Functional Structure Of Plant Communities Research Articles

Leaf trait plasticity reveals interactive effects of temporally disjunct grazing and warming on plant communities.

Changes in climate and grazing intensity influence plant-community compositions and their functional structure. Yet, little is known about their possible interactive effects when climate change mainly has consequences during the growing season and grazing occurs off growing season (dormant season grazing). We examined the contribution of trait plasticity to the immediate responses in the functional structure of plant community due to the interplay between these two temporally disjunct drivers. We conducted a field experiment in the northern Mongolian steppe, where climate was manipulated by open-top chambers (OTCs) for two growing seasons, increasing temperature and decreasing soil moisture (i.e., increased aridity), and grazing was excluded for one dormant season between these two growing seasons. We calculated the community-weighted mean (CWM) and the functional diversity (FD) of six leaf traits. Based on a variance partitioning approach, we evaluated how much of the responses in CWM and FD to OTCs and dormant season grazing occur through plasticity. The interactive effect of OTCs and the dormant season grazing were detected only after considering the role of trait plasticity. Overall, OTCs influenced the responses in CWM more than in FD, but the effects of OTCs were much less pronounced where dormant season grazing occurred. Thus, warming (together with decreased soil moisture) and the elimination of dormant season grazing could interact to impact the functional trait structure of plant communities through trait plasticity. Climate change effects should be considered in the context of altered land use, even if temporally disjunct.

Different responses of leaf and root economics spectrum to grazing time at the community level in desert steppe, China

The plant economic spectrum can explain the trade-off strategies of vascular plants between resource acquisition and storage. Grazing can alter the plant functional characteristics of grassland ecosystems, resulting in a shift in plant resource acquisition strategies. Taking fenced grassland as a control, in this study we quantified six leaf traits and four root traits of 14 plant species (those that comprised >85 % of the species community abundance) of different grazing time grasslands in desert grasslands in Ningxia. We examined how grazing time shapes the functional structure of plant communities and the resource acquisition strategy. The results revealed an inverse pattern of the fast-slow economic spectrum of leaf and root traits; that is, as grazing time increased, the leaf traits shifted from an acquisitive type to a conservative type of resource acquisition strategy. In contrast, the root traits showed a shift from a conservative type to an acquisitive type of resource acquisition strategy. Grazing time leads to a whole plant economic spectrum, and plant functional traits may facilitate their response to environmental change, the study of which can hereby deepen our understanding of the plant economics spectrum. Our study provides new evidence that leaf and root resource acquisition and utilization are relatively independent under grazing pressure.

The functional structure of plant communities drives soil functioning via changes in soil abiotic properties.

While biodiversity is expected to enhance multiple ecosystem functions (EFs), the different roles of multiple biodiversity dimensions remain difficult to disentangle without carefully designed experiments. We sowed plant communities with independent levels of functional (FD) and phylogenetic diversities (PD), combined with different levels of fertilization, to investigate their direct and indirect roles on multiple EFs, including plant-related EFs (plant biomass productivity, litter decomposability), soil fertility (organic carbon and nutrient pool variables), soil microbial activity (respiration and nutrient cycling), and an overall multifunctionality. We expected an increase in most EFs in communities with higher values of FD and/or PD via complementarity effects, but also the dominant plant types (using community weighted mean, CWM, independent of FD and PD) via selection effects on several EFs. The results showed strong direct effects of different dimensions of plant functional structure parameters on plant-related EFs, through either CWM or FD, with weak effects of PD. Fertilization had significant effects on one soil microbial activity and indirect effects on the other variables via changes in soil abiotic properties. Dominant plant types and FD showed only indirect effects on soil microbial activity, through litter decomposition and soil abiotic properties, highlighting the importance of cascading effects. This study shows the relevance of complementary dimensions of biodiversity for assessing both direct and cascading effects on multiple EFs.

Functional structure of plant communities along salinity gradients in Iranian salt marshes.

