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Aim: Assessing the performances of different sampling approaches for documenting community diversity may help to identify optimal sampling efforts and strategies, and to enhance conservation and monitoring planning. Here, we used two data sets based on probabilistic and preferential sampling schemes of Italian forest vegetation to analyze the multifaceted performances of the two approaches across three major forest types at a large scale. Location: Italy. Methods: We pooled 804 probabilistic and 16,259 preferential forest plots as samples of vascular plant diversity across the country. We balanced the two data sets in terms of sizes, plot size, geographical position, and vegetation types. For each of the two data sets, 1000 subsets of 201 random plots were compared by calculating the shared and exclusive indicator species, their overlap in the multivariate space, and the areas encompassed by spatially‐constrained rarefaction curves. We then calculated an index of performance using the ratio between the additional and total information collected by each sampling approach. The performances were tested and evaluated across the three major forest types. Results: The probabilistic approach performed better in estimating species richness and diversity of species assemblages, but did not detect other components of the regional diversity, such as azonal forests. The preferential approach outperformed the probabilistic approach in detecting forest‐specialist species and plant diversity hotspots. Conclusions: Using a novel workflow based on vegetation‐plot exclusivities and commonalities, our study suggests probabilistic and preferential sampling approaches are to be used in combination for better conservation and monitor planning purposes to detect multiple aspects of plant community diversity. Our findings can assist the implementation of national conservation planning and large‐scale monitoring of biodiversity. [ABSTRACT FROM AUTHOR]

Question: When evaluating forests in terms of their biodiversity, distinctiveness and naturalness, the affinity of the constituent species to forests is a crucial parameter. Here we ask to what extent are vascular plant species associated with forests, and does species' affinity to forests vary between European regions? Location: Temperate and boreal forest biome of Northwestern and Central Europe. Methods: We compiled EuForPlant, a new extensive list of forest vascular plant species in 24 regions spread across 13 European countries using vegetation databases and expert knowledge. Species were region‐specifically classified into four categories reflecting the degree of their affinity to forest habitats: 1.1, species of forest interiors; 1.2, species of forest edges and forest openings; 2.1, species that can be found in forest as well as open vegetation; and 2.2, species that can be found partly in forest, but mainly in open vegetation. An additional "O" category was distinguished, covering species typical for non‐forest vegetation. Results: EuForPlant comprises 1,726 species, including 1,437 herb‐layer species, 159 shrubs, 107 trees, 19 lianas and 4 epiphytic parasites. Across regions, generalist forest species (with 450 and 777 species classified as 2.1 and 2.2, respectively) significantly outnumbered specialist forest species (with 250 and 137 species classified as 1.1 and 1.2, respectively). Even though the degree of shifting between the categories of forest affinity among regions was relatively low (on average, 17.5%), about one‐third of the forest species (especially 1.2 and 2.2) swapped categories in at least one of the study regions. Conclusions: The proposed list can be used widely in vegetation science and global change ecology related to forest biodiversity and community dynamics. Shifting of forest affinity among regions emphasizes the importance of a continental‐scale forest plant species list with regional specificity. We compiled a new list of forest vascular plant species spread in large parts of the European temperate and boreal forest biome using vegetation databases and expert knowledge. Species were region‐specifically classified into four categories reflecting the degree of their affinity to forest habitats. EuForPlant can be used widely in vegetation ecology related to forest biodiversity and community dynamics. [ABSTRACT FROM AUTHOR]

