Functional Trait Data Research Articles

Impacts of climate, soil and biotic interactions on the interplay of the different facets of alpine plant diversity

Disentangling the processes that drive plant community assembly is critical for understanding the patterns of plant diversity. We studied how different abiotic and biotic factors shape the interplay between the facets of alpine plant diversity, functional (FD), phylogenetic (PD) and taxonomic diversity (TD), in three different mountain ranges with contrasting evolutionary histories and climate conditions (Pyrenees and Mediterranean-type mountains in central Spain and Chilean Andes). We hypothesized that the causal links vary in strength and sign across regions. We used species inventories, functional trait data, and a phylogeny from 84 plant communities spread throughout three high-mountain alpine grasslands. Structural equation models were used to test our causal hypotheses on the relationships observed between the three diversity facets, and the abiotic (elevation, potential solar radiation and soil total nitrogen) and biotic factors (C-score). Despite our causal model presented a high variability in each mountain range, TD always decreased with increasing elevation (sum of direct and indirect effects). We also found some patterns suggesting that assembly processes could be climatically/biogeographically structured such as the negative relationship between FD and elevation found in Mediterranean mountains and the negative relationship between FD and TD found in both Spanish mountain ranges (independently of their different climates). A remarkable finding of this study is that ecological factors such as soil total nitrogen and elevation indirectly alter the relationships between the diversity facets. Our results suggest that diversity facets are simultaneously affected by different ecological and biogeographical/evolutionary processes, resulting in some general trends but also in parallel idiosyncratic patterns. Our findings highlight that although FD stand out by its explanatory power of community processes, TD and PD provide a complementary and necessary view that should not be disregarded in the attempt to globally explain community assembly processes.

Trait-Environment Relationship of Aquatic Vegetation in a Tropical Pond Complex System

The relationship between organisms’ traits and the characteristics of their habitats has been a central theme in ecology. Using two complementary approaches to analyze three-matrices of species composition, functional trait, and environment data (RLQ and fourth-corner analyses), we tested if environmental gradient determines aquatic plant traits in ponds in the Pantanal wetland. Furthermore, we tried to understand if plant composition is spatially structured and if environmental gradient is correlated with taxonomic and functional community properties. We sampled aquatic plants coverage in 20 ponds and measured pond size, depth and pH to represent the environmental gradient. We found significant turnover of several traits of aquatic plants along the environmental gradient, being niche partitioning the most probable process structuring plant communities. There was no evidence of spatial autocorrelation determining species composition in the scale of the study, which may indicate that the annual flooding can act as homogenizing factor that promotes species co-occurrence along the ponds. Taxonomic abundance and functional richness were positively related with environmental gradient. Larger and deeper ponds provide higher resource availability thus supporting more functional attributes and vegetation cover. Our results support the hypothesis that niche process is the main driver of aquatic plants in the Pantanal.

Where do Functional Traits Come From? The role of theory and models

There is a growing focus on species’ traits in ecology, including initiatives to integrate trait data into biodiversity databases. This focus is motivated in part by a need to develop better predictive capacity for how species respond to environmental change. In this context, one is interested in functional traits – i.e. those with a defined link to environmental variability. This leads immediately to the questions of which traits to prioritise and how to characterise them. Here we argue that this can be achieved with greatest clarity by letting traits be defined by the equations of theoretical models that link individuals to their environments, i.e. mechanistic niche models. We illustrate this approach using the biophysical equations of heat and water exchange, and the metabolic equations of ontogentic growth. From this we derive a schema for a functional trait database that provides a high level of generality and consistency across taxa, and hooks into integrated predictive modelling frameworks. We argue that functional trait attribution at levels above the individual are unhelpful, but discuss how inferences can be made from individual-level functional trait data to populations and species.

