Search

Small temporary wetlands, like kettle holes, provide many valuable ecosystem functions and serve as refuge habitats in otherwise monotonous agricultural landscapes. However, the mechanisms that maintain biodiversity in these habitats are still poorly understood. In this study, we investigate how three taxa (vascular plants, ground beetles and spiders) respond to small-scale flooding and disturbance gradients in kettle holes as well as kettle hole area. For this purpose, we determined total, hygrophilic and red list species richness for all taxa and activity density for arthropods along transects extending from the edge towards the center of kettle holes. Furthermore, we calculated the community-weighted mean body size for arthropods and seed mass for plants as surrogates for the ability to respond to disturbance. Our analyses revealed that in particular plants and ground beetles showed strong responses along the small-scale spatial gradient. Total plant species richness decreased towards the center, while hygrophilic plant species increased. In contrast, both total and hygrophilic species richness of ground beetles increased towards the center. Spiders showed similar responses as ground beetles, but less pronounced. We found no evidence that disturbance at the edge of kettle holes leads to smaller body sizes or seed masses. However, arthropods in adjacent arable fields (one meter from the kettle hole edge) were particularly small. Kettle hole area had only weak effects on plants, but not on arthropods. Our study indicates that differences in the depth at the drier edge and the moist, regularly flooded center have a large and taxon-dependent influence on the species composition. Therefore, small-scale heterogeneity seems to be an important predictor for the maintenance of species diversity. [ABSTRACT FROM AUTHOR]

Calcareous grasslands harbor specialized species and are cultural relics. Therefore, they are prime habitates for conservation and restoration, but negative effects of inappropriate management, eutrophication and fragmentation continue to exist. These effects also influence grasslands which serve as target for restoration. Unfortunately, monitoring of long-term vegetation dynamics in calcareous grassland is rare. Here, we studied such changes over 35 years in the nature reserve 'Garchinger Heide', which is well known for its high abundance of rare species. Furthermore, it has been managed for conservation for more than 100 years. Therefore, species composition, total species richness, numbers of habitat specialists, red-list species and the proportion of graminoids were examined in 42 plots with frequency recording (1984–2018), and in 40 plots based on vegetation relevés (2003–2018). Ellenberg indicator values, specific leaf area, seed mass, and canopy height were analysed to detect patterns in trait response to environmental change. Within 35 years there were considerable vegetation dynamics. Specialist plants of calcareous grassland and red list species decreased, and insect-pollinated species declined in contrast to wind-pollinated species. Ellenberg N as well as graminoid abundance, canopy height, seed mass, and multi-trait functional dispersion increased, while specific leaf area showed no such change. Our results suggest that environmental change like deposition of atmospheric nitrogen, management regime, pollinator decline or isolation could be correlated with vegetation dynamics, while these correlations would need experimental confirmation. The grassland management certainly helped achieving several conservation goals, although it was not able to stop a decrease of rare species. The results show that also in nature reserves with long-term conservation management monitoring is essential to detect vegetation dynamics and to adjust the management to these changes. [ABSTRACT FROM AUTHOR]

• A nonlinear mixed effects H-D model was developed for the mid-montane humid evergreen broad-leaved forest in southwest China. • Tree species of natural mixed forests were classified by K-means clustering according to specific plant functional traits. • Tree height increased with increasing values of site quality and tree size equality, and vice versa. Tree height and diameter at breast height (DBH) are key survey factors in forest inventory. Compared to measuring DBH, the process of measuring tree height is time-consuming, labor-intensive and costly, especially in natural mixed forests. Tree height is therefore commonly predicted using height-diameter (H-D) models. Nevertheless, developing H-D models for natural mixed forests are hampered by the large diversity of tree species and the small number of rare tree species observed. In this study, a nonlinear mixed effects H-D model was established for a mid-montane humid evergreen broad-leaved forest in southwest China. For this purpose, we classified tree species by K-means clustering according to the specific plant functional traits. Data were collected from 5, 737 trees in 100 subplots with 86 species. The results revealed that the nonlinear mixed effects model of tree height accounted for 75% of the variation in tree height without significant heteroscedasticity, and that the model parameters had biological significance. In the 10-fold cross validation, no clear fluctuation in the model evaluation metrics was observed, indicating the absence of overfitting in the model. Of the 15 stand variables, dominant height (H d) and Margalef's index of DBH (D Mg), which contributed the most to the height-diameter model, were selected to expand the model. Our findings suggest that tree height increased with increasing values of H d and D Mg , and vice versa. This study highlights the feasibility of categorizing natural mixed forests by utilizing plant functional traits and the influential role of tree size inequality on tree height variation. [ABSTRACT FROM AUTHOR]