Questions: The effects of agriculture on forest biodiversity and ecosystem properties can persist decades or centuries after abandonment. Many Pacific island nations are experiencing declines in traditional agriculture. Seed dispersal and seedling recruitment are critical to forest regeneration, and this is particularly relevant for Polynesia where native seed disperser diversity is low and species have been extirpated to crisis levels. In this study we asked: are secondary lowland tropical forests converging to mature forest, and are there seedling recruitment and survival differences between forest types? Location: The Polynesian island of Tutuila, American Samoa, where traditional agriculture has been on the decline since the 1940s and secondary forests comprise 70% of all forest area. Methods: We surveyed 34 vegetation plots (containing 2,232 adult trees and 6,579 tree seedlings) across mature forest and >50 years old secondary lowland rain forest. We quantitatively compared forest diversity, structure and the 3-year seedling regeneration dynamics of the tree community. Results: Although species richness and stem densities were similar between mature and secondary forest, most diversity and structure parameters remained distinguishable between the two forest types. Basal area remained significantly higher in mature forest; the diagnostic tree species of mature and secondary forest differed; and community composition (as indicated by NMDS) remained significantly different. However, seedling survivorship did not differ between forest types and seedling recruitment patterns indicated that there remained a suite of effective seed dispersers on Tutuila. Conclusions: We conclude that (a) community differences between mature and secondary lowland rainforest were driven by the abundance of diagnostic species rather than exclusion of species from a forest type, and (b) there was no evidence of biophysical or ecological barriers to forest recovery of lowland secondary rain forest, or its convergence towards mature lowland rain forest. Nevertheless, more than 50 years after agricultural abandonment, secondary forest remains distinct from mature forest, highlighting that land use legacies are long-term drivers of forest composition and successional trajectory in post-agricultural landscapes of Polynesia. [ABSTRACT FROM AUTHOR]

Questions: How is community functional composition associated with environmental and historical factors and how is this relationship mediated by spatial and phylogenetic autocorrelation? Location: Atlantic Forest of South America. Methods: We compiled abundance data of 2,122 species (most trees) distributed across 281 communities, seven functional traits, and 29 environmental and historical predictors. We mapped traits using community-weighted means, and related traits to predictors by combining the fourth-corner and the extended RLQ approaches. Results: We found that decreases in rainfall, soil nutrition, biome stability in the last 120 kyr, and the increase in thermal variability were associated with high specific leaf area (SLA) and leaf N content, and reduced leaf thickness. In addition, increased temperature and soil sand content, and low biome stability in the last 21 kyr were associated with high wood density and leaf dry matter content, and reduced maximum plant height. Tree communities rich in taxa with N-rich thin leaves and high SLA were mostly located in semideciduous and deciduous forests (e.g., Fabaceae), while communities rich in taxa with N-poor thick leaves and low SLA were mostly found in rain forests (e.g., Myrtaceae and Lauraceae). Species with short stature, high wood density and heavy leaves were particularly abundant in the northern part of the Atlantic Forest (e.g., Myrtaceae), whereas tall species with light wood and leaves were abundant in the south (e.g., Lauraceae). There was not a particular direction in which seed dry mass increased most in response to predictors. Conclusions: Our study reinforces the view that the multifaceted nature of community assembly needs analytical approaches that integrate abundance, functional, phylogenetic, and spatial data to properly understand how environmental and historical factors determine the dominance of functional traits. The observed patterns suggest that different regions of a given biome function in different ways, and probably provide different ecosystem services. [ABSTRACT FROM AUTHOR]

Aim: Single‐species distributions are well known to present random, aggregate, or regular patterns. However, at the community level, multi‐species aggregate distribution patterns are not simply the lumped aggregate distribution of each species in the community. Actually, the superimposition of specimens of different species on a distribution map can present an interacting distributional pattern: different species may overlap with each other (or conversely, avoid each other). To this end, other than aggregation, it is necessary to further quantify distributionally overlapping patterns of different species at the community level. Methods and results: In this study, we combined the conspecific‐encounter index v and Moran's I index to disentangle community‐level distributional aggregation versus superimposition. Numerical simulations demonstrated that the two indices, calculated from biodiversity data collected using the sequential sampling of specimens along line transects, were effective and complementary in predicting multi‐species distribution patterns. The conspecific‐encounter index was sensitive to the change in the degree of distributional aggregation while being insensitive to the change in the distributionally overlapping pattern of different species at the community level. In contrast, Moran's I index can detect the change in the degree of distributional overlap while being insensitive to the change in the level of distributional aggregation at the community level. Moreover, through additional simulations, we showed that the conspecific‐encounter index was robust despite many specimens from dominant species being omitted in the sampling. Finally, an empirical test on the Barro Colorado Island (BCI) forest plot in Panama revealed that tree assemblages in that region presented both random and non‐overlapping distributions, the latter being reported herein for the first time. Conclusions: The performance of Moran's I index and the conspecific‐encounter index are complementary when disentangling multi‐species aggregate versus overlapping distributions at the community level. [ABSTRACT FROM AUTHOR]

