Testing the space-for-time assumption

News

Posted on Wednesday 4 November 2026

Postdoc Dominique Maucieri shares her findings surrounding how well space-for-time substitutions do at quantifying biodiversity changes compared with time series data.

Space-for-time substitutions are everywhere in biodiversity change research, and they likely aren't going anywhere anytime soon (Lovell et al. 2023). To measure changes in biodiversity over a long time scale, you need to have reliable funding sources and research support to be able to collect that data. Often this is difficult as funding cycles and graduate student degrees are only a few years long at a time. Instead a lot of researchers will utilize what is known as a space-for-time substitution where they will measure diversity over a gradient of disturbance or a gradient of different times since a disturbance has occurred and use that to inform what changes would occur over a time series.

However, there is a lot of debate within the scientific community about how well space-for-time substitutions capture biodiversity changes (Blois et al. 2013, Damgaard 2019, Lovell et al. 2023, Evans et al. 2025), yet there are not many studies trying to investigate these concerns. My work is focusing on how well the space-for-time substitution captures changes occurring over a time series. To do this I am utilizing the North American breeding bird survey (Ziolkowski et al. 2025) and examining changes in alpha diversity due to changes in land cover.

I am in the final stages of this project, so I don’t want to spoil the punch line too much before the paper comes out, but my work has shown that space-for-time substitutions systematically underestimate changes in diversity that are estimated over a time series. However, my work also shows ways that both space-for-time and time series measures can be altered so that there is better congruence between them. Stay tuned for this paper.

References

Blois, J. L., J. W. Williams, M. C. Fitzpatrick, S. T. Jackson, and S. Ferrier. 2013. Space can substitute for time in predicting climate-change effects on biodiversity. Proceedings of the National Academy of Sciences 110:9374–9379.

Damgaard, C. 2019. A Critique of the Space-for-Time Substitution Practice in Community Ecology. Trends in Ecology & Evolution 34:416–421.

Evans, M. E. K., P. B. Adler, A. L. Angert, S. M. N. Dey, M. P. Girardin, K. A. Heilman, S. Klesse, D. L. Perret, D. F. Sax, S. N. Sheth, M. Stemkovski, and J. L. Williams. 2025. Reconsidering space-for-time substitution in climate change ecology. Nature Climate Change 15:809–812.

Lovell, R. S. L., S. Collins, S. H. Martin, A. L. Pigot, and A. B. Phillimore. 2023. Space-for-time substitutions in climate change ecology and evolution. Biological Reviews 98:2243–2270.

Ziolkowski, D., M. Lutmerding, S. M. Skalos, W. B. English, and M.-A. R. Hudson. 2025, December 8. 2025 Release - North American Breeding Bird Survey Dataset (1966 - 2024).