Measuring Morphological Functional Leaf Traits From Digitized Herbarium Specimens Using TraitEx Software

Herbarium specimens are of vital importance for understanding biodiversity. There are more than 350 million specimens stored in herbaria worldwide (Thiers 2018) Globally, many herbaria have undertaken digitization projects of plant specimens, on a massive scale, to preserve them and to make the images easily accessible to users. Over the past years, with significant advances in the field of computer vision, new potential uses of digitized specimens have emerged, such as automated species identification using qualitative morphological traits. However, due to lack of efficient tools, efforts to extract functional (quantitative) morphological traits from digitized herbarium specimens are lagging behind. Functional trait data is of significant importance to understand the functioning of the ecosystem and interactions between biotic and abiotic factors. It is currently fragmented and initiatives such as TRY Trait database (https://www.try-db.org) are making efforts to fill the gaps in the observed trait matrix (Schrodt et al. 2015). In order to complement the global efforts, we have developed a software tool, TraitEx , which can measure quantitative traits such as the length, area, width and perimeter of leaves along with the petiole length from digitized herbarium specimens. TraitEx is a standalone Java-based open source tool developed after extensive interactions with biodiversity researchers. The main features of the tool are: (1) efficiently handling high-resolution specimen images, (2) accurately extracting measurements from specimens with varied leaf shapes that are mounted using white tape, (3) integrating ImageJ functionality (https://imagej.net/Welcome) to pre-process and edit the images, (4) measuring trait values to export in comma separated values (CSV) format along with original image and (5) reducing potential damage of fragile specimens, which might occur while physically measuring the traits. Along with user guide and documentation, TraitEx tool is available at https://bitbucket.org/traitExTool/traitextool. The tool is made available under the BSD-2-Clause License.

Latitudinal and climate effects on key plant traits in Chinese forest ecosystems

Abstracts A long-standing goal of ecology and forest management is to understand the environmental controls of resource utilization strategy of plants along geographical gradients. However, the mechanisms that guide this phenomenon, especially along latitude gradients, remain unclear. Using key leaf functional trait data of 1185 species within 120 sites in Eastern and Western China, we quantified the relationships between plant traits, namely leaf area (LA), specific leaf area (SLA), leaf nitrogen content, leaf phosphorus content, leaf dry matter content (LDMC) and leaf delta 13C (d 13C) content, and local climate along the latitude in Eastern and Western China. Our results revealed that: (1) Plant traits showed a wide variation across the study locations in China. The variation in plant traits was strongly correlated with latitude. (2) In Eastern China, latitude alone explained 54% and 53% of the variation in N:P and leaf phosphorus content (Pmass (g/kg)), respectively. In Western China, latitude alone explained 75% of the variation in leaf area. In Eastern China, most plant traits are significantly correlated with each other. However, this phenomenon is not obvious in Western China. (3) Immediate climate factors (mean climate in the month when the leaf traits were sampled) contributes most to explaining functional traits related to leaf nutrients, such as leaf nitrogen content (Nmass (g/kg), Narea (g/cm2)), leaf phosphorus content (Pmass (g/kg), Parea (g/cm2)), and annual mean climate contributes more to explaining functional traits related to leaf survival strategies. (4) In Eastern China, immediate climate and annual mean climate variables can explain the variance of 39.2% and 41.3% of plant traits variation, respectively. In Western China, the effect size of corresponding factors are 23.4% and 25.2%, respectively.

Plant Functional Diversity and the Biogeography of Biomes in North and South America

The concept of the biome has a long history dating back to Carl Ludwig Willdenow and Alexander von Humboldt. However, while the association between climate and the structure and diversity of vegetation has a long history, scientists have only recently begun to develop a more synthetic understanding of biomes based on the evolution of plant diversity, function, and community assembly. At the broadest scales, climate filters species based on their functional attributes, and the resulting functional differences in dominant vegetation among biomes are important to modeling the global carbon cycle and the functioning of the Earth system. Nevertheless, across biomes, plant species have been shown to occupy a common set of global functional “spectra”, reflecting variation in overall plant size, leaf economics, and hydraulics. Still, comprehensive measures of functional diversity and assessments of functional similarity have not been compared across biomes at continental to global scales. Here, we examine distributions of functional diversity of plant species across the biomes of North and South America, based on distributional information for > 80,000 vascular plant species and functional trait data for ca. 8,000 of those species. First, we show that despite progress in data integration and synthesis, significant knowledge shortfalls persist that limit our ability to quantify the functional biodiversity of biomes. Second, our analyses of the available data show that all the biomes in North and South America share a common pattern–most geographically common, widespread species in any biome tend to be functionally similar whereas the most functionally distinctive species are restricted in their distribution. Third, when only the widespread and functionally similar species in each biome are considered, biomes can be more readily distinguished functionally, and patterns of dissimilarity between biomes appear to reflect a correspondence between climate and functional niche space. Taken together, our results suggest that while the study of the functional diversity of biomes is still in its formative stages, further development of the field will yield insights linking evolution, biogeography, community assembly, and ecosystem function.