Salt marshes are unique habitats between sea or saline lakes and land that need to be conserved from the effects of global change. Understanding the variation in functional structure of plant community along environmental gradients is critical to predict the response of plant communities to ongoing environmental changes. We evaluated the changes in the functional structure of halophytic communities along soil gradients including salinity, in Iranian salt marshes; Lake Urmia, Lake Meyghan, Musa estuary, and Nayband Bay (Iran). We established 48 plots from 16 sites in four salt marshes and sampled 10 leaves per species to measure leaf functional traits. Five soil samples were sampled from each plot and 30 variables were analyzed. We examined the changes in the functional structure of plant communities (i.e., functional diversity [FD] and community weighted mean [CWM]) along local soil gradients using linear mixed effect models. Our results showed that FD and CWM of leaf thickness tended to increase with salinity, while those indices related to leaf shape decreased following soil potassium content. Our results suggest that the variations in functional structure of plant communities along local soil gradients reveal the effect of different ecological processes (e.g., niche differentiation related to the habitat heterogeneity) that drive the assembly of halophytic plant communities in SW Asian salt marshes.

Do non-native plants affect terrestrial arthropods in the sub-Antarctic Kerguelen Islands?

Biological invasions are a major threat to the terrestrial ecosystems of the sub-Antarctic islands. While non-native plants generally have negative impacts on native arthropods, few studies have investigated how both native and non-native arthropods and plants interact in the sub-Antarctic islands. This was the aim of our study, which was conducted on three islands of the Kerguelen archipelago. The design was based on the spatial proximity of areas dominated by non-native or native plant species. Trait-based indices were calculated to characterize the functional structure of plant communities, considering plant stature and leaf traits. Native and non-native vegetation had contrasting functional composition but their functional diversity was similar. The effects of the type of vegetation, native or non-native, and plant functional diversity on arthropods were tested. Native macro-arthropod richness and abundance were similar or higher in non-native vegetation, and benefited from greater plant functional diversity. Abundances of macro-herbivores, macro-decomposers and macro-predators were also similar or higher in non-native vegetation. Conversely, the abundances of micro-arthropods, Symphypleona springtails and Oribatida mites, were higher in native vegetation but we also found that plant functional diversity had a negative effect on Symphypleona. Our results suggest that non-native plants can affect micro-arthropods directly or indirectly, likely through their effects on abiotic factors. By affecting macro-arthropod abundances across different trophic groups and by depleting micro-arthropods, non-native plants can alter trophic interactions, functional balances and the functioning of whole ecosystem.

A trait-based approach in a Mediterranean vineyard: Effects of agricultural management on the functional structure of plant communities

In recent years, rainfed vineyards in the Mediterranean basin are being replaced by irrigated vineyards in some areas, a phenomenon that is expected to increase due to climate change. At the same time, the use of plant cover in vineyards has emerged as an alternative to other weed management practices (e.g., herbicide, tillage). Knowing how weed communities respond to these practices is essential to develop new and more sustainable vineyard management systems. However, there is a lack of research on this issue. This work examines, from a trait-based approach, the effects of weed management (herbicide, mowing, tillage), and deficit drip irrigation (irrigated, non-irrigated) on the functional structure of plant communities in a Mediterranean vineyard. Plant sampling was conducted from 2015 to 2018 in a previously established experiment in 2008. The experimental design was randomised blocks with four replications, including four management systems. Data for ten plant traits were collected from several databases and research work. The community-weighted mean of trait values were calculated, and RLQ and fourth-corner analyses were performed to establish the relationship between species-traits and management practices. In addition, functional groups were extracted by means of a cluster analysis on the RLQ ordination space and the Grime’s life strategy (CSR strategy) was computed to explore possible similarities with the functional structure of the community. A total of 29 herbaceous species were selected for their highest occurrence for statistical analysis. Results indicated that tillage and mowing were the main factors conditioning the functional structure of plant communities in this study. In general, weed management significantly affected leaf economics and regenerative traits, while irrigation influenced traits related to plant size. Phenological traits emerged as a major factor in understanding the response of plant communities to weed management practices. Furthermore, up to five functional groups were identified and associated with different management practices. Functional structure of the plant communities studied was consistent with CSR strategy, which showed a strong association with agricultural management. Irrigation favoured species with a more competitive strategy. Conversely, mowing in spontaneous plant cover limited the occurrence of these competitive species. This study provides knowledge about the ecology and plant traits that could contribute to the development of more sustainable weed management.

