Integrating Theoretical and Empirical Definitions of Ecological Stability: Are They Measuring the Same Thing?

Student: Claire Plunkett (Case Western Reserve University)
Mentor: Craig Jackson (Department of Mathematics and Computer Science)

Due to changing climates and habitat destruction, better understanding what influences the stability of ecosystems is increasingly important. Using data previously collected on plankton population sizes, we investigated how different definitions of stability relate by using a mathematical model to calculate stability in various ways. Additionally, we explored how the presence of weak links in a food web is related to stability.

In ecology, the topic of stability has been studied from both empirical and theoretical perspectives, leading to potentially conflicting definitions of stability. Theoretical stability depends on the community matrix of interaction strengths while empirical stability is often calculated as temporal variability of individual species and community populations. While studies have shown that measures of empirical stability are often related and measures of theoretical stability are often related, the connections between theoretical and empirical stability have yet to be sufficiently investigated.

In this study, we investigate the connection between different measures of theoretical and empirical stability using data from a freshwater plankton mesocosm experiment. Further, we explore whether stability is related to the presence of weak interactions, which are often thought to be stabilizing. We find that stability is correlated with interaction strength in 13 of 21 comparisons. Also, we find 2 significant relationships between empirical stability and interaction strength out of 21 comparisons, but we do not find any significant correlations between theoretical and empirical stability measures. This suggests that empirical and theoretical stability are measuring different attributes.