Long-term summer sunshine/moisture stress reconstruction from tree-ring widths from Bosnia and Herzegovina

Abstract

Abstract. We present the first summer sunshine reconstruction from tree-ring data for the western part of the Balkan Peninsula. Summer sunshine is tightly connected with moisture stress in trees, because the moisture stress and therefore the width of annual tree-rings is under the influence of the direct and interactive effects of sunshine duration (temperature, precipitation, cloud cover and evapotranspiration). The reconstruction is based on a calibrated z-scored mean chronology, calculated from tree-ring width measurements from 7 representative black pine (Pinus nigra Arnold) sites in Bosnia and Herzegovina (BiH). A combined regression and scaling approach was used for the reconstruction of the summer sunshine. We found a significant negative correlation (r = −0.54, p < 0.0001) with mean June-July sunshine hours from Osijek meteorological station (Croatia). The developed model was used for reconstruction of summer sunshine for the time period 1660-2010. We identified extreme summer events and compared them to available documentary historical sources of drought, volcanic eruptions and other reconstructions from the broader region. All extreme summers with low sunshine hours (1712, 1810, 1815, 1843, 1899 and 1966) are connected with volcanic eruptions.

A 1286‐year hydro‐climate reconstruction for the Balkan Peninsula

“…Juniperus excelsa (Touchan et al 2005), Pinus nigra K€ ose et al 2011;Levanic et al 2012;Poljan sek et al 2013;Klesse et al 2015) and Quercus sp. Juniperus excelsa (Touchan et al 2005), Pinus nigra K€ ose et al 2011;Levanic et al 2012;Poljan sek et al 2013;Klesse et al 2015) and Quercus sp.…”

“…There are several high-resolution reconstructions of hydro-climatic conditions from the eastern Mediterranean, derived from TRWof other species, e.g. Juniperus excelsa (Touchan et al 2005), Pinus nigra K€ ose et al 2011;Levanic et al 2012;Poljan sek et al 2013;Klesse et al 2015) and Quercus sp. Griggs et al 2007;Cufar et al 2008).…”

Overview of Dendroclimatological Studies in the Balkan Peninsula

“…Minor differences in the temperature/precipitation signal have also been reported for Greece (Klesse et al, 2014). Decreased sensitivity of radial growth to summer sunshine between 1977 and 1985 was also observed in the western part of the Balkan Peninsula, where a weaker sunshine signal was explained by changes in solar radiation due to increased cloud cover (Poljanšek et al, 2013). On the other hand, there is a very stable relationship between treering indices and June-July temperature in Albania .…”

“…Sunshine is not the most growth limiting factor on such sites but its values are closely connected to temperature and precipitation and therefore to moisture stress, as the most logical driver of tree growth on mountainous sites of the western part of the Balkan Peninsula, as well as in the eastern Alps (Hafner et al, 2013). A strong correlation between tree-ring widths and the sunshine signal was calculated for black pine sites in Bosnia and Herzegovina, where mean June-July sunshine hours were recognized as the most stable and influential factor on radial increment (Poljanšek et al, 2013). However, slightly more to the south, in Albania, June-July temperature was identified as the most influential climate factor, and reconstructed for the 1583-2010 period , while in Greece, 400 years of summer temperature and precipitation variability on Mt.…”

“…Heat waves, extremely warm and dry summers in the Balkan Peninsula are usually connected with the blocking conditions and the presence of an anomalous trough over North Atlantic and associated anticyclonic conditions over Euro-Mediterranean region. On the other hand, humid and cooler summers are connected with the blocking regime between Scandinavian Peninsula and British Isles and anticyclonic circulation over North Atlantic (Poljanšek et al, 2013, Ubrich et al 2012. Reconstruction of summer sunshine for the period 1660-2010 for the western part of the Balkan Peninsula (Poljanšek et al, 2013) enabled identification of pointer years, connected to historical data on drought and rainy events, as well as to some volcanic eruptions.…”