Summer moisture variability in east central sweden since the mid‐eighteenth century recorded in tree rings

Abstract

To make predictions of future climate it is necessary to understand the past climate—temperature as well as precipitation. While a wealth of temperature proxies exist from northern latitudes, there is still a lack of information about past precipitation variability. Here we present a 300‐year‐long tree‐ring width chronology from xeric‐site Scots pines (Pinus sylvestris L.) in Tyresta National Park, east central Sweden. Tree‐ring widths were compared to the long observed temperature and precipitation records from Stockholm during 1786–2000. Analyses of the climate/growth relationship showed that, in general, May–June precipitation had a dominating influence on pine growth. However, during dry periods, negative responses to June–July temperature were stronger, especially evident in the late nineteenth century. Periods of below‐average growth were associated with dry conditions in May–June, but occasionally periods of wet and cool summers also produced narrow rings. Periods of above‐average growth were linked to wet, but sporadically also cool and dry, early summers. The years between 1815 and 1833 appear to be particularly dry in the 300‐year context. Since growth anomalies are found in other Swedish drought‐sensitive tree‐ring chronologies during this period, it is likely that this dry period had a regional extent. This is the first tree‐ring chronology from southern Sweden that provides multi‐century information of past summer drought and moisture variability with high resolution and the study will add important information regarding past climate variability in southern Sweden.

Early nineteenth century drought in east central Sweden inferred from dendrochronological and historical archives

“…However, the climate in Sweden will never approach that of arid or semi-arid areas (because of its proximity to the North Atlantic Ocean and its high latitude), so the precipitation signal in tree-ring data from southern Sweden will not be as strong as the temperature signal in tree rings from northern Sweden. This has previously been highlighted in an analysis of the relationship between Scots pine growth and temperature/precipitation in Tyresta National Park, east central Sweden (Linderholm et al 2004). These authors showed that, in general, May-June precipitation had a dominating (positive, R = 0.43) influence on pine growth, but that June-July temperatures also influenced (negative, R = -0.30) growth (Linderholm et al 2004).…”

“…This has previously been highlighted in an analysis of the relationship between Scots pine growth and temperature/precipitation in Tyresta National Park, east central Sweden (Linderholm et al 2004). These authors showed that, in general, May-June precipitation had a dominating (positive, R = 0.43) influence on pine growth, but that June-July temperatures also influenced (negative, R = -0.30) growth (Linderholm et al 2004). This is due to the fact that pine growth in this area is influenced by both early summer precipitation and temperature.…”

“…Fritts 1976). Since we were interested in a proxy for drought, the sampling sites with an extremely thin or absent soil layer were selected so that the trees were likely subjected to moisture deficit in spring and summer (Linderholm et al 2004). Two samples from each tree were collected using an increment borer at a height of ca.…”

“…Quite possibly, Scots pine in Tyresta would also be able to withstand a dry late summer, provided that they had sufficient water available during the early stages of the growing season. Furthermore, occasional responses of low growth to drought by Scots pine in southern Sweden may be attributed to the sensitivity of these trees to both temperature and precipitation during the growing season, and that the relative influence on pine growth of these 2 climate variables may vary depending on the general climate conditions (Linderholm 1999, Linderholm et al 2004. For example, the effect of a summer with low precipitation may not be as severe on pine growth provided that summer temperatures are low.…”

Hydroclimate variability in Scandinavia over the last millennium – insights from a climate model–proxy data comparison

“…The use of tree-ring proxy evidence to study natural hydroclimate variability has however long been secondary when compared to the scientific attention focused on providing local and regional reconstructions (Gunnarson et al, 2011;Esper et al, 2012;McCarroll et al, 2013;Linderholm et al, 2014) and methodologies (Björklund et al, 2012 to study temperature variability over the last several millennia. Much of the tree-ring research at moisture-limited sites has until recently been limited to a handful of exploratory papers (Helama and Lindholm, 2003;Linderholm et al, 2004;Jöns-son and Nilsson, 2009;Drobyshev et al, 2011;Seftigen et al, 2013) that generally develop one or a few chronologies to provide local precipitation and drought histories. These studies, together with a steadily growing collection of highlatitude moisture sensitive tree-ring records (e.g., , now serve as a basis for new possibilities to expand the detail and accuracy with which the history of northern European moisture conditions can be described.…”