Intraspecific Trait Variability in Andropogon gerardii, a Dominant Grass Species in the US Great Plains

The climatic conditions in the North American Great Plains are highly variable, characteristic of an inter-continental climate. Antecedent climate history has impacted the flora of Great Plains grasslands, resulting in high species richness as well as dominance by only a few grass species, such as Andropogon gerardii. While the productivity of A. gerardii is well described, the individual physiological and morphological characteristics that confer species dominance over wide spatial gradients are not clearly understood. We performed a literature search to assess intra-specific trait variability of A. gerardii from as many locations as possible. Ultimately, only 13 locations in the Great Plains have reported common plant functional traits (PFTs) for this species. To best represent site-specific climate conditions, plant functional trait data (8 PFTs) were collected from literature reporting ambient growing conditions, and excluded experimental manipulations. For most PFTs, we found insufficient data to fully quantify the range of variation across the geographical extent of A. gerardii dominance. This is surprising given that we focused on the most abundant grass in one of the most well-studied regions globally. Furthermore, trait data collected from our literature search showed a high degree of variability, but no strong relationships were observed between mean trait values and climate predictors. Our review of the literature on A. gerardii suggests a role for trait variability as a mechanism enabling the dominance of this species across large regions such as the Great Plains of North America.

Tree crown overlap improves predictions of the functional neighbourhood effects on tree survival and growth

Abstract Investigations of forest community structure and dynamics have been facilitated by the use of neighbourhood models that examine the interactions between a focal tree and its neighbours using a fixed radius. However, different studies have chosen different radii without clear reasons, hampering the understanding of mechanisms structuring tree communities. Using functional trait and tree demography data from the Luquillo subtropical forest in Puerto Rico, we compared fixed‐neighbourhood models with a canopy overlap model, in which tree crown overlap is used as an indicator of neighbourhood crowding. Analyses that combine functional trait and demographic data provide a mechanistic understanding of observed patterns of community structure and dynamics as they provide insights into the linkages between phenotypes and the environment. Overall, canopy overlap models had better support when compared to neighbourhood models using a fixed radius, suggesting that the fixed radius approach does not capture the full extent of competitive interactions among trees. Moreover, the effects of functional neighbourhood on tree survival and growth differ depending on the type of approach used and lead to different conclusions with respect to the drivers of tree community dynamics. Synthesis. In summary, our findings highlight the utility of neighbourhood models based on tree crown overlap, and suggest that applying this same approach to different plots and forests will facilitate comparisons across systems and improve our understanding of the mechanisms that drive the structure and dynamics of tree communities.

Understanding the recruitment response of juvenile Neotropical trees to logging intensity using functional traits.

Selective logging remains a widespread practice in tropical forests, yet the long-term effects of timber harvest on juvenile tree (i.e., sapling) recruitment across the hundreds of species occurring in most tropical forests remain difficult to predict. This uncertainty could potentially exacerbate threats to some of the thousands of timber-valuable tree species in the Amazon. Our objective was to determine to what extent long-term responses of tree species regeneration in logged forests can be explained by their functional traits. We integrate functional trait data for 13 leaf, stem, and seed traits from 25 canopy tree species with a range of life histories, such as the pioneer Goupia glabra and the shade-tolerant Iryanthera hostmannii, together with over 30 yr of sapling monitoring in permanent plots spanning a gradient of harvest intensity at the Paracou Forest Disturbance Experiment (PFDE), French Guiana. We anticipated that more intensive logging would increase recruitment of pioneer species with higher specific leaf area, lower wood densities, and smaller seeds, due to the removal of canopy trees. We define a recruitment response metric to compare sapling regeneration to timber harvest intensity across species. Although not statistically significant, sapling recruitment decreased with logging intensity for eight of 23 species and these species tended to have large seeds and dense wood. A generalized linear mixed model fit using specific leaf area, seed mass, and twig density data explained about 45% of the variability in sapling dynamics. Effects of specific leaf area outweighed those of seed mass and wood density in explaining recruitment dynamics of the sapling community in response to increasing logging intensity. The most intense treatment at the PFDE, which includes stand thinning of non-timber-valuable adult trees and poison-girdling for competitive release, showed evidence of shifting community composition in sapling regeneration at the 30-yr mark, toward species with less dense wood, lighter seeds, and higher specific leaf area. Our results indicate that high-intensity logging can have lasting effects on stand regeneration dynamics and that functional traits can help simplify general trends of sapling recruitment for highly diverse logged tropical forests.

