Clonal growth of plants is mainly a result of the vegetative growth of organs hidden beneath the soil surface and producing potentially independent vegetative offspring. Clonal traits are difficult ...to measure due to inaccessibility of the space they inhabit and their morphological diversity. This causes great difficulties with descriptions, standardization of measurements across plant growth forms and, probably, a lack of appropriate questions that should be answered using them. The freely available CLO-PLA database (http://clopla.butbn.cas.cz/) can help to assess the roles of vegetative means of regeneration and spread in plant communities under the effect of various biotic and abiotic filters. It can serve as a source of reference on persistence traits of European temperate flora and, eventually, as a guide for trait sampling in other regions of the world.
The promise of “trait-based” plant ecology is one of generalized prediction across organizational and spatial scales, independent of taxonomy. This promise is a major reason for the increased ...popularity of this approach. Here, we argue that some important foundational assumptions of trait-based ecology have not received sufficient empirical evaluation. We identify three such assumptions and, where possible, suggest methods of improvement: (i) traits are functional to the degree that they determine individual fitness, (ii) intraspecific variation in functional traits can be largely ignored, and (iii) functional traits show general predictive relationships to measurable environmental gradients.
1. The environmental filtering hypothesis predicts that the abiotic environment selects species with similar trait values within communities. Testing this hypothesis along multiple — and interacting ...— gradients of climate and soil variables constitutes a great opportunity to better understand and predict the responses of plant communities to ongoing environmental changes. 2. Based on two key plant traits, maximum plant height and specific leaf area (SLA), we assessed the filtering effects of climate (mean annual temperature and precipitation, precipitation seasonality), soil characteristics (soil pH, sand content and total phosphorus) and all potential interactions on the functional structure and diversity of 124 dryland communities spread over the globe. The functional structure and diversity of dryland communities were quantified using the mean, variance, skewness and kurtosis of plant trait distributions. 3. The models accurately explained the observed variations in functional trait diversity across the 124 communities studied. All models included interactions among factors, i.e. climate-climate (9% of explanatory power), climate-soil (24% of explanatory power) and soil—soil interactions (5% of explanatory power). Precipitation seasonality was the main driver of maximum plant height, and interacted with mean annual temperature and precipitation. Soil pH mediated the filtering effects of climate and sand content on SLA. Our results also revealed that communities characterized by a low variance can also exhibit low kurtosis values, indicating that functionally contrasting species can co-occur even in communities with narrow ranges of trait values. 4. Synthesis. We identified the particular set of conditions under which the environmental filtering hypothesis operates in drylands world-wide. Our findings also indicate that species with functionally contrasting strategies can still co-occur locally, even under prevailing environmental filtering. Interactions between sources of environmental stress should be therefore included in global trait-based studies, as this will help to further anticipate where the effects of environmental filtering will impact plant trait diversity under climate change.
Functional trait differences between species are key drivers of community assembly and ecosystem functioning. Quantifying these differences routinely requires using approaches like the Gower distance ...to combine various types of traits into a multi‐trait dissimilarity.
Without special care, the Gower distance can however produce a multi‐trait dissimilarity with a disproportional contribution of certain traits, particularly categorical traits and bundle of correlated traits reflecting similar ecological functions. These effects persist even after applying multivariate analyses traditionally used to reduce trait dimensionality.
We propose the ‘gawdis’ R function, and corresponding package, to produce multi‐trait dissimilarity with more uniform contributions of different traits, including fuzzy coded ones. The approach is based on minimizing the differences in the correlation between the dissimilarity of each trait, or groups of traits, and the multi‐trait dissimilarity. This is done using either an analytical or a numerical solution, both available in the function.
