Abstract While ecological dissimilarity plays a critical role in biological invasions, it remains unclear whether ecological differences between alien species and co‐occurring species in their native range persist after introduction. Leveraging the unidirectional introduction of plant species native to the Mediterranean into California, we conducted a cross‐continental study to examine whether Mediterranean‐origin species are phylogenetically and functionally distinct from co‐occurring species in their native range, and whether these differences are maintained relative to California native species after introduction. Mediterranean‐origin species introduced to California were phylogenetically and functionally distant from co‐occurring native species in both native and introduced ranges. They also exhibited distinct patterns of trait coordination between stress tolerance‐related traits (e.g., leaf dry matter content) and resource acquisition‐related traits (e.g., leaf nitrogen concentration and specific root length), and a more acquisitive strategy across ranges. Synthesis . These findings suggest that ecological dissimilarity and persistent trait coordination of species in their home range may contribute to their establishment after introduction, highlighting the value of native‐range trait information for understanding invasion functional strategies in novel environments.
Abstract Ombrotrophic bogs, which store large amounts of carbon as peat, receive all their mineral nutrition through deposition. This limited nutrient input means they are particularly sensitive to local and global changes that displace vital cations. We review how acid deposition drives cation displacement (i.e. sodium, magnesium, potassium and calcium) in ombrotrophic bogs. We then synthesise the literature across scales of ecological organisation on the role of cation availability in shaping plant stoichiometry and function, community dynamics and ecosystem function. Acid deposition from industrialisation drives declines in cation concentrations in peat, and although recovery is underway, cations remain depleted in acid‐affected areas. Cation depletion could cause decreased Sphagnum spp. growth and decreased plant diversity. There is higher uncertainty in how cations contribute to ecosystem processes. Future trends will likely be dictated by climate change‐driven increases in marine deposition, which will increase cation concentrations in maritime bogs and alter ecological processes across scales. Synthesis . There is limited yet compelling evidence that cation availability is a key determinant of ecological processes across scales. We propose a research agenda to understand how past and future changes in cation availability may alter carbon cycling in bogs and explore potential management.
Abstract The terrestrial carbon sink depends not only on how much biomass forests accumulate, but also on how long that carbon remains stored in vegetation. This is known as vegetation carbon turnover time ( τ veg ), which varies with forest age, structure and climate. Furthermore, τ veg is widely expected to decline under climate change as warming and disturbance accelerate biomass loss. However, most evidence comes from mature forests, even as global forest demographics shift due to reforestation, disturbance and land‐use change. Younger forests differ in growth rates, mortality patterns and stand structure, which may create distinct turnover trajectories with rapid biomass accumulation potentially slowing τ veg . Here, we evaluated this possibility using 17 years of in situ data from a network of temperate, subtropical and tropical forest plots across China. We found that τ veg declined over time in mature forests but increased in younger ones. These opposing trends were shaped by age‐specific trade‐offs between growth and mortality, mediated by stand structure and environmental conditions. Synthesis . Our results demonstrate that forest age strongly influences vegetation carbon turnover and must be integrated into models to improve predictions of terrestrial carbon sink dynamics.
Abstract Successful large‐scale biological invasions require introduced species to either rapidly adapt to a broad range of—partly novel—environmental conditions, or to possess a high level of phenotypic plasticity. Replicated common garden experiments across the introduced range provide a powerful framework to investigate these complementary mechanisms. To better understand population differentiation, adaptation and plasticity of invasive Japanese knotweed ( Reynoutria japonica ) in Europe, we compared the performance of knotweed plants from 46 European populations, collected across a 2000 km latitudinal transect, in three common gardens with contrasting climatic conditions, one at the southern edge, one in the centre and one at the northern edge of the species' European distribution. The plants exhibited strong phenotypic plasticity across the three gardens, with a more acquisitive growth strategy in the southern garden, and a more conservative strategy and change of architecture in the climatically unfavourable north. Although we observed phenotypic selection on several leaf traits, with some differences in selection between the gardens, we found little evidence for population differentiation or local adaptation, that is variation in plant performance was not negatively related to climate or geographic distance. Greater plasticity in leaf thickness across gardens was linked to the production of fewer but larger shoots, indicating a trade‐off between growth and clonal expansion. In addition, populations from higher latitudes and regions with greater inter‐annual temperature variability displayed increased plasticity in shoot volume and shrubbiness, but reduced plasticity in shoot number. Synthesis . Our results suggest that local adaptation has not played a key role in the success of Japanese knotweed in Europe. Instead, its high overall phenotypic plasticity (‘general purpose genotype’), as well as evolutionary fine‐tuning of plasticity, may have contributed to the species' invasion success across a broad range of environments.
