Community Functional Diversity Research Articles

Soil Bacterial Community of Medicinal Plant Rhizosphere in a Mediterranean System

Several attempts have been made to evaluate the abundance and distribution of the bacterial community in the rhizosphere of medicinal plants. Many describe information based on an estimation of the community structure and the effects of plant cover in determining microbial community composition. The ability of plants to specifically shape their microbial community in general and medicinal plants in particular is largely unknown. With the arrival of molecular biology, understanding the microbial community’s composition, diversity, and function became possible. We hypothesized that microbial communities associated with medicinal shrubs would differ from each other. To test this hypothesis, we characterized the soil microbial composition under each of five Mediterranean medicinal plants, differentiated by their medicinal use and ecophysiological adaptation, namely, Salvia fruticosa, Pistacia lentiscus, Myrtus communis, Origanum syriacum, and Teucrium capitatum, and an open-space bare soil between the plants, inhabiting natural ecosystems characterized by similar climatic conditions typical of a Mediterranean environment. The results demonstrated the importance of plant ecophysiological adaptations, which play an important role in determining microbial community composition and functional diversity. The intensity of a plant’s response to its surroundings can have either positive or negative effects that will determine the microbial community composition and interactions among the belowground parts. A total of 11 phyla, 21 orders, and 409 genera were found in the soil rhizosphere in the vicinity of the four plants and open space samples. The distinguishing attributes of each shrub trigger and stimulate the microbial community’s rhizosphere. This results in distinct patterns of bacterial diversity and functionality between the different shrubs and the control. The rhizosphere bacterial community composition differed between the plants in a PERMANOVA test, but there was little difference in terms of phyla and order relative abundances. This study shows how five medicinal plants, coexisting in a common habitat, impact the bacterial community. The noticeable shift in bacterial composition further supports our discovery that root exudates effectively govern the makeup of soil bacterial communities.

Density data for Lake Erie benthic invertebrate assemblages from 1930 to 2019.

Benthic invertebrates are important trophic links in food webs and useful bioindicators of environmental conditions, but long-term benthic organism abundance data across broad geographic areas are rare and historic datasets are often not readily accessible. This dataset provides densities of benthic macroinvertebrates collected from 1930 to 2019 during surveys in Lake Erie, a Laurentian Great Lake. The surveys were funded by the governments of the United States and Canada to investigate the status and changes in the benthic community. From the total of 21 lake-wide and basin-wide benthic surveys conducted in Lake Erie from 1929 to 2019, we were able to acquire data for 17 surveys, including species-level data for 10 surveys and data by higher taxonomic groups for seven surveys. Our amassed Lake Erie dataset includes data from 11 surveys (including five with species-level data) conducted in the western basin in 1930-2019, seven surveys (six with species-level data) in the central basin, and eight surveys (seven with species-level data) in the eastern basin (1973-2019). This Lake Erie dataset represents the most extensive temporal dataset of benthic invertebrates available for any of the Laurentian Great Lakes. Benthic samples were collected using Ponar or Shipek bottom dredges and taxa densities were calculated as individuals per square meter using the area of the dredge. Density data are provided for taxa in the Annelida, Arthropoda, Mollusca, Cnidaria, Nemertea, and Platyhelminthes phyla. Current taxonomy was used for most groups but, in a few cases, older taxonomic names were used for consistency with historical data. Analysis of this dataset indicates that eutrophication, water quality improvement, and dreissenid introduction were the major drivers of changes in the benthic community in the western basin, while hypoxia was a major factor in the central basin, and dreissenid introduction was the most important driver in the eastern basin. Considering the rarity of high taxonomic resolution long-term benthic data for lake ecosystems, this dataset could be useful to explore broader aspects of ecological theory, including effects of eutrophication, hypoxia, invasive species, and other factors on community organization, phylogenetic and functional diversity, and spatial and temporal scales of variation in community structure. In addition, the dataset could be useful for studies on individual species, including abundance and distribution, species co-occurrence, and how the patterns of dominance and rarity change over space and time. Use of this dataset for academic or educational purposes is encouraged as long as this data paper is properly cited.

