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Questions: In the alpine region of the Himalaya, shrubs play a vital role in maintaining the diversity and functional composition of associated herbaceous communities through competition–facilitation interactions under varying environmental stress conditions. In this study, we specified the following questions: (1) what is the mode of interaction between dominant shrubs and the associated herbaceous communities; (2) how do differences in resource availability between contrasting microhabitats mediate interactions between shrub and herbaceous communities; and (3) how do dominant shrubs influence the functional composition of herbaceous communities under the canopy as compared to ones in the open? Study area: An alpine region of the western Himalaya, in India (32.24–33.15° N, 76.51–78.13° E). Methods: Field studies were conducted to evaluate the canopy effects of alpine shrubs such as Caragana versicolor, Juniperus polycarpos and Rhododendron anthopogon on species richness, abundance and functional composition of coexisting herbaceous communities. Results: The dominant alpine shrubs of the western Himalaya exert competitive interactions with associated herbaceous communities and have low species richness and abundance under their canopies compared to open habitats. Further, contrary to expectations, competitive interactions were more prominent at higher elevations than at lower ones, especially for J. polycarpos and C. versicolor. Although the shrub undercanopies possessed richer soil nutrient pools, this did not contribute toward the facilitation of herbaceous species under the canopies. Moreover, herbaceous species under the canopies were found to exhibit resource‐acquisitive functional strategies, whereas those in the open were resource‐conservative. Conclusions: The interaction between dominant alpine shrubs and the herbaceous community of the western Himalaya is competitive in nature, which influences species and functional composition and reorganizes herbaceous community assembly. Moreover, under future climate change scenarios the dominance of these shrubs will favour those herbaceous species that possess more competitive and resource‐acquisitive functional strategies. [ABSTRACT FROM AUTHOR]

Questions: We assessed interactions between climate change, bedrock types and snow cover duration on the trajectories of taxonomic and functional composition of subalpine plant communities. We predict (i) an increase in species richness on siliceous bedrock due to a reduced competition and a decrease in richness on calcareous bedrock due to increasing drought stress; (ii) decreasing snow cover duration should induce a higher shrub encroachment in hollows as compared to ridges; and (iii) increasing growing season temperature should induce taller sizes and more conservative growth traits, in particular in hollows. Location: Subalpine belt of the Grandes Rousses mountain range, southwestern Alps (France). Methods: 189 vegetation plots were sampled in 1997 and 2017–2018. The duration of snow cover was assessed during two years in 1995–1997 and five functional traits were measured on 108 species in 2021. We performed multivariate analyses, quantified community‐weighted means (CWM) of traits and used ANOVAs to detect responses to local‐scale factors and changes in snow cover, temperature and precipitation since 1997 according to a nearby meteorological station. Results: Overall, taxonomic composition weakly changed and changes were more dependent on the position of communities along the snow cover duration gradient than on their bedrock type. The abundance of drought‐tolerant species increased at the border of hollows and there was, over all communities, a slight increase in the abundance of dwarf shrubs and tall herbaceous species, a strong decrease in short herbaceous species and, thus, an overall decrease in species richness. There were important overall changes in CWM of size traits, in particular leaf area which increased the most in hollows irrespective of bedrock types. Conclusion: In this subalpine site the effects of decreasing snow cover duration overwhelmed the effects of bedrocks, which may explain the overall increase in competitive species and decrease in species richness. [ABSTRACT FROM AUTHOR]