Highlights • Mortality of coastal plants are driven by different growth stress under increasing salinity. • Deciduous baldcypress is more affected by nutrient stress than water stress. • Evergreen and N 2 -fixing waxmyrtle is more affected by water stress than nutrient stress. Abstract With rising sea levels, mortality of glycophytes can be caused by water and nutrient stress under increasing salinity. However, the relative effects of these two stressors may vary by species-specific functional traits. For example, deciduous species, with leaves typically emerging during low salinity periods of the year, may suffer less from water stress than evergreen species. We sampled two woody species with contrasting functional traits: the evergreen and N 2 -fixing waxmyrtle ( Morella cerifera ), and the deciduous and non-N 2 fixing baldcypress ( Taxodium distichum ) along a coastal river (South Carolina, USA) showing an increasing pattern of plant mortality along a salinity gradient. We first analyzed oxygen and hydrogen isotope ratios of plant stem water and river water to determine changes in plant source water at different sites. Then we analyzed foliar carbon and nitrogen isotope ratios (δ13C and δ15N) along with nitrogen and phosphorus content (%N and %P) as proxies for the water and nutrient stress. Results showed that: (1) the two species had different water sources at the higher salinity sites; (2) foliar δ15N values of baldcypress decreased with higher salinity while retaining a constant δ13C value, and both of these isotope values were positively related with foliar %P, suggesting greater nutrient stress but minor water stress under high salinity; and (3) foliar δ13C values of waxmyrtle increased with higher salinity while retaining a constant foliar δ15N value, and neither of the values was significantly related to foliar nutrients, suggesting greater water stress but minor nutrient stress under high salinity. The different responses of the two species to high salinity may be related to their differences in leaf phenology and N 2 -fixation. Our results suggest that nutrient stress, particularly of P, can contribute to stress and eventual high mortality of baldcypress exposed to salt water intrusion. [ABSTRACT FROM AUTHOR]

Abstract Collembola is an abundant group of soil organisms playing a major role on litter decomposition process and nutrient cycling in forest ecosystems. Habitat structure strongly influences Collembola assemblages as plant litter physical characteristics and quantity provide structural niches and determine the outcome of their interactions with predators. Collembola are also extremely sensitive to environmental conditions such as soil temperature that control their demographic parameters and activity. In this context, increasing temperature with the ongoing climate change can have strong impact on Collembola assemblages and their responses to predation either directly by altering their behaviour or indirectly by altering their habitat structure. We therefore examined how the increase of temperature combined to the decrease of specific leaf area (SLA, a major functional plant trait) of the European common oak (Quercus robur L.) and the presence of a centipede predator (Chilopoda: Lithobiidae) will affect the abundance of Folsomia candida (Collembola: Isotomidae) in a 5-week microcosm experiment. Increasing temperature, decreasing SLA and presence of centipede altered F. candida abundance. We observed a significant temperature × predation interaction suggesting differential effects of increasing temperature on F. candida abundance with and without predator. We also observed a significant SLA × predation interaction highlighting that lower SLA decreases F. candida abundance only in predator presence. Finally, our findings evidenced that increasing temperature and decreasing SLA amplify the negative effect of centipede predation on F. candida abundance, suggesting that both direct and indirect effects of climate change would conjointly strengthen the top-down control of predators on preys. Highlights • Temperature, SLA and centipede predation alter Collembola abundance. • +5 °C stimulates Collembola abundance only in centipede absence. • +10 °C strongly decreases Collembola abundance with and without centipede. • Lower SLA decreases Collembola abundance only in centipede presence. • Increasing temperature and decreasing SLA amplify centipede predation. [ABSTRACT FROM AUTHOR]