Functional trait coordination in the ancient and nutrient-impoverishedcampo rupestre: soil properties drive stem, leaf and architectural traits

AbstractOld, climatically buffered and infertile landscapes (OCBILs) are remarkably species-diverse, but the assembly of their ecological communities is largely unknown. Our goal was to understand how edaphic filters drive the functional structure of plant communities in an ancient and nutrient-impoverished ecosystem. We carried out a functional screening across four types of campo rupestre habitats with different edaphic conditions. We investigated trait–soil relationships for ironstone and quartzitic substrate to obtain the optimal trait values of each condition. In addition, we built unipartite networks to explore trait–trait relationships to assess functional coordination among organs. Lower soil pH and less soil water retention potential increased the proportion of smaller leaves, tissue dry mass and tissue density, resulting in more resource-conservative plant species and communities. Trait functions were tightly correlated among organs at both the plot and the individual level, indicating a trend of phenotypic integration. Architectural traits were central to coordination, suggesting their key role in integrating sap transport, mechanical support and leaf display. We conclude that the trait adjustments in response to soil parameters are important for the coexistence of a large number of species in the campo rupestre ecosystem.

Modern Climate and Soil Properties Explain Functional Structure Better Than Phylogenetic Structure of Plant Communities in Northern China

Mechanisms of plant community assembly at geographical scale are an interesting topic in ecology and biogeography, which are of great significance for the understanding of species coexistence and biodiversity conservation. But so far, only a few studies have simultaneously assessed the relative roles of multiple-scale factors in shaping phylogenetic and functional structure of plant communities at a macroecological scale. In this study, we linked modern climate, glacial-interglacial climate change and soil properties with phylogenetic and functional structure of shrub and herbaceous plant communities in Inner Mongolia, China, an arid and semi-arid region. Our results showed that functional structure of plant communities was more associated with modern climate and soil properties than phylogenetic structure, especially for the soil properties. Modern precipitation was found in all the combinations of variables that were most closely related to the community structure in this arid and semi-arid region. These findings suggest that phylogenetic and functional structure of biotic communities may be affected by processes at divergent spatial-temporal scales. That is, functional structure is better linked with modern and local factors, while phylogenetic structure is more associated with historical and 2 regional processes. This study highlights the importance of the associations between different biodiversity dimensions and divergent drivers.

Plant functional traits reveal strong effects of anoxia and nutrient limitation on species pool filtering in a riverine rich fen system

ABSTRACTBackground: In fens, plant species composition is predominantly controlled by two environmental factors: root anoxia and low nutrient availability.Aims: We asked how these filters were reflected to the functional structure of plant communities in natural and drained rich fens.Methods: We analysed traits related to species response to anoxia and nutrient availability, using single-trait and multi-trait approaches in fens of a river valley (Biebrza, Poland). We evaluated results concerning multi-trait indices using a null model consisting of simulated communities.Results: Mycorrhizal status and specific leaf area (SLA) clearly distinguished the communities with different levels of anoxia and nutrient deficiency. Mean values, ranges and variance of canopy height showed the differences in the distribution of plant heights among analysed communities.Conclusions: Functional traits distinguish plant communities of the most endangered mesotrophic fens from eutrophic and drained fens. We highlight the role of nutrient and oxygen deficiency in the assembly of fen vegetation and show the impact of the altered environment on the composition of communities in degraded habitats. We demonstrate that single-trait indices are suitable for identifying of environmental filtering in different types of fen communities. We suggest that caution is justified when using multi-trait indices to assess vegetation patterns.

Soil Abiotic Properties and Plant Functional Traits Mediate Associations Between Soil Microbial and Plant Communities During a Secondary Forest Succession on the Loess Plateau.

