Variation In Functional Diversity Research Articles

Plant spectral diversity from high‐resolution multispectral imagery detects functional diversity patterns in coastal dune communities

AbstractQuestionRemote sensing is a fundamental tool to monitor biodiversity and spectral diversity may represent a proxy for different biodiversity facets such as taxonomic (TD) and functional diversity (FD). We used fine‐resolution multispectral imagery to explore spectral diversity (SD) patterns across spatial scales (i.e., plot, transect, area), and assess SD relationships with TD and FD along an environmental gradient.LocationCoastal sand dune, Viareggio, Italy (“Migliarino–San Rossore–Massaciuccoli” Regional Park, 43°83′ N, 10°25′ E).MethodsWe measured TD as species richness, while SD and FD were computed using probability density functions based on pixel and species position in multivariate spaces. We compared SD and FD patterns in space occupation, and we tested whether these patterns are coordinated along the sea–inland gradient. We also assessed univariate relationships between SD and biodiversity facets, and we tested how these facets were partitioned across scales.ResultsWe found a strong correspondence between functional and spectral patterns in space occupation and along the environmental gradient, with a lack of significance when considering TD. However, TD and SD showed higher variation at broader scale while most FD variation occurred at plot level.ConclusionBy measuring FD and SD with a common methodological framework, we demonstrate that SD approximates functional patterns in plant communities. Moreover, we show that SD retrieved using high‐resolution images can capture different aspects of FD, and that the occupation of the spectral space is analogous to the occupation of the functional space.

Environmental correlates of tree functional diversity with different leaf habits across subtropical evergreen broadleaved forests

AbstractAimEvergreen and deciduous broadleaved plants have long been considered as different strategies to cope with environmental conditions, which are closely related to the trait syndromes associated with leaf habits. However, there are no assessments of differences in functional diversity among evergreen and deciduous species over a regional scale.LocationSubtropical evergreen broadleaved forest (SEBLF) of China.MethodsWe measured seven functional traits of 292 woody plant species in 250 forest plots across five locations in the SEBLF. We quantified functional richness (FRic), functional divergence (FDiv), and functional evenness (FEve) for evergreen vs deciduous species separately. We compared the patterns of variation of functional diversity for different leaf habits along geographical (latitude, longitude and elevation) and environmental (climate and soil) gradients.ResultsFunctional richness of evergreen species was higher than that of deciduous species, while FDiv and FEve were lower. FRic of evergreen species decreased while FDiv increased with increasing elevation. For deciduous species, FRic and FDiv decreased with increasing latitude. With the increase of longitude, only FDiv of evergreen species decreased. FEve of both leaf habits did not exhibit geographical patterns. Environmental variables explained 9%–38% and 4%–33% of the variation in functional diversity of evergreen and deciduous species respectively. The temperature range was the most important factor affecting FRic and FDiv of evergreen species, while FRic of deciduous species was mainly affected by precipitation of the driest quarter. FEve of both leaf habits was mostly affected by soil conditions.Main conclusionsFunctional diversity of subtropical forests in China revealed different geographical patterns across leaf habits. The functional diversity of evergreen species was mainly linked to temperature, while the deciduous species were driven by precipitation. Our study demonstrated that different functional diversity patterns of evergreen and deciduous broadleaved plants in response to environment can result in the coexistence of the two leaf habit types.

Global variation in unique and redundant mammal functional diversity across the daily cycle