Understanding the Recruitment Response of Juvenile Neotropical Trees to Logging Intensity Using Functional Traits

Selective logging remains a widespread practice in tropical forests, yet the long-term effects of timber harvest on juvenile tree (i.e., sapling) recruitment across the hundreds of species occurring in most tropical forests remain difficult to predict. This uncertainty could potentially exacerbate threats to some of the thousands of timber-valuable tree species in the Amazon. Our objective was to determine to what extent long-term responses of tree species regeneration in logged forests can be explained by their functional traits. We integrate functional trait data for 13 leaf, stem, and seed traits from 25 canopy tree species with a range of life histories, such as the pioneer Goupia glabra and the shade-tolerant Iryanthera hostmannii, together with over 30 yr of sapling monitoring in permanent plots spanning a gradient of harvest intensity at the Paracou Forest Disturbance Experiment (PFDE), French Guiana. We anticipated that more intensive logging would increase recruitment of pioneer species with higher specific leaf area, lower wood densities, and smaller seeds, due to the removal of canopy trees. We define a recruitment response metric to compare sapling regeneration to timber harvest intensity across species. Although not statistically significant, sapling recruitment decreased with logging intensity for eight of 23 species and these species tended to have large seeds and dense wood. A generalized linear mixed model fit using specific leaf area, seed mass, and twig density data explained about 45% of the variability in sapling dynamics. Effects of specific leaf area outweighed those of seed mass and wood density in explaining recruitment dynamics of the sapling community in response to increasing logging intensity. The most intense treatment at the PFDE, which includes stand thinning of non-timber-valuable adult trees and poison-girdling for competitive release, showed evidence of shifting community composition in sapling regeneration at the 30-yr mark, toward species with less dense wood, lighter seeds, and higher specific leaf area. Our results indicate that high-intensity logging can have lasting effects on stand regeneration dynamics and that functional traits can help simplify general trends of sapling recruitment for highly diverse logged tropical forests.

Towards an eco-evolutionary understanding of endemism hotspots and refugia.

Refugia are island-like habitats that are linked to long-term environmental stability and, as a result, high endemism. Conservation of refugia and endemism hotspots should be based on a deep ecological and evolutionary understanding of their functioning, which remains limited. Although functional traits can provide such insights, a corresponding, coherent framework is lacking. Plant communities in refugia and endemism hotspots should, due to long-term environmental stability, display unique functional characteristics linked to distinct phylogenetic patterns. Therefore, such communities should be characterized by a functional signature that exhibits: (1) distinct values and combinations of traits, (2) higher functional diversity and (3) a prevalence of similar traits belonging to more distantly related lineages inside, compared to outside, of endemism hotspots and refugia. While the limited functional trait data available from refugia and endemism hotspots do not allow these predictions to be tested rigorously, three potential applications of the functional signature in biogeography and conservation planning are highlighted. Firstly, it allows the functional characteristics of endemism hotspots and refugia to be identified. Secondly, the strength of the functional signature can be compared among these entities, and with the surrounding landscape, to provide an estimate of the capacity of endemism hotspots and refugia to buffer environmental changes. Finally, the pattern of the functional signature can reveal ecological and evolutionary processes driving community assembly and functioning, which can assist in predicting the effect of environmental changes (e.g. climate, land-use) on communities in endemism hotspots and refugia. The proposed functional signature concept allows the systematic integration of plant functional traits and phylogeny into the study of endemism hotspots and refugia, but more data on functional traits in these entities are urgently needed. Overcoming this limitation would facilitate rigorous testing of the proposed predictions for the functional signature, advancing the eco-evolutionary understanding of endemism hotspots and refugia.