Biodiversity promotes resistance but dominant species shape recovery of grasslands under extreme drought

Abstract How biodiversity underpins ecosystem resistance (i.e. ability to withstand environmental perturbations) and recovery (i.e. ability to return to a pre‐perturbation state), and thus, stability under extreme climatic events is a timely question in ecology. To date, most studies have focussed on the role of taxonomic diversity, neglecting how community functional composition and diversity beget stability under exceptional climatic conditions. In addition, land use potentially modulates how biodiversity and ecosystem functions respond to extreme climatic conditions. Using an 11‐year time‐series of plant biomass from 150 permanent grassland plots spanning a gradient of land‐use intensity, we examined how taxonomic and functional components of biodiversity affected resistance and recovery of biomass under extreme drought. The association between biodiversity, land use and biomass varied across years, especially in the driest years. Species‐rich or functionally diverse communities (associated with low land‐use intensity) buffered extreme droughts better, while species‐poor communities or those dominated by fast‐growing species (associated with high land‐use intensity) had higher recovery capabilities after a moderate‐to‐extreme drought. Synthesis. Our results show that plant community functional and taxonomic components determine grasslands resistance and recovery under moderate‐to‐extreme drought. In turn, this points to the importance of designing landscapes with both extensively and intensively managed grasslands. Functionally or taxonomically rich communities (favoured under low land‐use intensity) would preserve biomass under extreme droughts, whereas species‐poor or fast‐growing communities (favoured by high land‐use intensity) would restore biomass after extreme droughts.

Soil Microbial Community Structure and Functional Diversity Character of Abandoned Farmland in Minqin Oasis

To clarify the impact of the structure and function of soil microbial communities in the stage of abandoned farmland, three different stages of land abandoned in desert oasis areas were selected as the research objects. We used metagenomic sequencing technology to research soil microbial community structure and functional diversity characteristics of different stages of abandoned farmland. The results showed that there were significant differences in the relative abundance of the dominant phyla Actinobacteria, Proteobacteria, and Gemmatimonadetes in the soil of the three stages of returning farmland. Compared with that in the early stage of abandoned farmland, the later stage of abandoned farmland restoration increased the gene proportion involved in Quorum sensing, porphyrin and chlorophyll metabolism, pantothenate and CoA biosynthesis, and styrene degradation, and there was a significant difference in relative abundance (P<0.05), which indicated that different stages of abandoned farmland had changed the functional potential of the nutrient cycle and energy metabolism in soil microbial communities. The RDA results showed that EC, AK, and TN had a significant impact on the functional composition of soil microbes, and soil EC had the greatest impact on microbial functional composition. The results showed that different stages of abandoned farmland had a significant impact on the soil microbial community structure and functional composition. In the ecological restoration of abandoned farmland in Minqin Oasis, the sensitivity of microbial community structure and functional composition to soil restoration at different stages should be considered using comprehensive relevant indicators.

The impacts of different seasons on macroinvertebrate community structure and functional diversity in the Jingui River, China

Species diversity and functional diversity indices reflect the variations of community structure and their responses to environmental stress. This study clarifies the biodiversity of macroinvertebrates in the Jingui River of Shenzhen and their response to the aquatic environment across different seasons. Utilizing ten functional traits, we conducted a seasonal survey at ten sampling points to examine changes in macroinvertebrate species and functional diversity, along with their relationships with environmental variables in the JGR. The results of the study demonstrated that the species and functional diversity of macroinvertebrates were significantly affected by season. Redundancy analysis indicated that water velocity, hydrogen ion concentration, turbidity, water depth, and total nitrogen were the most important factors for macroinvertebrate functional diversity. Moreover, structural equation modeling demonstrated that seasonal variations in total nitrogen, ammonia nitrogen, nitrate nitrogen, conductivity, water velocity, and hydrogen ion concentration directly or indirectly impacted the species diversity and functional diversity of macroinvertebrates. This study provides valuable information into the seasonal variation characteristics of macroinvertebrate communities, contributing to a more comprehensive understanding of biodiversity crucial for maintaining river ecosystem functioning and stability.