AbstractAimOrganisms primarily influence ecosystems through their functional traits when they are physically active. Following the nocturnal bottleneck, the expansion of mammals into the daytime expanded mammalian functional diversity (FD), however there is also notable overlap in trait space across diel niches leading to redundant FD. We explore how the unique and redundant contribution of each diel niche varies spatially and in relation to natural variation in light and temperature.LocationGlobal.TaxonExtant mammals.MethodsBased on five major functional traits (body mass, litter size, diet breadth, foraging strata, habitat breadth) for 5033 extant terrestrial mammals, we determine biogeographical variation in nocturnal, crepuscular, cathemeral and diurnal FD. We calculate the proportion of mammalian FD that is unique to each diel niche, and the proportion that is redundant across the daily cycle.ResultsThe diversification of mammals into the daytime resulted in the creation of new FD (28.5% of FD is not nocturnal; Lower Quartile 17.3%; Upper Quartile 38.2%). Most of this expansion occurred at higher latitudes where uniquely cathemeral FD dominates (>55°N, 41.1% of mammalian FD; Lower Quartile 33.3%, Upper Quartile 53.6%), associated with fewer hours of biologically useful moonlight and daylight. Where there are more hours of biologically useful daylight, unique diurnal FD is common. However, more than half of non‐nocturnal FD is redundant, increasing ecosystem stability as different species carry out similar functions at different times of day, and suggesting that many mammals have not diversified far from their nocturnal ancestors.Main conclusionsOver much of the land surface more than a half of FD only occurs at night, underscoring the importance of nocturnal mammals for ecosystems. Understanding diel variation in FD not only informs on community structure and ecosystem function but also on ecosystem functional persistence in the Anthropocene, with pressures at night being particularly concerning.

A trait‐based approach to marine island biogeography

AbstractAimThe Island Biogeography Theory (IBT) and its multiple extensions explain species diversity patterns in insular systems. However, how these theories can predict the functional diversity patterns in island systems remains challenging. Here, we evaluated the predictions of the IBT, the General Dynamic Theory of Oceanic Island Biogeography (GDM) and the Glacial‐sensitive model of Island Biogeography (GSM) considering the functional diversity of reef fishes on islands.LocationTropical oceanic islands.TaxonActinopterygii.MethodWe combined literature data and online repositories to gather occurrence data and traits of reef fish species for 72 tropical oceanic islands. We then calculated five functional diversity indices (functional richness ‘FRic’, functional evenness ‘FEve’, functional divergence ‘FDiv’, functional over‐redundancy ‘FOR’ and functional vulnerability ‘FVul’). We used generalized additive mixed models to explore relationships among species richness and functional indices. Furthermore, we built Bayesian models to evaluate relationships between the functional diversity indices and several island features (isolation from the nearest reef, past and present reef area, and geological age) and two metrics that reflect the potential influence of Quaternary climatic changes (isolation from Quaternary refugia) and historical contingency (isolation from biodiversity centres).ResultsWe observed higher levels of FRic, FDiv and FOR on the Indo‐Pacific islands, whereas FEve and FVul showed higher values on the Atlantic and Eastern Pacific islands. We identified positive relationships between FRic, FDiv and FOR with species richness but negative relationships with FEve and FVul. We found that past and present reef areas best explained the variation in functional diversity among islands.Main ConclusionsThe functional diversity of reef fishes on oceanic islands showed a longitudinal gradient, which can be explained by differences in the evolutionary history among marine regions. Furthermore, past and present reef areas were found to be the best predictors of reef fish functional diversity on oceanic islands, extending the IBT, GDM and GSM for marine organisms within a trait‐based framework.

Interpreting spatially explicit variation in dietary proxies through species distribution modeling reveals foraging preferences of mammoth (Mammuthus) and American mastodon (Mammut americanum)

IntroductionThe end Pleistocene was a time of considerable ecological upheaval. Recent work has explored the megafauna extinction’s role in altering ecosystem processes. Analyses of functional traits withing communities reveal hidden consequences of the megafauna extinction beyond declines in taxonomic diversity. Functional diversity analyses offer new insight into our understanding of past ecosystems and may even inform future rewilding efforts. However, the utility of functional diversity may be hampered by the use of discrete, taxon-level functional traits, such as dietary categories, that mask variation in functional diversity over space and time.MethodsWe present an approach in which species distribution modeling, in Maxent, provides context for interpreting variation in two widely used proxies for diet among fossil taxa: stable isotope analysis and dental microwear texture analysis. We apply this approach to two ecologically distinct taxa, the American mastodon (Mammut americanum) and mammoths (Mammuthus) and investigate their resource use over space and time from the last glacial maximum to the end Pleistocene (25–11.7 thousand years before present).ResultsMammoth dietary behavior varies by context across their geographic distribution, despite possessing evolutionary adaptations that facilitate grazing. Mammoths exhibit a preference for grazing where species distribution modeling predicts the highest likelihood of occurrence but engage in more mixed-feeding outside of core likelihood areas. In contrast, dietary preferences for mastodon are less resolved and our analyses were unable to identify significant differences in diet across their distribution.DiscussionThe ecological roles of some species are context specific and need to be critically evaluated when planning for management of reintroductions or introducing novel species to restore lost ecological function.

