Distribution Of Functional Traits Research Articles

The Spatial Distribution of Copepod Functional Traits in a Highly Anthropized Mediterranean Coastal Marine Region

The Spatial Distribution of Copepod Functional Traits in a Highly Anthropized Mediterranean Coastal Marine Region

Spatial mapping of key plant functional traits in terrestrial ecosystems across China

Abstract. Trait-based approaches are of increasing concern in predicting vegetation changes and linking ecosystem structures to functions at large scales. However, a critical challenge for such approaches is acquiring spatially continuous plant functional trait maps. Here, six key plant functional traits were selected as they can reflect plant resource acquisition strategies and ecosystem functions, including specific leaf area (SLA), leaf dry matter content (LDMC), leaf N concentration (LNC), leaf P concentration (LPC), leaf area (LA) and wood density (WD). A total of 34 589 in situ trait measurements of 3447 seed plant species were collected from 1430 sampling sites in China and were used to generate spatial plant functional trait maps (∼1 km), together with environmental variables and vegetation indices based on two machine learning models (random forest and boosted regression trees). To obtain the optimal estimates, a weighted average algorithm was further applied to merge the predictions of the two models to derive the final spatial plant functional trait maps. The models showed good accuracy in estimating WD, LPC and SLA, with average R2 values ranging from 0.48 to 0.68. In contrast, both the models had weak performance in estimating LDMC, with average R2 values less than 0.30. Meanwhile, LA showed considerable differences between the two models in some regions. Climatic effects were more important than those of edaphic factors in predicting the spatial distributions of plant functional traits. Estimates of plant functional traits in northeastern China and the Qinghai–Tibetan Plateau had relatively high uncertainties due to sparse samplings, implying a need for more observations in these regions in the future. Our spatial trait maps could provide critical support for trait-based vegetation models and allow exploration of the relationships between vegetation characteristics and ecosystem functions at large scales. The six plant functional trait maps for China with 1 km spatial resolution are now available at https://doi.org/10.6084/m9.figshare.22351498 (An et al., 2023).

Quantifying the effect of competition on the functional assembly of bryophyte and lichen communities: A process‐based model analysis

Abstract Environmental filtering and competition are two fundamental processes that shape plant community assembly in terms of functional composition, that is, the distribution of trait values. Understanding the role of these two processes in the assembly of non‐vascular vegetation, such as bryophytes and lichens, is important since these communities provide essential ecosystem services in many regions around the world, and these depend on functional composition. Responses of non‐vascular communities to environmental selection pressures have been explored in a range of experimental and modelling studies. However, it is still largely unknown to what extent competition affects the distribution of functional traits of non‐vascular communities. Moreover, it remains poorly explored which traits that are associated with competition are key for shaping community functional assembly. Here, we integrated a field transplantation experiment with a process‐based model to disentangle the effects of environmental filtering and competition on the assembly of non‐vascular communities. Following the validation of environmental selection in the model using field observations, we performed a simulation experiment to understand the impacts of competition on trait distributions in non‐vascular communities growing in two temperate locations that differ in microclimatic conditions (a shaded and an open location). Our results suggest that the functional composition is likely a result of weak competition or may not depend on competitive exclusion at all while environmental filtering plays an essential role. Plant height seems to be a key trait for competition. However, no single‐trait competition scheme could consistently explain the observed functional composition of the studied non‐vascular communities. Synthesis. The presented model provides a new trait‐based approach for simulating the functional assembly of non‐vascular communities. Environmental filtering appears to be more essential than competition for predicting trait distributions of non‐vascular communities under temperate climatic conditions and we recommend caution in associating competition to a single trait while analysing community functional assembly.