Abstract In even‐aged tree stands, asymmetric competition for light usually leads to clear dominance structures. However, it is unclear whether the differences in individual tree size develop gradually or manifest themselves very early on, that is in the year of germination, and whether formerly suppressed trees can rise in rank while dominant trees fall. Using two experimental plots in which European beech ( Fagus sylvatica ) seeds were sown under the canopy of mature Norway spruce ( Picea abies ) trees in 1997, we studied the survival and height development of 2214 numbered seedlings on 324 subplots (0.5 m 2 in size) over a period of more than 25 years. We found that the survival probability of the tallest individuals at their seed site in the year of germination was significantly higher than that of smaller plants. We further found that these early dominance structures became increasingly consolidated over the years, reducing the mortality risk of the dominant trees. In a supplementary seed experiment, we showed that the height growth and biomass production of seedlings achieved in the first vegetation period depended largely on seed mass. Synthesis . Our study illustrates how intense intraspecific competition processes operate at very early developmental stages among even‐aged tree cohorts, following the general pattern of self‐thinning. We showed that the underlying dominance structures develop surprisingly early and that they persist. Our study also clearly indicates that dominance reversal, that is the fall of formerly dominant trees to lower ranks and the rise of formerly suppressed trees to the dominant layer, occurs infrequently, at least in the first 25 years of an even‐aged cohort.
Abstract Despite significant stochasticity, the occurrence of disturbance events is co‐determined by general ecological rules, such as temperature gradient with increasing altitude or stronger wind loads on slopes. A detailed understanding of past disturbance dynamics and their driving forces forms a crucial foundation for ensuring the sustainability of forest ecosystems. This is particularly important in the context of shifting disturbance regimes under accelerating climate change. The exceptionally well‐preserved Bohemian Forest Ecosystem, the largest contiguous forested area in Central Europe, provides a unique archive for studying past disturbance dynamics. Here, our objective is to clarify the ecological nature of disturbance phenomena to improve our understanding of forest ecosystem development. Using an extensive dendrochronological dataset of more than 7600 tree‐ring series distributed across diverse ecological gradients, we developed a unique transboundary disturbance chronology extending back to the early 17th century. Generalized linear mixed‐effects models were applied to assess relationships between environmental factors and disturbance regimes. Our results provide evidence of a slow but persistent acceleration of disturbance processes over the past 400 years. Elevation emerged as the strongest predictor of disturbance frequency. The likelihood of forest stand disturbance generally rises as altitude decreases, reflecting interspecific differences in morphological traits and elevation‐dependent tree‐growth potential. Forest type and aspect further modulated this effect, emphasizing the influence of local topography on the susceptibility to disturbances. Natural disturbance dynamics vary across the forest types rather than occurring in synchrony, thus promoting high disturbance complexity and forest landscape heterogeneity, particularly in primary forests. Synthesis . Under climate change and the underlying shift in the tree species composition, a higher probability of disturbances can be anticipated in mixed forests at lower elevations. However, our findings highlight the importance of maintaining the diversity of natural processes in supporting the resilience of forest communities to extreme and unpredictable disturbance events, thereby contributing to climate change mitigation.