The majority of studies that investigate plant functional trait effects on ecosystem properties use traits obtained from databases. However, we know little regarding their explanatory power proportionate to that of the semi-quantitative vegetation properties, and much less still is known when considering their temporal changes in a chronosequence. We determined whether soil chemical and biological properties were associated with plant functional traits, observed vegetation properties (“patch type” = bare soil, grassy, woody), and site age (10, 18, 28, and 55 years), at four spontaneously overgrown post-mining locations in the Czech Republic. Abiotic soil properties were expected to be closely related to the site age, while above and below ground macrofauna (epigeic and endogeic, respectively), mesofauna, and microbial biomass were expected to be related to the plant functional traits and patch types. Site age and plant functional traits were more important explanatory factors for most of the chemical, microbial, and macrofaunal soil properties than the patch types. Patch type was the only plant-related factor capable of explaining the mesofauna community variations. Epigeic macrofauna were found to correlate more strongly with the plant functional traits than endogeic macrofauna. The abundance of most fauna correlated positively with an increase in plant cover and litter input and was significantly higher in vegetated patches and old sites. [ABSTRACT FROM AUTHOR]

Spatial environmental heterogeneity is considered a fundamental factor for the maintenance of plant species richness. However, it still remains unclear whether heterogeneity may also facilitate coexistence at fine grain sizes or whether other processes, like mass effects and source sink dynamics due to dispersal, control species composition and diversity at these scales. In this study, we used two complimentary analyses to identify the role of heterogeneity within 15 m × 15 m plots for the coexistence of species-rich annual communities in a semi-arid environment along a steep precipitation gradient. Specifically, we: (a) analyzed the effect of environmental heterogeneity on species, functional and phylogenetic diversity within microsites (alpha diversity, 0.06 m 2 and 1 m 2 ), across microsites (beta diversity), and diversity at the entire plot (gamma diversity); (b) further we used two null models to detect non-random trait and phylogenetic patterns in order to infer assembly processes, i.e. whether co-occurring species tend to share similar traits (trait convergence) or dissimilar traits (trait divergence). In general, our results showed that heterogeneity had a positive effect on community diversity. Specifically, for alpha diversity, the effect was significant for functional diversity, and not significant for either species or phylogenetic diversities. For beta diversity, all three measures of community diversity (species, functional, and phylogenetic) increased significantly, as they also did for gamma diversity, where functional measures were again stronger than for species or phylogenetic measures. In addition, the null model approach consistently detected trait convergence, indicating that species with similar traits tended to co-occur and had high abundances in a given microsite. While null model analysis across the phylogeny partly supported these trait findings, showing phylogenetic underdispersion at the 1m 2 grain size, surprisingly when species abundances in microsites were analyzed they were more evenly distributed across the phylogenetic tress than expected (phylogenetic overdispersion). In conclusion, our results provide compelling support that environmental heterogeneity at a relatively fine scale is an important factor for species co-existence as it positively affects diversity as well as influences species assembly. Our study underlines the need for trait-based approaches conducted at fine grain sizes in order to better understand species coexistence and community assembly. [ABSTRACT FROM AUTHOR]

Impatiens parviflora (Balsaminaceae) is one of the most widespread invasive plant species in Central Europe. Nevertheless, both mechanisms and consequences of its invasion are still poorly understood. In this study we attempt to understand the impact of this species on native vegetation. The impact of I. parviflora on native vegetation was studied using removal experiment on permanent plots in oak-hornbeam forests in central Bohemia, Czech Republic. Nine pairs of plots were established in invaded vegetation, one plot in each pair stayed invaded and the other served as removal plot and all I. parviflora individuals were repeatedly removed from the plot. Species composition in 4 subsequent years was recorded in the plots. Species response to I. parviflora removal was correlated to plant traits to reveal trait characteristics of species suppressed by the invasion. Significant increase in both numbers and cover of native species was observed in removal plots in comparison with invaded plots during the experiment, with the greatest change in first two years after invader removal. Species composition also significantly differed between invaded and removal plots. Species with high affinity to removal plots, i.e. species that are most restricted by I. parviflora invasion, were mostly species with small releasing height and early start of flowering. Our results indicate that I. parviflora has negative impact on native vegetation but that the vegetation can recover within few years after the invader removal. Due to its extensive distribution and high turnover, removal of the species from larger plots is, however, not realistic in practice. [ABSTRACT FROM AUTHOR]