Restored intertidal eelgrass (Z. marina) supports benthic communities taxonomically and functionally similar to natural seagrasses in the Wadden Sea

Ecological restoration has become an important management-tool to counteract the widespread losses of seagrass meadows and their associated biodiversity. In the Dutch Wadden Sea, long-term restoration efforts have recently led to the successful restoration of annual eelgrass (Zostera marina) at high densities on a local scale. However, it is yet unknown if restored seagrass plants also lead to improved local biodiversity and ecosystem functioning in the intertidal zone. We therefore compared the macrozoobenthos communities of a small-scale restored meadow to 22 naturally occurring intertidal seagrass meadows. Using a taxonomic and trait-based approach we aimed to study 1) how intertidal seagrasses (Zostera marina and Zostera noltii) affect benthic communities and their functional trait distribution and 2) if a restored meadow facilitates benthic communities similar to natural meadows. We found that both natural and restored seagrasses increased abundances of benthic animals and the richness (both taxonomic and functional) of associated benthic communities compared to nearby unvegetated areas. Additionally, the presence of intertidal seagrass shifted benthic community composition both taxonomically and functionally, thus broadening the niche space for species inhabiting tidal flats. Seagrasses especially facilitated epifaunal species and traits associated with these animals. Surprisingly, our results indicate that the mere presence of seagrass aboveground structure is enough to facilitate benthic communities, as neither higher seagrass cover nor biomass increased benthic biodiversity in the intertidal zone. By studying the effect of seagrass restoration on benthic diversity, we found that the restored meadow functioned similarly to the natural meadows after only two years and that the success of our restoration efforts indeed led to local biodiversity enhancements. Our findings contribute to the understanding of the ecological functioning of intertidal seagrasses and can be used to define/refine conservation and restoration goals of these valuable ecosystems.

Global patterns and environmental drivers of forest functional composition

AbstractAimTo determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships.LocationGlobal.Time periodRecent.Major taxa studiedTrees.MethodsWe integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community‐weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes).ResultsOur models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within‐biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models.Main conclusionsWorldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within‐biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.

Changes in the leaf functional traits of mangrove plant assemblages along an intertidal gradient in typical mangrove wetlands in Hainan, China

The understanding of biodiversity-ecosystem functioning linkages under environment change has been advanced immensely by the development and application of the functional trait theory. Intertidal zones, characterized by significant environmental gradient differences, are severely threatened by sea-level rises caused by global warming. The functional trait distribution pattern for mangrove communities along the intertidal gradient and underlying mechanisms remain unclear. We investigated differences in the leaf functional traits of mangrove plant assemblages among the high, middle, and low intertidal zones, and their relationships to sediment physicochemical properties, in Dongzhaigang and Qinglan Harbor reserves, Hainan, China. In both reserves, most sediment physicochemical properties (pH; salinity; total potassium, carbon, nitrogen, and sulfur concentrations; organic carbon content; ammonium nitrogen and available phosphorus concentrations) differed significantly among gradient zones. The sediment pH, total phosphorus, and available potassium concentrations differed significantly between the dry and wet seasons. From the low to the high intertidal zone, the mangrove specific leaf area and leaf nitrogen and phosphorus concentrations increased significantly and the leaf thickness decreased significantly. The leaf tannin and lignin concentrations were significantly lower and the leaf phosphorus concentration, nitrogen concentration and hardness were significantly higher in the dry season than in the wet season. The sediment salinity, pH, and total sulfur and potassium contents were key factors affecting the distribution of mangrove leaf functional traits along the intertidal gradient. The changes in mangrove leaf functional traits reflect gradient-level responses to environmental stress and the sediment nutrient status. Our findings improve the understanding of the functional trait diversity and maintenance mechanisms of mangrove communities under environmental change and provide a new perspective for the prediction of how coastal mangroves will respond to future global warming.

Interactive effects of microbial functional diversity and carbon availability on decomposition – A theoretical exploration

Microbial functional diversity in litter and soil has been hypothesized to affect the rate of decomposition of organic matter and other soil ecosystem functions. However, there are no clear theoretical expectations on how these effects might change with substrate availability, heterogeneity in the substrate chemistry, and different aspects of functional diversity itself (number of microbial groups vs. distribution of functional traits). To explore how these factors shape the decomposition-diversity relation, we carry out numerical experiments using a flexible reaction network comprising microbial processes and interactions with bioavailable carbon (extracellular degradation, uptake, respiration, growth, and mortality), and ecological processes (competition among the different groups). We also considered diverse carbon substrates, in terms of varying nominal oxidation state of carbon (NOSC). The reaction network was used to test the effects of (i) number of microbial groups, (ii) number of carbon pools, (iii) microbial functional diversity, and (iv) amount of bioavailable carbon. We found that the decomposition rate constant increases with increasing substrate concentration and heterogeneity, as well as with increasing microbial functional diversity or variance of microbial traits, albeit these biological factors are less important. The multivariate dependence of the decomposition rate constant (and other decomposition and microbial growth metrics) on substrate and microbial factors can be described using power laws with exponents lower than one, indicating that diversity effects on decomposition and microbial growth are reduced at high substrate concentration and heterogeneity, or at high microbial diversity.