Abstract Alpine treeline ecotones, where forests transition to alpine ecosystems, display a variety of spatial patterns. These patterns, or treeline forms, are considered indicators of the processes that control treeline dynamics and may provide insight into future abundance, distribution and stature of tree species in montane ecosystems. However, consistent links between treeline forms and proposed variation in the relative strength of controlling processes are not well established. We examined whether the processes expected for krummholz island treelines (one specific treeline form) under the treeline pattern‐process framework operate at a treeline in Newfoundland, Canada. For this form, the framework hypothesis states that recruitment is limited, with changes in tree cover dependent on facilitation by established trees or krummholz. Additionally, it is hypothesized that growth and dieback limit adult tree statures, thereby causing established trees to form krummholz. To assess the effects of established individuals on recruitment, we transplanted black spruce ( Picea mariana ) and tamarack ( Larix laricina ) seedlings along transects leading from established krummholz islands (presumed facilitators) into alpine heath (presumably lacking facilitation) and monitored their survival. To explore biomass maintenance limitations among established, adult individuals, we quantified the presence and distribution of emergent stems extending above the krummholz mat. Seedling survival was high and despite changes in microsite conditions with distance from established individuals, we found no trends in survival. Assuming recruitment at other life stages is not limiting, tree cover may increase not only through the expansion of krummholz islands but also through the infilling of open vegetation patches. We observed that stems within krummholz islands were similar in height regardless of their position within the island, suggesting that their ability to maintain biomass is more likely driven by climatic conditions than sheltering from neighbouring individuals. This could indicate that this treeline may be undergoing krummholz release, a shift from stunted towards upright forms. Synthesis : Our study highlights a potential limitation of the treeline pattern‐process framework: spatial patterns represent snapshots of dynamic systems. Monitoring treeline populations will advance understanding of how treeline form develops and changes in response to climate change.
Abstract Boreal forests are integral for the maintenance of multiple ecosystem services to humanity, yet climate change, wildfire regimes and land‐use intensification are rapidly driving these conifer‐dominated systems towards a boreal‐temperate ecotone, characterized by a mixture of conifers and broadleaves, with uncertain implications for sustaining multiple ecosystem functions (i.e. multifunctionality). Here, we conducted a standardized 34‐year field manipulative experiment in a boreal‐temperate ecotone region of Northeast Asia, including four monocultures (conifers and broadleaves) and four two‐species mixed forests (each combining coexisting broadleaf and conifer trees). We aimed to assess the ecological impacts of these forest transitions in the boreal‐temperate ecotone. Our results showed that ecosystem multifunctionality depended strongly on tree species composition. Crucially, specific compositions generated distinct functional trade‐offs rather than uniform changes in ecosystem multifunctionality. For example, transitioning to incompatible mixed‐species stands maintained provisioning functions like wood production but resulted in significant reductions in critical regulating services, such as soil carbon sequestration, nutrient cycling and water regulation. We further provide evidence that these functional declines were mechanistically driven by selection effects that superseded niche complementarity. Specific tree compositions imposed constraints on soil resources and microbial properties, strongly influencing ecosystem services in the boreal‐temperate ecotone. Synthesis : This research provides new insights into identifying species compositions that enhance ecosystem services in the boreal‐temperate ecotone, thereby guiding climate change mitigation and forest management efforts in these sensitive regions.
