Question:Inferring community assembly mechanisms requires an understanding of the responses of plant communities to environmental gradients and spatial processes. In a tropical forest, we asked: (1) What environmental gradients are associated with variation in community functional composition and diversity? (2) How does explicitly accounting for spatial structure influence inference about these environmental effects? and (3) To what extent can the observed trait-environment relationships be explained by environmentally structured species turnover (i.e., changes in species composition along environmental gradients)? Location: A 30-ha Mo Singto old-growth tropical forest dynamics plot in Khao Yai National Park, Thailand. Methods:We applied a spatially explicit hierarchical Bayesian modeling (INLA-SPDE) framework to data from 135,000 woody plants, measuring eight functional traits and 24 environmental variables covering topography, soil nutrients, and canopy structure. The model estimates environmental effects while accounting for spatial autocorrelation in trait distributions. We further used null model tests to evaluate question (3). Results:Spatially explicit models identified topographic water availability (TWI) as the main environmental gradient associated with community-level trait patterns, aligning functional composition along the trade-off between acquisitive and conservative resource-use strategies. Inferences for several environmental variables changed substantially after accounting for spatial auto-correlation. Null model analyses indicated that most trait-environment relationships in the Mo Singto forest plot were consistent with environmentally structured species turnover, with only limited evidence for additional trait-environment associations, as shown by tree height. Conclusions:Our results indicate that when traits are represented at the species level, smaller-scale community-weighted mean (CWM) patterns are primarily explained by species replacement along environmental gradients. Our study also demonstrates that high-resolution, fully stem-mapped forest plots provide strong power to detect environmental signals and reveal spatially structured patterns in community functional composition. By combining spatially explicit models with null model inference, we show that robust interpretation of CWM trait-environment relationships requires jointly accounting for spatial structure and species turnover, which provides a clear framework for understanding how environmental gradients shape community functional patterns.
ABSTRACT Questions Wind is an understudied component of climate, with relatively few studies quantifying the effect of wind exposure on natural vegetation. Wind can, however, alter leaf microclimate, reduce soil water availability and physically damage plants, thereby influencing the growth of individual plants, with its effects potentially scaling up to affect plant community characteristics. The paucity of research assessing the relationship between wind conditions and plant communities' taxonomic and functional composition is a key gap in our understanding of environment–vegetation relationships in windy environments. Location Sub‐Antarctic Marion Island. Methods We test whether vegetation characteristics, including vascular plant species richness, composition, cover and functional traits, differ between the windward and sheltered sides of natural windbreaks. Results Wind exposure did not strongly affect vascular plant richness, cover or composition, with larger differences in these responses occurring between sampling sites than between windward and sheltered microsites. Wind most strongly affected maximum plant height (both for individual species and for the community), with significantly shorter‐statured plants observed in wind‐exposed microsites. In contrast, most species' leaf traits were unaffected by wind exposure, with only 21% of species–trait combinations differing significantly between microsites. In those cases, plants experiencing greater wind exposure had lower leaf area, specific leaf area or leaf dry matter content, with changes in leaf thickness varying among species. Conclusions Wind exposure did not strongly influence vascular plant community characteristics on Marion Island, apart from restricting vegetation height. Wind did, however, influence the occurrence and traits of some individual species, generally enhancing species avoidance or resistance to wind where its effects were significant. Broadly, these results indicate that wind can significantly influence plant size and some aspects of morphology, thereby reinforcing the need to explicitly consider wind as a potentially important climate variable, especially in habitats where wind is a prominent environmental factor and in areas where wind speeds are predicted to change.