The critical role of coastal protected areas in buffering impacts of extreme climatic conditions on bird diversity and their ecosystem services' provisioning in the Eastern Cape Province, South Africa.

In this study, we documented the diversity of bird species in the Eastern Cape coastal nature reserves (i.e., Hluleka, Dwesa, Silaka and Mkhambati nature reserves), and determined the potential role of each bird species in habitat maintenance using two functional traits (i.e., body mass and feeding mode) as the function's proxy. We applied the timed species count approach during bird observations, coupled with drive-by surveys to maximise spatial coverage of each nature reserve over four years. To evaluate functional diversity, bird species were classified based on functional traits such as the adult body, and their potential ecological role derived from their feeding mode and habitat associations. Over 864 h, we accumulated 818 bird records containing 178 different bird species that were classified into 58 families with 32 species occurring in all nature reserves. Shannon-Wiener Diversity Indices showed very high overall species diversity across the nature reserves (H > 3.5) with no differences detected across sites. Although no significant correlations between vegetation changes measured through Normalised Difference vegetation Index (NDVI) in each nature reserve and the number of bird records, forest bird species were dominant (42.1%; N = 178) throughout years of observation and diversity remained high (H > 3.5). Bird species abundance only increased significantly across all nature reserves during 2018-2019. All four nature reserves had a similar distribution of bird functional traits with both high functional richness (FRic = 1), and divergence (FDiv = 0.8) and moderate evenness (FEve = 0.4). Multiple Correspondence Analysis (MCA) demonstrated a positive correlation between bird sizes and functions with large birds mainly associated with predators and carrion. Small birds and medium birds had a similar composition of species in terms of functionality being seed dispersers across the nature reserves. A significant effect that insectivores and carrions displayed in MCA plots, suggest the availability of indirect pollination services. Despite extreme drought conditions across the country in 2019, NDVI levels remained largely consistent over time in these four reserves; and thus, they offer important refuge for birds during extreme climatic conditions such as drought.

Geology constrains biomineralization expression and functional trait distribution in the Mountainsnails

AbstractAimGeographic variation in metabolic resources necessary for functional trait expression can set limits on species distributions. For species that need to produce and maintain biomineralized traits for survival, spatial variation in mineral macronutrients may constrain species distributions by limiting the expression of biomineralized traits. Here, we examine whether Oreohelix land snails that express heavily biomineralized shell ornaments are restricted to CaCO3 rock regions, if they incorporate greater amounts of CaCO3 rock carbon in their shell than less biomineralized smooth forms, and if ornamentation increases shell strength.LocationWestern United States.TaxonOreohelix land snails.MethodsWe used random forest classification models at multiple spatial resolutions to evaluate the contribution of topographic, vegetation, climate, and geologic variables in predicting the presence of heavily biomineralized shell ornaments across the range of Oreohelix. We then measured and compared shell biometric variables, 14C/12C ratios, and peak force for fracture for ornamented and smooth forms from calcareous and non‐calcareous substrates.ResultsDistance to CaCO3 rock was the most important variable in all models and closer proximity to CaCO3 rock was associated with greater probability of local ornamentation classification. Pairwise comparisons of 14C/12C ratios in closely occurring ornamented vs. smooth population pairs revealed ornamented forms incorporate greater CaCO3 rock carbon than smooth forms. Ornamented types measured in this study were generally heavier and required greater peak force for fracture than smooth forms, except when comparing ornamented forms to smooth forms sampled from CaCO3 rock.Main ConclusionsBiomineralization expression, species distribution, and trait function appear to be constrained by mineral supply in a highly diverse group of land snails. This trait‐environment relationship provides a basis for future investigations of CaCO3 macronutrient constraints on shell form and species distribution in other terrestrial molluscs and has a direct impact on the management of Oreohelix species.

Tackling local ecological homogeneity: Finding intraspecific trait variability in local populations of Mediterranean plants.