• Phylogeny and functional trait analyses were used to test community assembly. • The relative importance of dominant ecological processes changed during succession. • Soil P content has a important impact on community assembly during succession. • Both environmental filtering and competitive exclusion played a role during succession. • The test of ecological processes could be biased if used one functional strategy. Understanding community assembly process could enhance forest conservation and restoration, while which dominant ecological process drives the community assembly during forest succession is still controversial. In this study, the phylogeny-based and functional trait-based indicators were used to investigate the community assembly processes during forest succession in southern China. 30 dominant species and 33 functional trait indicators related to plant competition, reproduction, and defense strategies, 7 environmental factors related to light availability and soil nutrients, and species richness were selected to explore the dominant ecological processes during succession via Monte Carlo method, structural equation model, multiple linear regression, and one-way ANOVA analysis. Results showed that both the community phylogenetic and functional trait structures changed during succession. Phylogenetic structure clustering and functional trait clustering were evident in early succession. In middle succession, the phylogenetic structure and functional trait structure were randomly dispersed. In middle and later succession, the phylogenetic structure clustering, functional trait clustering, and functional trait evenly dispersed were found. The environmental factors, especially the soil P content, and species richness were found to have significant effects on the community assembly processes during succession. Dominant species in early succession always occupied acquisitive strategies and had high light-use ability and low investment in defense, but dominant species in later succession showed more conservative strategies and exhibited diverse defense strategy, reproductive strategy, and light and nutrient resource-use strategy, apparently in order to adapt changing and more complex environments. The results demonstrate that the relative importance of ecological processes changed during succession. Environmental filtering mainly dominated in early succession, and its strength gradually decreased as succession progressed. Both environmental filtering and competitive exclusion had important effects on community assembly in later succession. The assessment of the relative importance of ecological processes during succession could be biased if only based on one plant functional strategy. [ABSTRACT FROM AUTHOR]

The effect of biodiversity on ecosystem functioning has been widely acknowledged, and the importance of the functional roles of species, as well as their diversity, in the control of ecosystem processes has been emphasised recently. However, bridging biodiversity and ecosystem science to address issues at a biogeographic scale is still in its infancy. Bridging this gap is the primary goal of the emerging field of functional biogeography. While the rise of Big Data has catalysed functional biogeography studies in recent years, comprehensive evidence remains scarce. Here, we present the rationale and the first results of a country-wide initiative focused on the C 3 permanent grasslands. We aimed to collate, integrate and process large databases of vegetation relevés, plant traits and environmental layers to provide a country-wide assessment of ecosystem properties and services which can be used to improve regional models of climate and land use changes. We outline the theoretical background, data availability, and ecoinformatics challenges associated with the approach and its feasibility. We provide a case study of upscaling of leaf dry matter content averaged at ecosystem level and country-wide predictions of forage digestibility. Our framework sets milestones for further hypothesis testing in functional biogeography and earth system modelling. [ABSTRACT FROM AUTHOR]

Cover crops are used during fallow periods to produce ecosystem services, especially those related to N management such as (i) capturing mineral-N from soil to reduce nitrate leaching, and (ii) improving N availability for the next main crop (green manuring). Bispecific mixtures consisting of legume and non-legume species could simultaneously produce these two services of nitrate saving and green manuring. The magnitude of these services can be estimated from indicators of agroecosystem functions such as crop growth rate, crop N acquisition rate and the C:N ratio of the cover crop. We developed a conceptual model for each indicator which was described using general linear models. A three-step procedure was used: (1) represent the behavior of each species based on a sub-model and calibrate each species in bispecific mixtures; (2) validate the complete-mixture models, corresponding to the sum of the two species sub-models, and the proportion of each species in the whole cover, and (3) validate the generality of sub-models and complete-mixture models to predict the agroecosystem function indicators of species in mixture not used for calibration. The combined use of (i) potential agroecosystem functions measured in sole crop in non-limiting conditions, (ii) difference in leaf functional traits, as indicators of plant strategies and (iii) environmental factors, was efficient in fitting and predicting the level of agroecosystem functions provided by a cover crop species in mixture in actual conditions. The models fitted for bispecific mixtures were efficient to represent the behavior of each species in mixture and to estimate the legume proportion which expressed the species dominance. The models were evaluated as satisfactory for crop growth rate and C:N ratio for their generality in predicting the agroecosystem functions provided in mixtures by other species not used in the model calibration step, which illustrates the relevance and robustness of the approach. [ABSTRACT FROM AUTHOR]