In the context of secondary forest succession, aboveground-belowground interactions are known to affect the dynamics and functional structure of plant communities. However, the links between soil microbial communities, soil abiotic properties, plant functional traits in the case of semi-arid and arid ecosystems, are unclear. In this study, we investigated the changes in soil microbial species diversity and community composition, and the corresponding effects of soil abiotic properties and plant functional traits, during a ≥150-year secondary forest succession on the Loess Plateau, which represents a typical semi-arid ecosystem in China. Plant community fragments were assigned to six successional stages: 1–4, 4–8, 8–15, 15–50, 50–100, and 100–150 years after abandonment. Bacterial and fungal communities were analyzed by high-throughput sequencing of the V4 hypervariable region of the 16S rRNA gene and the internal transcribed spacer (ITS2) region of the rRNA operon, respectively. A multivariate variation-partitioning approach was used to estimate the contributions of soil properties and plant traits to the observed microbial community composition. We found considerable differences in bacterial and fungal community compositions between the early (S1–S3) and later (S4–S6) successional stages. In total, 18 and 12 unique families were, respectively, obtained for bacteria and fungi, as indicators of microbial community succession across the six stages. Bacterial alpha diversity was positively correlated with plant species alpha diversity, while fungal diversity was negatively correlated with plant species diversity. Certain fungal and bacterial taxa appeared to be associated with the occurrence of dominant plant species at different successional stages. Soil properties (pH, total N, total C, NH4-N, NO3-N, and PO4-P concentrations) and plant traits explained 63.80% and 56.68% of total variance in bacterial and fungal community compositions, respectively. These results indicate that soil microbial communities are coupled with plant communities via the mediation of microbial species diversity and community composition over a long-term secondary forest succession in the semi-arid ecosystem. The bacterial and fungal communities show distinct patterns in response to plant community succession, according to both soil abiotic properties and plant functional traits.

Different trends in phylogenetic and functional structure of plant communities along an elevation gradient

AbstractThe study of diversity gradients due to elevation dates back to the foundation of biogeography and ecology. Although elevation‐driven patterns of plant diversity have been reported for centuries, uncertainty still exists about the assembly rules that drive these patterns. In this study, we revealed the causal factor of community assemblies for the diversity of tree and herb species along an elevation. To this end, we applied an integrated method using both functional traits and phylogeny, called the mean pairwise functional‐phylogenetic distance, to understand the assembly rules for woody and herbaceous species communities along an elevation gradient. At higher elevation sites, woody and herbaceous communities were comprised of species having similar traits. The phylogenetic trends for woody species were consistent with the functional trends; closely related species co‐occurred more frequently than expected at higher elevations. Phylogenetic trends for herb species were opposite to the functional trends; species with similar traits but having a random phylogenetic distribution co‐occurred at higher elevations. We suggest that the community assembly rules for woody and herb species vary with elevation; and functional constraints due to environmental filtering at higher elevation act as assembly rules along gradients in both woody and herbaceous communities, even though their phylogenetic backgrounds differ.

Effects of alien species Robinia pseudoacacia on plant community functional structure in hilly-gully region of Loess Plateau, China.

To investigate the effects of the introduction of Robinia pseudoacacia on the functional structure of plant communities, we selected paired-plots of R. pseudoacacia communities and native plant communities across different vegetation zones, i.e., steppe zone, forest-steppe zone, forest zone in hilly-gully region of Loess Plateau, China. We measured several functional characteristics and then compared the functional structures of R. pseudoacacia and native plant communities in different vegetation zones. The results showed that the variation of the functional traits across different vegetation zones were consistent in R. pseudoacacia community and native plant community, including leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, specific leaf area, and leaf tissue density. The leaf carbon concentration, leaf nitrogen concentration, and specific leaf area of the R. pseudoacacia community were significantly higher than those of the native plant community. The trend of change that the functional diversity indices, i.e., FRic, FEve, FDiv, FDis, Rao of the R. pseudoacacia community and the native plant community with vegetation zones were different. The introduction of R. pseudoacacia enhanced the plant community functional diversity in the forest zone but reduced community functional diversity in the steppe zone.