ABSTRACT Aims This study aimed to extract the gradience of competitor, stress‐tolerators, and ruderals strategy types of plants in a wetland and examine the capacity of free multispectral Sentinel‐2 data to model and map these strategies. Location The study was conducted in the Gandoman Wetland in Iran. Methods We sampled 55 plots across the wetland and measured leaf area, fresh weight, and dry weight to compute the specific leaf area and leaf dry matter content of the plants to derive the competitor, stress‐tolerator, and ruderal strategies. Then, a partial least squares regression was used to model scores of these strategies that were derived from the plot‐level field data using Sentinel‐2A data. Results Our analysis accurately modeled the competitor, stress‐tolerator, and ruderal score with R 2 = 0.798, 0.665, and 0.545, respectively. A map of these strategies was derived by combining the predicted raster maps of competitor, stress‐tolerator, and ruderal values. The results corroborate previous findings based on hyperspectral data that these strategy types in wetland areas can be successfully mapped using multispectral Sentinel‐2 data. Conclusion The research discovered significant differences in ecological strategies among wetland plants in Iran, with competitive species in the center and ruderal species around the periphery. These findings agree with existing knowledge of the site and the known land use. Our study emphasizes the potential of multispectral satellite data to map competitor, stress‐tolerator, and ruderal strategy types to understand ecosystem functioning.
Questions: Wildfire in dry conifer forests of the western United States is becoming more severe, creating the potential for alternative ecosystem successional trajectories in the absence of intervention. We characterized understory plant communities across a burn severity gradient in a ponderosa pine (Pinus ponderosa) forest 5 years after a mixed-severity fire to ask whether community composition exhibits persistent change in response to high-severity fire. Location: Ponderosa pine understory community, Flagstaff, Arizona, USA. Methods: We evaluated differences in taxonomic composition and plant functional traits on 60 1-m2 subplots measured annually in September from 2020 to 2024. Plants were identified to the species level, and species cover was visually estimated. We used six plant traits: specific leaf area (SLA; mm2 g-1), height (m), seed mass (mg), resprouting ability, nativity, and plant functional group (grass, forb, shrub, and tree). Results: Taxonomic and functional composition of unburned, low-severity, and high-severity understory communities were significantly distinct from each other 5 years post-fire. As burn severity increased, larger proportions of the understory were occupied by forbs and woody plants. Exotic plants increased dramatically with increasing severity, from < 1% relative cover in the unburned plots to a maximum of 75% in the high-severity plots. Plant species with resprouting ability were more abundant in unburned and low-severity than in the high-severity plots. High-severity communities also had the highest SLA. Conclusions: Our findings reveal that high-severity fire can overwhelm the resprouting ability of native plants, leading the understories in these areas to be colonized and dominated by fast-growing and exotic plants 5 years following wildfire. The persistence of novel understory communities following high-severity fire highlights the need for fuel management and maintenance of prescribed fire, as well as prompt restoration action after severe wildfires to maintain composition and structure in these communities.
Questions Plant functional types (PFTs) represent distinct evolutionary solutions to environmental filtering. Although previous studies in specific sites/countries in the high Andes have examined changes in PFT structure along environmental gradients, a comprehensive analysis spanning the entire mountain range is lacking. We asked: (1) How do regional PFT pools and spectra vary among the P & aacute;ramo, Puna and high Andean Patagonia biomes and across alpine to nival elevation belts? (2) Do PFT richness, diversity and abundance show consistent latitudinal and elevation trends, linked to climate and substrate conditions?Location High Andes of South America.Methods We developed a PFT classification system based on their general morphological plan, applicable across the entire latitudinal and elevational range of the high Andes. Using this framework, we classified 716 species/morphospecies into 14 PFTs and analysed PFT cover, spectra and diversity for 65 summits in 17 study sites within the GLORIA-Andes network.Results PFT richness and diversity declined with increasing latitude and elevation. At higher elevations, tussock graminoids decreased in relative cover, whereas shorter PFTs such as cushions, rosette herbs and prostrate shrubs became more important. When cover was weighted by PFT species richness, some groups including erect herbs in the P & aacute;ramo and rosette herbs in the Puna increased their importance. Convergence in PFT composition and abundance was higher in alpine and subnival belts, whereas nival summits showed greater between-region heterogeneity. These patterns were linked to abiotic factors, with lower PFT richness and diversity associated with higher scree and rock cover and colder air temperatures, and with regional differences in precipitation seasonality.Conclusions High Andean summits exhibit distinct PFT spectra across latitude and elevation. Functional diversity diminishes under more limiting conditions: higher elevations and further away from the equator, while short-stature, cold-tolerant PFTs gain relative importance. Erect shrubs and erect, rosette and prostrate herbs were the PFTs with the highest number of species, increasing their relative importance in most communities when weighting PFT cover by richness. This study provides a functional baseline for understanding and comparing community responses to climate change across the high Andes.