Herbaria as Functional Trait Databases

Although tropical rainforests play an important role in regulating the world’s climate, they are at the same time particularly vulnerable to changes in the climate. Intense and prolonged droughts, for instance, can lead to biomass loss which will further accelerate these changes. Especially for tree species it becomes problematic, due to their long lifespan, to quickly adapt to or evade unfavorable climatic conditions affecting the composition of the forest community as a whole and consequently the ecosystem services that the rainforests provide. A long-term drying trend currently threatens tropical regions worldwide but is especially strong in the central African rainforest, the second-largest rainforest on Earth. The impact of this decrease in precipitation on the vegetation is, however, still largely unknown due to the limited amount of historical eco-climatological data. Fortunately, these kind of data do exist albeit in a poorly accessible (analog) format in herbarium collections. To investigate if trees show changes in morphology and/or physiology invoked by climatic changes in the last century, the COBECORE team (Congo Basin Eco-Climatological Data Recovery and Valorization”) is exploring the usability of herbaria as potential sources of plant leaf functional trait data using established protocols adjusted to dried leaf material. Photosynthesis as well as gas exchange and transpiration are processes regulated by a plant’s leaves, and depend on the specific leaf area (SLA) and the number and size of the stomata. The less area the latter structures occupy on the leaf the less the plant will suffer from water losses which increases the resistance to drought of plants. We explored the recently digitized African Herbarium of the Botanic Garden Meise which contains over 1.2 million African specimens with a very good coverage of the Congo Basin, dating back to 1880. Currently, we obtained average SLA measurements for 833 herbarium specimens from 59 of the most common tree species of central African rainforests. Pictures for stomata counts and size measurements were taken from over one hundred specimens mainly focused on three Prioria species, giant tree species (up to 60 metres) currently suffering from overexploitation. The data generated in this project will be valuable to understand some lower-level vegetation responses such as plant water use needed to model and predict long-term climate change impacts on vegetation.

Divergent Secondary Metabolites and Habitat Filtering Both Contribute to Tree Species Coexistence in the Peruvian Amazon.

Little is known about the mechanisms promoting or limiting the coexistence of functionally divergent species in hyperdiverse tropical tree genera. Density-dependent enemy attacks have been proposed to be a major driver for the local coexistence of chemically divergent congeneric species. At the same time, we expect local soil conditions to favor the coexistence of species sharing similar functional traits related to resource use strategies, while environmental heterogeneity would promote the diversity of these traits at both local and large spatial scales. To test how these traits mediate species coexistence, we used functional trait data for 29 species from the tree genus Protium (Burseraceae), collected in 19 plots (2 ha each) in the Peruvian Amazon. We characterized the presence-absence of 189 plant secondary metabolites (SM) for 27 of these species, and 14 functional traits associated with resource use strategies (RUT) for 16 species. Based on these data, we found that SM were significantly more dissimilar than null expectations for species co-occurring within plots, whereas RUT were significantly more similar. These results were consistent with the hypothesis that density-dependent enemy attacks contribute to the local coexistence of congeneric species displaying divergent chemical defenses, whereas local habitat conditions filter species with similar RUT. Using measurements of nine soil properties in each plot, we also found a significant turnover of RUT traits with increasing dissimilarity of soil texture and nutrient availabilities, providing support for the hypothesis that soil heterogeneity maintains functional diversity at larger spatial scales (from 500 m up to ca. 200 km) in Protium communities. Our study provides new evidence suggesting that density-dependent enemy attacks and soil heterogeneity both contribute to maintaining high species richness in diverse tropical forests.

Assessing the relative influences of abiotic and biotic factors on American eel Anguilla rostrata distribution using hydrologic, physical habitat, and functional trait data

Species’ distributions are influenced by abiotic and biotic factors but direct comparison of their relative importance is difficult, particularly when working with complex, multi‐species datasets. Here, we compare the relative effects of hydrology, physical habitat, and co‐occurring fish functional traits on the contemporary (1950–1990) distribution of the American eel Anguilla rostrata in six Mid‐Atlantic (USA) rivers. To do so, we implement a null model approach that compares conditions at sites of known American eel presence to a random sample of sites throughout a broader landscape, allowing us to identify variables that may have the strongest influences on American eel distribution. Results suggest that, within this subset of the American eel's geographic range, the functional characteristics of locally co‐occurring fishes and habitat fragmentation by dams may have the strongest influences on American eel distribution, compared to other predictor variables included in the analysis. Given the widespread distribution and complex biology of this species, we caution that our results may not apply to all American eel subpopulations or life stages. Nonetheless, the observed importance of co‐occurring fish functional traits may inform American eel conservation and, more generally, provide a means to incorporate biotic influences in research on species’ distributions.