The antioxidation-related functional structure of plant communities: Understanding antioxidation at the plant community level

In the case of ecological stresses, reactive oxygen species (ROS) can be overproduced in plant cells, leading to lipid peroxidation that causes damage or death to cells. To prevent damage, plant tissues contain several antioxidants that scavenge ROS. However, antioxidation at the plant community level still remains unknown and may provide an insight into ecosystem functioning regarding stress resistance. To understand the property, we established the antioxidation-related functional structure based on the concept of the functional structure and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), reduced glutathione (GSH), carotenoid (Car) and proline (Pro) and the relative abundance of component species in natural plant communities on the Chinese hilly-gullied Loess Plateau. An information-theoretic (I-T) approach was used to infer the effects of antioxidation-related functional components and stresses that we investigated on lipid peroxidation at the plant community level quantified by the community-weighted mean of malondialdehyde (MDA). We found that the induction of lipid peroxidation was more closely associated with a soil available nitrogen deficiency than it was with an available phosphorus deficiency. However, the inducing effect of soil available nitrogen was finite. The prevention of lipid peroxidation was more closely associated with the community-weighted means of GSH and Pro (CWM GSH and CWM Pro) than it was with other antioxidation-related functional components. However, the efficiency of CWM Pro was quite low; CWM GSH exhibited inefficiency. In addition, antioxidation-related functional components were affected by neither soil available nitrogen nor available phosphorus. Furthermore, by estimating the relative weights of the antioxidants and considering the feasibility of community assemblages, we proposed that Stipa grandis, Leymus secalinus, Stipa bungeana, Phragmites australis, Potentilla tanacetifolia, Artemisia gmelinii, Artemisia scoparia, Heteropappus altaicus and Syringa oblata could be utilized in community assemblages to achieve an antioxidation-functional target. Additionally, appropriate phosphorus application for A. gmelinii and H. altaicus might contribute to maintaining their antioxidation.

Grazing‐induced shifts in community functional composition and soil nutrient availability in Tibetan alpine meadows

Summary The functional structure of plant communities can be altered by grazing through two main mechanisms: species turnover (i.e. changes in species occurrence and relative abundance) and intraspecific trait variability (ITV), which is driven by phenotypic responses of individual plants and shifts in the relative abundance of genotypic variants within species. Studies of grassland ecosystem function under grazing often focus on community changes induced by species turnover, which ignores the effects of ITV on biomass productivity, soil carbon or nutrient availability. By quantifying the relative contribution of both effects on shifts in community‐wide traits, we highlight the role of ITV in community functional response to grazing and its implications for ecosystem function in Tibetan alpine meadows. We measured three chemical traits (LC: leaf carbon, LN: leaf nitrogen and LP: leaf phosphorus concentrations) and two morphological traits (SLA: specific leaf area, LDMC: leaf dry matter content) that are critical components of plant production and forage quality in grazed and ungrazed plots. Using variance decomposition of community‐weighted means (CWM) for these foliar traits, we distinguished the relative importance of ITV vs. change in species occurrence and abundance in response to grazing and the associated changes in soil carbon and nutrient availability. The CWM for foliar nutrients and SLACWM increased in response to grazing together with decreases in soil carbon and nutrient stores, especially LPCWM enrichment and loss of available soil P. The LPCWM was strongly negatively correlated with LDMCCWM, which was significantly higher in ungrazed plots. These community‐wide trait responses to grazing were generally best captured by ITV and not changes in species occurrence and abundance, although ITV was consistently correlated with species turnover for all traits. Synthesis and applications. In response to continuous grazing, plants in Tibetan alpine meadows increase specific leaf area and foliar nutrients but tend to have lower leaf dry matter content, a response consistent with faster growth and regrowth under grazing. This intraspecific trait variability response drives a shift in community function from conservative, slow‐growing resource use in ungrazed meadows to exploitative resource use under grazing. This community‐wide functional response enhances forage quality, in turn favouring the secondary productivity of small herbivorous mammal communities, but also contributes to accelerated depletion of soil available phosphorus. We discuss the implications of these results for biodiversity conservation, ecosystem function and rangeland sustainability in the Qinghai–Tibetan Plateau, especially with regard to managing grazing rotation to strike a balance between favouring secondary productivity of domesticated stock vs. small herbivorous mammals.