Abstract: Silicon is described as beneficial for grasses by enhancing yield and fitness via a considerable contribution to pathogen, drought, and pest resistance. Silicic acid is the predominant form for uptake and transport within the plant and will precipitate in leaves. But it is unknown whether polymeric nanosilicon compounds in its synthetic form, with an increasing concentration in aquatic environments, can be suitable for plant nutrition. Therefore, we investigated the uptake, transport, and deposition of silicic acid/silica within plants using synthetic nanosilica. Our results show a significant difference in silicon (Si) content within the different tissues of Phragmites australis. The nanosilica had been dissolved prior to the uptake by plants. The chemical form of Si during uptake was not traceable. A significant enhancement in the condensation state of the silica was found from root to leaves especially from culm to leaf tips visible by the increasing content of Q4-groups in the NMR spectra. We conclude that synthetic nanosilica has the same quality as source for the beneficial element Si like natural silica. Since the condensation state is described to control silica solubility, we suggest that different condensation states within the plant may result in different remobilization of silicon during decomposition of the plant material. [Copyright &y& Elsevier]

There is an increasing recognition that microplastics contamination in soils has become an important threat for terrestrial ecosystems, and can interact with drought. In addition, due to the increasingly serious environmental pollution and the destruction of the ozone layer, the UV-B radiation to the earth's surface has gradually increased. However, we currently have no information about potential effects of microplastics, UV-B, and drought on plant communities. In order to make up for the vacancy, we conducted an experiment with grassland plant communities. Polyester fiber microplastics (absent, present), UV-B (fully transparent polythene film, attenuating UV-B radiation), and soil water conditions (well-watered, drought) were applied in a fully factorial design. A plant community consisting of four indigenous species and one invasive species, co-occurring in the terrestrial ecosystem of the northern temperate zone was established, and we investigated the effects of microplastics, UV-B, drought and their interactions on plant functional traits and plant community structure. We found that shoot and root biomass decreased with drought but increased with microfibers, and drought significantly decreased specific leaf area at the community level. Physiological and biochemical indexes of individual species and plant community were affected by microfibers, UV-B, drought and their interaction to a varying degree. More importantly, five species were divided into three clusters along PC1 corresponding to individuals from G. longituba and P. depressa , B. bipinnata and M. sativa , plus G. parviflora, which indicated that at the same conditions, G. parviflora would occupy unique ecological niches that affect the growth of native species. Our research offers insights into the mechanisms of the coexistence of native and invasive plants, as well as the ecological consequences of microplastics and other environment factors on plant communities. [Display omitted] • Polyester fiber-microplastics increased height and shoot biomass for all plant species, especially invasive species G. parviflora. • Drought negatively affected height and shoot biomass for all plant species. • At the same conditions, G. parviflora would occupy a unique ecological niche and affect the growth of native species. [ABSTRACT FROM AUTHOR]

• Afromontane palustrine wetlands are important for ecosystem service delivery. • Environmental factors influence the ecosystem services delivered most by wetlands. • Higher-altitude palustrine wetlands store carbon and contribute to climate regulation. • Wetland ecosystem services correlate with functional traits of dominant plants. • Wetland ecosystem services in lower-altitude areas face a higher level of threat. Although wetlands are among the most valuable ecosystems, the condition and extent of wetlands is declining worldwide, to the detriment of ecosystem service delivery. This study assessed the ecosystem services delivered by the Afromontane palustrine wetlands of Lesotho using the WET-EcoServices tool and explored the relationships of the services with environmental factors and plant functional traits using ordination techniques. Higher-altitude wetlands differed from the lower-altitude wetlands in the spectrum of services they deliver. These wetlands were mostly valued for carbon storage, provision of natural resources, streamflow regulation, maintenance of biodiversity and erosion control. Lower-altitude wetlands were valued for natural resources, cultivated foods, nitrate removal, phosphate trapping and streamflow regulation. The environmental factors affecting the delivery of ecosystem services most were altitude, longitude (directly correlated with rainfall in the context of Lesotho), landscape, soil parent material, slope and soil depth. The delivery of several services was also correlated with plant functional traits, for example, carbon storage and maintenance of biodiversity were positively correlated with plant shoot mass, total plant biomass and rooting depth. The location and environmental characteristics of a given wetland within a catchment and the functional characteristics of the wetland's dominant plant species have an influence on the ecosystem services that it delivers. However, the level of threat to ecosystem services is high, especially in the lower-altitude wetlands. The threats, which are mainly anthropogenic, are mostly associated with crop cultivation, overgrazing and trampling by livestock and economic development. Thus, for sustainable provision of wetland ecosystem services, these Afromontane palustrine wetlands require urgent attention and up-scaling of the conservation efforts. [ABSTRACT FROM AUTHOR]

