Contrasting effects of plant inter‐ and intraspecific variation on community‐level trait measures along an environmental gradient
TL;DR: The strength and direction of inter- and intraspecific plant community trait responses along a 900 m elevation gradient spanning alpine and subalpine plant communities in southern New Zealand are quantified to reveal highly complex plastic responses of plants to environmental changes, and highlight the need for greater consideration of the role that intrapecific variation plays in community-level processes.
Abstract: Summary 1. Despite widespread focus on interspecific variation in trait-based ecology, there is growing evidence that intraspecific trait variability can play a fundamental role in plant community responses to environmental change and community assembly. 2. Here, we quantify the strength and direction of inter- and intraspecific plant community trait responses along a 900 m elevation gradient spanning alpine and subalpine plant communities in southern New Zealand. We measured five commonly used leaf traits (i.e. dry matter content, N and P concentrations, leaf area and specific leaf area) on all 31 dominant and subordinate species recorded along the gradient, and examined their species-specific and community-level responses to elevation using both abundance-weighted and nonweighted averages of trait values. 3. By decomposing the variance of community-level measures of these traits across the gradient, we showed that the contribution of interspecific variation to the response of plant assemblages to elevation was stronger than that of intraspecific variation, for all traits except specific leaf area. Further, the relative contributions of interspecific effects were greater when abundance-weighted rather than nonweighted measures were used. We also observed contrasting intraspecific trait responses to the gradient among species (particularly for leaf N and P concentrations), and found both positive and negative covariation between inter- and intraspecific effects on community-level trait values. 4. The weak community-average trait responses to elevation, as found for specific leaf area (SLA) and leaf N and P concentrations, resulted from strong but opposing responses among vs. within species, which are not typically accounted for in species-based measures of plant community responses. For instance, increasing elevation (and associated factors such as a decrease in soil nutrient availability) favoured the dominance of species with relatively high leaf nutrient concentrations while simultaneously triggering an intraspecific decrease in the leaf nutrient concentrations of these species. 5. The context dependency of positive and negative covariation between inter- and intraspecific trait variability, and the species-specific nature of intraspecific shifts in functional trait values, reveal highly complex plastic responses of plants to environmental changes, and highlights the need for greater consideration of the role that intraspecific variation plays in community-level processes.
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National University of Cordoba1, Max Planck Society2, VU University Amsterdam3, Macquarie University4, University of Grenoble5, University of Lyon6, Industrial University of Santander7, Leipzig University8, University of Oldenburg9, Imperial College London10, University of Montpellier11, Forschungszentrum Jülich12, University of Western Sydney13, University of Minnesota14, University of New South Wales15, Royal Botanic Gardens16, Missouri Botanical Garden17, George Washington University18, Paul Sabatier University19, Smithsonian Tropical Research Institute20, Komarov Botanical Institute21, Institut national de la recherche agronomique22, University of Bordeaux23, Florida International University24, University of Insubria25, University of Milan26, Université de Sherbrooke27, Centro Agronómico Tropical de Investigación y Enseñanza28
TL;DR: Analysis of worldwide variation in six major traits critical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled found that occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs.
Abstract: The authors found that the key elements of plant form and function, analysed at global scale, are largely concentrated into a two-dimensional plane indexed by the size of whole plants and organs on the one hand, and the construction costs for photosynthetic leaf area, on the other.
1,814 citations
TL;DR: The extent of the trait data compiled in TRY is evaluated and emerging patterns of data coverage and representativeness are analyzed to conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements.
Abstract: Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
882 citations
University of Grenoble1, Centre national de la recherche scientifique2, Austral University of Chile3, Queen's University4, Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior5, Universidade Federal do Rio Grande do Sul6, Universidade Federal de Goiás7, State University of Campinas8, Sewanee: The University of the South9, Academy of Sciences of the Czech Republic10, Federal University of Rio Grande do Norte11, Swedish University of Agricultural Sciences12, University of Montpellier13, Institut national de la recherche agronomique14, Tohoku University15, United Nations University16, University of Florida17, Université du Québec à Montréal18, University of Maryland, College Park19, Université de Sherbrooke20, Landcare Research21, Spanish National Research Council22, Lund University23, University of Tokyo24, Algoma University25, Umeå University26, Natural History Museum27
TL;DR: This paper conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits.
Abstract: Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.
653 citations
286 citations
TL;DR: New evidence is reported that intraspecific variability can be a more important driver of the short-term functional response of plant communities following an extreme drought.
