GC050-08
Decoupling deltas: global deltas face rapid disconnection from their ecosystem services as human modification increases

Thursday, 10 December 2020: 04:28
Virtual
Martin Reader1, Alexander Damm2, Owen L Petchey3, Hugo Jan de Boer4, Maarten Eppinga1 and Maria J. Santos1, (1)URPP Global Change and Biodiversity, University of Zurich, Geography, Zurich, Switzerland, (2)Remote Sensing Laboratories, University of Zurich, Geography, Zurich, Switzerland, (3)URPP Global Change and Biodiversity, University of Zurich, Institute of Evolutionary Biology and Environmental Studies, Zurich, Switzerland, (4)Copernicus Institute of Sustainable Development, Universiteit Utrecht, Environmental Sciences, Utrecht, Netherlands
Recorded Presentation
Abstract:
Increasing modification of natural systems can increase the trade-offs between their ecosystem services (ES), and ultimately decouple societies from local ecosystem feedbacks. A unique mixture of terrestrial and coastal ES has allowed deltas to develop into globally important urban, agricultural and industrial centres, yet this very development threatens the services delta sustainability relies upon.

We examine how human modification of deltas affects their ES supply, and the relationships between their ES. We created a global dataset of 235 large deltas and calculated average values for 49 indicators of ES and four indicators of how humans modify deltas from their natural state (population, flow disruption, use of primary productivity and built infrastructure). We used a cluster ensemble to group the ES into four commonly occurring bundles (food, water, productivity and intactness), and created a typology of their relationships to modification.

Almost 29% of deltas showed at least one decoupled relationship, where the relationship between modification and ES disappeared or reversed. Every bundle decoupled from built infrastructure, whereas population showed linear relationships with food and productivity, and flow disruption displayed very weak relationships with ES. The productivity, food and water ES bundles showed overall synergies to one another, and a trade-off with intactness; however, these correlations weakened as deltas became more modified.

Our findings highlight the complexity of managing and restoring ES in rapidly developing deltas. Linear relationships, for example between population and intactness, indicate predictable outcomes, and the potential for recovery. Nonlinear decoupled relationships, such as those with built infrastructure, show that beyond a certain point feedbacks with ES break down and reducing modification may not help recover them. In summary, this global analysis is the first to illustrate how ES vary along a gradient of modification in deltas, and indicates need to balance modification and ES use for sustainable delta futures.

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