scholarly journals Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

2015 ◽  
Author(s):  
Jonathan S Lefcheck ◽  
J. Emmett Duffy
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
A Priori ◽  
Functional Trait ◽  
Trophic Levels ◽  
Equation Modeling ◽  
Experimental Investigations

The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori altered functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within multiple levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on general linear mixed effects models. Combining inferences from 8 traits into a single multivariate index increased prediction accuracy of these models relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context.

scholarly journals Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

2015 ◽  
Author(s):  
Jonathan S Lefcheck ◽  
J. Emmett Duffy
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
A Priori ◽  
Functional Trait ◽  
Trophic Levels ◽  
Equation Modeling ◽  
Experimental Investigations

The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori altered functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within multiple levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on general linear mixed effects models. Combining inferences from 8 traits into a single multivariate index increased prediction accuracy of these models relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context.

scholarly journals Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

2015 ◽  
Author(s):  
Jonathan S Lefcheck ◽  
J. Emmett Duffy
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
A Priori ◽  
Functional Trait ◽  
Trophic Levels ◽  
Equation Modeling ◽  
Experimental Investigations

The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori manipulated functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within two levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on general linear mixed effects models. Combining inferences from 8 traits into a single multivariate index increased prediction accuracy of these properties relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within and between trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context.

scholarly journals Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

2014 ◽  
Author(s):  
Jonathan S Lefcheck ◽  
J. Emmett Duffy
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Functional Diversity ◽  
Functional Traits ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
Trophic Levels ◽  
Ecosystem Functions ◽  
Equation Modeling ◽  
Experimental Investigations

The use of functional traits to explain biodiversity effects on ecosystem functioning has attracted intense recent interest, yet very few a priori manipulations of functional diversity have been attempted to date, especially from a food web perspective. Here, we simultaneously manipulated multiple functional traits of estuarine grazers and predators within multiple levels of species richness to test whether species richness or functional diversity is a better predictor of ecosystem functioning in multitrophic estuarine food webs. Community functional diversity better predicted the majority of ecosystem responses based on results from generalized linear mixed effects models. Structural equation modeling revealed that this outcome was independently attributable to functional diversity of both trophic levels, with stronger effects observed for predators. Functional complementarity was also important, as species with different combinations of traits influenced different ecosystem functions. Our study is the first to extend experimental investigations of functional diversity to a multilevel food web, and demonstrates that functional diversity is more effective than species richness in predicting ecosystem functioning in a food web context.

scholarly journals The meaning of functional trait composition of food webs for ecosystem functioning

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150268 ◽  
Author(s):  
Dominique Gravel ◽  
Camille Albouy ◽  
Wilfried Thuiller
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Functional Trait ◽  
Plant Ecology ◽  
Functional Composition ◽  
Top Down ◽  
Bottom Up ◽  
Functional Trait Diversity

There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists.

scholarly journals Biodiversity–ecosystem functioning relationships in fish communities: biomass is related to evenness and the environment, not to species richness

2019 ◽  
Vol 286 (1906) ◽  
pp. 20191189 ◽  
Author(s):  
Aurore Maureaud ◽  
Dorothee Hodapp ◽  
P. Daniël van Denderen ◽  
Helmut Hillebrand ◽  
Henrik Gislason ◽  
...  
Keyword(s):  
Species Richness ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
Fish Assemblages ◽  
Current Knowledge ◽  
Marine Ecosystem ◽  
Experimental Studies ◽  
Fish Communities ◽  
Trophic Levels ◽  
Fish Biomass