Local homogeneity, in ecology, is the often undisclosed assumption that variability within populations is negligible or mostly distributed evenly. In large areas, this can lead to the aggregation of different populations without regard for their unique needs and characteristics, such as drought sensitivity and functional trait distributions. Here, we discuss whether this assumption can be justified, and we hypothesize that discerning the source of variation between plasticity and adaptation could be a feasible approach to formulate an informed decision. We test this hypothesis on plants, resorting to a common garden experiment to determine the source of variation of several plant functional traits at a local scale (~60 km) of three wild species: Quercus ilex, Pistacia lentiscus, and Cistus salviifolius. Individuals of each species were sourced from three key sites chosen along a local aridity gradient. Our approach led to the rejection of the local homogeneity assumption for Q. ilex and C. salviifolius at this scale due to the adaptive divergence observed among neighboring populations. This case study provides evidence that addressing local homogeneity can highlight diverging populations in a relatively simple way. We conclude that gathering empirical evidence on intraspecific variability is a feasible approach that can provide researchers with solid bases to decide whether to adopt the local homogeneity assumption or not.

Increased hydraulic risk in assemblages of woody plant species predicts spatial patterns of drought-induced mortality

Predicting drought-induced mortality (DIM) of woody plants remains a key research challenge under climate change. Here, we integrate information on the edaphoclimatic niches, phylogeny and hydraulic traits of species to model the hydraulic risk of woody plants globally. We combine these models with species distribution records to estimate the hydraulic risk faced by local woody plant species assemblages. Thus, we produce global maps of hydraulic risk and test for its relationship with observed DIM. Our results show that local assemblages modelled as having higher hydraulic risk present a higher probability of DIM. Metrics characterizing this hydraulic risk improve DIM predictions globally, relative to models accounting only for edaphoclimatic predictors or broad functional groupings. The methodology we present here allows mapping of functional trait distributions and elucidation of global macro-evolutionary and biogeographical patterns, improving our ability to predict potential global change impacts on vegetation.

Scale variance in the carbon dynamics of fragmented, mixed-use landscapes estimated using model–data fusion

Abstract. Many terrestrial landscapes are heterogeneous. Mixed land cover and land use generate a complex mosaic of fragmented ecosystems at fine spatial resolutions with contrasting ecosystem stocks, traits, and processes, each differently sensitive to environmental and human factors. Representing spatial complexity within terrestrial ecosystem models is a key challenge for understanding regional carbon dynamics, their sensitivity to environmental gradients, and their resilience in the face of climate change. Heterogeneity underpins this challenge due to the trade-off between the fidelity of ecosystem representation within modelling frameworks and the computational capacity required for fine-scale model calibration and simulation. We directly address this challenge by quantifying the sensitivity of simulated carbon fluxes in a mixed-use landscape in the UK to the spatial resolution of the model analysis. We test two different approaches for combining Earth observation (EO) data into the CARDAMOM model–data fusion (MDF) framework, assimilating time series of satellite-based EO-derived estimates of ecosystem leaf area and biomass stocks to constrain estimates of model parameters and their uncertainty for an intermediate complexity model of the terrestrial C cycle. In the first approach, ecosystems are calibrated and simulated at pixel level, representing a “community average” of the encompassed land cover and management. This represents our baseline approach. In the second, we stratify each pixel based on land cover (e.g. coniferous forest, arable/pasture) and calibrate the model independently using EO data specific to each stratum. We test the scale dependence of these approaches for grid resolutions spanning 1 to 0.05∘ over a mixed-land-use region of the UK. Our analyses indicate that spatial resolution matters for MDF. Under the community average baseline approach biological C fluxes (gross primary productivity, Reco) simulated by CARDAMOM are relatively insensitive to resolution. However, disturbance fluxes exhibit scale variance that increases with greater landscape fragmentation and for coarser model domains. In contrast, stratification of assimilated data based on fine-resolution land use distributions resolved the resolution dependence, leading to disturbance fluxes that were 40 %–100 % higher than the baseline experiments. The differences in the simulated disturbance fluxes result in estimates of the terrestrial carbon balance in the stratified experiment that suggest a weaker C sink compared to the baseline experiment. We also find that stratifying the model domain based on land use leads to differences in the retrieved parameters that reflect variations in ecosystem function between neighbouring areas of contrasting land use. The emergent differences in model parameters between land use strata give rise to divergent responses to future climate change. Accounting for fine-scale structure in heterogeneous landscapes (e.g. stratification) is therefore vital for ensuring the ecological fidelity of large-scale MDF frameworks. The need for stratification arises because land use places strong controls on the spatial distribution of carbon stocks and plant functional traits and on the ecological processes controlling the fluxes of C through landscapes, particularly those related to management and disturbance. Given the importance of disturbance to global terrestrial C fluxes, together with the widespread increase in fragmentation of forest landscapes, these results carry broader significance for the application of MDF frameworks to constrain the terrestrial C balance at regional and national scales.

