Do trees respond to pollution? A network study of the impact of pollution on spruce growth from Europe

• Published in: Environmental pollution (1987) Vol. 350; p. 124012
• Main Authors: Shetti, R., Boonen, K., Smiljanić, M., Tejnecký, V., Drábek, O., Lehejček, J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2024
• Subjects: Environmental signals; Forests; Krkonoše mountains; Krušné hory; Picea abies [L.] Karst; Pollution; Tree rings; Tree rings; Forests; Pollution; Krušné hory; Picea abies [L.] Karst; Environmental signals; Krkonoše mountains; pollution; environmental signals; forests; tree rings
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2024.124012

Tree rings have been reliably used as an environmental proxy over the past decades for environmental reconstructions, simulations and forecasting. In our study, we investigated whether tree-ring chronologies are impacted by pollution. We chose sites in the Krušné hory and the Krkonoše Mountains in the Czech Republic which have a known history of pollution. We sampled Norway spruce (Picea abies [L.] Karst) in both ranges and compared their chronologies. We found no significant difference in the overall radial growth in the chronologies from both regions. However, we observed an increased heterogeneity in the growth of trees from the 1970s till the 1990s. Coherently, a severe reduction in tree growth from the late 1970s and a recovery towards the early 1990s was evident. We collected and analysed soil samples for pH and exchangeable element concentrations. All seven sampling sites' soils were strongly acidic (pHCaCl2 = 3.3 ± 0.4). The average soil base saturation at Krušné hory was higher than at Krkonoše (39% versus 12%), likely due to more intensive liming.
Further, we compared these chronologies to other sites in Europe. Analysing 89 sites, we found that most (9 out of 14) of the sites with significantly reduced radial tree growth were located within the former ‘Black Triangle’, an area which was subjected to heavy industrialisation and pollution from the 1960s to the 1990s. Atmospheric sulphur deposition was found to negatively affect radial tree-growth, while limited quantities of oxidised nitrogen appeared to have a positive effect. Our results are consistent with previous research, indicating that atmospheric SO2 pollution and subsequent acid fog and rime have led to a reduction in annual radial tree growth across the Black Triangle.
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•1.Spruce from the Czech Republic show significantly reduced growth from 1970s till late 1990s.•2.Soils at all sampled sites were severely acidic (pH 2.5 to 4) impacting the tree growth.•3.Reduced tree growth could be due to airborne translocation of pollution.•4.Spruce growth from the Black-Triangle region is more impacted than in Western Europe.