scholarly journals Food web structure alters ecological communities top-heaviness with little effect on the biodiversity-functioning relationship

2020 ◽  
Author(s):  
Eva Delmas ◽  
Daniel B. Stouffer ◽  
Timothée Poisot

In a rapidly changing world, the composition, diversity and structure of ecological communities face many threats. Biodiversity-Ecosystem Functioning (BEF) and community food-chain analyses have focused on investigating the consequences of these changes on ecosystem processes and the resulting functions. These different and diverging conceptual frameworks have each produced important results and identified a set of important mechanisms, that shape ecosystem functions. But the disconnection between these frameworks, and the various simplifications of the study systems are not representative of the complexity of real-world communities. Here we use food webs as a more realistic depiction of communities, and use a bioenergetic model to simulate their biomass dynamics and quantify the resulting flows and stocks of biomass. We use tools from food web analysis to investigate how the predictions from BEF and food-chain analyses fit together, how they correlate to food-web structure and how it might help us understand the interplay between various drivers of ecosystem functioning. We show that food web structure is correlated to the community’s efficiency in storing the captured biomass, which may explain the distribution of biomass (top heaviness) across the different trophic compartments (producers, primary and secondary consumers). While we know that ecological network structure is important in shaping ecosystem dynamics, identifying structural attributes important in shaping ecosystem processes and synthesizing how it affects various underpinning mechanisms may help prioritize key conservation targets to protect not only biodiversity but also its structure and the resulting services.

2006 ◽  
Vol 199 (1) ◽  
pp. 93-106 ◽  
Author(s):  
Tomas Jonsson ◽  
Patrik Karlsson ◽  
Annie Jonsson

2012 ◽  
Vol 367 (1605) ◽  
pp. 3033-3041 ◽  
Author(s):  
Claudio de Sassi ◽  
Phillip P. A. Staniczenko ◽  
Jason M. Tylianakis

Body size is a major factor constraining the trophic structure and functioning of ecological communities. Food webs are known to respond to changes in basal resource abundance, and climate change can initiate compounding bottom-up effects on food-web structure through altered resource availability and quality. However, the effects of climate and co-occurring global changes, such as nitrogen deposition, on the density and size relationships between resources and consumers are unknown, particularly in host–parasitoid food webs, where size structuring is less apparent. We use a Bayesian modelling approach to explore the role of consumer and resource density and body size on host–parasitoid food webs assembled from a field experiment with factorial warming and nitrogen treatments. We show that the treatments increased resource (host) availability and quality (size), leading to measureable changes in parasitoid feeding behaviour. Parasitoids interacted less evenly within their host range and increasingly focused on abundant and high-quality (i.e. larger) hosts. In summary, we present evidence that climate-mediated bottom-up effects can significantly alter food-web structure through both density- and trait-mediated effects.


Oikos ◽  
2010 ◽  
Vol 119 (12) ◽  
pp. 1984-1992 ◽  
Author(s):  
Tara E. Sackett ◽  
Aimée T. Classen ◽  
Nathan J. Sanders

2013 ◽  
Vol 15 (11) ◽  
pp. 2563-2576 ◽  
Author(s):  
Tânia Salvaterra ◽  
Dannielle S. Green ◽  
Tasman P. Crowe ◽  
Eoin J. O’Gorman

2020 ◽  
Author(s):  
Arnaud Sentis ◽  
José M. Montoya ◽  
Miguel Lurgi

Climate warming and biological invasions are key drivers of biodiversity change. Their combined effects on ecological communities remain largely unexplored. We investigated the direct and indirect influences of warming on invasion success, and their synergistic effects on community structure and dynamics. Using size-structured food web models, we found that warming increased invasion success. The direct physiological effects of warming on invasions were minimal in comparison to indirect effects mediated by changes on food web structure and stability. Warmed communities with less connectivity, shortened food chains and reduced temporal variability were more susceptible to invasions. The directionality and magnitude of invasions effects on food webs varied across warming regimes. Warmer communities became smaller, more connected, and with more predator species when invaded than their colder counterparts. They were also less stable and their species more abundant. Considering food web structure is crucial to predict invasion success and its impacts under warming.


Author(s):  
Kevin S. McCann

This chapter extends the consumer–resource theory to include simple but common three-species modules behind the construction of whole food webs, with particular emphasis on food chains and omnivory. It first considers some common simple modular food web structures and whether the dynamics of subsystems can be seen using the framework laid out in previous chapters. Specifically, it asks when common food web structure increases or weakens the relative interaction strengths and/or when a food web structure modifies flux between consumers and resources in a density-dependent manner such that the food web tends to increase flux rates in some situations and decrease the coupling in other situations. The chapter also explores how stage structure can influence food chain stability before concluding with a review of empirical evidence on the dynamical implications of omnivory for food webs.


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