Plant traits modulate grassland stability during drought and post‐drought periods

Abstract Grasslands are subject to climate change, such as severe drought, and an important aspect of their functioning is temporal stability in response to extreme climate events. Previous research has explored the impacts of extreme drought and post‐drought periods on grassland stability, yet the mechanistic pathways behind these changes have rarely been studied. Here, we implemented an experiment with 4 years of drought and 3 years of recovery to assess the effects of drought and post‐drought on the temporal stability of above‐ground net primary productivity (ANPP) and its underlying mechanisms. To do so, we measured community‐weighted mean (CWM) of six plant growth and nine seed traits, functional diversity, population stability and species asynchrony across two cold, semiarid grasslands in northern China. We also performed piecewise structural equation models (SEMs) to assess the relationships between ANPP stability and its underlying mechanisms and how drought and post‐drought periods alter the relative contribution of these mechanisms to ANPP stability. We found that temporal stability of ANPP was not reduced during drought due to grasses maintaining productivity, which compensated for increased variation of forb productivity. Moreover, ANPP recovered rapidly after drought, and both grasses and forbs contributed to community stability during the post‐drought period. Overall, ANPP stability decreased during the combined drought and post‐drought periods because of rapid changes in ANPP from drought to post‐drought. SEMs revealed that the temporal stability of ANPP during drought and post‐drought periods was modulated by functional diversity and community‐weighted mean traits directly and indirectly by altering species asynchrony and population stability. Specifically, the temporal stability of ANPP was positively correlated with functional divergence of plant communities. CWMs of seed traits (e.g. seed width and thickness), rather than plant growth traits (e.g. specific leaf area and leaf nutrient content), stabilized grassland ANPP. Productivity of plant communities with large and thick seeds was less sensitive to precipitation changes over time. These results emphasize the importance of considering both the functional trait distribution among species and seed traits of dominant species since their combined effects can stabilize ecosystem functions under global climate change scenarios. Read the free Plain Language Summary for this article on the Journal blog.

Assemblage Patterns of Microalgae along the Upstream to Downstream Gradient of the Okavango Delta: Abundance, Taxonomic Diversity, and Functional Diversity

This study addresses the gap in understanding the diversity, species, and functional trait distribution of different algal groups that occur in the Okavango Delta (a near-pristine subtropical wetland in northwestern Botswana) across hydrological and habitat gradients. We systematically characterize the delta’s algal flora, addressing the gap left by previous research that was limited to single algal groups (e.g., diatoms) and/or only looking at upstream areas in the Okavango River basin. We analyzed 130 algal samples from 49 upstream and downstream sites with higher and lower flooding frequency, respectively, across a river-to-floodplain habitat gradient. Chlorophyta and Bacillariophyta dominated both abundance and taxon richness (>80%) of the total 494 taxa found from 49,158 algal units counted (cells, colonies, coenobia, and filaments). Smaller algae were more abundant in downstream floodplains than in upstream channels and lagoons. Motile and siliceous algae were much more abundant than non-motile, nitrogen fixing, and phagotrophic algae. The frequency of these traits was associated more with flooding frequency than habitat type. The highest algal richness and diversity were found downstream, where shallow floodplain ecosystems with seasonally fluctuating water depths offer greater habitat heterogeneity, and macronutrients are resuspended. The increasing threats from upstream water abstraction plans, fracking, and climate change require enhanced protection and monitoring of the Okavango Delta’s natural annual flood-pulse to maintain the high species and functional diversity of this unique wetland’s microalgae.

Assembly of functional diversity in an oceanic island flora.