ABSTRACT Aim Long‐term vegetation study through resurveys is essential for quantifying how biodiversity changes over time. The accuracy of resurvey data is influenced by plot relocation errors, arising from the spatial uncertainty of historical plot locations. Preferential location of resurvey plots potentially underestimates vegetation change in time, whereas random location may overestimate it. To address these methodological issues, we compared preferential and random relocation approaches to assess how plot location error influences observed temporal vegetation changes, focusing on diversity patterns across two common grassland types in Central Europe. Location Northeastern Austria and the southern Czech Republic. Methods We compared two methods for locating plots in resurveys at 50 sites along the Austrian‐Czech border: (a) resurvey plots located preferentially by the surveyor in the field in a place with vegetation similar to that described in the historical plot and (b) resurvey plots located randomly within a 300‐m spatial buffer around the probable location of the historical plot, within the same land‐cover type. We then compared changes in species richness, composition, and Ellenberg‐type indicator values between the two resurvey plot location methods. Results Across the entire dataset, species richness change and the Jaccard dissimilarity index were lower in the preferentially located than in the randomly located plots, while other metrics (species richness, number of species lost and gained, species composition, top winners and losers, Ellenberg‐type indicator values) showed no significant differences. In mesic grasslands, the resurvey plot location approach had the greatest effect on species richness. In contrast, in dry grasslands, it introduced uncertainty into the detection of compositional changes. Conclusions While both approaches yielded overall similar results, resurvey plots located preferentially indicated smaller changes in species richness and composition change than random plots. Results in resurvey studies based on quasi‐permanent plots should therefore be interpreted with caution, as plot location may affect temporal change detection in long‐term vegetation assessments.
ABSTRACT Questions The resilience of Afromontane ericaceous ecosystems depends heavily on their soil seed banks, yet the regeneration ecology of the dominant woody genus Erica is poorly known. We asked: (1) How do environmental variables and anthropogenic disturbance influence woody species distribution in standing vegetation and soil seed banks? (2) What is the relationship between soil seed bank density and greenhouse germination potential (emergence) of Erica species, and how does it vary among topographic positions? (3) What are the implications for field seedling establishment and conservation? Location Bale Mountains National Park, Southern Ethiopia. Methods Fifty microplots were established across three principal experimental sites (northeast slopes, southwest slopes, and the Sanetti Plateau). Standing vegetation composition, disturbance intensity (quantified on a five‐level scale), and environmental variables were recorded. The soil seed bank was assessed by physical extraction and a 180‐day greenhouse germination trial. Erica seed density and germination potential (seedlings emerged per m 2 ) were analyzed using generalized linear mixed models to test the effects of elevation, aspect, stoniness, and disturbance. Results We recorded 92 species in standing vegetation and 88 in the germinated seed bank; both were dominated by Asteraceae (22%) and Poaceae (8%). Erica seed density was highest on the Sanetti Plateau (9300 ± 3560 seeds m −2 ) but greenhouse germination potential there was extremely low (11 ± 20 seedlings m −2 ). Conversely, southwest‐facing slopes had lower seed density (2460 ± 938 seeds m −2 ) but significantly higher germination (160 ± 300 seedlings m −2 ). Elevation and surface stoniness were the primary abiotic constraints on Erica distribution ( p < 0.01). Disturbance significantly reduced Erica cover, field seedling establishment, moss, and litter ( p < 0.001). The relationship between seed density and germination was weak and non‐significant ( R 2 = 0.04, p = 0.061). Conclusions Erica regeneration is limited primarily by environmental filters and disturbance during the germination and establishment phase, rather than by seed availability, consistent with the regeneration niche concept. Conservation strategies must prioritize reducing livestock pressure and fire frequency, especially on the plateau, and protect southwest‐facing slopes as natural refugia for regeneration. Assisted restoration interventions are required in severely degraded areas to overcome the establishment bottleneck.