Variation in functional trait diversity from tropical to cold-temperate forests and linkage to productivity

Functional trait diversity is an integrative plant trait index that represents an emerging and promising approach for exploring gross primary productivity (GPP); however, it is necessary to determine how these indices vary at large scales in natural forests to establish their linkage to GPP. Here, we explored spatial variation in functional diversity and underlying linkages to GPP in the natural forests of China. Specifically, we consistently measured 10 leaf traits related to the GPP of 366 tree species in nine typical forests along the North-South Transect of Eastern China and calculated three functional diversity indices (functional richness, FRic; functional evenness, FEve; and functional divergence, FDiv) for each community. All three indices consistently varied in different directions along the transect, due to the impact of climate (temperature and precipitation). FRic increased with temperature and precipitation, whereas FDiv decreased. FRic and FDiv (but not FEve) were identified as important metrics influencing GPP at large scales. Functional diversity, climate, and soil combined explained 90.4% of total variation in GPP from cold-temperate to tropical forests. The results confirmed that there is spatial variation in functional trait diversity, and that functional diversity is important for determining spatial variation in GPP in natural forests at large scales and should be integrated into ecological models.

Characterizing seasonal variation in foliar biochemistry with airborne imaging spectroscopy

Foliar biochemical traits are important indicators of ecosystem functioning and health that are impractical to characterize at large spatial and temporal scales using traditional measurements. However, comprehensive inventories of foliar traits are important for understanding ecosystem responses to anthropogenic and natural disturbances, as inputs into ecosystem process models, and for quantifying spatial variation in functional diversity. Imaging spectroscopy has been demonstrated as a valuable tool for developing maps of ecologically important foliar traits at large scales, but its application to mapping foliar traits over the course of the growing season has been limited. We collected high-resolution imaging spectroscopy data over Blackhawk Island, Wisconsin, USA at eight time points during the 2018 growing season (May – October). Using partial least squares regression (PLSR) we developed predictive models applicable to all dates to produce canopy-level maps of eight traits related to ecophysiological function: chlorophyll content, leaf mass per area and concentrations of calcium, nitrogen, phosphorus, potassium, phenolics and lignin. The accuracy of our models varied across traits (R2: 0.25–0.86); traits with well-defined absorption features were retrieved with high accuracy including chlorophyll (R2: 0.86; %RMSE: 11.0) and total phenolics (R2: 0.86; %RMSE: 11.0). We also assessed how well our models estimated biochemistry on novel species and new dates using a cross-validation analysis. Chlorophyll and total phenolics were well estimated across withheld dates and species, whereas calcium was estimated poorly on both withheld species (R2: 0.08) and dates (R2: 0.07). Our canopy-level maps of macronutrients (N, P and K) showed general trends of decreasing concentration over the course of the year, reflecting dilution by carbon-rich compounds during the growing season and resorption during senescence. Conversely, recalcitrant compounds including lignin and calcium increased until late summer, after which they stabilized. These results demonstrate the potential of current and proposed spaceborne imaging spectroscopy missions for mapping seasonal patterns in foliar biochemistry at a global scale.