The relationship between biodiversity and ecosystem functioning (BEF) is a topic of considerable interest to scientists and managers because a better understanding of its underlying mechanisms may help us mitigate the consequences of biodiversity loss on ecosystems. Our current knowledge of BEF relies heavily on theoretical and experimental studies, typically conducted on a narrow range of spatio-temporal scales, environmental conditions, and trophic levels. Hence, whether a relationship holds in the natural environment is poorly understood, especially in exploited marine ecosystems. Using large-scale observations of marine fish communities, we applied a structural equation modelling framework to investigate the existence and significance of BEF relationships across northwestern European seas. We find that ecosystem functioning, here represented by spatial patterns in total fish biomass, is unrelated to species richness—the most commonly used diversity metric in BEF studies. Instead, community evenness, differences in species composition, and abiotic variables are significant drivers. In particular, we find that high fish biomass is associated with fish assemblages dominated by a few generalist species of a high trophic level, who are able to exploit both the benthic and pelagic energy pathway. Our study provides a better understanding of the mechanisms behind marine ecosystem functioning and allows for the integration of biodiversity into management considerations.

scholarly journals Top predators govern multitrophic diversity effects in tritrophic food webs

2020 ◽  
Author(s):  
Ruben Ceulemans ◽  
Christian Guill ◽  
Ursula Gaedke
Keyword(s):  
Temporal Variation ◽  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Trophic Level ◽  
Ecosystem Functioning ◽  
Initial Conditions ◽  
Trophic Levels ◽  
Natural Food ◽  
Model Parameters

AbstractIt is well known that functional diversity strongly affects ecosystem functioning. However, even in rather simple model communities consisting of only two or, at best, three trophic levels, the relationship between multitrophic functional diversity and ecosystem functioning appears difficult to generalize, due to its high contextuality. In this study, we considered several differently structured tritrophic food webs, in which the amount of functional diversity was varied independently on each trophic level. To achieve generalizable results, largely independent of parametrization, we examined the outcomes of 128, 000 parameter combinations sampled from ecologically plausible intervals, with each tested for 200 randomly sampled initial conditions. Analysis of our data was done by training a Random Forest model. This method enables the identification of complex patterns in the data through partial dependence graphs, and the comparison of the relative influence of model parameters, including the degree of diversity, on food web properties. We found that bottom-up and top-down effects cascade simultaneously throughout the food web, intimately linking the effects of functional diversity of any trophic level to the amount of diversity of other trophic levels, which may explain the difficulty in unifying results from previous studies. Strikingly, only with high diversity throughout the whole food web, different interactions synergize to ensure efficient exploitation of the available nutrients and efficient biomass transfer, ultimately leading to a high biomass and production on the top level. The temporal variation of biomass showed a more complex pattern with increasing multitrophic diversity: while the system initially became less variable, eventually the temporal variation rose again due to the increasingly complex dynamical patterns. Importantly, top predator diversity and food web parameters affecting the top trophic level were of highest importance to determine the biomass and temporal variability of any trophic level. Overall, our study reveals that the mechanisms by which diversity influences ecosystem functioning are affected by every part of the food web, hampering the extrapolation of insights from simple monotrophic or bitrophic systems to complex natural food webs.

Examination of customer-centric measures among different types of customers in the context of major Canadian ski resort

2018 ◽  
Vol 30 (2) ◽  
pp. 438-459
Author(s):  
Matti J. Haverila ◽  
Kai Christian Haverila
Keyword(s):  
Customer Satisfaction ◽  
Structural Equation ◽  
A Priori ◽  
Equation Modeling ◽  
Marketing Practice ◽  
Content Type ◽  
Ski Resort ◽  
Different Types ◽  
Managerial Implications ◽  
Satisfaction Model

Purpose Customer-centric measures such as customer satisfaction and repurchase intent are important indicators of performance. The purpose of this paper is to examine what is the strength and significance of the path coefficients in a customer satisfaction model consisting of various customer-centric measures for different types of ski resort customer (i.e. day, weekend and ski holiday visitors as well as season pass holders) in a ski resort in Canada. Design/methodology/approach The results were analyzed using the partial least squares structural equation modeling approach for the four different types ski resort visitors. Findings There appeared to differences in the strength and significance in the customer satisfaction model relationships for the four types of ski resort visitors indicating that the a priori managerial classification of the ski resort visitors is warranted. Originality/value The research pinpoints differences in the strength and significance in the relationships between customer-centric measures for four different types ski resort visitors, i.e. day, weekend and ski holiday visitors as well as season pass holders, which have significant managerial implications for the marketing practice of the ski resort.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

scholarly journals Aboveground impacts of a belowground invader: how invasive earthworms alter aboveground arthropod communities in a northern North American forest