Question: Fine‐scale environmental heterogeneity supports floristic diversity in forest ecosystems by increasing the variety of niches available for specialist species. Although recognized in concept, the niche function of microsites has not been well documented. This study tests whether microsites at the base of large trees are physically or edaphically distinct from the forest floor in general, and whether forest herb composition responds to this form of heterogeneity. Location: Long‐established deciduous forest in the unglaciated section of southeastern Ohio, USA. Methods: We measured fourteen herb‐relevant environmental variables and censused the herb flora at the bases of large trees and in control plots away from trees. Results: Moss cover, exposed root cover, and canopy openness were significantly greater at large‐tree bases than in control plots, while leaf litter cover was significantly lower at tree bases. Species richness and stem density were higher in tree‐base plots, and multivariate species composition differed significantly between tree bases and controls. Two species, Eurybia divaricata and Cardamine douglassii, were significantly more abundant at tree bases. Gradients of litter cover and root exposure accounted for the compositional difference between tree bases and controls. Coarse woody debris, moss cover, and soil root fraction accounted for differences orthogonal to the tree‐base/control axis indicating heterogeneity within tree‐base microsites. Conclusions: Tree bases are physically distinct microsites which support diversity by providing niches to some forest herb species. Because availability of such microsites is linked to tree size, this aspect of community diversity appears to be controlled by stand development. [ABSTRACT FROM AUTHOR]

Questions: Land use legacies in current forest understorey vegetation, thoroughly studied in temperate regions, were investigated in a Mediterranean context. We tested the effect of three historical variables on current forest plant communities and traits: forest temporal continuity (ancient: forested before 1860, recent: reforested after 1860, and very recent forest: reforested after 1958) and type of land use in 1860 and 1958 (forest, pasture or arable land). Location: The Regional Natural Park of Luberon (southeastern France). Methods: We used a comprehensive vegetation plot database (473 species in 1,429 plots). Species' response to historical variables was tested with logistic regressions, and the relationship between plant traits and historical variables was analysed with RLQ and fourth‐corner analyses. Results: Among all studied species, 250 responded to forest temporal continuity, 208 to 1860 land use, and 246 to 1958 land use. Species associated with ancient forests were more frequently forest specialists or forest edge species, shade‐tolerant and perennials, while species associated with recent and very recent forests were more frequently annuals, anemochorous and heliophilous species. Species exhibited different traits and ecological preferences according to the type of land use prior to forest: therophytes were more frequent on former arable land while chamaephytes were more frequent on former pasture. Trait responses to 1860 and 1958 land uses were globally consistent. Conclusions: The effect of forest temporal continuity and past land use on forest understorey communities was consistent with other studies in northern Europe or northern America, which suggests that the same ecological processes apply in temperate lowland and Mediterranean regions. This study highlights a succession of plant communities in the long term and different trajectories of succession according to the type of former agricultural use. The long‐term legacies of past land use in current forest plant communities highlight the importance to preserve ancient forests, where typical forest species can be maintained. [ABSTRACT FROM AUTHOR]