Reef Fish Diversity Across the Temperate South Pacific Ocean

Patterns of species richness and their structuring forces at multiple scales provide a critical context for research efforts focusing on ecology, evolution, and conservation. Diversity gradients have been demonstrated in tropical reef fish, but corresponding patterns and mechanisms remain poorly understood in temperate regions. We conducted hierarchical (spatially nested) sampling of temperate reef fish faunas across > 140 degrees of longitude in the eastern and western South Pacific Ocean. Our sampling efforts spanned five distinct provinces: the Southeast Australian Shelf (SAS), Northern and Southern New Zealand (N-SNZ), Juan Fernandez and Desventuradas Islands (JFD), and the Warm Temperate Southeastern Pacific (WTPA). We evaluated (i) spatial variation in patterns of species richness and abundance (using Chao 1 index), and distribution of functional diversity (using several functional attributes: max body size, trophic groups, feeding guilds, trophic level, habitat use, gregariousness, and activity patterns) and (ii) scale-dependencies in these patterns. Species richness declined from west to east across the temperate South Pacific, but this pattern was detectable only across larger spatial scales. A functional redundancy index was significantly higher in the western South Australian Shelf at multiple scales, revealing that species contribute in equivalent ways to an ecosystem function such that one species may substitute for another. We also detected that patterns of variation in functional diversity differed from patterns of variation in species richness, and were also dependent on the spatial scale of analysis. Lastly, we identified that species’ traits are not equally distributed among reef fish assemblages, where some provinces are characterized by a distinct functional component within their reef fish assemblages. Planktivorous and schooling species, for instance, dominated the assemblages in the eastern Pacific, which is characterized by higher primary productivity and steep bathymetric slopes favoring these traits. Demersal and pairing behavior traits dominated the reef fish assemblages in western Pacific provinces (SAS, SNZ). We conclude that combining the identifies and species’ traits allow us to disentangle historical, biogeographic and environmental factors that structure reef fish fauna.

Windstorm effects on herbaceous vegetation in temperate forest ecosystems: Changes in plant functional diversity and species trait values along a disturbance severity gradient

Catastrophic wind disturbance affects not only forest structure and regeneration, but also functional and compositional dynamics of the herbaceous layer. However, the issue of changes in functional diversity and functional trait values of the understory layer in response to wind disturbance has not been addressed so far. This study aims at investigating the patterns of variations in functional diversity, trait values and species richness of herbaceous species following wind disturbance.The study was carried out in the Piska Forest, a woodland complex in northern Poland, which was almost completely destroyed by a windstorm in 2002 and part of which was successively set aside to study the effects of natural disturbance on forest ecosystems. Vegetation surveys were conducted at 112 sample plots between 2014 and 2015. Four forest habitat types were identified and individually examined. The degree of disturbance severity was assessed as percentage of dead trees on all trees per surface unit. A set of twelve functional traits was assigned to the recorded species.Three functional diversity metrics (richness, evenness and divergence) were calculated based on the selected functional traits. We assessed the relationship between each of such metric and disturbance severity for each habitat type. The relationship between species richness and disturbance severity was also determined. We then estimated the relative importance of habitat type and disturbance severity on both functional diversity and species richness. Lastly, we examined the response of functional trait values to both disturbance severity and habitat type.Our results showed that wind disturbance effects on functional diversity are not univocal and that they strongly depend on habitat type. In fact, while in coniferous stands disturbance determined a decrease of functional divergence and left functional richness unaltered, in mixed-coniferous habitats it enhanced functional richness and did not affect functional divergence. In mixed-deciduous habitats, both functional richness and divergence decreased. In swamp habitats no major changes in functional diversity were observed. Changes in functional evenness were not significant. At the same time, disturbance significantly enhanced species richness in all forest habitats, but the coniferous one. It was not possible to clearly disentangle the relative contribution of disturbance and habitat type, since the two are strictly correlated. Out of the tested functional traits, only SLA, seed releasing height and share of stress-tolerant species exhibited significant response along the tested disturbance gradient. Most of the other traits reacted only to variations in the habitat type.