Functional Traits and Plasticity of Plants in Ecological Research and Education

Abstract Plant functional traits are any morphological, physiological and phenological features, which indirectly affect plant fitness through their three basic components of plant individual performance - growth, reproduction and survival. These features represent also a keystone for plant functional groups, which are similar in three aspects - function on the level of organism, response to environmental factors and effect on ecosystems. Functional approach in ecology and vegetation study enables to evaluate plant communities on the base of species function in a community, and to relate functional structure of plant communities to particular environmental gradients. Species plasticity has many aspects that mirror species adaptations to the environmental conditions and which then also translate into functional structuring of plant communities. This approach is thus a novel and exciting mode how to carry on plant ecology, both in research and education at universities.

Partitioning phylogenetic and functional diversity into alpha and beta components along an environmental gradient in aMediterranean rangeland

AbstractQuestionsTo what extent is the functional structure of plant communities captured by phylogenetic structure? Are some functional dimensions better represented by phylogenetic relationships? In an empirical study, we propose to test the congruence between phylogenetic and functional structure at the alpha and the beta scale along an environmental gradient.LocationCausse duLarzac, southernFrance.MethodsWe measured species abundances and eight key functional traits in 12 plant communities distributed along a gradient of soil depth and resource availability in aMediterranean rangeland. A phylogenetic super‐tree of the species was assembled, and after quantifying the degree of phylogenetic signal present in each trait, we quantified taxonomic (TD), phylogenetic (PD) and functional (FD) diversity both within (alpha scale) and among (beta scale) communities, taking species abundances into account. We tested for trends in diversity along the environmental gradient, and looked for congruence among different facets of diversity, both at the alpha and the beta scale.ResultsWe found a significant phylogenetic signal for seven out of eight traits. However, when accounting for trends in taxonomic diversity (i.e. richness and evenness),PDdid not capture the strong functional structure observed within and among the communities. At the alpha scale, we found an overall pattern of phylogenetic convergence of abundant species, which did not reflect the observed functional divergence. At the beta scale, despite some congruence between betaPDand betaFDfor three individual traits, phylogenetic dissimilarities did not capture the overall environmental and functional sorting of species according to habitats.ConclusionsWe show that even when traits display a significant phylogenetic signal,PDdoes not capture the complex functional structure of communities in response to environmental gradients. Nevertheless, results suggest that phylogenetic relationships may partially capture differences in the beta niche of species and provide additional insights on assembly processes not captured by the set of measured functional traits. Only by accounting for patterns in taxonomic diversity were we able to disentangle the functional and evolutionary determinants of species assembly along the gradient.

Hierarchical effects of environmental filters on the functional structure of plant communities: a case study in the French Alps

Understanding the influence of the environment on the functional structure of ecological communities is essential to predict the response of biodiversity to global change drivers. Ecological theory suggests that multiple environmental factors shape local species assemblages by progressively filtering species from the regional species pool to local communities. These successive filters should influence the various components of community functional structure in different ways. In this paper, we tested the relative influence of multiple environmental filters on various metrics of plant functional trait structure (i.e. ‘community weighted mean trait’ and components of functional trait diversity, i.e. functional richness, evenness and divergence) in 82 vegetation plots in the Guisane Valley, French Alps. For the 211 sampled species we measured traits known to capture key aspects of ecological strategies amongst vascular plant species, i.e. leaf traits, plant height and seed mass (LHS). A comprehensive information theory framework, together with null model based resampling techniques, was used to test the various environmental effects. Particular community components of functional structure responded differently to various environmental gradients, especially concerning the spatial scale at which the environmental factors seem to operate. Environmental factors acting at a large spatial scale (e.g. temperature) were found to predominantly shape community weighted mean trait values, while fine‐scale factors (topography and soil characteristics) mostly influenced functional diversity and the distribution of trait values among the dominant species. Our results emphasize the hierarchical nature of ecological forces shaping local species assemblage: large‐scale environmental filters having a primary effect, i.e. selecting the pool of species adapted to a site, and then filters at finer scales determining species abundances and local species coexistence. This suggests that different components of functional community structure will respond differently to environmental change, so that predicting plant community responses will require a hierarchical multi‐facet approach.