Summer Moisture Variability in East Central Sweden Since the Mid-Eighteenth Century Recorded in Tree Rings

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.