• Compared to temporal, spatial trait variability in desert shrubs is larger and more important for estimating ecohydrological states/fluxes. • Temporal trait variability further improves leaf area index predictions and generates greater water use efficiency. • The impact of spatiotemporally variable trait parameters on predicted ecohydrological processes depends on the future climate projections. Although spatial heterogeneity of soil properties, topography, and climate is commonly incorporated into ecohydrological models, the spatial and temporal variability in plant functional traits is typically overlooked. The objective of our study is to evaluate the impact of trait parameter variability on modeled ecohydrological processes. We implemented a model-data fusion approach to constrain spatiotemporally dynamic parameters in plant functional traits at two desert shrubland sites located along a topographic and climate gradient in the Mojave Desert. Our results showed that the estimates for specific leaf area and rooting depth for the broadleaf-evergreen-shrub plant-functional-type showed spatial variability, with lower specific leaf area and deeper rooting depth found at the low elevation site. We also found that the specific leaf area estimates changed over time at both sites in response to water stress, but with different sensitivities, possibly depending on species and/or climate. The spatial variability in trait parameter estimates was greater than temporal variability and played a more important role in accurately simulating ecohydrological processes, but including the temporal variability in specific leaf area further improved seasonal predictions. In simulations forced by future climate projections under the Representative Concentration Pathway 4.5 (RCP 4.5) and 8.5 (RCP 8.5) greenhouse gas emissions scenarios, spatial variability in trait parameters impacted predictions of both carbon and water fluxes, while temporal variability in trait parameters resulted in predictions of higher ecological function and water use efficiency. The higher water use efficiency led to improved ecohydrological function in simulations under RCP 4.5, but it showed little capacity for buffering intensive water stresses under the more pessimistic RCP 8.5 scenario, indicating that with spatiotemporally variable trait parameters, the impact on predicted ecohydrological processes depends on the climate projections. Overall, our modeling results prompt further field-based examination of temporal and belowground trait variability in desert shrublands, and they raise the question of how combined spatiotemporal variabilities of multiple traits may support ecohydrological function under water stress. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (ECM) fungi are closely related to vegetation compositions, edaphic properties, and site-specific processes. However, the coevolutionary mechanisms underlying the spatial distributions in floristic and ECM fungal composition in the context of biotic adaptations and abiotic variances remain unclear. We combine a total of 25 ECM fungus-associated environmental variables to impose three types of composite scores and then quantify the environmental gradients of geographical site, soil chemical property and vegetation functional trait across 122 grids of 20 m × 20 m in a 25-hm2 forest plot. Significant dissimilarities in vegetational and ECM fungal abundance and composition existed along the above environmental gradients. Specifically, a contrasting floristic distribution (e.g., Betula platyphylla vs. Tilia mandshurica) existed between the northeastern and southwestern areas and was closely related to the nutrient and moisture gradients (with high levels in the west and low levels in the east). Furthermore, the ECM fungal communities were more abundant in the nutrient-poor and low-moisture environments than in the nutrient-rich and high-moisture environments, and the mixed-forest in the middle-gradient sites between the northeastern and southwestern areas harbored the highest ECM fungal diversity. These findings suggest that predictable within-site vegetation succession is closely related to ECM-associated determinants and the natural spatial heterogeneity of edaphic properties at a local scale. Unlabelled Image • Geographic, edaphic and floristic gradients are separately determined by composite scores. • Tree and ECM fungal species show significant dissimilarities along environmental gradients. • Environmental gradients interactively influence floristic and ECM fungal life strategies. • ECM-associated determinants jointly reflect local-scale ecological processes. [ABSTRACT FROM AUTHOR]