Dendroclimatic potential of dendroanatomy in temperature-sensitive Pinus sylvestris

Jesper Björklund,Kristina Seftigen,Patrick Fonti,Daniel Nievergelt,Georg Von Arx

doi:10.1016/j.dendro.2020.125673

Jesper Björklund, Kristina Seftigen + Show 3 more

Open Access

https://doi.org/10.1016/j.dendro.2020.125673

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Abstract

The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the latitudinal tree line, where ring width, X-ray MXD as well as the blue intensity counterpart MXBI were compared with dendroanatomical parameters. Maximum radial cell wall thickness as well as anatomical MXD and latewood density appeared to be the most promising parameters for temperature reconstruction. In fact, these parameters compare favorably to MXD derived from X-ray techniques as well as MXBI, in terms of shared variation and temperature correlations across frequencies and over time. The reasons for these results are thought to be the unprecedentedly high measurement resolution of the anatomical technique, which provide the optimal resolution – the cell – whereas X-ray techniques have a slightly lower resolution and BI techniques even lower. While the results of this study are encouraging, further tests on longer and multigenerational chronologies are required to more generally and fully assess the dendroclimate potential of anatomical parameters.

Highlights

Tree-ring based climate proxies have an outstanding position in current paleoclimatology because they are annually resolved with an absolute dating-accuracy, and in direct consequence, because their performance as climate predictors can be statistically tested for robustness (e.g., Briffa, 1999; Jones et al, 2009)
We screened a total number of 10 anatomical parameters (Fig. 2), and maximum latewood density (MXD) from BI and X-ray techniques, as well as ring width (RW), earlywood width and latewood width derived from the anatomical survey
The highest Rbar was found for maximum radial cell wall thickness (Max. rCWT) and anatomical MXD (Fig. 1), at 0.72 and 0.61 respectively

Summary

Introduction

Tree-ring based climate proxies have an outstanding position in current paleoclimatology because they are annually resolved with an absolute dating-accuracy, and in direct consequence, because their performance as climate predictors can be statistically tested for robustness (e.g., Briffa, 1999; Jones et al, 2009). If the trees’ ring-characteristics exhibit high shared variation, quantified through average pair-wise correlations, the so-called Rbar statistic (Briffa and Jones, 1990; Wigley et al, 1984), it indicates that the targeted trees have been exposed to, and record, similar environmental signals (Fonti et al, 2010; Fritts, 1976; Jones et al, 2009; Vaganov et al, 2011). This further implies that fewer trees are needed to explore the imprinted climatic targets (manifested through a higher expressed population signal (EPS), Wigley et al, 1984).

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