Abstract Studying how global change factors influence plant‐consumer interactions (i.e. interactions with herbivores and pathogens) enables us to predict the future responses of plant communities to global change. We aimed to determine the direct and indirect effects of global change on plant‐consumer interactions of Plantago lanceolata (ribwort plantain). In experimental grassland plots exposed for 10 years to elevated CO 2 concentrations (+300 ppm), warming (+3°C), drought and their combinations, we measured leaf traits of P. lanceolata , including leaf dry matter content, specific leaf area, carbon‐to‐nitrogen ratio, leaf toughness, phenol concentration and the concentrations of other secondary metabolites. We quantified field consumption damage as the % leaf area affected, distinguishing between types of herbivore and pathogen damage. A laboratory pairwise choice experiment examined the feeding preferences of Locusta migratoria (migratory locust) for leaves sampled from the different global change treatments. Elevated CO 2 , warming and drought affected plant‐consumer interactions of P. lanceolata both directly and indirectly, the latter being mediated by shifts in plant traits. For instance, warming directly favoured powdery mildew infection and sucking damage, and indirectly increased sucking damage by reducing the concentration of a flavonoid glycoside. Plant traits were not influenced by interactions between global change factors, but consumption damage was—warming increased sucking damage under ambient precipitation but not under drought, and elevated CO 2 decreased chewing damage under ambient temperature but not under warming. Synthesis : Warming, elevated CO 2 , drought and their interactions had direct and indirect (plant‐trait‐mediated) effects on field plant consumption and feeding preferences of the locust L. migratoria . The effects, however, largely differed between different consumption types, despite all being studied on the same species in the same system, highlighting the complexity of these interactions. Future studies should thus avoid excessive generalizations and attempt to study a broad range of plant traits and consumers under realistic, multifactorial global change conditions.
Abstract Plant invasions pose a threat to native biodiversity and are often mediated by below‐ground processes such as plant–soil feedback. Because induced defence responses can alter interactions between plants and soil biota, the strength may depend not only on plant origin but also on whether defence pathways have been activated during soil conditioning. We tested how induced resistance mediated by jasmonic acid and salicylic acid in conditioning‐phase plants influences soil‐legacy effects on five pairs of native and naturalized alien focal plant species. In the conditioning phase, we grew the 10 focal species and 5 additional nonfocal native species. To activate defence pathways that are naturally induced by herbivores and pathogens, we sprayed them with jasmonic acid, salicylic acid or water (control). Thereafter, the five pairs of focal species were planted on the conditioned soils to test soil‐legacy effects. Conditioned soils, particularly conspecific soils, pronouncedly reduced focal plant growth. In the absence of resistance induction in conditioning‐phase plants, native focal plants suffered stronger growth reductions than naturalized aliens. However, resistance induction largely mitigated this disadvantage, reducing differences in performance between native and naturalized alien plants. Synthesis . Our findings indicate that induced resistance can reshape soil legacies that reduce the disadvantage of native plants relative to aliens, revealing an overlooked mechanism through which defence pathways interact with soils to influence plant invasions.
1. Kelp forests are foundation habitats that create structurally complex and biodiverse marine ecosystems, yet their extent and ecological integrity are increasingly threatened by rising ocean temperatures and the resulting tropicalisation of temperate coasts. Quantitative assessments of these changes remain very limited, and understanding them is particularly critical in climate transition zones, where ecological shifts can be rapid and pronounced. 2. We conducted a 5-year (2020-2024) survey for kelp-fish communities at four representative regions along similar to 600 km of the Iberian coast (n = 450 transects), spanning a gradient of current and projected tropicalisation. The analysis focused on how kelp species identity and abundance, local sea surface temperature (SST) and reef-fish assemblage characteristics influence fish population metrics and the community temperature index (CTI). 3. In total, 53 fish species and 4 species of kelps were found. Perennial kelp composition closely followed the SST gradient, with the boreal kelp Laminaria hyperborea dominating in cooler sites (Coruna and Viana), whereas the Lusitanian kelp Laminaria ochroleuca prevailed in warmer sites (Vigo and Peniche). Coruna displayed the highest kelp diversity and abundance, while the southernmost Peniche exhibited the highest fish diversity. 4. Kelp-abundant regions exhibited lower fish CTIs than expected from local SST, suggesting a potential canopy buffering effect against tropicalisation. In contrast, Peniche, with lower kelp abundance, showed minimal CTI-SST offset, higher proportions of warm-affinity taxa and the greatest fish diversity, indicating a more advanced tropicalisation stage. 5. Synthesis. Our spatially resolved benchmark indicates that abundant kelp cover can delay tropicalisation by lowering the realised thermal affinity of reef-fish communities, while increases in fish biodiversity may signal the early stages of this process. These results underscore the dual role of kelp forests as biodiversity reservoirs and climate buffers, and provide a transferable framework for understanding how foundation species mediate community responses to ocean warming across ecosystems. Safeguarding and restoring kelp forests should therefore be a priority for sustaining temperate-reef resilience under climate change.
