A declining rate of recovery following disturbance has been proposed as an important early warning for impending tipping points in complex systems. Despite extensive theoretical and laboratory studies, this ‘critical slowing down’ remains largely untested in the complex settings of real-world ecosystems. Here, we provide both observational and experimental support of critical slowing down along natural stress gradients in tidal marsh ecosystems. Time series of aerial images of European marsh development reveal a consistent lengthening of recovery time as inundation stress increases. We corroborate this finding with transplantation experiments in European and North American tidal marshes. In particular, our results emphasize the power of direct observational or experimental measures of recovery over indirect statistical signatures, such as spatial variance or autocorrelation. Our results indicate that the phenomenon of critical slowing down can provide a powerful tool to probe the resilience of natural ecosystems.
Bibliographical noteFunding Information:
We thank B.R. Silliman for discussion on the experimental setup. A. Jacobs, J. van Dalen and L. van IJzerloo are recognized for their assistance in the field and A. Wielemaker-van den Dool for assistance with GIS. We thank VFA. de Witte for useful comments on earlier versions of the manuscript. The work of J.v.B. and T.J.B. is funded by the European Commission through FP7 ENV2009-1, Contract 244104-THESEUS. J.v.B. was further supported by the VNSC project ‘Vegetation modelling HPP’ (contract 3109 1805) and the Schure-Beijerinck-Popping fund of the Royal Dutch Academy of Science to visit S.K. and V.D. T.J.B. was further supported by the NWO funded BE-SAFE project grant 850.13.011. G.R.G. and M.L.K. were supported by funds from the US Geological Survey Climate and Land Use Research & Development program, and the US National Science Foundation LTER 1237733. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.