Integrating Theoretical and Empirical Definitions of Ecological Stability

Student: Shannon Schlater
Mentor: Amy Downing (Department of Zoology)

Species can positively or negatively interact with one another, and can do so strongly or weakly. We used field data from experimental ponds of fluctuating plant (phytoplankton) and herbivore (zooplankton) populations to determine how each species interacts with one another. We were then able to show that weaker interactions tend to stabilize ecosystems.

Researchers have found that most natural food webs consist of many weak and few strong interactions. Weak interactions are believed to be stabilizing in communities as they dampen the strength of strong interactions, ultimately, reducing the magnitude of population oscillations. Using time-series data from an aquatic mesocosm experiment consisting of zooplankton and algae, we were able to use a multivariate autoregressive modeling approach to determine community matrices composed of species’ interaction strengths. Consistent with previous findings we found community matrices with many weak interactions generally exhibited stabilizing characteristics. However, we also found that weak interactions may not be an equally strong stabilizing mechanism for different measures of stability.