Biomass and Functional Diversity of Microbial Communities in Catenas of Reserved and Arable Gray Soils and Chernozems

Biomass and Functional Diversity of Microbial Communities in Catenas of Reserved and Arable Gray Soils and Chernozems

Interactive dynamics between rhizosphere bacterial and viral communities facilitate soybean fitness to cadmium stress revealed by time-series metagenomics

The distinctive symbiotic relationship between rhizobacteria and soybean (Glycine max) can enhance soil fertility and assist soybean defense heavy metal stress, such as cadmium (Cd), in soils. Soil viruses are critical for modulating microbial activities and enhancing host adaptability to soil contamination by encoding auxiliary metabolic genes (AMGs). However, the community structure, functional diversity and ecological roles of soil viruses and their dynamic interactions with soil-dwelling microbes under Cd stress remain unclear. Here, we characterized the bulk and rhizosphere bacterial community in a Cd-contaminated soybean field at five growth stages and investigated the rhizosphere microbial functional traits and the viral community after flowering using metagenomics. We showed that the rhizosphere bacterial community exhibited a stronger soybean development-dependent diversity pattern relative to bulk soil and had a more critical role in predicting Cd accumulation. The relative abundance of Actinobacteria in the rhizosphere increased with soybean development, particularly in the families Nocardioidaceae and Intrasporangiaceae, which were further identified as the main contributors of amino acid transport E and secondary metabolites Q genes. Viral analysis suggested an interactive and complementary assembly between viral and bacterial communities. Importantly, viruses exhibited a broader host range during the flowering period, and infected specific functional taxa such as Bradyrhizobium and Nocardioides, highlighting their potential impact on the rhizobia-soybean symbiosis and soybean growth and fitness. Furthermore, AMGs related to element cycling and microbial metabolism were identified and functionally and phylogenetically characterized, suggesting the contribution of these virus-encoded genes to biogeochemical cycles and soybean fitness under Cd stress. Together, our results expand our understanding of the ecological functions of rhizosphere viruses in Cd pollution-stressed soils, and provide insights in developing new strategies for bioremediation of contaminated soils.

Trawling-induced change in benthic effect trait composition – A multiple case study

IntroductionThe importance of the response-effect trait dichotomy in marine benthic ecology has garnered recent attention. Response traits, characterising species responses to environmental variations, have been a dominant focus in the development of ecological indicators for ecosystem health assessment. In contrast, effect traits, expressing effects of organism activities on the ecosystem, still do not benefit from an equal interest in spite of the complementary facet that they provide to complete our understanding of functional diversity and ecosystem vulnerability. In this study, we explore the consequences of disturbance by bottom trawl fisheries on benthic effect trait composition.MethodsTo this end, we used different contexts of environmental and trawling conditions from thirteen case studies in European waters and apply the same analytical procedure to derive a gradient that solely account for trawling-induced disturbance (Partial RLQ analysis).ResultsBottom trawling was found to be a selective force of benthic effect trait composition in a majority of case studies. In general, tube-dwelling species were more typical of low trawling frequencies, whereas deep burrowing species were more resistant at high trawling frequencies. Although we report significantly deleterious effects of trawling on benthic ecosystem functions, the effect trait pattern along the gradient was never related to life span, a key response trait generally assumed to express recoverability following disturbance. Furthermore, we show that trends in species multi-functionality and community functional diversity can be negative or positive along the trawling intensity gradient.DiscussionWe discuss the relevance of these results in light of recent developments in the framework of response and effect trait dichotomy, and provide guidelines of trait data analysis in the context of trawl fisheries impact on the sea floor. Our findings emphasize the importance of fundamental concepts from functional ecology in this context and represent a first step toward an assessment of trawling effect more oriented on benthos-mediated biogeochemical processes.

Community structure and functional diversity of soil nematodes from Udupi district, Karnataka, India

Nematodes constitute the most significant, most numerous, and diversified set of multicellular organisms on the earth. They live in various environments and exhibit a wide range of behavioural patterns. In the soil food web, they can be found at various trophic levels as herbivores (plant parasitic nematodes), bacterivores, fungivores, omnivores, and predators. As there were fewer studies on nematode ecology in the Udupi region, the present study aims to study the community structure and functional diversity of soil nematodes. Soil samples were collected following opportunistic random sampling employing a soil auger and were stored at 40C until transported to the laboratory. Nematodes were isolated from soil, killed, fixed, dehydrated, and displayed on a glass slide after isolation. The standard keys were used to identify the individual to genera level. 62 genera of soil nematodes belonging to 26 families and 7 orders were identified. Predator were the most prevalent communities. Various statistical indices for assessing nematode population ecology and nematodes specific indices were also calculated and it indicated a significant abundance of large plant parasitic nematodes. The region exhibits low levels of labile organic carbon and nutrient enrichment (Enrichment Index (EI):14.06 to 21.22). Despite this, the soil food web in the region is well-structured, indicated by Structure Index (SI) (85.51 to 89.74). Prevalence of fungal decomposition dominance and the soil appears to be minimally disturbed, as indicated by high channel index values and low Basal Index (BI) values, respectively