Forest area has dramatically increased since the beginning or middle of the 19th century in European countries. At least half of the forests present today have grown on formerly cultivated lands, pastures or heathlands. However, net forest expansion largely masks a slow but irretrievable erosion of ancient forests. Meanwhile, forest resource harvesting (biomass, litter) has fundamentally changed during the last two centuries, moving from intensive biomass removal to increased growing stocks in different European countries. This article reviews the current knowledge on the long‐term legacies of past land use and forest management practices and their effects on the functions, diversity and composition of understory vegetation of current forest ecosystems. First, we define the concepts of forest continuity and ancient forest. Then, based on the French case, we present the advances in historical sources, which make it possible to better reconstruct the change in land use and forest management practices over the last two hundred years. We review how understory plant communities and their traits respond to forest continuity and to different types of former agricultural uses, both at local and landscape scales. We then address three important issues for conservation and management: the conservation value of ancient forests, the impact of forest management on the ecological integrity of ancient forests, and the under‐explored legacies of former forest management practices on soil and understory vegetation. Lastly, we propose five main fronts for future research efforts: (a) explore all types of cartographic, written sources and environmental markers; (b) develop modelling approaches to understand how past land use shapes plant communities; (c) better define the conservation value of ancient forests in conservation and management policies; (d) investigate how drivers of global change interact with forest management and land use legacies and (e) explore land use legacies in mountain and Mediterranean socio‐ecological systems. [ABSTRACT FROM AUTHOR]

Aim: Examining tree species–environment association can offer insight into the drivers of vegetation patterns and key information of practical relevance to forest management. Here, we aim to quantify the contribution of climate and soil gradients to variation in Central African tree species composition (abundance and occurrence). Location: Tropical rain forests of southern and eastern Cameroon. Methods: We established 82 1‐ha permanent plots across seven localities and censused all trees ≥10 cm in diameter, representing a total of 37,733 trees and 455 species. In 60 of those plots, we measured 10 soil variables describing texture and nutrients levels and extracted 10 bioclimatic variables from global‐gridded climate databases. We synthesized the main environmental gradients by conducting principal component analyses on climate and soil data, respectively. We performed unconstrained and constrained non‐symmetric correspondence analyses to account for the individual and joint contributions of climate and soil on species abundance and occurrence. Results: Climate and soil contributed similarly to variances of species abundance and occurrence (12–15% variance for climate vs 11–12% variance for soil). Climate influence mostly concerns some abundant species, while some of the less abundant species were mainly driven by soil. Fractions of species variances accounted for by climate and soil show strong correlation when assessed from species occurrence and abundance data. Conclusion: Variation in occurrence and abundance of tropical forest trees can be partly shaped by both climate and soil gradients in Cameroon, which emphasizes the importance to jointly consider soil and climate in species distribution modeling. Less abundant species may express environmental influence differently than abundant species and convey complementary information about community assemblage. Though showing congruent patterns here, species abundance and occurrence reflect different interacting community processes and both should be examined to better understand vegetation patterns. [ABSTRACT FROM AUTHOR]

Questions: How do contrasting environmental conditions among forests and hedgerows affect the vegetative and reproductive performance of understorey forest herbs in both habitats? Can hedgerows support reproductive source populations of forest herbs, thus potentially allowing progressive dispersal of successive generations along these linear habitats? Location: Hedgerows and deciduous forest patches in agricultural landscapes across the European temperate biome. Methods: First, we assessed differences in environmental conditions among forests and hedgerows. Next, we quantified plant performance based on a set of functional life‐history traits for four forest herbs (Anemone nemorosa, Ficaria verna, Geum urbanum, Poa nemoralis) with contrasting flowering phenology and colonisation capacity in paired combinations of forests and hedgerows, and compared these traits among both habitats. Finally, we assessed relationships between plant performance and environmental conditions in both habitats. Results: All study species showed a higher above‐ground biomass in hedgerows than in forests. For Poa nemoralis and Geum urbanum, we also found a higher reproductive output in hedgerows, which was mainly correlated to the higher sub‐canopy temperatures therein. The "ancient forest herb" Anemone nemorosa, however, appeared to have a lower reproductive output in hedgerows than in forests, while for Ficaria verna no reproductive differences were found between the two habitats. Conclusions: This is the first study on such a broad geographical scale to provide evidence of reproductive source populations of forest herbs in hedgerows. Our findings provide key information on strategies by which forest plants grow, reproduce and disperse in hedgerow environments, which is imperative to better understand the dispersal corridor function of these wooded linear structures. Finally, we highlight the urgent need to develop guidelines for preserving, managing and establishing hedgerows in intensive agricultural landscapes, given their potential to contribute to the long‐term conservation and migration of forest herbs in the face of global environmental change. [ABSTRACT FROM AUTHOR]

