The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Andrea Rinaldo - One of the best experts on this subject based on the ideXlab platform.
-
covariations in ecological scaling laws fostered by community dynamics
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Silvia Zaoli, Andrea Giometto, Amos Maritan, Andrea RinaldoAbstract:Scaling laws in ecology, intended both as functional relationships among ecologically relevant quantities and the probability distributions that characterize their occurrence, have long attracted the interest of empiricists and theoreticians. Empirical evidence exists of power laws associated with the number of species inhabiting an Ecosystem, their abundances, and traits. Although their functional form appears to be ubiquitous, empirical scaling exponents vary with Ecosystem Type and resource supply rate. The idea that ecological scaling laws are linked has been entertained before, but the full extent of macroecological pattern covariations, the role of the constraints imposed by finite resource supply, and a comprehensive empirical verification are still unexplored. Here, we propose a theoretical scaling framework that predicts the linkages of several macroecological patterns related to species’ abundances and body sizes. We show that such a framework is consistent with the stationary-state statistics of a broad class of resource-limited community dynamics models, regardless of parameterization and model assumptions. We verify predicted theoretical covariations by contrasting empirical data and provide testable hypotheses for yet unexplored patterns. We thus place the observed variability of ecological scaling exponents into a coherent statistical framework where patterns in ecology embed constrained fluctuations.
-
covariations in ecological scaling laws fostered by community dynamics
arXiv: Populations and Evolution, 2017Co-Authors: Silvia Zaoli, Andrea Giometto, Amos Maritan, Andrea RinaldoAbstract:Scaling laws in ecology, intended both as functional relationships among ecologically-relevant quantities and the probability distributions that characterize their occurrence, have long attracted the interest of empiricists and theoreticians. Empirical evidence exists of power laws associated with the number of species inhabiting an Ecosystem, their abundances and traits. Although their functional form appears to be ubiquitous, empirical scaling exponents vary with Ecosystem Type and resource supply rate. The idea that ecological scaling laws are linked had been entertained before, but the full extent of macroecological pattern covariations, the role of the constraints imposed by finite resource supply and a comprehensive empirical verification are still unexplored. Here, we propose a theoretical scaling framework that predicts the linkages of several macroecological patterns related to species' abundances and body sizes. We show that such framework is consistent with the stationary state statistics of a broad class of resource-limited community dynamics models, regardless of parametrization and model assumptions. We verify predicted theoretical covariations by contrasting empirical data and provide testable hypotheses for yet unexplored patterns. We thus place the observed variability of ecological scaling exponents into a coherent statistical framework where patterns in ecology embed constrained fluctuations.
Helmut Hillebrand - One of the best experts on this subject based on the ideXlab platform.
-
effects of experimental warming on biodiversity depend on Ecosystem Type and local species composition
Oikos, 2017Co-Authors: Daniel S Gruner, Matthew E S Bracken, Stella A Berger, Britas Klemens Eriksson, Lars Gamfeldt, Birte Matthiessen, Stefanie Moorthi, Ulrich Sommer, Helmut HillebrandAbstract:Climatic warming is a primary driver of change in Ecosystems worldwide. Here, we synthesize responses of species richness and evenness from 187 experimental warming studies in a quantitative meta-analysis. We asked 1) whether effects of warming on diversity were detectable and consistent across terrestrial, freshwater and marine Ecosystems, 2) if effects on diversity correlated with intensity, duration, and experimental unit size of temperature change manipulations, and 3) whether these experimental effects on diversity interacted with Ecosystem Types. Using multilevel mixed linear models and model averaging, we also tested the relative importance of variables that described uncontrolled environmental variation and attributes of experimental units. Overall, experimental warming reduced richness across Ecosystems (mean log-response ratio = –0.091, 95% bootstrapped CI: –0.13, –0.05) representing an 8.9% decline relative to ambient temperature treatments. Richness did not change in response to warming in freshwater systems, but was more strongly negative in terrestrial (–11.8%) and marine (–10.5%) experiments. In contrast, warming impacts on evenness were neutral overall and in aquatic systems, but weakly negative on land (7.6%). Intensity and duration of experimental warming did not explain variation in diversity responses, but negative effects on richness were stronger in smaller experimental units, particularly in marine systems. Model-averaged parameter estimation confirmed these main effects while accounting for variation in latitude, ambient temperature at the sites of manipulations, venue (field versus lab), community trophic Type, and whether experiments were open or closed to colonization. These analyses synthesize extensive experimental evidence showing declines in local richness with increased temperature, particularly in terrestrial and marine communities. However, the more variable effects of warming on evenness were better explained by the random effect of site identity, suggesting that effects on species’ relative abundances were contingent on local species composition.