Functionality and Effectiveness of Marine Protected Areas in Southeastern Brazilian Waters for Demersal Elasmobranchs

Ensuring the efficacy of Marine Protected Areas (MPAs) requires that adequate management strategies be implemented according to the MPA’s objectives. Within the scope of species conservation, achieving MPA objectives demands understanding of the role played by MPAs for the target species. In 2014, Brazilian stakeholders and experts set the action plan for elasmobranchs’ conservation, which intended to create new protected areas and expand the existing ones. Nevertheless, more than 65% of Brazilian elasmobranch species are threatened by anthropogenic pressures such as fisheries and habitat loss. In addition, their ecological aspects are not well studied, which might jeopardize the success of the proposed actions. To assess the functionality and effectiveness of two no-take MPAs for sixteen demersal species, the Wildlife Refuge of Alcatrazes (WRA) and the Tupinambás Ecological Station (TES), we evaluated the community structure, space-time variations in functional diversity and changes in fishery indicators. Community dynamics were driven by inshore intrusion and time persistent effects of a cold and nutrient-rich water mass, the South Atlantic Central Water, which increased the relative abundance of species, functional groups, and overall diversity. Spatially, the heterogeneity of benthic habitats, due to the action of stronger waves in specific parts of the MPAs, reflects a diverse community of benthic invertebrates, explaining differences in relative abundance and similarities in space use by the functional groups. Regarding effectiveness, the MPAs make up a key network with the surrounding protection areas to support the ecosystem maintenance on the central and northern coast of the São Paulo state. The establishment of the TES has positively influenced the community throughout the years while the recent creation of the WRA may have promoted some improvements in fisheries indicators for a threatened guitarfish. We propose different functions of the Alcatrazes archipelago for each species and suggest some measures to enhance not only elasmobranch conservation but also the MPAs’ effectiveness.

Patterns of species and functional diversity of macrofaunal assemblages and the bioassessment of benthic ecological quality status in the southern Yellow Sea

Macrofauna are useful indicators of benthic ecological quality status, which were studied in summer and autumn of 2020 in the southern Yellow Sea, China. A total of 134 species were identified, and polychaetes represented the most dominant group. The dominant species across both seasons were Ophiura sarsii vadicola, Trigonothracia jinxingae, Heteromastus filiforms, Ninoё palmata, Thyasira tokunagai, Sigambra hanaokai, Ehlersileanira incisa hwanghaiensis, and Portlandia japonica. The average values of macrofaunal abundance and biomass were 386.68 ind./m2 and 28.21 g/m2, respectively. Species diversity during the autumn was slightly higher than that in the summer. Seasonal variations in functional diversity were also observed. BIOENV results indicated that water depth, bottom water temperature, and sediment phaeophorbide content was the optimal combination of parameters to explain macrofaunal assemblage variation. Bioassessment results, based on H’, AMBI, and M-AMBI, showed that most sites in the southern Yellow Sea could be classed as moderate or good status.

Virtual teamwork in healthcare delivery: I-O psychology in telehealth research and practice

[...]research on virtual healthcare teams will take place primarily in field-based versus laboratory-based settings, which may improve the ecological validity of research findings when applied in practice. [...]the rapid transition to telehealth due to the COVID-19 pandemic presents a significant opportunity for longitudinal research to study healthcare teams with a prior (and, perhaps long-term) history of face-to-face (FTF) interactions that now take place with some extent of virtuality. [...]in the inpatient setting, teams engaging in virtual rounding or teams working within inpatient COVID-19 care units will exhibit variations in functional diversity (e.g., clinical expertise), technology used (e.g., videoconferencing, telephone), and geographic dispersion (e.g., locally within the hospital with some in/out of the patient room) throughout the duration of a patient’s hospitalization. [...]there is an opportunity to move beyond subjective satisfaction and experience indicators of virtual team performance to more objective outcomes.

Functional Traits of Bats Associated with the Use of Wetlands in Colombian Tropical Dry Forests