Questions: Woody encroachment in savannas has been associated with changing taxonomic composition and ecosystem function. Interestingly, there is little understanding of how encroachment impacts plant functional diversity and how those changes relate to plant demography, a crucial mediator between taxonomic composition and ecosystem function. Location: Southeastern Brazil. Methods: Using a landscape scale fire suppression experiment in a diverse Brazilian savanna, we quantify how change in species composition over seven years impacted vegetative and reproductive tree functional diversity as determined by new recruits, dead and surviving trees. Results: Over seven years, tree above‐ground biomass increased by 15%, while total species richness did not change. Despite minor changes, species composition remained overall similar (82%), with few species contributing significantly to plot dissimilarity over time. There were small changes in vegetative traits, where the community‐weighted mean increased in maximum tree height (↑ 2.1%) and specific leaf area (↑ 5.3%), and decreased in wood density (↓ 1.3%) and bark thickness (↓ 9.4%). Changes in reproductive traits were larger than in vegetative traits, with an increase in the prevalence of monoecy (↑ 32.6%), dioecy (↑ 44.2%), large seeds (↑ 20.3%), animal‐mediated seed dispersal (↑ 4.9%) and pollination by very small insects (↑ 45.5%), and a decrease in the prevalence of hermaphroditism (↓ 9%), small seeds (6.8%) and pollination by small insects (12.5%). The overall decrease in bark thickness and increase in monoecy and dioecy were mainly driven by characters of the new recruits, while the overall increase in specific leaf area (SLA) and decrease in small seeds appeared largely determined by the loss of trees possessing those traits. Conclusions: Encroachment leads to changes that are likely increasing ecosystem vulnerability to fire and drought. Further, the compositional changes observed appear to drive marked change in reproductive traits, indicating increasing dependence on animals for dispersal and reproduction. Understanding post‐hoc encroachment impacts in an era of widespread pervasive encroachment is fundamental to reconciling ecosystem functions such as nutrient cycling and pollination services as there is a loss of species with open ecosystem life‐history strategies. Among savannas, there remains an urgent need to understand relationships between woody cover and ecosystem function to determine thresholds in woody cover promoting resilient savanna ecosystems. [ABSTRACT FROM AUTHOR]

Questions: Ecological succession is the process during which ecosystems recover after disturbances. Studies investigating community reassembly during tropical forest succession have rarely compared lianas to trees. We addressed two questions: (1) how do changes in stem density, total basal area and species richness of lianas and trees compare throughout a secondary succession, and to what extent does the relative basal area of lianas change along a secondary succession; and (2) how do the successional trajectories of functional community trait values of lianas and trees compare? Location: Yoko forest reserve, central Congo basin. Methods: Using univariate Bayesian modeling techniques, we analyzed differences in successional pathways between lianas and trees in terms of community structure, and functional assembly in a replicated chronosequence spanning from young to old‐growth forests. Results: We found divergent structural trajectories between lianas and trees along the forest chronosequence. The stem density of lianas peaked at the intermediate stage, while that of trees almost linearly decreased from early to late stages of succession. The basal area of lianas increased at a higher rate than that of trees, which translated into a marginal increase of liana relative basal area over succession. On the contrary, we observed a lower rate of increase in species richness for lianas than trees over succession. We found a progressive convergence in the responses of lianas and trees to changes with succession in terms of specific leaf area and leaf nitrogen content, but a diverging response in terms of leaf phosphorus content. These functional composition patterns most probably resulted from environmental filtering, induced by a change from nitrogen to phosphorus limitation as the succession progressed to a mature forest. Conclusions: These findings underscore the rapid colonization of tropical forests by lianas after agricultural abandonment, presumably by deploying a more diverse leaf economic spectrum early in succession. [ABSTRACT FROM AUTHOR]

Question: Differences in understorey vegetation between ancient and recent forests have been thoroughly explored; however, few studies have investigated the legacies of different former land uses in recent forests. Indeed, due to more intense agricultural practices (tillage and fertilisation), legacy effects are expected to be stronger in former cropland or meadows than in former pastures. Our objectives were to compare soil conditions, taxonomic composition and functional composition of understorey plant communities in recent forests located on former pastures, meadows or cropland, with ancient forests as a reference. Location: Tarentaise Valley, Savoy, France. Methods: Based on land‐use maps surveyed between 1862 and 1864, we selected 82 forest sites with different former land uses in mountain forests in the French Alps and carried out soil sampling and botanical surveys. To account for potential confounding factors (altitude, canopy cover, tree species composition), we applied multiple linear regressions to analyse soil properties, canonical correspondence analysis to analyse plant taxonomic composition and multispecies generalised linear mixed‐effects models to analyse relationships between plant functional composition and former land uses. Results: The soils of former cropland were richer in nutrients and more alkaline compared to other past land uses, while soils on former pastures and meadows differed only slightly from ancient forests. Ancient forests were characterised by acidophilic, shade‐tolerant, low‐stature, forest‐dependent species, whereas former cropland was characterised by calcicolous non‐forest species. Former pasture and meadow communities displayed a distinct taxonomic composition compared to other past land uses, but a functional composition closer to ancient forest than to former cropland. Conclusion: Former cropland has a stronger legacy effect than former pastures or meadows. This could explain small differences between ancient and recent forests observed in previous studies conducted in mountain landscapes where former cropland was rare. [ABSTRACT FROM AUTHOR]

