Assessing the reliability of predicted plant trait distributions at the global scale.

AIM: Predictions of plant traits over space and time are increasingly used to improve our understanding of plant community responses to global environmental change. A necessary step forward is to assess the reliability of global trait predictions. In this study, we predict community mean plant traits at the global scale and present a systematic evaluation of their reliability in terms of the accuracy of the models, ecological realism and various sources of uncertainty. LOCATION: Global. TIME PERIOD: Present. MAJOR TAXA STUDIED: Vascular plants. METHODS: We predicted global distributions of community mean specific leaf area, leaf nitrogen concentration, plant height and wood density with an ensemble modelling approach based on georeferenced, locally measured trait data representative of the plant community. We assessed the predictive performance of the models, the plausibility of predicted trait combinations, the influence of data quality, and the uncertainty across geographical space attributed to spatial extrapolation and diverging model predictions. RESULTS: Ensemble predictions of community mean plant height, specific leaf area and wood density resulted in ecologically plausible trait-environment relationships and trait-trait combinations. Leaf nitrogen concentration, however, could not be predicted reliably. The ensemble approach was better at predicting community trait means than any of the individual modelling techniques, which varied greatly in predictive performance and led to divergent predictions, mostly in African deserts and the Arctic, where predictions were also extrapolated. High data quality (i.e., including intraspecific variability and a representative species sample) increased model performance by 28%. MAIN CONCLUSIONS: Plant community traits can be predicted reliably at the global scale when using an ensemble approach and high-quality data for traits that mostly respond to large-scale environmental factors. We recommend applying ensemble forecasting to account for model uncertainty, using representative trait data, and more routinely assessing the reliability of trait predictions.

Floristic patterns of alluvial forests in Atlantic Forest and Pampa: Climate and geographic insertion as determining factors.

The aims of this study were to identify floristic assemblages for alluvial forests in the Atlantic Forest and Pampa regions in Brazil, assess the level of floristic similarity between assemblages, and determine environmental gradients and indicator species for these assemblages. Surveys carried out in alluvial forests in the Atlantic Forest and Pampa regions were selected, based on which a presence/absence matrix was built for tree species. A cluster analysis was performed to verify the existence of species assemblages. Floristic similarity was determined by means of the Sorensen Distance measure, from which a dendrogram was developed. The floristic matrix was ordinated by means of NMDS. A PCA was performed with climatic data from areas to determine environmental gradients. An assessment of indicator species was carried out afterwards. Two groups of areas not related to the separation of the regions became visible from the dendrogram and were corroborated by NMDS. Temperature, rainfall and altitude gradients were synthesized by the PCA. Gymnanthes klotzschiana and Andira fraxinifolia were the most relevant species, respectively, in the Paraná-Uruguay and Atlantic assemblages. Alluvial forests were gradually separated in two floristic assemblages associated with river basins and migration routes, while especially influenced by tropicality and altitude gradients.

Functional niche differences between native and invasive tree species from the southern Brazilian mixed forest.

Biological invasion is a major threat to global biodiversity and ecosystem services. We examined the functional traits similarity between a set of native and non-native invasive tree species from the Southern Brazilian subtropical mixed forest, part of an important global hotspot for biodiversity conservation. We hypothesized that invasive species occupy marginal niche spaces. We ordered the species using the Principal Component Analysis based on their wood density, leaf area, and specific leaf area. These are all important traits that summarize essential ecological strategies associated with resource acquisition and conservation. Functional overlaps between non-native and native species were analyzed through kernel density estimation of continuous traits data. While native and non-native invasive species were distributed along the same functional gradients, the position of non-native species in the functional space is species and traits specific. We concluded that within Brazilian subtropical mixed forests, the functional dissimilarity as a key factor in invasion success could not be generalized for all species and traits.

Floristic-functional variation of tree component along an altitudinal gradient in araucaria forest areas, in Southern Brazil.

We aimed to investigate the taxonomic and functional variations of tree component of Araucaria Forest (AF) areas located along an altitudinal gradient (700, 900 and 1,600 m asl), in the southern region of Brazil. The functional traits determined were leaf area, specific leaf area, wood density, maximum potential height and dispersal syndromes and deciduousness. The data were analyzed through a functional and taxonomic dissimilarity dendrograms, community-weighted mean trait values, parametric and nonparametric tests, and Principal Component Analysis. The largest floristic-structural similarity was observed between the lower altitude areas (700 and 900 m asl), whose Bray-Curtis distance was 0.63. The area at 700 m asl was characterized by a predominance of deciduous and semi-deciduous species, with a high number of self- and wind-dispersed species, whereas the area at 1,600 m asl exhibited a predominance of animal-dispersed and evergreen species. It was also observed that there were significant variations for leaf traits, basic wood density and maximum potential height. Over all altitudinal gradient, the ordinations indicated that there was no evidence of functional differentiation among dispersal and deciduousness groups. In conclusion, the evaluated Araucaria Forest areas presented high floristic-functional variation of the tree component along the altitudinal gradient.