Question Local species pool and assembly processes play crucial roles in maintaining soil microbial and woody plant diversity in forest ecosystems. However, their effects on beta diversity patterns remain poorly understood along an altitudinal gradient.Location Fanjing Mountain, Guizhou Province, China.Methods We established 8 1-hectare plots along an altitudinal gradient (600 m-2100 m), assessing alpha and beta diversity, species pool of woody plants, and soil microbial community biotic and abiotic conditions. Community assembly was estimated using the beta Nearest Taxon Index, beta diversity via the Jaccard index, and species pool via species richness of woody plants and soil microbes in each 1-hm2 plot. A total of 200 sampling plots (20 m & times; 20 m) were analyzed.Results There was a decrease in the alpha diversity of woody plants and soil bacteria, but an increase in the beta diversity of soil fungi and bacteria, along the altitudinal gradient. Composition dissimilarities of woody plants and soil microbes, as well as both species turnover and nested components of beta diversity, expanded with increasing altitudinal distance. Deterministic processes, particularly heterogeneous selection, primarily governed soil bacterial community assembly. In contrast, stochastic processes, mainly dispersal limitation and drift, governed woody plants and fungal communities. The local species pool emerged as a primary driver of beta diversity, indirectly influencing it through assembly processes in woody plants and soil bacterial communities. While assembly processes of woody plants and soil bacterial communities significantly positively affected their respective beta diversity, soil fungal assembly processes showed no such effect.Conclusion These findings highlight that the local species pool contributed more to beta diversity patterns than assembly processes along altitudinal gradients, advancing our understanding of biodiversity maintenance mechanisms in montane ecosystems.
Aims Riparian ecosystems host a wide array of plant species and functions, resulting in different primary production patterns that may be inferred with remote sensing indicators. We aimed to assess the relationship between monthly spectral greenness and vascular plant biodiversity in riparian forests using Sentinel-2 images.Location Cantabrian region, Spain.Methods We evaluated the effects of six indicators of riparian vegetation composition and functional diversity (Gini-Simpson; species richness; plant height range; specific leaf area range; and the relative abundance of evergreen and exotic species) on two Sentinel-2-derived spectral greenness indices (Enhanced Vegetation Index, EVI; Normalized Difference Vegetation Index, NDVI) using linear mixed models, adding the elevation and the month as additional predictors, and the year as a random factor.Results We found that all of the indicators had significant positive effects on spectral greenness, with Gini-Simpson being the strongest predictor, followed by plant height and specific leaf area ranges. These effects varied throughout the year, with stronger influences on NDVI during the dormancy season and on EVI during the growth and peak-production season. The abundances of evergreen and exotic species were weaker predictors, yet significant.Conclusions The results confirm the significant relationship between riparian vegetation greenness and compositional and functional diversity. This reinforces the use of spectral indices to assess the ecology of riparian plant communities and to further understand spatial patterns of ecosystem functioning across river networks. Given the seasonal variation in the patterns, we encourage the analysis of the whole phenological cycle instead of single-date indices.