Question: Environmental filtering plays an important role in plant community assembly. To what extent does the broad‐scale environment influence the functional composition of woody plants in China's forests? Is there stronger trait convergence under harsher environmental conditions? Location: China. Methods: We characterized community traits and their relationships to climate and soil, using a data set with 1312 plots of tree communities composed of 1591 tree species and 10 functional traits across China. Using quadratic models, we explored how community traits change with different environmental factors. Results: Trait spectra at the species level and the community level were significantly correlated, and the first two principal components captured 74.5% of the variation in community‐weighted mean traits. The trait spectra showed a clear elevational pattern and varied along climate and soil gradients. Compared with random expectations, the multi‐trait functional diversity showed a divergence pattern on poor soils at the plot scale. Conclusions: Two well‐known dimensions, the leaf economics spectrum and size‐related spectrum, could be extended from the species level to the community level. Environment, especially climate conditions, drives the trait spectra and their elevational patterns at the broad scale, indicating environmental filtering might shape the trait composition of tree communities in China. However, stronger environmental filtering does not occur under harsher environmental conditions. [ABSTRACT FROM AUTHOR]

Questions: Human disturbance is increasingly affecting forest dynamics across the tropics. Forests can recover via natural secondary succession to pre‐disturbance levels of biodiversity, species composition, and ecosystem carbon stocks. Central Africa will be subject to increasingly high shifting‐cultivation pressure in the next decades, but succession trajectories of these ecosystem properties are still poorly known for the Congo basin. We addressed two questions: (1) how does taxonomic and functional composition and diversity shift during secondary succession; and (2) how fast do above‐ground carbon stocks recover during secondary succession in tropical forests? Location: Central Congo basin. Methods: We conducted an inventory of trees (diameter at breast height [DBH] ≥ 10 cm), measured species traits and soil texture and carbon content in 18 plots, located along six secondary succession stages (i.e., from agricultural to old growth forest sites). We measured tree diameter, height for 20% of trees distributed across diameter classes, wood traits from all species, and leaf traits from species that contributed to 85% of the plot basal area. Results: We showed that secondary forests recover relatively fast in terms of tree species diversity, alpha functional diversity, and fine‐root carbon, with near‐old‐growth forest values after six decades past disturbance, while floristic composition exhibited slower recovery. Secondary forests only partially shifted from acquisitive to a conservative life history, with shifts in leaf traits being largely decoupled from wood traits. Only 43% of above‐ground carbon recovered after 60 years of forest regrowth, potentially through a slow recovery of the large‐sized tree stems that dominate carbon stocks of old‐growth forests. Conclusions: Our findings underline the capacity of Afrotropical forests to recover species and alpha functional diversity after clear‐cutting through shifting cultivation. Simultaneously, old‐growth forests harbor a particular floristic community and store a large quantity of carbon with much longer recovery trajectories, stressing the need for conservation of these forests in the Congo basin. [ABSTRACT FROM AUTHOR]