Understanding the role of functional traits in shaping plant phenology is crucial for understanding how organisms adapt to changing environmental conditions. As climate change alters seasonal timing and disrupts ecological interactions, identifying relationships between phenology and traits is essential for predicting species' responses and potential mismatches. While vegetative traits such as plant height and leaf area are often associated with phenological variation, floral traits, which are closely linked to reproductive success, remain largely unexplored, despite their potential to significantly influence phenology. This study aims to understand the relative influence of floral and vegetative traits on patterns of species-specific phenological variation. We monitored the year-round phenology (initial growth, leaf out, onset, peak, end and duration of flowering, fruiting and senescence) of 68 herbaceous perennial plant species in three German botanical gardens (Halle, Jena, Berlin). We measured four vegetative traits-plant height, leaf area, specific leaf area (SLA) and leaf dry matter content (LDMC)-as well as 12 floral traits related to flower morphology, flower number, nectar and pollen, with all measurements conducted for each species in each garden at flowering time. As a basis for the inclusion of floral traits in studies on phenology-trait relationships, we used these data to analyse underlying trait correlations and trade-offs between floral and vegetative traits. Analysis of boosted regression trees that accounted for phylogenetic dependence of the species showed that vegetative traits, especially vegetative height, were most important for explaining patterns in reproductive and vegetative phenology. Taller plants showed later initial growth and later flowering and fruiting compared to smaller plants, and higher LDMC was associated with later senescence. Floral traits had an additional relative influence on phenological patterns but were of minor importance overall. Synthesis: Our study confirms that vegetative traits offer a robust explanatory framework for phenology, while also emphasizing the value of considering both vegetative and floral traits in understanding these patterns. Our findings offer a basis for exploring the functional relevance of rarely measured floral traits, such as pollen traits, within the plant economic spectrum and in plant-pollinator interaction studies.
Browsing by ungulates directly influences understorey plant communities through selective removal of certain species and indirectly by modifying plant competition, environmental conditions and successional dynamics. In Central Europe, roe deer (Capreolus capreolus) are the most widely distributed ungulate species forming locally dense populations. Understanding the effects of roe deer is essential for sustainable forest management, particularly in the context of changing environmental conditions such as increased tree mortality and expanding canopy gaps. To disentangle the direct effects of roe deer from indirect environmental modifications, we investigated the herb layer (vascular plants <1 m), shrub layer (woody plants 1-6 m) and environmental variables inside and outside 75 exclosures (6 m & times; 6 m) in a temperate mixed deciduous forest in Central Germany. These exclosures were located either under a closed canopy (n = 54) or within experimental gaps (n = 21) and were surveyed 5 years after their establishment. Roe deer increased herb layer species richness overall, but reduced functional diversity in closed forests. Canopy gaps decreased herb layer species richness but increased shrub layer cover. Soil pH was independently positively associated with herb layer species richness, but not with functional diversity and to a lesser extent with shrub layer cover. Structural equation models showed that canopy gaps increased light availability 1 m aboveground, but this effect was counteracted by already increased shrub layer cover. By reducing shrub layer cover, roe deer indirectly increased herb layer species richness. Roe deer presence directly reduced herb layer functional diversity, but also indirectly mitigated this negative effect by lowering shrub cover and thereby increasing light availability. Synthesis. Forest gaps primarily reshape herb layer composition by increasing light availability and shrub layer encroachment. Roe deer influence herb layer community assembly both directly and indirectly via modification of the shrub layer and light availability and thus shifting plant-plant competition. These findings emphasize the complex role of browsers in structuring herb layer communities and help to understand how changes in roe deer populations and canopy gaps will shape the future of temperate European forests.
