Quantifying the relevance of alternative stable states in many-species food webs

Alternative stable ecosystem states are possible under the same environmental conditions in many models of 2-3 interacting species and an array of feedback loops. However, multi-species food webs might dissipate the feedbacks that create alternative stable states through species-specific traits and feedbacks. To test this potential, we develop a manyspecies model of consumer-resource interactions with two classes of feedbacks: specialized feedbacks where individual resources become unpalatable at high abundance, or aggregate feedbacks where overall resource abundance reduces consumer recruitment. We quantify how trophic interconnectedness and species differences in demography affect the potential for either feedback to produce alternative stable states dominated by consumers or resources. We find that alternative stable states are likely to happen in many-species food webs when aggregate feedbacks or lower species differences increase redundancy in species contributions to persistence of the consumer guild. Conversely, specialized palatability feedbacks with distinctive species roles in consumer guild persistence reduce the potential for alternative states but increase the likelihood that losing vulnerable consumers cascades into a food web collapse at low stress levels, a dynamic absent in few-species models. Altogether, among-species trait variation can limit the set of processes that create alternative stable states and impede consumer recovery from disturbance.