Bats have a major functional role in wetlands; understanding how functional traits of bats depend on environmental characteristics can facilitate management of ecosystems and their services. In this study, we investigated how bat functional diversity has been affected by different anthropogenic impacts in wetlands of the Trans-Andean tropical dry forest of Colombia. Specifically, we analyzed how different functional traits responded to changing environmental conditions and land use and land cover patterns. We sampled six wetlands during the dry periods of the hydrological cycle from 2014 to 2018 and modeled the functional diversity as a function of environmental variables. To understand the association of bat community structure with environmental variables and biotic factors, we combined the RLQ analysis and the fourth-corner approach to relate environmental characteristics and species traits. The percentages of water surface area and pasture land were found to be associated with the general traits of bats when analyzed using the relative abundance of species. In addition, changes in functional diversity appeared to be driven mainly by larger species (e.g., Phyllostomus hastatus, Artibeus lituratus), whose presence was primarily associated with heterogeneous areas. The fourth-corner analysis revealed that the greatest length of skull is the trait that best describes the presence of bats in landscapes of pastures, water bodies, and high abundance of the shrubs Vismia sp. and Cecropia sp. These results suggest that combinations of specific features are important drivers of variation in functional diversity between wetlands. Considering the high vulnerability of Colombian wetlands, our findings provide fundamental information for the development of strategies for monitoring wetland biodiversity. The results can help identify priority conservation sites and improve environmental decision making.

From town to town: Predicting the taxonomic, functional and phylogenetic diversity of birds using NDVI

Biodiversity mapping in urban areas is imperative for their conservation. Remote sensors produce environmental information, such as the Normalized Difference Vegetation Index (NDVI), an indicator of vegetation cover in urban areas. NDVI can be used to predict the taxonomic, functional and phylogenetic bird diversity in urban areas. Moreover, a predictive model constructed in one city can be used to predict the bird diversity in other cities. The objectives of this study were: 1) to construct and evaluate predictive models between NDVI and taxonomic, functional and phylogenetic diversity of birds in Mar del Plata city, Argentina; and 2) to extrapolate these models to two other cities in the region: Balcarce and Miramar. Generalized additive models were applied to relate bird diversity variations to NDVI. In Mar del Plata, the taxonomic and functional diversity increased with increasing NDVI values, and the predictive models explained 64–81% of the taxonomic and functional diversity variation. The models correctly predicted taxonomic and functional diversity values in additional transects not included in the models, although they had a low predictive power of phylogenetic diversity. The models constructed in Mar del Plata adequately predicted the spatial variation of species diversity (Shannon index) in Balcarce and Miramar, the spatial variation of species richness in Balcarce, and the variation of functional diversity in Miramar. Our analysis revealed that a predictive model of bird diversity based on NDVI patterns created in one city can also depict the expected species diversity in other cities, being a time-saving and cost-effective method to create a tool for urban biodiversity conservation.

The effects of soil phosphorus on aboveground biomass are mediated by functional diversity in a tropical cloud forest

Soil phosphorus is a key driver of plant biodiversity and aboveground biomass (AGB) in tropical forests. A plant community’s ability to exploit such limiting resources may be better represented by functional diversity than species or phylogenetic diversity, and may therefore have the higher predictive power regarding how soil phosphorus influences AGB in tropical forests. However, nearly no studies have tested this in tropical high-altitude forest ecosystems. Here we aim to test: 1) the relative influence of three biodiversity metrics (functional diversity, species diversity, and phylogenetic diversity) on aboveground biomass in a tropical cloud forest and 2) the interrelationships among soil phosphorus, biodiversity, and AGB in this ecosystem. In a tropical cloud forest in Hainan Island, China, we measured 13 key functional traits for 195 species in 48 plots of size 20 × 20 m2 each. We also measured soil phosphorus in all plots and computed the community phylogeny. Using this dataset, we tested the interrelationships among soil phosphorus, species diversity, functional diversity, phylogenetic diversity, and AGB using Generalized Additive Modeling and Redundancy Analysis. Functional diversity was significantly positively related to AGB, whereas species diversity and phylogenetic diversity were not significantly related to AGB. Functional diversity explained 53% of AGB, while species diversity and phylogenetic diversity only explained 17% and 6%, respectively. Soil phosphorus explained 56% of the variation in functional diversity, but only explained 22%, 13% and 21% of the variation in species diversity, phylogenetic diversity and AGB, respectively. Functional diversity, rather than species and phylogenetic diversity, are the better predictors of AGB. The influence of functional diversity on AGB appears to be linked to how variation in soil phosphorus affects functional diversity. We suggest that functional diversity should be incorporated into models that are designed to test how soil resources influence ecosystem function in tropical forest ecosystems.