How do distinct facets of tree diversity and community assembly respond to environmental variables in the subtropical Atlantic Forest?

This study assessed the impact of altitude, precipitation, and soil conditions on species richness (SR), phylogenetic diversity (PD), and functional diversity (FD) standardized effect sizes in subtropical Brazilian Atlantic Forest tree communities. We considered specific trait information (FDs) for FD, reflecting recent adaptive evolution, contrasting with deeper phylogenetic constraints in FD. Three functional traits (leaf area-LA, wood density-WD, and seed mass-SM) were examined for their response to these gradients. Generalized least squares models with environmental variables as predictors and diversity metrics as response variables were used, and a fourth-corner correlation test explored trait-environmental relationships. SR decreased with altitude, while PD increased, indicating niche convergence at higher altitudes. Leaf area and seed mass diversity also decreased with altitude. For LA, both FD and FDs were significant, reflecting filtering processes influenced by phylogenetic inheritance and recent trait evolution. For SM, only the specific trait structure responded to altitude. LA and SM showed significant trait-environmental relationships, with smaller-leaved and lighter-seeded species dominant at higher altitudes. Soil gradients affect diversity. Fertile soils have a wider range of LA, indicating coexistence of species with different nutrient acquisition strategies. WD variation is lower for FDs. SM diversity has different relationships with soil fertility for FDs and FD, suggesting phylogeny influences trait variation. Soil pH influences WD and LA under acidic soils, with deeper phylogenetic constraints (FD). Environmental factors impact tree communities, with evidence of trait variation constraints driven by conditions and resources. Subtropical Atlantic forests' tree assemblies are mainly influenced by altitude, pH, and soil fertility, selecting fewer species and narrower trait spectra under specific conditions (e.g., higher altitudes, pH). Functional diversity patterns reflect both phylogenetic and recent evolution constraints, with varying strength across traits and conditions. These findings highlight the intricate processes shaping long-lived species assembly across diverse environments in the Southern Brazilian Atlantic Forest.

Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation.

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land-climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles.

Spatial and temporal structure of diversity and demographic dynamics along a successional gradient of tropical forests in southern Brazil.

Analysis of the structure, diversity, and demographic dynamics of tree assemblages in tropical forests is especially important in order to evaluate local and regional successional trajectories.We conducted a long-term study to investigate how the structure, species richness, and diversity of secondary tropical forests change over time. Trees (DBH ≥ 5 cm) in the Atlantic Forest of southern Brazil were sampled twice during a 10-year period (2007 and 2017) in six stands (1 ha each) that varied in age from their last disturbance (25, 60, 75, 90, and more than 100 years). We compared forest structure (abundance and basal area), species richness, alpha diversity, demographic rates (mortality, recruitment, and loss or gain in basal area), species composition, spatial beta diversity, and temporal beta diversity (based on turnover and nestedness indices) among stand ages and study years.Demographic rates recorded in a 10-year interval indicate a rapid and dynamic process of species substitution and structural changes. Structural recovery occurred faster than beta diversity and species composition recovery. The successional gradient showed a pattern of species trade-off over time, with less spatial dissimilarity and faster demographic rates in younger stands. As stands grow older, they show larger spatial turnover of species than younger stands, making them more stochastic in relation to species composition. Stands appear to split chronologically to some extent, but not across a straightforward linear axis, reflecting stochastic changes, providing evidence for the formation of a nonequilibrium community. Policy implications. These results reiterate the complexity and variability in forest succession and serve as a reference for the evaluation and monitoring of local management and conservation actions and for defining regional strategies that consider the diversity of local successional trajectories to evaluate the effectiveness of restoration measures in secondary forests of the Atlantic Forest biome.

Ligustrum lucidum W. T. Aiton (broad-leaf privet) demonstrates climatic niche shifts during global-scale invasion.

Biological invasions are a major threat to global biodiversity. Ligustrum lucidum, native to temperate Asia, is one of the most invasive plant species in the world. Climate is an important ecological factor influencing species distribution. Therefore, we investigated the climatic niche of L. lucidum in various regions of the world to determine whether it uses different climatic conditions in its invasive ranges than in its native range. The geographical coordinates of its occurrence were extracted from the Global Biodiversity Information Facility and Southern African Plant Invaders Atlas databases. Climatic variables and altitude data were obtained from WorldClim. We evaluated niche overlap and performed niche similarity tests, and estimated niche shift parameters. L. lucidum occurs mostly in warm temperate climates. Niche overlap between native and invaded areas was low. Niche similarity tests indicated that the species could expand its occurrence into regions with climates similar to and different from that of its native range. We concluded that L. lucidum uses different realized climatic niches in its invasive ranges than in its native range. Warmer and wetter climatic conditions may not necessarily constrain this species from establishing populations outside of its native range.