Functional diversity and carbon storage of plant community elevation patterns and carbon accumulation mechanisms in desert shrubland of Yanqi Hola Mountain, China

Exploring the distribution characteristics of plant community functional diversity, functional traits and plant and soil carbon stocks along elevation and the effects of functional diversity and functional traits on carbon stocks is of great significance for revealing the distribution characteristics of plant community functional diversity and carbon stocks in the desert area and understanding the carbon accumulation mechanism. In this study, we took the leaf functional traits of plant community species and the carbon stocks of plants and soils of sample plots in the pre-Hola Mountain desert area as the research objects and explored their altitudinal distribution characteristics and their interrelationships. The results showed that (1) the plant carbon storage capacity of the shrub - herb association was the strongest, and the soil carbon storage capacity of the herb association was the strongest. (2) Functional richness and plant carbon storage capacity tended to increase and then decrease with elevation, while functional evenness and leaf phosphorus content tended to decrease and then increase with elevation. Functional dispersion, leaf water content, chlorophyll content, leaf carbon, nitrogen content, and soil carbon stock all showed a gradual increase with elevation, and the total carbon stock gradually increased with elevation in the middle and low elevation areas (1200–1800 m), and showed a wave-like change in the high elevation areas (1800–2400 m). (3) The accumulation of soil carbon stocks in the study area is mainly dominated by the “mass ratio hypothesis”, while the accumulation of plant carbon stocks is mainly dominated by the “ecological niche complementarity hypothesis”, and plant and soil carbon stocks are mainly affected by the specific leaf area and the content of carbon, nitrogen, and phosphorus in leaves.

Community composition, and not species richness, of microbes influences decomposer functional diversity in soil

Diversity-function relationships in producers, and how these are influenced by consumers, are well known. However, these are not well known for microbial decomposers in soil. It is also unknown whether and how consumers such as large mammalian herbivores influence soil microbial decomposer diversity-function relationships. We used a 14-year-old herbivore-exclusion experiment in the Trans-Himalayan drylands of northern India to address whether microbial functions vary with microbial diversity (both species richness and composition), and whether herbivores alter the diversity-function relationships. We analyzed soils from n = 10 paired grazed-and-fenced plots three times during the growth season of 2019. Data were from 16S rDNA gene amplicon sequencing of 7.6 million reads covering 1937 operational taxonomic units (OTU) of bacteria across 47 phyla (of which 924 OTUs were identifiable to genus level), and 1800 catabolic profiles across 30 substrates related to carbon metabolism. We found that functional diversity was positively related to microbial community composition, but not to species richness; it was also unaffected by large mammalian herbivore-exclusion to indicate resilience and resistance. This positive relationship between community composition and functional diversity challenges the prevailing notion of functional redundancy in hyper-diverse soil microbial communities since certain combinations of species could outperform others and determine decomposition processes and services. Structural equation models suggested that the strength of this relationship is favoured by availability of soil moisture. Microbial functions varied more strongly with temporal variables (e.g., seasonality) than with spatial variables (e.g., edaphic factors such as soil texture and pH). Although interpretations can be constrained by which and how many functions are investigated, the relationship was generalizable and robust once 16 or more functions were quantified. Decomposition in drylands may be particularly susceptible to how the identity of the microbial species, and not the number of species, responds to rising precipitation variability under ongoing and projected climate change.