Questions: We consider whether: (a) fire frequency and hydrologic trends drive changes in subalpine forest community diversity and; (b) if there are cumulative effects on diversity when frequent fire and hydrologic drying occur synchronically? Location: We use three high elevation sites from Wyoming, USA to investigate the response and resiliency of subalpine forests in the Rocky Mountains to centennial‐to‐millennial drought and fire disturbances in regards to shifts in pollen richness, evenness and diversity. Methods: 'We examine ecological changes measured by pollen richness, evenness and diversity between subalpine communities under drying and wetting conditions to determine if there is an amplified effect when differing fire frequencies are considered. Using the inverse Simpson index of pollen diversity on pollen percentages as an estimate of biodiversity. Results: Periods of frequent fire display significantly higher diversity (p < 0.05) than periods of infrequent or intermediate fire return intervals regardless of hydrologic trends at Little Windy Hill Pond. Further, sites in the northern and southern Rocky Mountains appear to operate under differing fire regimes with sites in the northern Rocky Mountains not recording periods of frequent fire (>225 year mean fire return interval) through the Holocene. Conclusions: Changes in past pollen abundance and diversity have the ability to capture past landscape structure and ecosystem turnover prior to European settlement of the Americas. If fire regimes in subalpine forests of the Rocky Mountains continue trending towards higher frequencies there is the potential for these areas to experience an increase in vegetation diversity. [ABSTRACT FROM AUTHOR]

Questions: Forest fragmentation affects biodiversity locally (α diversity) and beyond — at relatively larger scales (γ diversity) — by increasing dispersal and recruitment limitations. Yet, does an increase in fragmentation affect the relationship between α and γ diversity and what can we learn from it? Location: Northern France. Methods: We surveyed 116 forest patches across three fragmentation levels: none (continuous forest); intermediate (forest patches connected by hedgerows); and high (isolated forest patches). Plant species richness of both forest specialists and generalists was surveyed at five nested spatial resolutions across each forest patch: 1 m2; 10 m2; 100 m2; 1,000 m2; and total forest patch area. First, we ran log‐ratio models to quantify the α–γ relationship. We did that separately for all possible combinations of fragmentation level (none vs intermediate vs high) × spatial scale (e.g., α‐1 m2 vs γ‐10 m2) × species type (e.g., α‐specialists vs γ‐specialists). We then used linear mixed‐effects models to analyze the effect of fragmentation level, spatial scale, species type and all two‐way interaction terms on the slope coefficient extracted from all log‐ratio models. Results: We found an interaction effect between fragmentation level and species type, such that forest specialists shifted from a linear (i.e., proportional sampling) to a curvilinear plateau (i.e., community saturation) relationship at low and high fragmentation, respectively, while generalists shifted from a curvilinear to a linear pattern. Conclusions: The impact of forest fragmentation on the α–γ relationship supports generalist species persistence over forest specialists, with contrasting mechanisms for these two guilds. As fragmentation increases, forest specialists shift from proportional sampling towards community saturation, thus reducing α diversity likely due to dispersal limitation. Contrariwise, generalists shift from community saturation towards proportional sampling, thus increasing α diversity likely due to an increase in the edge:core ratio. To ensure long‐term conservation of forest specialists, one single large forest patch should be preferred over several small ones. [ABSTRACT FROM AUTHOR]