2021 ◽  
Author(s):  
Malte Jochum ◽  
Lise Thouvenot ◽  
Olga Ferlian ◽  
Romy Zeiss ◽  
Bernhard Klarner ◽  
...  
Keyword(s):  
Species Richness ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Trophic Levels ◽  
Arthropod Community ◽  
Arthropod Communities ◽  
Earthworm Invasion ◽  
Invasive Earthworms ◽  
Invasion Impacts ◽  
Arthropod Abundance

AbstractDeclining arthropod communities have recently gained a lot of attention with climate and land-use change among the most-frequently discussed drivers. Here, we focus on a seemingly underrepresented driver of arthropod-community decline: biological invasions. For ∼12,000 years, earthworms have been absent from wide parts of northern North America, but they have been re-introduced with dramatic consequences. Most studies investigating earthworm-invasion impacts focus on the belowground world, resulting in limited knowledge on aboveground-community changes. We present observational data on earthworm, plant, and aboveground-arthropod communities in 60 plots, distributed across areas with increasing invasion status (low, medium, high) in a Canadian forest. We analyzed how earthworm-invasion status and biomass impact aboveground arthropod community abundance, biomass, and species richness, and how earthworm impacts cascade across trophic levels. We sampled ∼13,000 arthropods, dominated by Hemiptera, Diptera, Araneae, Thysanoptera, and Hymenoptera. Total arthropod abundance, biomass, and species richness declined significantly from areas of low to those with high invasion status with reductions of 61, 27, and 18%, respectively. Structural Equation Models unraveled that earthworms directly and indirectly impact arthropods across trophic levels. We show that earthworm invasion can alter aboveground multitrophic arthropod communities and suggest that belowground invasions can be important drivers of aboveground-arthropod decline.

scholarly journals Context-dependency in biodiversity-multifunctionality relationships is driven by nitrogen availability and plant functional composition

2020 ◽  
Author(s):  
Noémie A. Pichon ◽  
Seraina L. Cappelli ◽  
Santiago Soliveres ◽  
Tosca Mannall ◽  
Thu Zar Nwe ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Functional Diversity ◽  
Experimental Studies ◽  
Plant Species Richness ◽  
Trophic Levels ◽  
Context Dependency ◽  
Composition Gradient ◽  
Nitrogen Enrichment ◽  
Functional Composition

SummaryThe ability of an ecosystem to deliver multiple functions at high levels (multifunctionality) typically increases with biodiversity but there is substantial variation in the strength and direction of biodiversity effects, suggesting context-dependency. However, the drivers of this context dependency have not been identified and understood in comparative meta-analyses or experimental studies. To determine how different factors modulate the effect of diversity on multifunctionality, we conducted a large grassland experiment with 216 communities, crossing a manipulation of plant species richness (1-20 species) with manipulations of resource availability (nitrogen enrichment), plant functional composition (gradient in mean specific leaf area [SLA] to manipulate abundances of fast vs. slow species), plant functional diversity (variance in SLA) and enemy abundance (fungal pathogen removal). We measured ten functions, above and belowground, related to productivity, nutrient cycling and energy transfer between trophic levels, and calculated multifunctionality. Plant species richness and functional diversity both increased multifunctionality, but their effects were context dependent. Species richness increased multifunctionality, but only when communities were assembled with fast growing (high SLA) species. This was because slow species were more redundant in their functional effects, whereas fast species tended to promote different functions. Functional diversity also increased multifunctionality but this effect was dampened by nitrogen enrichment, however, unfertilised, functionally diverse communities still delivered more functions than low diversity, fertilised communities. Our study suggests that a shift towards exploitative communities will not only alter ecosystem functioning but also the strength of biodiversity-functioning relationships, which highlights the potentially complex effects of global change on multifunctionality.

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