Aims Alliaria petiolata is an introduced understory herb invasive in North America, where it often forms dense monocultures with diminished native plant diversity. Recent studies indicate expanding populations of Odocoileus virginianus (white-tailed deer) may facilitate Alliaria invasion via selective herbivory and disturbance. We investigated: (i) how deer exclosure affects Alliaria cover and dominance, (ii) how deer exclosure affects herb layer composition, and (iii) how these effects differ between areas with naturally differing Alliaria density.Location Mature oak forest in east central Minnesota, United States, 2018-2023.Methods We erected deer exclosures in high- and low-density Alliaria areas in 2018. Exclosure plots were paired with similar open (unexclosed) plots, yielding 12 plot pairs. From 2018 to 2023, we measured cover of the most common herb layer species, Alliaria juveniles and adults, and height of dominant species. We conducted a comprehensive vegetation survey in 2022.Results Deer exclosure had no effect on Alliaria, and few on community composition in the low-density Alliaria area. In the high-density area, exclosure was associated with diminished Alliaria cover and dominance compared with paired open plots. Community composition changed significantly over time between exclosed and open plots, especially in the high-density area. These changes were driven by (1) an increase in presence, cover, and dominance of Laportea canadensis, (2) significant increases in relative cover and dominance of Fraxinus spp., and (3) significant decreases in relative cover and dominance of Cryptotaenia canadensis, all in exclosures.Conclusions Our results indicate that deer have significant impacts on herb layer composition, including enhancement of Alliaria cover and dominance, but that effects on both also differ markedly between areas with different naturally occurring Alliaria densities. This supports the role of deer in Alliaria spread indicated by previous studies and the suggestion that Alliaria may be more of a "passenger" than a "driver" of community change.
Questions Plant interactions shape community composition, but most research on this topic is done on vascular plants with less focus on bryophytes, despite their dominance in many ecosystems. Bryophytes modulate the soil microclimate and thereby also the conditions for germination and early growth of vascular plants. Vascular plants typically grow faster than bryophytes, but their potential dominance requires successful germination which, in turn, is modulated by the moisture, temperature, and pH conditions created by different bryophyte species.Location Sub-Arctic heath and peatlands in northern Sweden.Method To quantify if, and in case how, bryophyte species affect seed germination timing and growth of vascular plants we sowed seeds of Taraxacum officinale, Deschampsia cespitosa, and Plantago major in patches dominated by seven bryophyte species in northern Sweden. To quantify how the surface structure of bryophyte stands affects vascular plant germination and growth, we performed a surface removal treatment. In addition, to identify if bryophytes' exudates affect germination timing and efficiency, we included a laboratory assay using species-specific extracts of the surface-removed bryophyte parts.Results Bryophyte effects on vascular plant establishment are highly species specific: Flexitrichum flexicaule allowed for earlier germination and more vigorous plant growth, while Tetralophozia setiformis and Racomitrium lanuginosum inhibited germination completely. Emergence of D. cespitosa occurred earlier among darker bryophytes, most likely because of the interplay of bryophyte reflectance and temperature. Overall, plant biomass was best explained by bryophyte pH and moisture, but not consistently among vascular plant species.Conclusions These findings indicate that bryophytes can greatly influence vascular plant establishment. The mechanisms by which this takes place are highly species specific and dependent on the bryophyte as well as the vascular plant species. Expansion of vascular plants in bryophyte-dominated communities is likely for Arctic ecosystems, but invasion success will vary and depend on the traits of the dominant bryophyte species.
Question Central Anatolia is part of the Irano-Anatonian biodiversity hotspot, encompassing a diverse range of steppe grasslands, shrublands, and forests. Despite their high biodiversity and crucial ecosystem services, its ancient grass or subshrub-dominated steppe and forest-steppe vegetation is often neglected and, in many cases, considered as secondary vegetation resulting from extensive deforestation. However, the conditions that explain the distribution of the ecosystems in this semi-arid region remain poorly understood. Considering recent developments in the understanding of open ecosystems, we aim to understand what explains the distribution of tree cover in Central Anatolia.Location Central Anatolia, T & uuml;rkiye.Methods We analyzed the influence of a comprehensive set of variables that shape tree cover distribution obtained from remote sensing and global and local databases. We used regression models to model tree presence and cover, considering the effects of climate, soils, topography, land use, and disturbances.Results Tree presence and cover were limited by poor and sodic-saline soils and limited by climate factors, including temperature and precipitation extremes. Trees were more prevalent in mountainous regions and in topographic conditions that enhance local resource availability and provide protection from disturbances and land-use impacts. Trees were also limited by agriculture and livestock density, although their presence increased in the proximity of human settlements.Conclusions Our findings indicate that environmental determinants, including climate, soils, topography, and disturbance regimes, shape tree cover in Central Anatolia, questioning the common belief that low tree cover is mainly due to extensive deforestation by humans. Our results have implications for the management and conservation of these ecosystems, particularly with respect to climate change, which could further exacerbate existing constraints on tree growth. Our findings can also inform the conservation efforts of ancient steppe grasslands and forests, as well as contribute to more resilient afforestation strategies.