Global trait-environment relationships of plant communities.

Plant functional traits directly affect ecosystem functions. At the species level, trait combinations depend on trade-offs representing different ecological strategies, but at the community level trait combinations are expected to be decoupled from these trade-offs because different strategies can facilitate co-existence within communities. A key question is to what extent community-level trait composition is globally filtered and how well it is related to global versus local environmental drivers. Here, we perform a global, plot-level analysis of trait-environment relationships, using a database with more than 1.1 million vegetation plots and 26,632 plant species with trait information. Although we found a strong filtering of 17 functional traits, similar climate and soil conditions support communities differing greatly in mean trait values. The two main community trait axes that capture half of the global trait variation (plant stature and resource acquisitiveness) reflect the trade-offs at the species level but are weakly associated with climate and soil conditions at the global scale. Similarly, within-plot trait variation does not vary systematically with macro-environment. Our results indicate that, at fine spatial grain, macro-environmental drivers are much less important for functional trait composition than has been assumed from floristic analyses restricted to co-occurrence in large grid cells. Instead, trait combinations seem to be predominantly filtered by local-scale factors such as disturbance, fine-scale soil conditions, niche partitioning and biotic interactions.

Floristic-functional variation of tree component along an altitudinal gradient in araucaria forest areas, in Southern Brazil

ABSTRACT We aimed to investigate the taxonomic and functional variations of tree component of Araucaria Forest (AF) areas located along an altitudinal gradient (700, 900 and 1,600 m asl), in the southern region of Brazil. The functional traits determined were leaf area, specific leaf area, wood density, maximum potential height and dispersal syndromes and deciduousness. The data were analyzed through a functional and taxonomic dissimilarity dendrograms, community-weighted mean trait values, parametric and nonparametric tests, and Principal Component Analysis. The largest floristic-structural similarity was observed between the lower altitude areas (700 and 900 m asl), whose Bray-Curtis distance was 0.63. The area at 700 m asl was characterized by a predominance of deciduous and semi-deciduous species, with a high number of self- and wind-dispersed species, whereas the area at 1,600 m asl exhibited a predominance of animal-dispersed and evergreen species. It was also observed that there were significant variations for leaf traits, basic wood density and maximum potential height. Over all altitudinal gradient, the ordinations indicated that there was no evidence of functional differentiation among dispersal and deciduousness groups. In conclusion, the evaluated Araucaria Forest areas presented high floristic-functional variation of the tree component along the altitudinal gradient.

Demographics and spatial pattern on three populations of Myrtaceae in the Ombrophilous Mixed Forest / Demografia e padrão espacial de três populações de Myrtaceae na Floresta Ombrófila Mista

ABSTRACT: The aim of this study was to characterize the demographic structure and spatial pattern of Campomanesia xanthocarpa (Mart.) O. Berg, Myrcianthes gigantea (D. Legrand) D. Legrand and Myrciaria delicatula (DC.) O. Berg. Within one hectare of Ombrophilous Mixed Forest, all the three populations' individuals were counted and measured with regard to their height and diameter. From the collected data, the assessment of the demographic structure was realized after the individual's size classification. Spatial pattern was determined by applying the Standardized Morisita's Index. C. xanthocarpa and M. delicatula showed an inverted-J frequency distribution in the individuals size classes, which differed from M. gigantea that did not follow the same pattern. The spatial pattern of C. xanthocarpa and M. delicatula populations was found mainly to be aggregated; whereas, M. gigantea showed spatial randomness. The three Myrtaceae populations responded differently with regard to structure and spatial distribution in sites with the same environmental filters.

RESUMO: Objetivou-se caracterizar a estrutura demográfica e o padrão espacial de Campomanesia xanthocarpa (Mart.) O. Berg, Myrcianthes gigantea (D. Legrand) D. Legrande Myrciaria delicatula (DC.) O. Berg, bem como, verificara influência de variáveis ambientais sobre essas populações. Em um hectare de Floresta Atlântica, todos os indivíduos das três populações foram contados e mensurados quanto à altura e diâmetro. A estrutura demográfica foi avaliada após classificação de tamanho dos indivíduos, o padrão espacial pelo Índice de Morisita Padronizado. Campomanesia xanthocarpa e M. delicatula apresentaram distribuição de frequência dos indivíduos em classes de tamanho em J invertido, já a espécie M. gigantea não seguiu o mesmo comportamento. O padrão espacial das populações de C. xanthocarpa e M. delicatula foi, predominantemente, agregado e, para M. gigantea, o padrão foi aleatório. Verifica-se que as populações de Myrtaceae possuem respostas diferenciadas quanto à estrutura e distribuição espacial em sítios com os mesmos filtros ambientais.