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Food Webs in Variable Environments

The response of ecosystems to different kinds of disturbances is governed by their species composition and trophic structure. Of particular current concern is the response of ecosystems to climate change. Climate data as well as climate model predictions indicate that the intensity and frequency of weather extremes have increased and will continue to do so if global temperature increases as forecasted.

Such increased environmental variability may lead to increased species extinction risks and hence have important consequences for the structure and functioning of ecosystems. Here we use stochastic food web models to explore the effects environmental variability on ecosystems.

Project 1: Effects of Biodiversity on Food Web Dynamics in a Variable Environment

It has been argued that biodiversity can act as an insurance against perturbations caused by environmental variability. If species respond differently to the environmental variability theory suggests that increasing the number of species will increase the probability of finding tolerant species, leading to increased stability at community level.

In this project we explore how biodiversity and the degree of correlation in species responses to environmental variability affect the extinction risk of species in multitrophic communities.

Linda Kaneryd, Peter Münger & Bo Ebenman

Project 2: The Role of Adaptive Consumers in a Variable Environment

Traditionally, modeling of ecosystems using computers has not very often included the dynamical change of species interactions that continuously occur in natural systems. One such interaction change is the adaptive ability of consumers in their choise of prey, which has been suggested to enhance community persistence and buffer against fluctuations in the environment.

This is very interesting, since 1) for a long time, theory has had difficulties in replicating stable systems of such great size that we see in nature, and 2) the environmental variation is predicted to increase as a consequence of global increase in temperature and other anthropogenic changes.

In this project, we explore the role of such adaptive consumers in silico, using model food-webs of different size exposed to high environmental variability.

David Gilljam, Alva Curtsdotter & Bo Ebenman

Project 3: Consequences of Variation in Species Interactions or Demography

Environmental variation has the potential to substantially influence individual species as well as communities. The nature of this influence, however, will depend on both community structure and what species trait is affected. Often the effect of environmental variation is assumed to only affect demographic rates. However environmental variation can also affect the interactions between species.

In this project we therefore explore in silico, using model food-webs of different size exposed to high environmental variability, how the relationship between species extinction risk and biodiversity is affected by introducing the variation either in the demographic rates or in the species' interaction strengths. 

Alva Curtsdotter, David Gilljam & Bo Ebenman

Responsible for this page: Alva Curtsdotter

Last updated: 02/18/11