Floodplain land cover affects biomass distribution of fish functional diversity in the Amazon River

Land-cover change often shifts the distribution of biomass in animal communities. However, the effects of land-cover changes on functional diversity remain poorly understood for many organisms and ecosystems, particularly, for floodplains. We hypothesize that the biomass distribution of fish functional diversity in floodplains is associated with land cover, which would imply that fish traits affect behavioral and/or demographic responses to gradients of land cover. Using data from surveys of 462 habitats covering a range of land-cover conditions in the Amazon River floodplain, we fitted statistical models to explain landscape-scale variation in functional diversity and biomass of all fish species as well as subsets of species possessing different functional traits. Forest cover was positively associated with fish biomass and the strength of this relationship varied according to functional groups defined by life history, trophic, migration, and swimming-performance/microhabitat-use traits. Forty-two percent of the functional groups, including those inferred to have enhanced feeding opportunities, growth, and/or reproductive success within forested habitats, had greater biomass where forest cover was greater. Conversely, the biomass of other functional groups, including habitat generalists and those that directly exploit autochthonous food resources, did not vary significantly in relation to forest cover. The niche space occupied by local assemblages (functional richness) and dispersion in trait abundances (functional dispersion) tended to increase with forest cover. Our study supports the expectation that deforestation in the Amazon River floodplain affects not only fish biomass but also functional diversity, with some functional groups being particularly vulnerable.

The Combined Role of Retention Pattern and Post-Harvest Site Preparation in Regulating Plant Functional Diversity: A Case Study in Boreal Forest Ecosystems

Changes in the light availability in forests generated by diversified retention patterns (e.g., clear cut, partial harvest) have been shown to strongly filter the plant species present. Modified soil microsite conditions due to post-harvest site preparation (e.g., mechanical site preparation, prescribed fire) might also be an important determinant of plant diversity. The objective here was to detect how retention pattern and post-harvest site preparation act as filters that explain the understory functional diversity in boreal forests. We also assessed whether these effects were dependent on forest attributes (stand type, time since fire, and time since harvest). We retrieved data from seven different studies within 101 sites in boreal forests in Eastern Canada. Our data included forests harvested with two retention patterns: careful logging and clear cut, plus unharvested control forests. Three post-harvest site preparation techniques were applied: plow or disk trenching after careful logging, and prescribed fire after clear cut. We collected trait data (10 traits) representing plant morphology, regeneration strategy, or resource utilization for common species. Our results demonstrated significant variation in functional diversity after harvest. The combined effect of retention pattern and site preparation was the most important factor explaining understory diversity compared to retention pattern only and forest attributes. According to RLQ analysis, harvested forests with site preparation favored traits reflecting resistance or resilience ability after disturbance (clonal guerilla species, geophytes, and species with higher seed weight). Yet harvested forests without site preparation mainly affected understory plant species via their light requirements. Forest attributes did not play significant roles in affecting the relationship between site preparation and functional diversity or traits. Our results indicated the importance of the compounding effects of light variation and soil disturbance in filtering understory diversity and composition in boreal forests. Whether these results are also valid for other ecosystems still needs to be demonstrated.

The effect of environmental filtering on variation in functional diversity along a tropical elevational gradient

AbstractQuestionsElevational gradients encompass multiple resource or non‐resource stressors, but how these different gradients drive functional structure is not well understood. Abiotic variables and functional traits were sampled along a 1,400 m tropical elevational gradient to answer the following questions: (a) how do the functional diversity and functional structure of tree communities change with environment; (b) how does the different assembly vary along the elevational gradient?LocationTropical forests on Hainan Island, South China.MethodsAlong an elevational gradient from 180 m to 1,521 m, sixty 0.05‐ha transects were established. We recorded all woody stems ≥5 cm dbh (diameter at breast height) and measured functional traits and soil features in each transect. The patterns of abiotic variables, functional diversity and community‐weighted mean (CWM) of functional traits were explored along the elevational gradient by using a regression model. The assembly along the elevational gradient was compared with a null model that shuffled species identities.ResultsThe functional richness (FRic), functional dispersion (FDis) and CWMs of specific leaf area, leaf phosphorus and nitrogen content decreased with increasing elevation, as well as with the first axis of the principal components analysis (PCA1) of abiotic variables. The CWMs of leaf dry matter content and maximum height did not show significant change with elevational change, but the CWM of maximum height increased with PCA1. Both FRic and FDis became less divergent and more convergent with increasing elevation and with PCA1, which differed from the predicted outcome under the null model.ConclusionsAll these observations support that environmental filtering selects species with either acquisitive or conservative strategies at low elevations, but it only selects species with conservative strategies at high elevations. The presence of different stressors, resources (water) and non‐resources (temperature and pH) leads to distinct community assemblages with different functional structures.