Questions: Large trees provide structural heterogeneity that may influence the distribution and diversity of epiphytes, yet this has not been fully examined in northern temperate rainforest trees. How does epiphyte diversity, percent cover and composition vary among trunk and branch zones within northern temperate rainforest trees? Are there steep gradients in environmental conditions or resources within northern temperate rainforest trees? To what degree do species show specialization to particular zones within northern temperate rainforest trees? Location: Temperate rainforest on the Olympic Peninsula in Washington State, USA. Methods: We recorded epiphyte richness, percent cover, and composition in 78 plots from six tree zones (three trunk zones and three branch zones) in six large bigleaf maple (Acer macrophyllum) trees. At each survey point, we measured temperature, relative humidity, canopy cover, moss depth, height in tree, and branch diameter to examine the degree of habitat specialization along measured environmental and resource gradients and the importance of structural heterogeneity for epiphyte species diversity in entire trees. Results: Rarefied epiphyte richness was 25% higher on the trunk than in the branches, and there was little overlap in species composition between trunk and branch zones. Species composition changed with height as well as decreasing canopy cover along the trunk. Within the branches, epiphyte composition was related to branch diameter and moss depth; while the inner and mid‐branch zone communities were similar, the outer branch community differed. Microclimate variables did not vary significantly among tree zones and were not related to epiphyte distributions. Conclusions: The structural heterogeneity of large A. macrophyllum trees created gradients in canopy cover and substrate characteristics that enabled up to 13 different epiphyte species to coexist. Thus, these trees are critical structures for the maintenance of forest diversity. [ABSTRACT FROM AUTHOR]

Question: Biodiversity surveys of epiphytic bryophytes and lichens on standing trees are mostly restricted to the lowermost 2 m, since sampling above this level is time‐consuming and therefore expensive. However, sampling only the stem base is likely to result in underestimation of forest epiphyte diversity, because microclimate and physico‐chemical site conditions, both of which vary with height above the ground, play important roles for poikilohydric organisms. We investigate variation in epiphyte diversity and composition along the vertical gradient in forests and discuss factors that may potentially account for height‐dependent distribution patterns. Location: Montane primeval beech forest Havešová in the Carpathians, eastern Slovakia. Methods: Ten circular plots, each 500 m2, were selected randomly in an area severely affected by windfall. Epiphytes were sampled along the stems of recently uprooted trees, from base to the canopy. Mean Ellenberg indicator values (EIV) for light, moisture, acidity and nitrogen availability were used as surrogate variables for environmental interpretation of compositional patterns for sampling segments of 2 m along the stem. Results: By sampling only the lowest 2 m, 10% of the total bryophyte and 48% of the lichen species would have been missed. We detected systematic patterns of compositional variation for both groups along the vertical gradient. While pleurocarpous mosses and liverworts were mostly restricted to the stem base, acrocarpous mosses and crustose lichens occurred along the stem almost to the top. Foliose and fruticose lichens were concentrated at intermediate heights and in the upper canopy. Patterns of variation in EIVs suggested that increasing light availability, decreasing moisture and increasing inputs of acidic and nitrous substances are responsible for the compositional shifts along the vertical gradient. Conclusions: Sampling only the stem base implies severe underestimation of the epiphyte diversity in temperate broad‐leaved forests. The middle and the upper parts of tree stems have distinctive compositions of epiphytic cryptogams, because microclimate and physico‐chemical site factors vary with height above the ground. [ABSTRACT FROM AUTHOR]