-
the relationship between species richness and evenness a meta analysis of studies across aquatic Ecosystems
Oecologia, 2012Co-Authors: Janne Soininen, Sophia I Passy, Helmut HillebrandAbstract:Biological diversity comprises both species richness, i.e., the number of species in a community, and evenness, measuring how similar species are in their abundances. The relationship between species richness and evenness (RRE) across communities remains, however, a controversial issue in ecology because no consistent pattern has been reported. We conducted a systematic meta-review of RRE in aquatic Ecosystems along regional to continental gradients and across trophic groups, differing in body size by 13 orders of magnitude. Hypotheses that RRE responded to latitudinal and scale variability across trophic groups were tested by regression analyses. Significant correlations of species richness and evenness only existed in 71 out of 229 datasets. Among the RRE, 89 were negative and 140 were positive. RRE did not vary with latitude but showed a positive response to scale. In a meta-analysis with Ecosystem Type as a single explaining variable, RRE did not vary among Ecosystem Types, i.e. between marine and freshwater. Finally, autotrophs had more positive RRE than heterotrophs. The weak RRE in many aquatic datasets suggests that richness and evenness often reflect independent components of biodiversity, highlighting that richness alone may be an incomplete surrogate for biodiversity. Our results further elucidate that RRE is driven by organismal and environmental properties, both of which must be considered to gain a deeper understanding of large-scale patterns of biodiversity.
-
consumer versus resource control of producer diversity depends on Ecosystem Type and producer community structure
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Helmut Hillebrand, Elizabeth T Borer, Daniel S Gruner, Matthew E S Bracken, Elsa E Cleland, James J Elser, Stanley W Harpole, Jacqueline T Ngai, Eric W SeabloomAbstract:Consumer and resource control of diversity in plant communities have long been treated as alternative hypotheses. However, experimental and theoretical evidence suggests that herbivores and nutrient resources interactively regulate the number and relative abundance of coexisting plant species. Experiments have yielded divergent and often contradictory responses within and among Ecosystems, and no effort has to date reconciled this empirical variation within a general framework. Using data from 274 experiments from marine, freshwater, and terrestrial Ecosystems, we present a cross-system analysis of producer diversity responses to local manipulations of resource supply and/or herbivory. Effects of herbivory and fertilization on producer richness differed substantially between systems: (i) herbivores reduced species richness in freshwater but tended to increase richness in terrestrial systems; (ii) fertilization increased richness in freshwater systems but reduced richness on land. Fertilization consistently reduced evenness, whereas herbivores increased evenness only in marine and terrestrial Ecosystems. Producer community evenness and Ecosystem productivity mediated fertilization and herbivore effects on diversity across Ecosystems. Herbivores increased producer richness in more productive habitats and in producer assemblages with low evenness. These same assemblages also showed the strongest reduction in richness with fertilization, whereas fertilization increased (and herbivory decreased) richness in producer assemblages with high evenness. Our study indicates that system productivity and producer evenness determine the direction and magnitude of top-down and bottom-up control of diversity and may reconcile divergent empirical results within and among Ecosystems.
Per-arne Amundsen - One of the best experts on this subject based on the ideXlab platform.
-
Ecosystem Type shapes trophic position and omnivory in fishes
Fish and Fisheries, 2018Co-Authors: Javier Sánchez-hernández, Per-arne AmundsenAbstract:The identification of patterns in ecological characteristics of organisms is a central challenge in macroecology with a growing research interest. The goal of this study was to establish whether patterns in trophic ecology (trophic position and omnivory) of fishes can be extended to an Ecosystem dimension (freshwater vs. marine environments), based on the premise that differences in environmental and ecological conditions of aquatic Ecosystems have a large influence on the feeding ecology of fishes. To elucidate any relationship between trophic ecology and Ecosystem Type, we compiled a database using a global data set for fishes (http://www.fishbase.org). The database included 5,426 species distributed in 53 orders based on three common feeding strategies (herbivory, filter‐feeding and predatory). Trophic position and omnivory increased from freshwater to marine Ecosystems in filter‐feeding and predatory species. In herbivore species in contrast, omnivory decreased, whereas no statistically significant trends were found for trophic position, which may reflect a similar diet specialization on primary producers regardless of Ecosystem Type. These findings suggest that Ecosystem Type has a marked effect on trophic position and omnivory in fishes, but the impact depends on the Type of feeding strategy. Prey availability, inherent feeding traits linked to the phylogenetic relatedness of species, ontogenetic effects, spatial variability (habitat‐related factors) and body size are considered as responsible factors for the observed patterns. Our findings demonstrate consistent patterns in trophic characteristics of organisms linked to Ecosystem Type and underline the usefulness of fishes as model organisms to test macroecology hypotheses.
Andrea Giometto - One of the best experts on this subject based on the ideXlab platform.
-
covariations in ecological scaling laws fostered by community dynamics
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Silvia Zaoli, Andrea Giometto, Amos Maritan, Andrea RinaldoAbstract:Scaling laws in ecology, intended both as functional relationships among ecologically relevant quantities and the probability distributions that characterize their occurrence, have long attracted the interest of empiricists and theoreticians. Empirical evidence exists of power laws associated with the number of species inhabiting an Ecosystem, their abundances, and traits. Although their functional form appears to be ubiquitous, empirical scaling exponents vary with Ecosystem Type and resource supply rate. The idea that ecological scaling laws are linked has been entertained before, but the full extent of macroecological pattern covariations, the role of the constraints imposed by finite resource supply, and a comprehensive empirical verification are still unexplored. Here, we propose a theoretical scaling framework that predicts the linkages of several macroecological patterns related to species’ abundances and body sizes. We show that such a framework is consistent with the stationary-state statistics of a broad class of resource-limited community dynamics models, regardless of parameterization and model assumptions. We verify predicted theoretical covariations by contrasting empirical data and provide testable hypotheses for yet unexplored patterns. We thus place the observed variability of ecological scaling exponents into a coherent statistical framework where patterns in ecology embed constrained fluctuations.