Abstract We propose that transgenerational epigenetic inheritance (TEI), the transmission of environmental memories across generations, functions as an epigenetic engine for rapid adaptation to environmental changes. We argue that this engine serves a dual purpose: it acts as a direct, powerful mechanism for phenotypic adaptation to sudden environmental changes and as a transient bridge that maintains population viability, buying time for genetic rescue. We synthesize evidence that small RNAs, DNA methylation, and histone modifications form a coordinated circuit that converts environmental cues into stable phenotypic memories. The output of this engine is calibrated based on environmental predictability, which typically leads to adaptive outcomes. Scaling these mechanisms reveals their ecological reach: transgenerational memory reshapes species interactions and, through the transgenerational ecosystem legacy hypothesis , links epigenetic priming to nutrient cycling regimes. We introduce the dynamic clutch framework , in which TEI acts as a transient coupling between phenotypic memory and evolutionary change, facilitating short‐term ecological rescue while modulating the pace of genetic adaptation. Synthesis . By integrating molecular, ecological, and evolutionary principles, this review provides a predictive framework for understanding and harnessing non‐genetic inheritance in a rapidly changing world.
Making predictions about the persistence of plant populations under climate change requires explicitly incorporating environmental drivers into population models. However, local density and demographic processes, including reproductive trade-offs, that may influence how populations respond to environmental drivers are rarely incorporated into these models. For plant species that reproduce both clonally and sexually, trade-offs between reproductive modes can have important demographic consequences, affect the strength of density dependence and ultimately influence population-level responses to climate. We used a manipulated rainfall experiment (experimentally imposed drought and irrigation) across 4 years on an in situ population of a long-lived forb, Primula hendersonii, to examine the influence of rainfall, seasonal variation in ambient temperature and local conspecific density on: (1) demographic rates (survival, growth, sexual and clonal reproduction), (2) trade-offs between clonal and sexual reproduction and (3) density-dependent population growth. In addition to observed density in the field experiment, we paired a manipulative density and watering experiment in pots to confirm the observational effects of density on demographic rates. We detected a reproductive trade-off where prior flowering reduced the probability of making clonal offspring, but prior clonality did not affect future flowering. Clonality was also lowest for plants growing at high density. When these effects were scaled to the population level using integral projection models, population growth rates were reduced when flowering did not reduce clonal reproduction (no trade-off), at high density and under simulated drought. Manipulated density in a separate pot experiment resulted in a similar negative effect of local conspecific density on clonal reproduction compared to field observations, as well as for plant growth under both ambient and reduced water availability, supporting that density effects can be detected in observational demographic datasets where environmental drivers are explicitly examined. Synthesis. Our results demonstrate that interactive effects of clonal reproduction and intraspecific density are important contributors to plant demography and that high local density increases the negative impact of drought on population growth rates. We show that quantifying density-dependent responses to climate while considering the role of clonal reproduction is necessary to understand the consequences of future climate conditions.
