Six Temperature Proxies of Scots Pine from the Interior of Northern Fennoscandia Combined in Three Frequency Ranges

Abstract

Six chronologies based on the growth of Scots pine from the inland of northern Fennoscandia were built to separately enhance low, medium, and higher frequencies in growth variability in 1000-2002. Several periodicities of growth were found in common in these data. Five of the low-frequency series have a significant oscillatory mode at 200-250 years of cycle length. Most series also have strong multidecadal scale variability and significant peaks at 33, 67, or 83-125 years. Reconstruction models for mean July and June-August as well as three longer period temperatures were built and compared using stringent verification statistics. We describe main differences in model performance ( 2 = 0.53-0.62) between individual proxies as well as their various averages depending on provenance and proxy type, length of target period, and frequency range. A separate medium-frequency chronology (a proxy for June-August temperatures) is presented, which is closely similar in amplitude and duration to the last two cycles of the Atlantic multidecadal oscillation (AMO). The good synchrony between these two series is only hampered by a 10-year difference in timing. Recognizing a strong medium-frequency component in Fennoscandian climate proxies helps to explain part of the uncertainties in their 20th century trends.

Modeling of bud break of Scots pine in northern Finland in 1908–2014

“…Although observations from Karasjok and Sodankylä are similar to a large degree, the April and May mean temperatures from Karasjok in particular have a small increasing trend over the century that makes a difference. Recent findings, for example, on temperature development based on dendroclimatological studies of pine in the upper Fennoscandia and NW Russia ( McCarroll et al, 2013 ; Lindholm et al, 2014 ) are in line with our results on thermal development.…”

Higher Winter-Spring Temperature and Winter-Spring/Summer Moisture Availability Increase Scots Pine Growth on Coastal Dune Microsites Around the South Baltic Sea

“…A high tolerance to poor soils, droughts and frost events makes Scots pine the desired species for windbreak plantations (Brown and Schwemler, 1990) within coastal areas, in land reclamation treatments (Metslaid et al, 2016), and for anti-erosion purposes (Koprowski et al, 2010). In boreal forests of northern Europe, summer temperature is frequently reported as the primary limiting factor of Scots pine growth (RW and MXD: Schweingruber et al, 1988;Düthorn et al, 2013Düthorn et al, , 2015Lindholm et al, 2014;Lange et al, 2018;BI: McCarroll et al, 2002;Björklund et al, 2014). In the central part of the species distribution in Europe, i.e., in a transition zone from boreal to temperate forests and toward the south of its distributional range, winter or winter-spring temperatures mainly and positively influence Scots pine growth (RW: Pärn, 2002;Hordo et al, 2011;Balanzategui et al, 2018;Metslaid et al, 2018;Matisons et al, 2019;Harvey et al, 2020;EBI: Seftigen et al, 2020).…”

Current Networks of Long Proxies for Building Reconstruction Models of the Atlantic Multidecadal Oscillation

“…If raw tree-ring measurements were available they were standardized using two methods that preserve medium and low-frequency variability: 1) the conservative negative exponential or lines of zero or negative slope (NE) [10] [11] and 2) more flexible 180-year splines (Sp180) [12]- [15]. Thus for each data set two chronologies were produced and compared.…”