The impact of smash-ridge tillage on agronomic traits of tobacco plants, soil enzymatic activity, microbial community structure, and functional diversity

ABSTRACT Smash-ridge tillage is a novel cultivation technique that significantly influences the quality of arable land and crop yield. In this study, we employed high-throughput 16S rRNA sequencing and Biolog-ECO methods to systematically investigate the impact of smash-ridge tillage on soil microbial community structure and functional diversity. The results demonstrate that both ST30 and ST50 treatments significantly enhance the average plant height, average plant diameter, average fresh root weight, stem fresh weight, and leaf area of tobacco plants, with the ST50 treatment exhibiting superior performance. Furthermore, both ST30 and ST50 treatments exhibit significantly higher soil enzyme activity and microbial community diversity compared to the CK treatment. They also improve the soil microbial utilization of carbon sources. Additionally, the ST50-treated soil samples demonstrate 15 microbial functional pathways that exceed those of the CK and ST30 treatments. In conclusion, the Smash-ridge tillage treatment at a depth of 50 cm yields more favorable results. This study provides a theoretical foundation for enhancing soil quality in Smash-ridge tillage by elucidating the mechanisms through which it impacts soil microbial ecology.

Lack of strong seasonality in macrobenthic communities from the northern Barents Sea shelf and Nansen Basin

The Barents Sea has been coined ‘the Arctic hotspot’ of climate change due to the rapidity with which environmental changes are taking place. This transitional domain from Atlantic to Arctic waters is home to highly productive benthic communities. This system strongly fluctuates on a seasonal basis in its sympagic-pelagic-benthic coupling interactions, with potential effects on benthic standing stocks and production. Recent discoveries have questioned the marked seasonality for several high Arctic seafloor communities in coastal waters of Svalbard. Still, the seasonal variability of benthic process in the extensive Barents Sea open shelf remains poorly understood. Therefore, we studied the seasonality of macrofauna communities along a transect in the northwestern Barents Sea comprising two hydrographic domains (Arctic vs. Atlantic Water, across the Polar Front) and three geomorphological settings (shelf, continental slope and abyssal plain). Overall, we did not find strong signs of seasonal variation in taxonomic community structure and functional diversity. However, we found some weak signs of seasonality when examining each station separately, especially at a station close to the Polar Front, with high seasonal fluctuations in abiotic drivers indicating a stronger pelagic-benthic coupling. The lack of seasonality found both at the shelf stations south and north of the Polar Front could be related to organic matter stored in the sediments, reflected in constant levels of total organic carbon in surface sediment across time for all stations. We did observe, as expected, highly spatially structured environmental regimes and macrofauna communities associated to them from shelf to slope and basin locations. Understanding the underlying spatio-temporal mechanisms by which soft-bottom benthic communities are structured along environmental gradients is necessary to predict future impacts of climate change in this area. Our results indicate that short-term climate driven changes in the phenology of pelagic ecosystem components might not be directly reflected in the Arctic benthic system, as seafloor processes seem to be partially decoupled from those in the overlying water.

Land abandonment transforms soil microbiome stability and functional profiles in apple orchards of the Chinese Losses Plateau

Land abandonment is considered an effective strategy for ecological restoration on a global scale. However, few studies have focused on how environmental heterogeneity associated with the age of land abandonment affects the assembly and potential functions of the soil microbial community. In the present study, we investigated the community assembly of soil bacteria and fungi as well as the stability of soil networks and their potential functions in the chronosequence of abandoned apple orchards. We elucidated that the Shannon diversity of bacteria and the richness of fungi increased as land abandonment progressed. In addition, land abandonment destabilized the microbial network stability but increased network complexity. Soil available nitrogen, total carbon, and moisture are the potentially important factors in shaping the soil microbial assembly. Importantly, we showed that the microbial community diversity and functional diversity presented a synchronization effect in response to the different stages of land abandonment. Furthermore, specific bacterial taxa related to carbon fixation, dissimilatory nitrate reduction, and organic phosphorus mineralization were significantly enriched during the early abandonment stage. Collectively, these results indicate that land abandonment significantly transformed soil microbiome assembly and functional adaptation during the restoration process. These findings provide valuable insights into the influence of ecological restoration on soil microbiome and ecosystem functions in arable areas.