Abstract: Climate change is expected to increase the magnitude and the frequency of extreme climatic events such as droughts. Better understanding how plant communities will respond to these droughts is a major challenge. We expect the response to be a shift in functional trait values resulting from both species turnover and intraspecific trait variability, but little research has addressed the relative contribution of both components. We analysed the short-term functional response of subalpine grassland communities to a simulated drought by focusing on four leaf traits (LDMC: leaf dry matter content, SLA: specific leaf area, LNC: leaf nitrogen concentration and LCC: leaf carbon concentration). After evaluating species turnover and intraspecific variability separately, we determined their relative contribution in the community functional response to drought, reflected by changes in community-weighted mean traits. We found significant species turnover and intraspecific variability, as well as significant changes in community-weighted mean for most of the traits. The relative contribution of intraspecific variability to the changes in community mean traits was more important (42-99%) than the relative contribution of species turnover (1-58%). Intraspecific variability either amplified (for LDMC, SLA and LCC) or dampened (for LNC) the community functional response mediated by species turnover. We demonstrated that the small contribution of species turnover to the changes in community mean LDMC and LCC was explained by a lack of covariation between species turnover and interspecific trait differences.Synthesis. These results highlight the need for a better consideration of intraspecific variability to understand and predict the effect of climate change on plant communities. While both species turnover and intraspecific variability can be expected following an extreme drought, we report new evidence that intraspecific variability can be a more important driver of the short-term functional response of plant communities.
238 citations
Cites background or result from "Contrasting effects of plant inter‐..."
...On the other hand, several studies have shown that trait shifts mediated by species turnover play a strong structuring role among communities located along broad environmental gradients (Ackerly & Cornwell 2007; Kichenin et al. 2013)....
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...Opposite contributions of species turnover and intraspecific variability to community mean LNC have been recently observed along an elevation gradient (Kichenin et al. 2013)....
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...This between-species idiosyncratic pattern corroborates previous studies exploring trait–environment relationships (Albert et al. 2010; Kichenin et al. 2013)....
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References
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TL;DR: The nature of crop responses to nutrient stress is reviewed and compares these responses to those of species that have evolved under more natural conditions, particularly in low-nutrient envi ronments.
Abstract: Our understanding of plant mineral nutrition comes largely from studies of herbaceous crops that evolved from ruderal species characteristic of nutri ent-rich disturbed sites (52). With the development of agriculture, these ancestral species were bred for greater productivity and reproductive output at high nutrient levels where there was little selective advantage in efficient nutrient use. This paper briefly reviews the nature of crop responses to nutrient stress and compares these responses to those of species that have evolved under more natural conditions, particularly in low-nutrient envi ronments. I draw primarily upon nutritional studies of nitrogen and phos phorus because these elements most commonly limit plant growth and because their role in controlling plant growth and metabolism is most clearly understood (51). Other more specific aspects of nutritional plant ecology not discussed here include ammonium/nitrate nutrition (79), cal cicole/calcifuge nutrition (51,88), heavy metal tolerance (4), and serpentine ecology (133).
4,176 citations
"Contrasting effects of plant inter‐..." refers background in this paper
...One possibility is the ‘nutrient luxury consumption’ hypothesis (Chapin 1980; van Wijk et al. 2003) that postulates a positive selection for plant species with active nutrient retention strategies in conditions of increasing nutrient stress. Interestingly, across a different gradient of soil N availability, P erez-Ramos et al. (2012)...
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...One possibility is the ‘nutrient luxury consumption’ hypothesis (Chapin 1980; van Wijk et al. 2003) that postulates a positive selection for plant species with active nutrient retention strategies in conditions of increasing nutrient stress....
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TL;DR: It is asserted that community ecology should return to an emphasis on four themes that are tied together by a two-step process: how the fundamental niche is governed by functional traits within the context of abiotic environmental gradients; and how the interaction between traits and fundamental niches maps onto the realized niche in the context a biotic interaction milieu.
Abstract: There is considerable debate about whether community ecology will ever produce general principles. We suggest here that this can be achieved but that community ecology has lost its way by focusing on pairwise species interactions independent of the environment. We assert that community ecology should return to an emphasis on four themes that are tied together by a two-step process: how the fundamental niche is governed by functional traits within the context of abiotic environmental gradients; and how the interaction between traits and fundamental niches maps onto the realized niche in the context of a biotic interaction milieu. We suggest this approach can create a more quantitative and predictive science that can more readily address issues of global change.
