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Assessing non-linearity in European temperature-sensitive tree-ring data

2019; Elsevier BV; Volume: 59; Linguagem: Inglês

10.1016/j.dendro.2019.125652

1612-0051

Fredrik Charpentier Ljungqvist, Peter Thejll, Jesper Björklund, Björn E. Gunnarson, Alma Piermattei, Miloš Rydval, Kristina Seftigen, Bård Støve, Ulf Büntgen,

Forest ecology and management

We test the application of parametric, non-parametric, and semi-parametric calibration models for reconstructing summer (June–August) temperature from a set of tree-ring width and density data on the same dendro samples from 40 sites across Europe. By comparing the performance of the three calibration models on pairs" of tree-ring width (TRW) and maximum density (MXD) or maximum blue intensity (MXBI), we test whether a non-linear temperature response is more prevalent in TRW or MXD (MXBI) data, and whether it is associated with the temperature sensitivity and/or autocorrelation structure of the dendro parameters. We note that MXD (MXBI) data have a significantly stronger temperature response than TRW data as well as a lower autocorrelation that is more similar to that of the instrumental temperature data, whereas TRW exhibits a redder" variability continuum. This study shows that the use of non-parametric calibration models is more suitable for TRW data, while parametric calibration is sufficient for both MXD and MXBI data – that is, we show that TRW is by far the more non-linear proxy.