Question In dense tropical forests, climbers and hemiepiphytes depend on the quantity and quality of direct light more than other plant life forms. What are their responses with respect to quantitative changes of canopy structure and light regime after a hurricane? Here, we study their contribution to closure of the canopy and changes in light regime, with the help of hemispherical photography. Their change in space and time may serve as an illustration and measure of key processes after repetitive large disturbances. Location Martinique, the Plateau Concorde, in an evergreen montane forest. Methods After Hurricane Dean, a diachronic study (2008-2012) was carried out. Four parallel surface areas 50 × 10 m were set up. Canopy structure and light conditions were assessed with hemispherical photographs, using a polar projection fisheye lens. All standing trees >5 cm DBH, and all climbers and hemiepiphytes were mapped and identified to species. Correspondence analysis ( CA) using selected life traits illustrated the distribution of climbers present on trees per category (a total of four). The number of individuals and species which have disappeared or appeared per category was calculated. Results From 2009 to 2012, the total number of climbers and hemiepiphytes decreased from 248 to 225, but in different proportions according to strata. Climbers were classified into categories in function of the range of responses (i.e. resistance and responsiveness). Conclusion Our study demonstrates the potential to detect climber/hemiepiphyte strategies after a large disturbance using hemispherical photography and plant traits. [ABSTRACT FROM AUTHOR]

Question In a recent re-classification of Amazonian floodplain types, a new category was established for paleo-várzea. Although the geological basis for this classification is sound, a key question is whether it can be supported by botanical criteria, where floodplain paleo-várzea forests contain distinct tree assemblages compared to other major floodplain types. Location Central Amazonian floodplains, Brazil. Methods We used 41 tree inventories from floodplain paleo-várzea, várzea and igapó forests to perform a meta-analysis. Diversity and richness estimators were applied at the level of genus and the examination of floristic composition was performed at family and generic levels. Generic composition across the three floodplain types was investigated using GNMDS and cluster analysis. Similarity coefficients and ANOSIM were applied to quantify floristic resemblance at the generic level between forest types. Indicator species analysis ( ISA) was used to identify any indicator genera for the forest types evaluated. Results Alpha diversity and generic richness in paleo-várzea forest was similar to várzea. Igapó forest was clearly the least diverse. Family composition was similar across the three forest types; Fabaceae was the dominant family on all three floodplains. Pouteria, Licania and Eschweilera presented the highest importance values in paleo-várzea, but these genera were also important in várzea and igapó. Nevertheless, ANOSIM analyses show that generic composition differed significantly between the three forest types, and a GNMDS ordination and cluster analysis portrays paleo-várzea tree composition as intermediate between várzea and igapó. ISA revealed that Euterpe, Dipteryx and Goupia were the most important indicator genera of paleo-várzea. Conclusions We conclude that paleo-várzea floodplain tree assemblages are dissimilar to those of várzea and igapó, but contain components typical of both these floodplain types, explaining their intermediate positioning in our analyses. This floral mix probably allows paleo-várzea alpha diversity to be similar to that of várzea. [ABSTRACT FROM AUTHOR]

Question When can we assume that inter-specific trait variation is higher than intra-specific trait variation in plant community ecology? Location Old-growth deciduous forest in the Gault Nature Reserve, Mount St. Hilaire ( Quebec, Canada,45′32.957″ N, 73′08.884″ W), with a shorter environmental gradient than normally exists in community studies. Methods We measured 15 functional traits on all tree saplings occurring in 39 (5-7-m radius) sample plots. Using variance decomposition from mixed models and from sums of squares of community-weighted traits, we determined the relative importance of temporal, spatial, inter-specific, intra-specific and intra-individual variation in each trait. In total, we collected trait information on 3317 leaves from 786 twigs sampled on 422 saplings. Results For 12 of 15 traits, over 50% of the total variance existed between species and inter-specific variation was always the most important source of variation. However for 14 traits, intra-specific and environmental variation represented up to 28% of the total variation. Variation in community-weighted trait means was mostly generated by changes in species composition, but intra-specific trait variation was the dominate cause for leaf nitrogen, specific leaf area and tree branching. The intra-individual and temporal sources of variation were not important. Conclusions Trait variation should be dominated by inter-specific differences in most studies since they involve systems with more pronounced environmental gradients, higher species richness and more β-diversity than used here. However, in studies with short gradients, or when using more plastic traits, it will be necessary to measure trait values for each site. It is important to quantify the β-diversity of the environmental gradients in question in order to compare results across studies. [ABSTRACT FROM AUTHOR]