3,715 citations
"Contrasting effects of plant inter‐..." refers background in this paper
...unit in trait-based ecology (Reich et al. 1999; Garnier et al. 2001; McGill et al. 2006)....
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...These analyses generally assume that differences in trait values are much larger among than within species (Reich et al. 1999; Garnier et al. 2001; McGill et al. 2006), and therefore that species can be reasonably characterized by their mean trait values....
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TL;DR: This paper provides an international methodological protocol aimed at standardising this research effort, based on consensus among a broad group of scientists in this field, and features a practical handbook with step-by-step recipes, for 28 functional traits recognised as critical for tackling large-scale ecological questions.
Abstract: There is growing recognition that classifying terrestrial plant species on the basis of their function (into 'functional types') rather than their higher taxonomic identity, is a promising way forward for tackling important ecological questions at the scale of ecosystems, landscapes or biomes. These questions include those on vegetation responses to and vegetation effects on, environmental changes (e.g. changes in climate, atmospheric chemistry, land use or other disturbances). There is also growing consensus about a shortlist of plant traits that should underlie such functional plant classifications, because they have strong predictive power of important ecosystem responses to environmental change and/or they themselves have strong impacts on ecosystem processes. The most favoured traits are those that are also relatively easy and inexpensive to measure for large numbers of plant species. Large international research efforts, promoted by the IGBP–GCTE Programme, are underway to screen predominant plant species in various ecosystems and biomes worldwide for such traits. This paper provides an international methodological protocol aimed at standardising this research effort, based on consensus among a broad group of scientists in this field. It features a practical handbook with step-by-step recipes, with relatively brief information about the ecological context, for 28 functional traits recognised as critical for tackling large-scale ecological questions.
3,288 citations
"Contrasting effects of plant inter‐..." refers methods in this paper
...For each species, all leaves were pooled within plots and measured for average leaf area (LA, mm), specific leaf area (SLA, mm mg ) and leaf dry matter content (LDMC, mg g ) following Cornelissen et al. (2003). Leaf nitrogen content (LNC, %) and leaf phosphorus content (LPC, %) were measured on ground homogenized subsamples using Kjeldahl analysis....
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TL;DR: An unambiguous definition of plant trait is given, with a particular emphasis on functional trait, and it is argued that this can be achieved by developing "integration functions" which can be grouped into functional response (community level) and effect (ecosystem level) algorithms.
Abstract: In its simplest definition, a trait is a surrogate of organismal performance, and this meaning of the term has been used by evolutionists for a long time. Over the last three decades, developments in community and ecosystem ecology have forced the concept of trait beyond these original boundaries, and trait-based approaches are now widely used in studies ranging from the level of organisms to that of ecosystems. Despite some attempts to fix the terminology, especially in plant ecology, there is currently a high degree of confusion in the use, not only of the term "trait" itself, but also in the underlying concepts it refers to. We therefore give an unambiguous definition of plant trait, with a particular emphasis on functional trait. A hierarchical perspective is proposed, extending the "performance paradigm" to plant ecology. "Functional traits" are defined as morpho-physiophenological traits which impact fitness indirectly via their effects on growth, reproduction and survival, the three components of individual performance. We finally present an integrative framework explaining how changes in trait values due to environmental variations are translated into organismal performance, and how these changes may influence processes at higher organizational levels. We argue that this can be achieved by developing "integration functions" which can be grouped into functional response (community level) and effect (ecosystem level) algorithms.
3,262 citations
TL;DR: A framework using concepts and results from community ecology, ecosystem ecology and evolutionary biology to provide a linkage between traits associated with the response of plants to environmental factors and traits that determine effects of plants on ecosystem functions is presented.
Abstract: Summary 1. The concept of plant functional type proposes that species can be grouped according to common responses to the environment and/or common effects on ecosystem processes. However, the knowledge of relationships between traits associated with the response of plants to environmental factors such as resources and disturbances (response traits), and traits that determine effects of plants on ecosystem functions (effect traits), such as biogeochemical cycling or propensity to disturbance, remains rudimentary. 2. We present a framework using concepts and results from community ecology, ecosystem ecology and evolutionary biology to provide this linkage. Ecosystem functioning is the end result of the operation of multiple environmental filters in a hierarchy of scales which, by selecting individuals with appropriate responses, result in assemblages with varying trait composition. Functional linkages and trade-offs among traits, each of which relates to one or several processes, determine whether or not filtering by different factors gives a match, and whether ecosystem effects can be easily deduced
2,786 citations