Precipitation change is an important component of the ongoing climate change and substantially influences terrestrial nutrient and carbon (C) dynamics. However, the mechanisms by which increasing precipitation affects plant-microbial nitrogen (N) assimilation and ecosystem C and N retention remain unclear. Using isotopic tracing along a manipulated precipitation gradient in a water- and nutrient-limited alpine ecosystem, we investigated how increasing precipitation alters plant nutrient strategies, plant-microbial N partitioning and ecosystem C and N retention. Increased precipitation enhanced plant and microbial N assimilation, ecosystem N retention and plant C fixation. However, these effects were not consistent across ecosystem components. Increasing precipitation progressively promoted grass-forb ratio and community-level acquisitive root traits, whereas mycorrhizal colonization was greatest at intermediate precipitation. Plant biomass C and N accumulation remained responsive across a broader portion of the precipitation gradient than did microbial N assimilation, thereby shifting plant-microbial N partitioning. Structural equation modelling indicated that the plant pathway plays a stronger role than the microbial pathway in mediating the effects of increasing precipitation on ecosystem N retention and C fixation. Our findings suggest that ecosystem responses to increasing precipitation depend on how different biotic components respond and interact. Synthesis: Increasing precipitation reshapes plant-microbial nutrient partitioning and ecosystem C and N retention in alpine ecosystems. Our findings highlight the need to account for non-linear and contrasting responses among different ecosystem components when predicting the consequences of future climate change for alpine ecosystem functioning. This work contributes to providing a basis for tracking how alpine ecosystems may reorganize under future climate change.
Soil acidification and ion dynamics are pivotal in the decline of plant diversity and alterations in community composition resulting from nitrogen (N) deposition. Nevertheless, the intricate interactions among these factors pose challenges in discerning direct causal linkages. We investigated the direct and indirect effects of soil acidification on plant community in response to N enrichment by integrating field surveys with a series of microcosm experiments conducted in a temperate grassland. Prolonged N addition led to a decrease in the species richness and above-ground biomass of forbs. Microcosm experiments demonstrated that forb species exhibited a unimodal response in their shoot and root traits along N gradients, peaking at low N levels, whereas grass species showed a relatively broad threshold. Experimental manipulations that involved solely increasing hydrogen (H+) ions due to soil acidification had minimal effects on the growth of both forb and grass species. In contrast, simulated acidification, accompanied by concurrent ion alterations, particularly the accumulation of toxic metals, more significantly suppressed the growth of forb species compared with grass species. These results suggest that changes in soil cations, rather than H+ toxicity alone, are responsible for the decline of forb species in the community. Synthesis. These findings challenge the prevailing assumption that soil acidification is the direct cause of plant species decline in grasslands affected by N deposition. This study enhances our mechanistic understanding of ecosystem responses to N deposition and provides evidence-based guidance for grassland restoration under global changes.
Biodiversity can stabilize ecosystem functioning, yet this relationship is often weakened under environmental change such as nutrient enrichment. The mechanisms underlying this weakening remain unclear, particularly whether it arises from shifts in species that consistently contribute to community dynamics or from increased species turnover. Species that persist through time are expected to underpin stability by maintaining species stability and asynchronous dynamics, whereas transient species, characterized by low temporal occupancy, primarily contribute to compositional turnover with limited stabilizing effects. Disentangling the roles of these two groups may therefore explain how nutrient enrichment alters biodiversity-stability relationships. Using data from 49 grasslands with and without fertilization, we partitioned communities into persistent and transient species based on temporal occupancy. We quantified their respective contributions to community temporal stability and evaluated how fertilization altered the relationships between species richness, species asynchrony, species stability and community stability using structural equation models. Community stability was primarily driven by persistent species: communities with more stable and asynchronous persistent species exhibited higher temporal stability. In unfertilized conditions, species richness was positively associated with the stability and asynchrony of persistent species, as well as with the asynchrony between persistent and transient species, which were linked to higher community stability. Under fertilization, these pathways were weakened, as fertilization reduced persistent species stability and persistent-transient asynchrony, resulting in lower community stability. Transient species contributed little to stability in either condition and may obscure biodiversity-stability relationships when not explicitly accounted for. Synthesis. These results indicate that biodiversity-stability relationships are mediated predominantly by species that persist through time, consistent with theoretical expectations that invariability emerges from stable and asynchronous population dynamics. Nutrient enrichment weakens these relationships by disrupting the stabilizing role of persistent species rather than by increasing the contribution of transient species. Accounting for species temporal persistence thus provides a mechanistic basis for predicting how global change alters ecosystem stability.