Bacterial communities in residential wastewater treatment plants are physiologically adapted to high concentrations of quaternary ammonium compounds

AbstractBenzalkonium chloride (BAC) is a quaternary ammonium compound (QAC) widely used as the active ingredient of disinfectants. Its excessive discharge into wastewater is constant and in high concentrations, likely affecting the physiology of microbial communities. We compared the physiological community profile of activated sludge (AS) bacteria with and without prior in vitro exposure to a high concentration of BAC (10 mg L−1). We measured the community functional diversity, carbon substrate multifunctionality, and the median effective concentration that inhibits carbon respiration (EC50) using Biolog EcoPlates supplemented with a gradient of 0–50 mg L−1 of BAC. Surprisingly, we did not find significant differences in the physiological parameters among treatments. Certain abundant bacteria, including Pseudomonas, could explain the community's tolerance to high concentrations of BAC. We suggest that bacterial communities in wastewater treatment plants’ AS are “naturally” adapted to BAC due to frequent and high‐dose exposure. We highlight the need to understand better the effects of QACs in wastewater, their impact on the selection of tolerant groups, and the alteration in community metabolic profiles.

Functional identity of dominant species in a predator community prevails over functional diversity in shaping the top‐down control of herbivores

Abstract Decline in species richness as well as changes in community evenness or functional diversity have been hypothesised to jointly affect ecosystem functioning. However, disentangling the relative effects of these changes in community structure is hard as these different aspects often covary with species richness in real‐world ecosystems. In this study, we investigated the individual and interactive effects of functional diversity and community evenness of predators on the level of control of herbivorous prey. Using a highly replicated mesocosm experiment, we crossed three levels of functional diversity of arthropod predators with two levels of community evenness while controlling for the effect of species richness. Using this experimental setting, we hypothesised that the effect size of functional diversity of predators depends on community evenness. We expected a positive effect of functional diversity of predators on top‐down control at high level of community evenness while we thought that species identity and their associated traits should drive most of the effect on top‐down control at low level of community evenness. Our results did not provide any evidence for an interaction between functional diversity and community evenness nor any beneficial effect of increased functional diversity overall on predation rates of herbivorous prey. In addition, our results revealed that species and functional identity drives most of the effects of predator community composition on top‐down control of their prey in our study system. Assemblages composed of active hunters with low handling time and no starvation ability tended to have the highest impacts on prey biomass. By indicating that top‐down control of herbivorous prey by arthropod predators is mainly driven by species and functional identity and not by functional diversity, our study provides insights into the consequences of ongoing species loss on ecosystem functioning. Future research should now explore the predictability of trophic interactions based on functional traits of predator and herbivorous prey to anticipate the consequences of changes in species composition on ecosystem functioning. Read the free Plain Language Summary for this article on the Journal blog.

Leaf functional diversity and environmental filtering in a tropical dry forest: Comparison between two geological substrates.

The role of geological substrate in shaping plant community functional diversity remains poorly understood. Considering the involvement of leaves in the energy, water, and nutrient economics of plants, we hypothesized that leaves experience geology-related filtering, which in turn shapes their functional attributes and community leaf functional diversity on different substrates. We studied tropical dry forest communities on limestone and siliciclastic phyllite-derived soils, comparing their functional diversity and soil physico-chemical properties. We predicted the most benign habitat (less severe filter) to be associated with higher leaf functional diversity and an acquisitive strategy prevalence, while the more stressful habitat should show conservative leaf traits and lower leaf functional diversity. We measured six traits in 31 common tree species (representing ~80% of community crown cover): leaf area, specific leaf area, leaf thickness, leaf dry matter content, petiole length, and leaf blade narrowness. Leaf functional diversity was assessed through the functional trait dispersion metric. Intraspecific functional variation was examined in 25 species shared between substrates. The limestone substrate was more fertile (higher phosphorous) with higher water retention, while phyllite had higher nitrogen and lower humidity. Principal component analysis segregated plots by substrate, with limestone plots being more clustered. Community leaf functional diversity was higher in the limestone forest. Most species examined showed inter-substrate trait differences in at least one leaf functional trait. The two substrates constituted distinct growth environments, with the more benign substrate associated with higher community leaf functional diversity. The intraspecific analysis revealed the prevalence of acquisitive traits in the more benign and more conservative traits in the more stressful habitat. This study advances our understanding of the role of geological substrate as an environmental filter in tropical dry forests, influencing leaf functional responses and emphasizing the importance of intraspecific functional variation.

Avian species functional diversity and habitat use: The role of forest structural attributes and tree diversity in the Midlands Mistbelt Forests of KwaZulu-Natal, South Africa.