Oceanic island floras are well known for their morphological peculiarities and exhibit striking examples of trait evolution1-3. These morphological shifts are commonly attributed to insularity and are thought to be shaped by the biogeographical processes and evolutionary histories of oceanic islands2,4. However, the mechanisms through which biogeography and evolution have shaped the distribution and diversity of plant functional traits remain unclear5. Here we describe the functional trait space of the native flora of an oceanic island (Tenerife, Canary Islands, Spain) using extensive field and laboratory measurements, and relate it to global trade-offs in ecological strategies. We find that the island trait space exhibits a remarkable functional richness but that most plants are concentrated around a functional hotspot dominated by shrubs with a conservative life-history strategy. By dividing the island flora into species groups associated with distinct biogeographical distributions and diversification histories, our results also suggest that colonization via long-distance dispersal and the interplay between inter-island dispersal and archipelago-level speciation processes drive functional divergence and trait space expansion. Contrary to our expectations, speciation via cladogenesis has led to functional convergence, and therefore only contributes marginally to functional diversity by densely packing trait space around shrubs. By combining biogeography, ecology and evolution, our approach opens new avenues for trait-based insights into how dispersal, speciation and persistence shape the assembly of entire native island floras.

Soil microbial community composition and functions are disrupted by fire and land use in a Mediterranean woodland

The intersection of fire, land use transformations, and climate change is putting Mediterranean climate-type ecosystems at risk of soil degradation and loss of ecosystem services. Ondik et al. (2022b) showed that in a Mediterranean dry sclerophyll woodland of South Australia, high severity fire and clearing and grazing practices impacted both physicochemical and biological soil quality indicators. Building upon the work of Ondik et al. (2022b) this study aims to 1) identify soil physicochemical properties impacted by fire and land management that are indirect drivers of changes to soil microbial community composition and 2) determine whether the observed changes to soil microbial community composition affect soil microbial functions. Via a redundancy analysis, we identified fire and management-induced changes to pH, soil water repellency, nutrient stoichiometry, and total nutrient content as significant drivers of the composition of soil microbial communities. We then measured basal respiration, substrate induced respiration, and the carbon mineralisation quotient, and calculated functional trait distributions among microbial communities by linking 16S and 18S rRNA sequences to respiration modes and functional guilds, respectively. We found that fire reduced soil microbial respiration and the relative abundance (RA) of microbial symbionts, anaerobic bacteria, and microaerophilic bacteria, while increasing the RA of aerobic bacteria. Furthermore, management increased the RA of post-fire ectomycorrhizal fungi and may have reduced pathogenic load, microbial efficiency, and wood saprotrophs, while increasing litter, soil, and other saprotrophic species that are adapted to grasslands. This study shows that, through changes to microbial community composition, high severity wildfire and land management affected soil respiration rates, bacterial modes of respiration, prevalence of symbiotic bacteria and fungi, and microbial substrate preference. Having identified the main physicochemical drivers of changes to microbial community composition, we provide valuable insights into how fire and land management can impact soils in Mediterranean woodland.

Soil versus atmospheric drought: A test case of plant functional trait responses.

Climate change alters mean global surface temperatures, precipitation regimes, and atmospheric moisture. Resultant drought affects the composition and diversity of terrestrial ecosystems worldwide. To date, there have been no assessments of the combined impacts of reduced precipitation and atmospheric drying on functional trait distributions of any species in an outdoor experiment. Here, we examined whether soil and atmospheric drought affected the functional traits of a focal grass species (Poa secunda) growing in monoculture and eight-species grass communities in outdoor mesocosms. We focused on specific leaf area (SLA), leaf area, stomatal density, root:shoot ratio, and fine root:coarse root ratio responses. Leaf area and overall growth were reduced with soil drying. Root:shoot ratio only increased for P. secunda growing in monoculture under combined atmospheric and soil drought. Plant energy allocation strategy (measured using principal components) differed when P. secunda was grown in combined soil and atmospheric drought conditions compared with soil drought alone. Given a lack of outdoor manipulations of this kind, our results emphasize the importance of atmospheric drying on functional trait responses more broadly. We suggest that drought methods focused purely on soil water inputs may be imprecisely predicting drought effects on other terrestrial organisms as well (other plants, arthropods, and higher trophic levels).