Aims Concentrated flow erosion resistance of herbaceous vegetation is linked to vegetation-level root length density ( RLD). However, RLD measurements involve destructive and time-consuming sampling. Since plant species richness, functional diversity and functional composition are expected to affect RLD through either non-additive diversity effects or biomass ratio effects, we evaluated whether these measures can be used as a proxy for RLD in levee grassland communities. Location Levee grassland communities, Scheldt estuary, northern Belgium. Methods We assessed the strength of correlation between empirically quantified RLD and species richness, functional diversity and functional composition of levee grasslands. More specifically, we used nine below-ground and ten above-ground plant traits retrieved from public databases, and applied linear regressions and partial least square regressions. Results Plant functional diversity was a better proxy for RLD than plant species richness, with better predictive performance for below-ground than for above-ground traits. More specifically, the highest predictive power was achieved through integration of functional diversity, functional composition and species richness. This suggests that variation in RLD is driven by a combination of both non-additive diversity effects and biomass ratio effects. Conclusions This study provides a first positive indication of the value of plant functional traits retrieved from databases to predict RLD for river levee grasslands. Furthermore, although less reliable than below-ground traits, above-ground traits are still useful for RLD prediction when information on below-ground traits is lacking. [ABSTRACT FROM AUTHOR]

Question Fertilization, i.e. nutrient addition, and changes in grazing intensity are important factors associated with global change that threaten grasslands worldwide. How does the plant community assembly in Mediterranean grasslands respond after 11 yr to a single fertilization event? Location Species-rich Mediterranean grassland, Navarra, northern Spain. Methods In 2003, 11 permanent plots were established in a Mediterranean grassland: six plots were fertilized and five were used as controls. Fertilization consisted in the addition of sewage sludge on the soil surface. Grazing was excluded during the course of the experiment. Changes in vegetation abundance were monitored from 2004 to 2014. In 2012, key plant functional traits (height, leaf area, SLA, LDMC) of the most frequent species were collected. We measured taxonomic and functional species composition and diversity. Niche overlap compared to null models was used to assess the mechanisms influencing community assembly. Results Species composition changed markedly in the fertilized plots. These changes were accompanied by a reduction in taxonomic diversity. One yr after starting the experiment there were no differences in functional composition (i.e. CWM trait values) between fertilized and control plots (excluding SLA), but 11 yr later fertilized plots were composed of taller plants with larger SLA and lower LDMC. We found a major reduction in niche overlap in plant height and SLA after fertilizing associated with a replacement in several species that could be indicative of competitive exclusion (principle of limiting similarity). Conversely, we found an increase in niche overlap in leaf area indicating that competition increases similarity among species (weaker competitor exclusion or abiotic filtering). At the end of the experiment, we found large differences in SLA and LDMC between fertilized and control plots. Conclusions A single fertilization event that occurred 11 yr ago triggered a wave of changes in grassland community assembly that are still on-going. Fertilization enhanced the establishment of taller species with larger leaf areas, which displaced, by competitive exclusion, the species that had previously been present. Community assembly patterns in Mediterranean grassland are highly sensitive to abrupt changes in resource availability. [ABSTRACT FROM AUTHOR]

Question Variability in species function is often studied by using phylogenetic relatedness as a surrogate for functional similarity between species, rather than by measuring functional traits directly. The phylogenetic-based method is far less data-intensive than trait-based methods. However, to what extent community-level variability in species function is driven by phylogenetic history has rarely been explored in terms of composition and diversity. In this paper we test this empirically by asking: do differences in the functional composition and diversity of species assemblages (i.e. plots) along an environmental gradient mirror differences in phylogenetic structure? Location Coastal dune communities of the Tyrrhenian coast of Italy. Methods We calculated fuzzy-weighted mean trait values and the Rao index for dominant species in 405 plots using 16 functional traits that were measured in the field or from other sources. Based on a phylogenetic distance matrix among species obtained from an aged phylogenetic supertree, we applied matrix correlation tested against appropriate null models to calculate how much of the plot-to-plot variability in functional composition (measured through fuzzy weighting) and diversity (measured with the Rao index) is predicted by the corresponding phylogenetic metrics. Results At the species pool level there was evidence for a phylogenetic signal in trait variation. Furthermore, we found that differences in species functional diversity among plots were closely related to their phylogenetic variability, but this was not true for functional composition. Conclusions The results show that even when there is evidence of phylogenetic trait conservatism at the species pool level, phylogeny may be unable to capture all aspects of functional community structure. This emphasizes the need for caution when interpreting measures of phylogenetic community structure as proxies of functional community structure. [ABSTRACT FROM AUTHOR]