Forest transformation has major impacts on biodiversity and ecosystem functioning. Identifying the influence of forest habitat structure and composition on avian functional communities is important for conserving and managing forest systems. This study investigated the effect of forest structure and composition characteristics on bird species community structure, habitat use and functional diversity in 14 Mistbelt Forest patches of the Midlands of KwaZulu-Natal in South Africa. We surveyed bird communities using point counts. We quantified bird functional diversity for each forest patch using three diversity indices: functional richness, functional evenness and functional divergence. We further assessed species-specific responses by focussing on three avian forest specialists, orange ground-thrush Geokichla gurneyi, forest canary Crithagra scotops and Cape parrot Poicephalus robustus. We found that bird community and forest-specialist species responses to forest structure and tree species diversity differed. Also, forest structural complexity, canopy cover and tree species richness were the main forest characteristics better at explaining microhabitat influence on bird functional diversity. Forest patches with relatively high structural complexity and tree species richness had higher functional richness. Different structural characteristics influenced habitat use by the three forest specialists. Tree species diversity influenced C. scotops and G. gurneyi positively, while P. robustus responded negatively to forest patches with high tree species richness. Our study showed that site-scale forest structure and composition characteristics are important for bird species richness and functional richness. Forest patches with high tree species diversity and structural complexity should be maintained to conserve forest specialists, bird species richness and functional richness.

Trait driven or neutral: understanding the change in functional trait diversity during early plant succession using Price partitions

Habitat filtering, species interactions and neutral colonization as well as extinction dynamics govern the sequence of community assembly and functional diversity (FD) during primary plant succession. To study the factors that influence changes in FD we here use data on plant seed size, seed numbers and specific leaf area from 107 study plots along a 7 year sequence of primary succession (2005–2011) in a 6 ha German artificial catchment. We show that the temporal variability in functional diversity can be partitioned into the effects of trait expression, species richness and plant cover. We observed a dominant role of species richness and community composition on FD. Trade-offs in the influence of species richness and plant cover tended to decrease the change in FD. Average FD steadily increased during the first 4 years of succession (2005–2008). The degree of annual changes in FD were highly plot specific. Average change in FD was comparatively low during the first 4 years and later high. Soil characteristics and light conditions did not significantly influence the detectable change in functional diversity. We conclude that the high plot-specific spatial variability of the annual changes in FD transformed the initially catchment-wide homogeneous distribution of plant species into a mosaic of very different local plant communities. Our partitioning results also indicate that the successional sequences in FD are in accordance with a hidden Markov series.

Environmental filtering and environmental stress shape regional patterns of riparian community assembly and functional diversity

Abstract Riparian plant communities are key to ecosystem functioning and important providers of ecosystem services on which wildlife and people depend. Ecosystem functioning and stability depend on functional diversity and redundancy. Therefore, understanding which and how different drivers shape community assembly processes and functional patterns is crucial. However, there is limited knowledge of these processes at larger scales for the entire riparian vascular plant community. Two community assembly processes dominate: environmental filtering, where species living in similar environments have similar traits leading to trait convergence; and limiting similarity, where similar traits cause species to compete more strongly leading to trait divergence. We assessed functional diversity patterns of riparian vascular plant communities across an Atlantic–Mediterranean biogeographical gradient in north Portugal. We used functional diversity indices and null models to detect community assembly processes and whether these processes change along environmental gradients. We hypothesised that environmental filtering associated with precipitation and aridity would be the prevailing assembly process at a regional scale. We also expected a shift from environmental filtering to limiting similarity as precipitation‐related stress declined. As hypothesised, patterns of functional diversity were consistent with environmental filtering of species occurrences at the regional scale. Functional patterns were also consistent with a shift between environmental filtering and limiting similarity as cold and aridity stress declined. Under stressful environmental conditions, communities showed lower functional divergence and richness than expected by chance. Environmental filtering was more strongly associated with minimum temperatures than precipitation and aridity. Underlining the need for hierarchical approaches and the analysis of multiple climatic stressors, our results highlighted the relevance of large‐scale environmental stress gradients and the potential role of community assembly in influencing riparian functional diversity. Alterations in stress filters due to climate change will affect assembly processes and functional patterns, probably affecting ecosystem functioning and stability.