Questions The structure and dynamics of tropical forests face increasing pressures from historical land use and climate change. We asked: (1) Is there a significant difference in forest structure and species composition over 23 years? (2) Which tree species increase or decrease in stem density and/or basal area during this period? (3) Does drought exert a more pronounced effect on the tree community in a more recently disturbed site?Location Guaxindiba State Ecological Station in S & atilde;o Francisco do Itabapoana (21 degrees 24 ' S, 41 degrees 04 ' W), Rio de Janeiro, Brazil.Methods Over 23 years, we monitored all trees with >= 10 cm diameter at breast height (DBH) in four permanent 0.25-ha plots established in 1995 at each of two sites: one with signs of selective logging until 1960 (US60) and another selectively logged until 1990 (LS90). We assessed changes in basal area, stem density, species richness, evenness and turnover, and calculated recruitment, mortality and relative growth. Climate variability was assessed using precipitation and temperature anomalies and maximum cumulative water deficit.Results Both sites showed slow recovery, with small increases in stem density and basal area and declines in species richness and evenness. Dominant species, such as Metrodorea nigra and Marlimorimia contorta, gained prominence, indicating a possible inhibitory role in the successional process. Recruitment decreased and mortality increased over time at both sites, possibly related to drought events. LS90 experienced greater species loss and structural changes compared to US60. Highlighting persistent selective logging legacies, exacerbated by recurrent droughts.Conclusions Selective logging and recurrent droughts created long-lasting impacts on the semi-deciduous seasonal Atlantic Forest (SSAF), reducing resilience and slowing ecological recovery. Community trajectories converged towards floristic simplification, with drought-tolerant dominants displacing less resilient species. These findings underscore the vulnerability of seasonal tropical forests to compound disturbance and climate stress, emphasizing the need for targeted conservation to enhance resilience, sustain biodiversity and preserve ecosystem services.
Aims Total above-ground biomass is a key indicator of grassland productivity and ecosystem functioning. While responses of total biomass to environmental gradients are well studied, it remains unclear which abundance groups, dominant, subordinate or rare species, drive these responses and whether aggregate patterns reflect species-level sensitivities or emerge from compensatory dynamics. We aimed to disentangle the contributions of different abundance groups to community-level biomass-environment relationships.Location Poland and Czechia (Sudetes Mountains).Methods We used vegetation-plot data from species-rich mesic hay meadows, integrating species-specific biomass measurements. We partitioned community biomass into three groups based on relative abundance: dominant, subordinate and rare species. We used random forest and linear mixed-effects models to quantify environmental sensitivity at group and species levels. Spatial biomass stability and compensatory dynamics were assessed using coefficients of variation and species synchrony metrics along soil, climatic and topography-related gradients.Results Random forest models for non-dominant groups (subordinate and rare) closely matched the performance and predictor importance of the total biomass model, despite weak and heterogeneous responses of individual species to abiotic gradients. In contrast, dominant species, when considered as an aggregate, showed no detectable environmental signal, whereas they exhibited strong species-specific responses, exceeding those of subordinate and rare species. This apparent mismatch arose from strong asynchrony and compensatory turnover among dominant species along environmental gradients. Non-dominant species responded more synchronously to environmental variation, increasing positive covariance among species.Conclusions Our results reveal a decoupling between species-level environmental sensitivities and abundance-group biomass responses, demonstrating that community-level patterns emerge from the dominance structure and covariance of species responses rather than from mean species effects alone. Biomass stability in the dominant group emerges from compensatory dynamics among species, whereas non-dominants respond synchronously to environmental gradients and drive community-level biomass responses. Changes within the non-dominant biomass thus provide sensitive indicators of environmental variation.