Grasslands maintained with frequent fire promote cold‐tolerant species

AbstractQuestionIn temperate grasslands and savannas that were historically maintained by frequent, low‐intensity fires, disturbance by fire may promote community resistance to winter climate change by favouring slow‐growing, resource‐conservative species that may also be more cold‐tolerant. The lack of functional trait data for measuring cold tolerance, however, has prevented testing this idea. We ask, are slower growing, resource‐conservative species more cold‐tolerant than fast‐growing species, and are plant responses to fire frequency and cold tolerance related?LocationPrairies and savannas of south‐central Wisconsin, USA.MethodsWe measured leaf cold tolerance for 120 plant species from prairies and savannas and compared cold tolerance to fire affinity as well as other functional traits describing plant strategies.ResultsAs predicted, resource‐conservative species are more cold‐tolerant than fast‐growing species in temperate grasslands and savannas. Cold tolerance is also associated with disturbance regime such that species found in frequently burned sites are more cold‐tolerant.ConclusionsThe ability to predict the degree of susceptibility of species and communities to winter climate change and extreme climate events, such as freezing, will provide insight into the conservation and management practices to promote species persistence into the future. Under climate change, communities composed of more stress‐tolerant species may be more likely to persist. Our results demonstrate that cold‐tolerant species are more common in temperate grasslands and savannas managed with frequent, low‐intensity fire that simulate historic disturbance regimes. Identifying and maintaining ecosystems composed of stress‐tolerant species may play a key role in preserving natural communities under environmental uncertainty.

MADA: Malagasy Animal trait Data Archive.

Species are characterized by their behavioral, physiological, and ecological attributes, which determine their role in ecosystems. In turn, ecosystems and their functions are defined by the species that inhabit them. Thus, evaluating the functional diversity and distributions of species is of utmost importance to studies of biogeography, community ecology, macroevolution, and conservation. The functional diversity of species are determined by traits such as diet, foraging strata, trophic level, activity cycle, litter size, generation length, habitat breadth, and body mass. While there has been a recent growth of information regarding the vertebrate taxa of Madagascar, this information is not always easy to access (non-digitized), and is often fragmented by taxon, location, trait, or combinations thereof. Here, we present the Malagasy Animal trait Data Archive (MADA), a compilation of these and other functional traits, representing the ecological and geographical diversity of all 214 extant mammal and 242 bird species of Madagascar. Data were collected from extensive literature reviews. This Archive is currently limited by select cases of missing data, errors, and uncertainty in the literature; however, it represents the most comprehensive collection of functional trait data of Malagasy mammals and birds to date. The structure of the database allows for different levels of information (and specificity) in each entry and organization by taxon, range, bioclimate, and trait. MADA will be continuously updated as new data become available. Potential uses of MADA include ecological research on the trait or trophic structure of communities, inquiries regarding the mechanisms of community assembly, comparative studies of functionally (dis)similar species, and conservation efforts concerned with the loss of ecosystem function. Madagascar is simultaneously home to one of the most exclusive, diverse, and endangered faunas of the world, making MADA a uniquely valuable resource for biodiversity science and conservation. No copyright restrictions are associated with this dataset. We would appreciate that researchers cite this paper if using all or part of the datasets.

Community assembly of the ferns of Florida.

Many ecological and evolutionary processes shape the assembly of organisms into local communities from a regional pool of species. We analyzed phylogenetic and functional diversity to understand community assembly of the ferns of Florida at two spatial scales. We built a phylogeny for 125 of the 141 species of ferns in Florida using five chloroplast markers. We calculated mean pairwise dissimilarity (MPD) and mean nearest taxon distance (MNTD) from phylogenetic distances and functional trait data for both spatial scales and compared the results to null models to assess significance. Our results for over vs. underdispersion in functional and phylogenetic diversity differed depending on spatial scale and metric considered. At the county scale, MPD revealed evidence for phylogenetic overdispersion, while MNTD revealed phylogenetic and functional underdispersion, and at the conservation area scale, MPD revealed phylogenetic and functional underdispersion while MNTD revealed evidence only of functional underdispersion. Our results are consistent with environmental filtering playing a larger role at the smaller, conservation area scale. The smaller spatial units are likely composed of fewer local habitat types that are selecting for closely related species, with the larger-scale units more likely to be composed of multiple habitat types that bring together a larger pool of species from across the phylogeny. Several aspects of fern biology, including their unique physiology and water relations and the importance of the independent gametophyte stage of the life cycle, make ferns highly sensitive to local, microhabitat conditions.

