Synchronous Growth Releases in Peatland Pine Chronologies as an Indicator for Regional Climate Dynamics—A Multi-Site Study Including Estonia, Belarus and Sweden

Aleksei Potapov,Tanel Kaart,Arvo Järvet,Ando Lilleleht,Sandra Metslaid,Johannes Edvardsson,Maris Hordo,Sandra Toomik,Andres Kiviste,Maxim Yermokhin

doi:10.3390/f10121097

Abstract

Fourteen tree-ring chronologies developed from 788 peatland Scots pines sampled at sites in Estonia, Belarus and Sweden were compared for common growth trends and possible links to regional climate dynamics. Several synchronous growth release events were detected, especially during the 1910s, 1930s, and around 1970 and 1990, indicating that hydrological shifts and associated tree growth responses have been governed by similar forcing mechanisms, at least during the 20th century. In general, the best agreements were observed between the tree populations from Estonia and Belarus, but synchronous growth changes could also be detected between the Swedish and Estonian material. Trends detected in single tree-ring chronologies may be linked to local peatland management or land-use changes, whereas common variations detected at multiple sites are more likely linked to hydrological changes in the peatlands associated with regional climate dynamics. Understanding the links between climate and processes that involve peatland hydrology and vegetation responses is important since peatland ecosystems are key players in the global carbon cycle.

Highlights

Peatland ecosystems are characterized by high soil moisture and partially decomposed vegetation accumulated as peat in soil layers [1]
We examined the following hypotheses: (1) the effects of large-scale climatic drivers result in synchronous long-term growth trends of trees from various peatland sites within a region; (2) climatic signals contained in mid- and low-frequency variability in ring-width series can serve as a proxy for reconstructing peatland hydrology; and (3) changes in the long-term dynamics of tree radial growth in peatlands are not exclusively associated with man-made disturbances, such as ditching, and with groundwater levels (GWL) fluctuations driven by climatic variability
Growth release events were dated for each study area according to %GC series (Figure 1a) when the majority of the trees showed changes in radial growth dynamics (Figure 1b)

Summary

Introduction

Peatland ecosystems are characterized by high soil moisture and partially decomposed vegetation accumulated as peat in soil layers [1]. Hydrological variability of peatlands depends on various climatic factors and affects peatland vegetation and carbon storage dynamics [2,3,4]. Even in their natural state, peatlands are considered complex and dynamic ecosystems, but peatland management or land-use changes may induce even more rapid shifts affecting local hydrology [1]. Throughout human history, peat and peatlands have been utilized for a wide range of purposes including fuel for heating, agriculture, timber production, and plantation soils improvement. The share of artificially drained peatlands is about 6% [5], but for Fennoscandia and the Baltics this figure is higher and the number of peatlands disturbed by ditching as a silvicultural treatment is substantial [1]

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Conclusion