Questions The loss of semi-natural grasslands due to land-use changes has accelerated secondary succession, in a process known as woody plant encroachment (WPE). In recent decades, the implications of this phenomenon have begun to be studied more intensively; however, the effects on plant functional diversity and strategies have not received the same level of attention. In this study, we evaluated how the functional traits and functional diversity of plant communities change along a gradient of WPE. We also analysed how ecological and disturbance indicators vary with increasing cover of encroaching species.Location Sub-Mediterranean calcareous grasslands in the northern Iberian Peninsula.Methods We surveyed 144 plots distributed across four study sites and along a gradient of woody cover. Species-level trait and ecological and disturbance indicator values were compiled from published databases and combined with plot-level cover to calculate community-weighted means (CWMs) and functional diversity indices. Study site and encroachment effects were evaluated using multivariate (PERMANOVA) and mixed-effects modelling approaches.Results Community functional composition shifted along the encroachment gradient, from grasslands characterised by hemicryptophytes, short-distance dispersal and wind pollination to more encroached communities associated with taller life forms (phanerophytes and chamaephytes), longer dispersal distances and greater entomophily. Functional dispersion increased with encroachment, particularly beyond around 30% woody cover. Ecological indicator values indicated progressively moister, shadier and more acidic conditions with increasing shrub cover, accompanied by lower disturbance frequency. Encroachment effects were strongly site-dependent, as supported by a significant study site (SITE) and woody plant encroachment level (LEVEL) interaction in multivariate trait space (PERMANOVA) and by frequent SITE & times; LEVEL effects across response variables.Conclusion Woody encroachment is associated with consistent community-level functional and ecological shifts, but the magnitude and direction of these changes depend strongly on study site (local context). Integrating trait-based metrics with ecological and disturbance indicators helps interpret grassland-shrubland transitions and supports site-specific management of semi-natural grasslands undergoing WPE.
Aim Ordination methods are widely used in vegetation science to summarize multivariate patterns in species composition and environmental gradients. Although statistical tools for fitting ordination models are well developed in R, tools for producing tidy, reproducible, and extensible way remain fragmented. We present barrel, an R package that provides a modular grammar for ecological ordination plotting based on the ggplot2 ecosystem. Methods barrel implements a consistent interface for adding ordination elements such as confidence ellipses, group centroids, and environmental vectors to ordination diagrams. The package supports both unconstrained and constrained ordination methods and includes automatic axis labeling, significance-based filtering, and multiple geometric representations. The package also supports both classical and robust estimation of group ellipses for graphical summaries in the presence of ecological outliers. Results barrel enables the rapid construction of reproducible ordination graphics through two complementary interfaces: autoplot() for automated figure generation and stat_barrel_*() layers for advanced customization within ggplot2. The package facilitates exploratory analysis, teaching, and the production of publication-quality ordination figures across a wide range of ecological applications. Conclusions barrel provides a reproducible and extensible framework for ordination plotting in R that unifies common ecological visualization workflows within a tidy and customizable grammar-of-graphics approach.
Aim Alpine vegetation is highly sensitive to global warming, as these ecosystems are shaped by cold temperatures. Upward migration of thermophilic species increases species richness at high elevations but may threaten cryophilic specialists. We assessed temporal changes in species richness, species turnover, and key drivers of vegetation change across summits, with a focus on potential tipping points in the nival belt.Location Four siliceous summits ranging from 2180 to 3287 m a.s.l. in the Texel Group (South Tyrol, Italy).Methods Vegetation and soil temperature data from 21 years (2003-2024) were analyzed using generalized linear mixed-effects models (GLMMs) to assess shifts in species composition, ecological indicator values, and elevational distribution patterns.Results An ongoing increase in species richness (overall +13%) and thermophilization was observed on all summits except the subnival one, with a significant decline only in the southern slope of the lowest summit. A rapid increase in richness on the highest summit over the past 7 years (+75%) coincided with a longer growing season and higher mean soil temperatures. Colonization happened mostly in the eastern aspect, where soil temperature was highest.Main Conclusions New findings reveal that the nival belt, previously stable in species numbers, is now undergoing rapid vegetation change and provides the first evidence of thermophilization in the nival belt of the Central Alps. This might respond to the overcoming of a mean soil temperature of 4.9 degrees C during the growing season, an ecological threshold associated with closed grasslands. In parallel to upward shifts of some species, cryophilic specialists face increasing habitat loss and fragmentation. Cooler northern aspects may act as short-term microrefugia, but long-term persistence will depend on the interplay between colonization, facilitation, extinction, and the availability of refuges in a rapidly changing alpine environment.