Interactions between abiotic gradients determine functional and phylogenetic diversity patterns in Mediterranean‐type climate mountains in the Andes

AbstractQuestionsHow do phylogenetic and functional trait dispersions respond to multiple abiotic gradients? Are functional trait and phylogenetic dispersions coupled across different spatial scales? Does phylogenetic signal on functional trait data help to elucidate the degree to which phylogenetic information is providing novel information?LocationThree massifs in mediterranean‐type climate zone of the high Andes, central Chile.MethodsWe sampled plant species composition in 20 alpine sites above the tree line at three different spatial scales: plot (20 m × 20 m), subplot (2.4 m × 2.4 m) and cell (30 cm × 30 cm). Functional and phylogenetic mean pair‐wise distances (MPD) calculated using data on six functional traits (maximum plant height, plant size, leaf area, specific leaf area, leaf dry matter content and leaf thickness) and a molecular phylogeny (rbcL and matK) were compared to the patterns expected under a null model to characterize the functional and phylogenetic dispersion along interacting elevation and potential solar radiation gradients.ResultsOur results show that functional and phylogenetic dispersion were related and influenced by potential solar radiation, but the effect of this factor varied with elevation. Overdispersion was found in the most stressful sites, while clustering was observed where the conditions were milder, suggesting a relevant role of facilitation and competitive interactions, respectively. While Blomberg's K statistic indicated no phylogenetic signal for the studied plant traits, Pagel's λ indicated phylogenetic signal, but not of strong intensity (<1), suggesting that the correlation between the functional and phylogenetic diversities was low and that additional unmeasured traits with phylogenetic signal were likely to be important in determining the structure of the studied communities.ConclusionsOur results support the hypothesis that biotic interactions modulated by environmental conditions are important for alpine plant community assembly. Moreover, they reinforce the notion that multiple processes shape community structure, and this can be elucidated by examining interacting environmental gradients, such as elevation and potential solar radiation, and taking into account multiple spatial scales. Our results reinforce the use of both functional and phylogenetic diversities simultaneously and discourage the use of phylogenetic diversity as a surrogate of functional structure.

Linking Taxonomic Diversity and Trophic Function: A Graph-Based Theoretical Approach

The purpose of this study is to develop a novel, visual method in analyzing complex functional trait data in freshwater ecology. We focus on macroinvertebrates in stream ecosystems under a gradient of habitat degradation and employ a combination of taxonomic and functional trait diversity analyses. Then we use graph theory to link changes in functional trait diversity to taxonomic richness and habitat degradation. We test the hypotheses that: 1) taxonomic diversity and trophic functional trait diversity both decrease with increased habitat degradation; 2) loss of taxa leads to a decrease in trophic function as visualized using a bipartite graph; and 3) loss of taxa will result in loss of redundancy. The first hypothesis was supported by the similarity of Shannon-Wiener diversity values for taxa and trophic function, correlated at r = 81%. The bipartite graph theoretic approach we developed clearly was effective in showing the linkages between taxonomic diversity and trophic functional traits related to habitat condition. In the most impaired site, loss of taxa led to the complete loss of some trophic functions and significantly less overall redundancy, supporting the third hypothesis. The implications are that taxa loss directly affects trophic function and that loss of taxonomic diversity may affect ecosystem function.

The PCA index for measuring functional diversity and its application to Juglans mandshurica communities in the Beijing mountains, China

Methods for measuring functional diversity are essential for functional studies of plant communities. A useful method, the PCA index, based on principal component analysis ordination of functional trait data was introduced and applied to functional diversity analysis of Juglans mandshurica communities in the Beijing Mountains. Thirty-five [Formula: see text] quadrats were established in Juglans mandshurica communities. Species composition, functional traits and environmental factors were measured and recorded. The four common indices, FAD, MFAD, FDp and FDc, were used and compared with the PCA index in the analysis. The results showed that the PCA index was successful in quantifying functional diversity and describing its relationships with environmental variables; therefore, it was an effective index in functional diversity analyses. Functional diversity in Juglans mandshuricacommunities varied widely. Elevation and aspect were the key factors affecting functional diversity in communities. Functional diversity increased with elevation increases and with the change in aspect from North to South. Functional diversity was significantly correlated with species richness and heterogeneity.