Evidence of unprecedented rise in growth synchrony from global tree ring records


Changes in the temporal coherence between populations, which can influence their stability, resilience and persistence, remain a critical uncertainty of climate change. Recent studies have documented increasing spatial synchrony between populations at continental scales and linked it to anthropogenic climate change. However, the lack of long-term and global baseline perspectives on spatial synchrony presents a challenge to understanding the importance of these trends. Here, we show a steady rise in the spatial synchrony of annual tree growth from a global tree ring database over the past 50 years that is consistent across continents, species and environmental conditions and is unprecedented for the past millennium. Increasing growth synchrony coincided with warming trends and potentially rising synchrony in the temperature records. We discuss the potential driving mechanisms and the limitations in the interpretation of this trend, and we propose that increasing mutual dependency on external factors (also known as Moran’s effect) linked to rising global temperatures is the most likely driver of more homogeneous global growth dynamics.

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Fig. 1: Sampling locations of the database, with the last year of data included per sampled population.
Fig. 2: The recent increase in global synchrony in tree growth greatly exceeds the variability observed in the past 1,000 years and is consistent across all of Earth’s continents.
Fig. 3: Relationship between increasing synchrony and warmer climate.
Fig. 4: Concomitant increase in temperature synchrony between forest sampling locations supports a strengthening of Moran’s effect as a main driver of rising synchrony in recent years.

Data availability

All the data used in this study are publicly available. The tree-growth data are available via the NOAA web repository at https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/tree-ring. The combined land-surface air and sea-surface water temperature anomaly data from GISTEMP Team 2018 are available via the NASA repositories at https://datahub.io/core/global-temp#data-cli. The annual precipitation and mean temperature data from the Princeton Reanalysis data version 2 are available at http://hydrology.princeton.edu/data.pgf.php. The nitrogen deposition data from the ISIMIP2b input data are available at https://www.isimip.org/gettingstarted/details/24/. The ENSO, SOI and NAO time series from NOAA are available at ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/enso-li2013.txt and https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/. The version of the data used in this manuscript is available at https://figshare.com/articles/dataset/Data_for_Evidence_of_unprecedented_rise_in_growth_synchrony_from_global_tree_ring_records_/12623501.

Code availability

The R script used to analyse the data and generate the graphs is available at https://figshare.com/articles/dataset/Annex_5_script/12623492. The graphs were generated in R and then imported to Inkscape for final formatting.


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We thank all the generous contributors of the ITRDB; without them this work would not be possible. We thank T. Mandra and J. Maxwell for providing insightful comments in earlier versions of this manuscript. This work was supported by the Swiss National Science Foundation (SNF) through the Early Postdoc.Mobility scheme, and the Harvard Forest.

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R.D.M., J.H. and N.P. conceived and designed the main research questions and methodology. R.D.M. and T.T.R. analysed the data. R.D.M. created the figures and the first draft of the manuscript. All authors contributed to the interpretation and writing in successive versions of the manuscript.

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Correspondence to Rubén Delgado Manzanedo.

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Manzanedo, R.D., HilleRisLambers, J., Rademacher, T.T. et al. Evidence of unprecedented rise in growth synchrony from global tree ring records. Nat Ecol Evol (2020). https://doi.org/10.1038/s41559-020-01306-x

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