Aim Environmental filtering shapes the trait and phylogenetic structure of plant assemblages along environmental gradients, though its effects may differ among ecological strategies. To address this, we analyzed the community assembly of epiphytic and lithophytic bromeliads along a coastal-inland gradient, testing predictions of the stress dominance hypothesis (SDH) and phylogenetic niche conservatism (PNC).Location Residual hills of central Rio Grande do Sul, southern Brazil, spanning a vegetation gradient from humid Atlantic Forest to seasonal and savanna-like woodlands.Methods We surveyed 61 bromeliad species across 71 sites along a 600-km climatic gradient encompassing variation in temperature, humidity, and solar radiation. For each species, we recorded three categorical traits related to water-use strategies: rosette form, rosette size, and photosynthetic pathway. We assessed how trait composition, phylogenetic relationships, and environmental factors interact along the gradient using fourth-corner tests, entropy-based diversity metrics, phylogenetic RLQ ordination, and the net relatedness index (NRI).Results Trait composition shifted along the gradient, with atmospheric CAM species dominating inland and tank-forming C3 species prevailing near the coast. Epiphytes exhibited stronger environmental filtering and greater climatic sensitivity than lithophytes. Environmental filtering promoted convergence of ecological traits under stress but did not produce corresponding phylogenetic structure, providing only partial support for SDH. In contrast, the persistence of tank-forming C3 lineages in humid coastal habitats reflected PNC.Conclusions Epiphytes persist through dispersal and recurrent trait convergence under climatic stress, whereas lithophytes reflect long-term continuity in ancestral niches on rocky outcrops. Ecological filtering and evolutionary constraint operate as distinct yet complementary pathways: SDH drives adaptive trait convergence under stress, while PNC maintains lineage persistence under stability. Together, these processes define the balance between ecological strategy and evolutionary constraint that shapes bromeliad assemblages along the coastal-inland gradient.
Question In addition to altering ecosystem states, anthropogenic changes may also alter the drivers of community dynamics within these ecosystems. Previous research has shown nitrogen as a key driver of community dynamics in grassland ecosystems, including those present at our study site. We sought to test whether these nutrient responses will shift as changes to disturbance regimes facilitate woody encroachment.Location Successional grassland at Cedar Creek Ecosystem Science Reserve (Minnesota, USA).Methods As part of an investigation into the drivers and consequences of Eastern White Pine (Pinus strobus) encroachment at this site, we surveyed pine abundance and herbaceous community composition in 32 treatment plots, following 18 years of experimental fire, nitrogen, and herbivore manipulation.Results Although pine abundance varied widely in unburned plots, it did not significantly respond to nitrogen addition or herbivory. As expected, pine encroachment was dramatically inhibited in burned plots. Species richness in the herbaceous community did not differ significantly between treatments. The Shannon diversity index responded interactively to fire and nitrogen, with nitrogen addition decreasing diversity in unburned plots but increasing diversity in burned plots. Nitrogen's effects on the overall composition of the herbaceous plant community were contingent upon fire. Within the burned treatment, nitrogen addition led to an increase in the cover of invasive C3 grasses. Within the unburned treatment, nitrogen had no consistent effect on herbaceous species composition.Conclusions Despite research showing nitrogen as a key driver of community dynamics in the grasslands of our study site, we found that this effect is contingent on the presence of fire and absence of woody encroachment. With this variation in nitrogen effects, we see that a factor playing a major role in structuring a community can cease to play that role as disturbance regimes and ecosystem states are altered.
