addition on the accumulation of plant‐ (lignin phenols) and microbial‐derived (amino sugars) residues. We found that N addition significantly increased lignin phenol content and its contribution to SOC in the topsoil, whereas lignin phenols exhibited a hump‐shaped response peaking under moderate N levels in the subsoil. Amino sugar concentrations and their relative contribution to SOC increased in both soil layers under N addition but declined at the highest N input. The dominant factors regulating residue accumulation varied with soil depth: in the topsoil, microbial K −/ r ‐traits and community composition primarily explained lignin phenol and amino sugar dynamics, while in the subsoil, mineral‐associated protection and microbial composition were the key drivers. These findings underscore the depth‐dependent nature of SOC formation pathways and highlight the importance of incorporating both plant‐ and microbial‐derived residues into Earth System Models to improve projections of carbon‐climate feedback under changing nitrogen regimes. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Mangrove forests are important blue carbon ecosystems, yet long‐term above‐ground biomass (AGB) dynamics in arid deltaic systems remain poorly understood. Here, we integrated field‐derived AGB data with multisource remote sensing and machine learning models (random forest, gradient‐boosted regression tree, support vector regression and classification and regression trees) to map historical patterns and predict future AGB dynamics in the Indus Delta mangroves for 2030, 2040 and 2050. AGB increased significantly over time, with mean values rising from 18.13 ± 9.1 Mg/ha in 2002 to 25.75 ± 8.32 Mg/ha in 2022, as indicated by Mann–Kendall trend analysis. Among models, GBRT performed best ( R 2 = 0.65, RMSE = 0.52) and projected continued increases in AGB to 30.31 ± 4.8 Mg/ha in 2030, 40.12 ± 6.4 Mg/ha in 2040 and 48.6 ± 7.9 Mg/ha in 2050. AGB was positively associated with vegetation indices and negatively related to land surface temperature and land‐use change. Synthesis . Mangrove AGB in the Indus Delta is increasing and is projected to continue rising under current conditions, highlighting substantial carbon sequestration potential in arid coastal systems. The strong performance of machine learning models demonstrates their utility for large‐scale biomass prediction, while the observed environmental controls emphasize the importance of sustaining freshwater input, sediment supply and restoration efforts for long‐term ecosystem resilience and blue carbon management. Read the free Plain Language Summary for this article on the Journal blog.

Abstract In brood‐site pollination mutualisms, where flowers provide nutrition and shelter to pollinator offspring in exchange for pollination, resource allocation to inflorescences is directly related to plant and pollinator fitness. We determine resource allocation to components of an enclosed monoecious Ficus inflorescence or syconium that, besides seeds, also houses and provides nutrition to pollinator wasp offspring, each developing within individual uniovulate galled flowers. Besides biomass, we determine elemental concentrations as parameters of resource allocation. For the first time, we apply the biogeochemical niche (BN) concept to a mutualism and construct the BN of syconial occupants using the elementomes and stoichiometric ratios of plant, seed and pollinator tissue. We predicted that BNs of seeds and galls containing wasps should differ due to differences in tissue type, facilitating their co‐development. We also measure trophic stoichiometric ratios (TSRs) for various elements to determine resource mismatch between consumers and resources. We found that the syconium wall, which insulates and protects developing seeds and wasps, constituted 58% of syconial biomass. Individual pollinators and their galls were significantly heavier than seeds indicating that their development is resource‐intensive. As predicted, seeds and adult female pollinators had significantly different BNs, highlighting differences in nutritional needs of these mutualistic occupants within a shared nutrient‐providing resource. Pollinators had significantly lower C:N and C:P ratios than the syconial wall indicating limitation of N and P within host resources. The BN of pollinator wasps was distinguished by significantly higher concentrations of nitrogen, phosphorus, zinc and sulphur compared to the syconium wall or seeds. TSRs of >4 for nitrogen and sulphur highlight the heightened resource mismatch that pollinators likely face for these elements during their development. We found no overlap in the BNs of male and female pollinator wasps, likely due to their starkly different anatomical and functional traits. Overall, our study demonstrates how BNs and TSRs can reveal trading of resources within mutualisms highlighting non‐overlapping requirements for elements and the potential limitations they can pose for resource providers and consumers. These parameters can serve as common currencies for comparisons across mutualistic interactions. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Amphibians are frequently identified as highly vulnerable to climate change, yet the mechanisms driving this sensitivity remain uncertain. Approaches that explicitly link physiological mechanisms to environmental variation provide powerful tools for forecasting climate vulnerability. However, their reliability depends on assumptions that accurately reflect the conditions amphibians experience in nature. Here, we evaluate the physiological mechanisms most often invoked to explain amphibian climate vulnerability, including overheating, desiccation, energetic constraints and seasonal dormancy and assess the ecological realism of current modelling frameworks. We show that broad‐scale assessments often overlook widespread behavioural buffering, such as nocturnal activity, subterranean refuge use and close association with saturated microhabitats, which substantially reduce exposure to extreme temperatures and water loss. We also identify opportunities to improve mechanistic models by incorporating microclimatic heterogeneity, behavioural avoidance of stressful conditions and hydric landscape dynamics. Doing so will clarify when and where climate change poses a true physiological threat and provide greater insight into the processes shaping amphibian extinction risk. Grounding mechanistic forecasts in ecological reality is essential for avoiding mischaracterization of risk and for directing limited resources towards amphibian research, species and regions most in need. Read the free Plain Language Summary for this article on the Journal blog.