Whether climate change will make food webs more or less stable (i.e. ecological stability) is a fundamental but elusive question. Ecological stability consists of multiple components, typically including asymptotic resilience and resistance to perturbations, and temporal stability of communities’ dynamics. When warmer temperature increases interaction strength among predator-prey pairs, asymptotic resilience decreases. However, warmer temperature can also have no effect on asymptotic resilience, or even positive effects, by decreasing interaction strength. Similarly, warmer temperature can have positive or negative effects on resistance to perturbations and temporal stability of community dynamics. In addition, warmer temperature goes hand in hand with biodiversity changes, another key factor shaping ecological stability. The effects of biodiversity on ecological stability can also be positive or negative. How warmer temperature and biodiversity changes jointly affect ecological stability is therefore uncertain, as most studies focus on only one of these two factors. The co-occurrence of both global changes in natural ecosystems warrants an integrative approach to studying their joint effects. In this study, we aim to quantify the long-term effects of temperature and biodiversity on the ecological stability of 20 natural food webs, in which population dynamics and temperature have been monitored for 10 to 30 years.
We first employed convergent cross mapping to reconstruct the topology of the 20 food webs. Next, we quantified the time-varying interaction matrix with the technique of multiview distance regularised S-map, from which we then computed dynamic and structural stability of each food web as the absolute value of the dominant eigenvalue (hereafter called “eigenvalue”) and trace, respectively. We next computed temporal stability of each food web as coefficient of variation of community dynamics. A larger value of eigenvalue, trace and coefficient of variation indicate a lower stability.
Across food webs, we found that warmer temperature consistently led to lower dynamic, structural and temporal stability, as warmer temperature had higher eigenvalue, trace and variation, respectively. In contrast, species richness decreased and increased structural stability and temporal stability, respectively, while Simpson only changed temporal stability and made it larger. Our results suggest that, in long term natural ecosystems, warmer temperature can erode stability of ecosystems in multiple aspects while biodiversity changes may not have consistently effect on stability.