-
covariations in ecological scaling laws fostered by community dynamics
arXiv: Populations and Evolution, 2017Co-Authors: Silvia Zaoli, Andrea Giometto, Amos Maritan, Andrea RinaldoAbstract:Scaling laws in ecology, intended both as functional relationships among ecologically-relevant quantities and the probability distributions that characterize their occurrence, have long attracted the interest of empiricists and theoreticians. Empirical evidence exists of power laws associated with the number of species inhabiting an Ecosystem, their abundances and traits. Although their functional form appears to be ubiquitous, empirical scaling exponents vary with Ecosystem Type and resource supply rate. The idea that ecological scaling laws are linked had been entertained before, but the full extent of macroecological pattern covariations, the role of the constraints imposed by finite resource supply and a comprehensive empirical verification are still unexplored. Here, we propose a theoretical scaling framework that predicts the linkages of several macroecological patterns related to species' abundances and body sizes. We show that such framework is consistent with the stationary state statistics of a broad class of resource-limited community dynamics models, regardless of parametrization and model assumptions. We verify predicted theoretical covariations by contrasting empirical data and provide testable hypotheses for yet unexplored patterns. We thus place the observed variability of ecological scaling exponents into a coherent statistical framework where patterns in ecology embed constrained fluctuations.
Elise Pendall - One of the best experts on this subject based on the ideXlab platform.
-
Ecosystem Type drives tea litter decomposition and associated prokaryotic microbiome communities in freshwater and coastal wetlands at a continental scale
Science of The Total Environment, 2021Co-Authors: Stacey M Trevathantackett, Sebastian Kepferrojas, Aschwin H Engelen, Paul H York, Anne Ola, Jeffrey J Kelleway, Kristin I Jinks, Emma L Jackson, Maria Fernanda Adame, Elise PendallAbstract:Wetland Ecosystems are critical to the regulation of the global carbon cycle, and there is a high demand for data to improve carbon sequestration and emission models and predictions. Decomposition of plant litter is an important component of Ecosystem carbon cycling, yet a lack of knowledge on decay rates in wetlands is an impediment to predicting carbon preservation. Here, we aim to fill this knowledge gap by quantifying the decomposition of standardised green and rooibos tea litter over one year within freshwater and coastal wetland soils across four climates in Australia. We also captured changes in the prokaryotic members of the tea-associated microbiome during this process. Ecosystem Type drove differences in tea decay rates and prokaryotic microbiome community composition. Decomposition rates were up to 2-fold higher in mangrove and seagrass soils compared to freshwater wetlands and tidal marshes, in part due to greater leaching-related mass loss. For tidal marshes and freshwater wetlands, the warmer climates had 7-16% less mass remaining compared to temperate climates after a year of decomposition. The prokaryotic microbiome community composition was significantly different between substrate Types and sampling times within and across Ecosystem Types. Microbial indicator analyses suggested putative metabolic pathways common across Ecosystems were used to breakdown the tea litter, including increased presence of putative methylotrophs and sulphur oxidisers linked to the introduction of oxygen by root in-growth over the incubation period. Structural equation modelling analyses further highlighted the importance of incubation time on tea decomposition and prokaryotic microbiome community succession, particularly for rooibos tea that experienced a greater proportion of mass loss between three and twelve months compared to green tea. These results provide insights into Ecosystem-level attributes that affect both the abiotic and biotic controls of belowground wetland carbon turnover at a continental scale, while also highlighting new decay dynamics for tea litter decomposing under longer incubations.
-
root effects on the temperature sensitivity of soil respiration depend on climatic condition and Ecosystem Type
Soil & Tillage Research, 2020Co-Authors: Elise Pendall, Feike A Dijkstra, Ming NieAbstract:Root activity may alter the temperature sensitivity (Q₁₀) of soil respiration. However, we lack a comprehensive understanding of root effects on Q₁₀ across different climatic regions and Ecosystem Types. Here, we conducted a global synthesis of 87 observations of Q₁₀ values of soil respiration and its components from 40 published studies. We found that roots significantly enhanced Q₁₀ of soil respiration because root and rhizosphere respiration was more temperature-sensitive than the respiration of root-free soil, especially in cold regions (mean annual temperature <10 °C). Moreover, roots significantly enhanced Q₁₀ of soil respiration in grassland and cropland but not in forest Ecosystems. Overall, our results suggest that the positive effects of roots on Q₁₀ largely depend on climatic condition and Ecosystem Type, and are potentially useful for parameterizing and benchmarking biogeochemical and Earth system models.
