Spruce is commercially and ecologically one of the most important coniferous trees in Europe. Its range extends from the Alps, the Carpathians and the Balkans in the south, to the northern regions of Scandinavia and Russia. In our country, it is naturally found in mountainous areas, but also in cold floodplains, and is a tree species with wide ecological adaptability. However, in the recent years of climate change, this tree has found itself on the retreat from the lower and middle areas of the Czech Republic, where it has historically been planted – as unnatural and, from today's point of view, unsuitable forest habitats. Together with climate change, which causes rising air temperatures and more frequent droughts, the survival of spruce in the lowlands is becoming more and more difficult. Nevertheless, it is often grown in these locations as one of the most productive commercial trees. Spruce reacts to poor dry natural conditions with lower growth, which in a long-term stressful environment can be manifested by yellowing and drying of the needles and reduced defence against secondary pests and diseases.
A team of Czech and Italian scientists has confirmed that a dry environment with lower rainfall totals is limiting for spruce growth in the lowlands. Their work focused on spruce forests in the Central Bohemian region around Kostelec, Karlštejn, and Cukrák. Meteorological and dendrochronological data were collected in these sites. Dendrochronology is a scientific method in which a tree trunk is drilled and a portion of the wood is removed. Subsequently, the growth of the tree in individual years can be monitored according to the size of the annual rings. By comparing these data, scientists have been able to observe the effect of fluctuations in precipitation and temperature on the rate of spruce growth in individual growing seasons.
It turned out that spruce forests in the lowlands are not primarily limited by air temperature, but by the amount and deficit of precipitation. Long and intense summer droughts in spruce lead to reduced photosynthesis and insufficient supply of water-transported nutrients, resulting in reduced wood growth during the growing season.
D’Andrea, G.; Šimůnek, V.; Pericolo, O.; Vacek, Z.; Vacek, S.; Corleto, R.; Olejár, L.; Ripullone, F. Growth Response of Norway Spruce (Picea abies [L.] Karst.) in Central Bohemia (Czech Republic) to Climate Change. Forests 2023, 14, 1215. https://doi.org/10.3390/f14061215
Written by: Oldřich Vojtěch