Properly taking into account the contribution of multiple traits into multi‐trait dissimilarity is key for interpreting the ecological effects of complex species differences. The gawdis r package in CRAN can be further applied to improve equitability in distance‐based measures in other field of research, such as social sciences or marketing surveys, which routinely analyse mixed type data.
gawdis: An R package for multi‐trait diversity‐YouTube
Question: Which functional diversity indices have the power to reveal changes in community assembly processes along abiotic stress gradients? Is their power affected by stochastic processes and ...variations in species richness along stress gradients? Methods: We used a simple community assembly model to explore the power of functional diversity indices across a wide range of ecological contexts. The model assumes that with declining stress the influence of niche complementarity on species fitness increases while that of environmental filtering decreases. We separately incorporated two trait-independent stochastic processes — mass and priority effects — in simulating species occurrences and abundances along a hypothetical stress gradient. We ran simulations where species richness was constant along the gradient, or increased, decreased or varied randomly with declining stress. We compared observed values for two indices of functional richness — total functional dendrogram length (FD) and convex hull volume (FRic) — with a matrix-swap null model (yielding indices SESFD and SESFRic) to remove any trivial effects of species richness. We also compared two indices that measure both functional richness and functional divergence — Rao quadratic entropy (Rao) and functional dispersion (FDis) — with a null model that randomizes abundances across species but within communities. This converts them to pure measures of functional divergence (SESRao and SESFDis). Results: When mass effects operated, only SESRao and SESFDis gave reasonable power, irrespective of how species richness varied along the stress gradient. FD, FRic, Rao and FDis had low power when species richness was constant, and variation in species richness greatly influenced their power. SESFRic and SESFD were unaffected by variation in species richness. When priority effects operated, FRic, SESFRic, Rao and FDis had good power and were unaffected by variation in species richness. Variation in species richness greatly affected FD and SESFD. SESRao and SESFDis had low power in the priority effects model but were unaffected by variation in species richness. Conclusions: Our results demonstrate that a reliable test for changes in assembly processes along stress gradients requires functional diversity indices measuring either functional richness or functional divergence. We recommend using SESFRic as a measure of functional richness and either SESRao or SESFDis (which are very closely related mathematically) as a measure of functional divergence. Used together, these indices of functional richness and functional divergence provide good power to test for increasing niche complementarity with declining stress across a broad range of ecological contexts.
This dataset presents comprehensive and easy-to-use information on 29 functional traits of clonal growth, bud banks, and lifespan of members of the Central European flora. The source data were ...compiled from a number of published sources (see the reference file) and the authors' own observations or studies. In total, 2,909 species are included (2,745 herbs and 164 woody species), out of which 1,532 (i.e., 52.7% of total) are classified as possessing clonal growth organs (1,480, i.e., 53.9%, if woody plants are excluded). This provides a unique, and largely unexplored, set of traits of clonal growth that can be used in studies on comparative plant ecology, plant evolution, community assembly, and ecosystem functioning across the large flora of Central Europe. It can be directly imported into a number of programs and packages that perform trait-based and phylogenetic analyses aimed to answer a variety of open and pressing ecological questions.
Trait probability density (TPD) Carmona, Carlos P.; de Bello, Francesco; Mason, Norman W. H. ...
Ecology,
12/2019, Letnik:
100, Številka:
12
Journal Article
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Functional diversity (FD) has the potential to address many ecological questions, from impacts of global change on biodiversity to ecological restoration. There are several methods estimating the ...different components of FD. However, most of these methods can only be computed at limited spatial scales and cannot account for intraspecific trait variability (ITV), despite its significant contribution to FD. Trait probability density (TPD) functions (which explicitly account for ITV) reflect the probabilistic nature of niches. By doing so, the TPD approach reconciles existing methods for estimating FD within a unifying framework, allowing FD to be partitioned seamlessly across multiple scales (from individuals to species, and from local to global scales), and accounting for ITV. We present methods to estimate TPD functions at different spatial scales and probabilistic implementations of several FD concepts, including the primary components of FD (functional richness, evenness, and divergence), functional redundancy, functional rarity, and solutions to decompose beta FD into nested and unique components. The TPD framework has the potential to unify and expand analyses of functional ecology across scales, capturing the probabilistic and multidimensional nature of FD. The R package TPD (https://CRAN.R-project.org/package=TPD) will allow users to achieve more comparative results across regions and case studies.