Nematode functional traits and community structure change from river to the terrestrial border in Segara Anakan Mangrove, Indonesia

Abstract. Maharning AR, Ardli ER, Prabowo RE. 2023. Nematode functional traits and community structure change from river to the terrestrial border in Segara Anakan Mangrove, Indonesia. Biodiversitas 24: 2434-2446. We intended to explore the spatial distribution of nematode functional traits and community structure in Segara Anakan Mangrove, Indonesia. Samples were retrieved from 14 stations, extending from the river to the area adjacent to terrestrial forest. We used taxonomic and functional trait identification, covering body shape, length, tail shape, feeding type, and life history as independent traits, and combined traits by collecting traits describing individual nematodes. The principal component analysis suggested that predatory or omnivorous or long-size nematodes mainly inhabited stations adjacent to the terrestrial forest but were unclear for the mid-stations. There were 29 combined traits and 38 genera of nematodes observed. The detrended correspondence analysis revealed that nematode compositional changes from the river to the terrestrial adjacent area were clearer for the combined traits and nematode genera. Seven combined traits and 12 genera inhabited only the particular stations of the study site. The common nematodes were slender, 1-2 mm long, elongated filiform tails, non-selective deposit feeders, and very tolerant to pollutants, which lived in almost all stations (92.86%). The genus relative abundance (>10%) included Anoplostoma, Eubostrichus, and Chromadorina. The results suggest that distance from the river might regulate the habitability of nematodes, in which nematode functional traits play roles.

Fish functional gradients along a reservoir cascade

Abstract The transformations of fish assemblages caused by reservoir cascades can be severe at the reach scale, but basin‐scale effects are less clear. However, prevailing river concepts provide a framework for predicting basin‐scale effects. To determine if predictions made by the River Continuum Concept relative to the function of fish assemblages are sustained in a temperate river transformed into a reservoir cascade, we examined longitudinal trends in the distribution of fish functional traits over 23 reservoirs of the Tennessee River, U.S.A. In all, 115 species were recorded representing 62 traits, with trait richness increasing longitudinally in a downstream direction. Trophic, reproductive, and habitat traits showed various increasing and decreasing patterns up and down the reservoir cascade. The observed gradients in trait richness and trait distributions were generally consistent with those expected in unregulated rivers, with few unexpected results. The transformation of lotic systems into lentic ones has changed habitats and sources of food and encouraged the proliferation of certain feeding (e.g., detritivores, planktivores, invertivores, piscivores), reproduction (e.g., nest spawners polyphils, broadcast spawners phytolithophils), and habitat (slow current, lacustrine, large river) traits. In essence, reservoirs have expanded downstream habitats in an upstream direction, and thus allowed upstream expansion of species and traits that would have normally not been well represented in upper reaches of the Tennessee River basin. Nevertheless, the impounded Tennessee River has maintained much of its functional integrity, despite extensive alterations to the riverscape. We suggest that, while reservoirs have been shown to have major local‐scale effects on riverine fish assemblages, with access to riverine habitats, and with proactive conservation strategies, fish functional richness can remain remarkably high at the basin scale.

Bee functional traits and their relationship to pollination services depend on many factors: A meta‐regression analysis

Abstract Understanding relationships between organisms and the ecosystem services they provide is crucial for predicting the impacts of continued biodiversity changes. Functional traits of organisms can affect ecosystem properties and are thus increasingly used to predict long‐term ecosystem functioning. Bees are ideal taxa for using functional approaches given their role in pollination for many plant species and wide diversity of traits. Although distributions of bee functional traits are being documented in the literature, there is a clear lack of understanding of how they relate to ecosystem functioning (i.e. pollination). To address this knowledge gap, we conducted a meta‐regression analysis with the following objectives: (1) quantify the effects of bee functional traits on pollination and (2) assess sources of heterogeneity to identify variables that might explain variation across studies. Seventeen studies met our criteria for inclusion, yielding 45 individual effect sizes for six traits (body size, tongue length, diet breadth, nesting, parasitism, and sociality). Overall, bee functional traits had a significant effect on pollination; however, effect sizes were weak with high variability across studies. Sources of heterogeneity included the metrics used to quantify pollination, the number of bee genera analysed in a study, and whether traits were measured categorically or continuously. These results indicate a need for more research to improve understanding of trait–pollination relationships. For some bee traits, effects on pollination may be dependent on other factors like bee abundance, environmental context, and the plant species evaluated in studies.