Network resilience of mutualistic ecosystems and environmental changes: an empirical study

Abstract

It is theorized that a mutualistic ecosystem's resilience against perturbations (e.g. species extinction) is determined by a single macroscopic parameter (network resilience), calculable from the network. Given that such perturbations occur owing to environmental changes (e.g. climate change and human impact), it has been predicted that mutualistic ecosystems that exist despite extensive environmental changes exhibit higher network resilience; however, such a prediction has not been confirmed using real-world data. Thus, in this study, the effects of climate change velocity and human activities on mutualistic network resilience were investigated. A global dataset of plant-animal mutualistic networks was used, and spatial analysis was performed to examine the effects. Moreover, the potential confounding effects of network size, current climate and altitude were statistically controlled. It was demonstrated that mutualistic network resilience was globally influenced by warming velocity and human impact, in addition to current climate. Specifically, pollination network resilience increased in response to human impact, and seed-dispersal network resilience increased with warming velocity. The effect of environmental changes on network resilience for plants was remarkable. The results confirmed the prediction obtained based on the theory and imply that real-world mutualistic networks have a structure that increases ecosystem resilience against environmental changes. These findings will enhance the understanding of ecosystem resilience.

Keywords: climate change; human impact; mutualistic networks; network resilience; network science.

Figure 1.

Scatter plots of network resilience (residuals) versus environmental parameters (residuals) in pollination networks. (a) Plant network resilience versus human impact. (b) Animal network resilience versus annual mean temperature.

Figure 2.

Scatter plots of plant network resilience (residuals) versus environmental parameters (residuals) in seed-dispersal networks. (a) Plant network resilience versus warming velocity. (b) Animal network resilience versus precipitation seasonality.