Trait based ecology has developed fast in the last decades, aiming to both explain mechanisms of community assembly, and predict patterns in nature, such as the effects of biodiversity shifts on key ...ecosystem processes. This body of work has stimulated the development of several conceptual frameworks and analytical methods, as well as the production of trait databases covering a growing number of taxa and organizational levels (from individuals to guilds). However, this breeding ground of novel concepts and tools currently lacks a general and coherent framework, under which functional traits can help ecologists organize their research aims, and serve as the common currency to unify several scientific disciplines. Specifically, we see a need to bridge the gaps between community ecology, ecosystem ecology, and evolutionary biology, in order to address the most pressing environmental issues of our time. To achieve this integration goal, we define a trait-integration continuum, which reconciles alternative trait definitions and approaches in ecology. This continuum outlines a coherent progression of biological scales, along which traits interact and hierarchically integrate from genetic information, to whole organism fitness-related traits, to trait syndromes and functional groups. Our conceptual scheme proposes that lower-level trait integration is closer to the inference of ecoevolutionary mechanisms determining population and community properties, whereas higher-level trait integration is most suited to the prediction of ecosystem processes. Within these two extremes, trait integration varies on a continuous scale, which relates directly to the inductive-deductive loop that should characterize the scientific method. With our proposed framework, we aim to facilitate scientists in contextualising their research based on the trait-integration levels that matter most to their specific goals. Explicitly acknowledging the existence of a trait-integration continuum is a promising way for framing the appropriate questions, thus obtaining reliable answers and results that are comparable across studies and disciplines.
Global environmental change affects the sustained provision of a wide set of ecosystem services. Although the delivery of ecosystem services is strongly affected by abiotic drivers and direct land ...use effects, it is also modulated by the functional diversity of biological communities (the value, range, and relative abundance of functional traits in a given ecosystem). The focus of this article is on integrating the different possible mechanisms by which functional diversity affects ecosystem properties that are directly relevant to ecosystem services. We propose a systematic way for progressing in understanding how land cover change affects these ecosystem properties through functional diversity modifications. Models on links between ecosystem properties and the local mean, range, and distribution of plant trait values are numerous, but they have been scattered in the literature, with varying degrees of empirical support and varying functional diversity components analyzed. Here we articulate these different components in a single conceptual and methodological framework that allows testing them in combination. We illustrate our approach with examples from the literature and apply the proposed framework to a grassland system in the central French Alps in which functional diversity, by responding to land use change, alters the provision of ecosystem services important to local stakeholders. We claim that our framework contributes to opening a new area of research at the interface of land change science and fundamental ecology.
Summary
Trait‐based approaches are increasingly being used to test mechanisms underlying species assemblages and biotic interactions across a wide range of organisms including terrestrial arthropods ...and to investigate consequences for ecosystem processes. Such an approach relies on the standardized measurement of functional traits that can be applied across taxa and regions. Currently, however, unified methods of trait measurements are lacking for terrestrial arthropods and related macroinvertebrates (terrestrial invertebrates hereafter).
Here, we present a comprehensive review and detailed protocol for a set of 29 traits known to be sensitive to global stressors and to affect ecosystem processes and services. We give recommendations how to measure these traits under standardized conditions across various terrestrial invertebrate taxonomic groups.
We provide considerations and approaches that apply to almost all traits described, such as the selection of species and individuals needed for the measurements, the importance of intraspecific trait variability, how many populations or communities to sample and over which spatial scales.
The approaches outlined here provide a means to improve the reliability and predictive power of functional traits to explain community assembly, species diversity patterns and ecosystem processes and services within and across taxa and trophic levels, allowing comparison of studies and running meta‐analyses across regions and ecosystems.
This handbook is a crucial first step towards standardizing trait methodology across the most studied terrestrial invertebrate groups, and the protocols are aimed to balance general applicability and requirements for special cases or particular taxa. Therefore, we envision this handbook as a common platform to which researchers can further provide methodological input for additional special cases.
A lay summary is available for this article.
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