1. Darwin proposed that competition should be strongest among close relatives because shared ancestry drives functional similarity and ecological overlap. Empirical support for phylogenetic effects on competition has been mixed, with some studies finding that congeners exclude one another and others documenting stable coexistence. This variation reflects differences in spatial scale and environmental context: At regional scales, demographic stochasticity and habitat heterogeneity can obscure competitive signals, whereas at local scales and under controlled conditions, competitive patterns may become detectable. Geographic distance may therefore provide complementary information about competition by capturing differences in adaptive history not fully reflected in phylogenetic relationships. 2. I tested three hypotheses linking evolutionary divergence and environmental context to competition among Quercus congeners: (i) distantly related species produce greater overall growth because they use resources differently and interfere less with each other; (ii) species from widely separated geographic regions show greater growth asymmetry because they evolved different competitive abilities under distinct selective pressures; and (iii) both effects weaken under drought stress, where water limitation constrains growth across lineages and reduces the influence of evolutionary history. 3. Eight Quercus species from Asia, Europe and North America were grown in pairwise combinations under wet and dry soil conditions in a greenhouse experiment. I quantified pair-level performance using an overall growth response metric (interspecific competition index) and relative performance within pairs using a growth asymmetry metric (competitive asymmetry index). Phylogenetic and geographic distances between species served as continuous predictors of both responses. 4. Overall growth increased with phylogenetic distance: Distantly related species produced more combined growth than close relatives. Growth asymmetry within pairs increased with geographic distance: Species from widely separated regions showed larger dominance hierarchies, with one species consistently outgrowing the other. Neither relationship was modified by the moisture gradient, indicating that these dimensions of evolutionary divergence influenced seedling competition independently of the soil water availability examined here. 5. Synthesis. Phylogenetic and geographic distances captured distinct dimensions of competition among Quercus congeners. Evolutionary divergence predicted how much biomass species produced together, consistent with distantly related species using resources differently. Geographic separation predicted which species dominated, consistent with species from different regions evolving different competitive abilities. The persistence of both relationships across moisture treatments suggests these historical dimensions shape seedling competition in ways robust to variation in water availability.
Nutrient resorption from leaves and translocation to twigs and other woody tissues during leaf senescence is a crucial strategy for plant nutrient conservation. The nutrients retained in twigs provide essential resources for new growth, especially when root nutrient acquisition is restricted by low soil temperatures during early spring. However, the interconnections between leaf nutrient resorption and twig nutrient accumulation during autumn, and their influence on spring phenology, remain poorly understood. We selected 20 woody species with a wide range of leaf traits in a common garden and investigated the relationships among leaf resorption efficiency, twig accumulation efficiency of nitrogen (N) and phosphorus (P), and autumn-spring phenology. We found that leaf N resorption (54.27%) was significantly higher than leaf P resorption (42.42%). Additionally, twig N accumulation efficiency (40.00%) was significantly higher than twig P accumulation (18.37%), with both positively correlated with leaf nutrient resorption efficiency. Species with acquisitive traits exhibited higher N and P resorption efficiency, along with higher P accumulation efficiency in twigs. Soil fertility had a relatively minor influence on both leaf nutrient resorption and twig nutrient accumulation. In addition, autumn and spring phenological events were linked to plant internal nutrient dynamics. Species with later leaf shedding and shorter leaf fall duration in autumn tended to exhibit greater leaf P resorption efficiency. Furthermore, species with higher twig nutrient accumulation efficiency showed earlier bud break and a longer period of leaf-out in the subsequent spring. Modular network analysis and structural equation model further indicated that leaf nutrient resorption was strongly related to leaf economic traits, while leaf nutrient resorption was indirectly linked to bud-break timing through twig nutrient accumulation. Synthesis. Our findings suggest that plant internal nutrient dynamics are not only consequences of phenology but may also influence phenological timing. These results highlight the importance of nutrient resorption and storage strategies in regulating seasonal growth patterns and indicate that internal nutrient cycling may affect plant performance and ecosystem functioning under varying environmental conditions.