Does accounting for within-individual trait variation matter for measuring functional diversity?

Trait-based approaches to disentangle assembly processes in ecological communities typically rely on average trait values obtained from the literature or databases. Recently, ecologists have shown growing concern in accounting for intraspecific variation in trait-based metrics. Besides intraspecific variation, plants and animals exhibit functional trait variation within the same individual (within-individual variation), which may exceed intraspecific variation and constitute a functional trait itself, influencing ecosystem functioning through individual performance variation. However, the role of within-individual variation in functional diversity (FD) remains unexplored. Here, we used sequential foraging observations of four bird species to quantify the magnitudes of interspecific, intraspecific and within-individual functional trait (foraging item, maneuver and stratum) variation. Then, we estimated functional richness using different hierarchical levels of increasing data resolution: (1) average trait values (based on our own literature search, on a global dataset, on the first observation of each foraging sequence and on complete foraging sequences), (2) average trait values plus intraspecific trait variation, and (3) average trait values plus intraspecific and within-individual trait variation. We also performed a series of simulations accounting for different levels of within-individual trait variation. For the empirical data, both intraspecific and within-individual variation accounted for more than 84% of total variation in functional traits, and for one trait (foraging maneuver) within-individual variation accounted for 84.31%. Although all FD metrics showed significant positive correlations, their magnitude consistently decreased when intraspecific and within-individual variations were taken into account (Pearson’s correlations from 0.99 to 0.28). Simulations also showed that not accounting for within-individual variation strikingly underestimated functional richness, even at the lowest levels (<5%) of within-individual variation. Our results reveal that within-individual variation may represent a major source of functional trait variation. Overall, the inclusion of within-individual variation in trait-based approaches would improve our understanding and use of FD estimators and determine to what extent it matters for assembly processes.

Functional diversity performs a key role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria from soil.

Functional diversity covers diverse functional traits of microorganisms in an ecosystem. Thus, we hypothesized that it could play an important role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria. These bacteria have been considered as biofertilizer for sustainable agriculture development. Soils were collected from different sites of agricultural field and performed several microbiological tests in which we observed considerable differences in heterotrophic microbial abundance and microbial activities among the microcosms. Functional diversity depends on both microbial richness and evenness. Based on the results of metabolic fingerprinting of the carbon sources of BiOLOG-ECO plates, richness and evenness was measured by determining Shannon diversity index and Gini coefficient, respectively. The results showed significant differences in both microbial richness and evenness, suggesting considerable variation of functional diversity among the microcosms. Thereafter, nitrogen-fixing and phosphate-solubilizing bacteria were isolated on Burk's and Pikovskaya media, respectively. The results revealed considerable variation of both types of bacterial abundance among the microcosms. Microcosm (T2) showing the highest functional diversity houses the maximum numbers of nitrogen-fixing and phosphate-solubilizing bacteria. Similarly, the microcosm (T5) exhibiting the lowest functional diversity houses the minimum numbers of nitrogen-fixing and phosphate-solubilizing bacteria. Thus, a strong positive correlation was observed between functional diversity and both types of bacterial abundance among the soil samples. Higher richness and evenness lead to the development of increased functional diversity that facilitates to accommodate substantial numbers of nitrogen-fixing and phosphate-solubilizing bacteria in soil. Taken together, the results demonstrated that functional diversity plays an important role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria from soil.