An ecological network approach to predict ecosystem service vulnerability to species losses

Aislyn A Keyes,John P Mclaughlin,Allison K Barner,Laura E Dee

doi:10.1038/s41467-021-21824-x

Aislyn A Keyes, John P Mclaughlin + Show 2 more

Open Access

https://doi.org/10.1038/s41467-021-21824-x

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Abstract

Human-driven threats are changing biodiversity, impacting ecosystem services. The loss of one species can trigger secondary extinctions of additional species, because species interact–yet the consequences of these secondary extinctions for services remain underexplored. Herein, we compare robustness of food webs and the ecosystem services (hereafter ‘services’) they provide; and investigate factors determining service responses to secondary extinctions. Simulating twelve extinction scenarios for estuarine food webs with seven services, we find that food web and service robustness are highly correlated, but that robustness varies across services depending on their trophic level and redundancy. Further, we find that species providing services do not play a critical role in stabilizing food webs – whereas species playing supporting roles in services through interactions are critical to the robustness of both food webs and services. Together, our results reveal indirect risks to services through secondary species losses and predictable differences in vulnerability across services.

Highlights

Human-driven threats are changing biodiversity, impacting ecosystem services
We aim to understand the extent that species losses in food webs can pose indirect threats to ecosystem services, asking three questions: (1) Is food web robustness correlated with or decoupled from ecosystem service robustness across different sequences of species extinctions? (2) Does the robustness to species losses vary across ecosystem services? (3) Are the species that contribute to ecosystem services, either directly or in supporting roles, critical to food web persistence? We address these questions by simulating 12 extinction sequences on three empirical, estuarine food webs with ecosystem services added (Fig. 1a–c)
We find that food web and ecosystem service robustness are highly correlated, but that robustness varies across ecosystem services depending on their trophic level and redundancy

Summary

Introduction

Human-driven threats are changing biodiversity, impacting ecosystem services. The loss of one species can trigger secondary extinctions of additional species, because species interact–yet the consequences of these secondary extinctions for services remain underexplored. The removal of highly connected species causes many secondary extinctions and rapid food web collapse in grassland ecosystems[12] Findings like these could have important implications for the extent that species losses could trigger losses of ecosystem services indirectly —which we call ecosystem service robustness. Impacts to food webs that trigger species losses and secondary extinctions may not impact ecosystem services—or may differ across services —if the lost species are not ecosystem service providers or their critical supporting species The risk of ecosystem service loss could be higher than the risk of food web collapse—when threats cause losses of ecosystem service providers that most other species do not depend on (Fig. 2a) Which of these scenarios is most likely to occur remains unknown, and likely depends on when species are lost and their role in the focal ecosystem service. We investigate the relationship between risk to food webs and ecosystem services from species losses here through an extension of robustness analyses from network ecology

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