Impact of meteorological conditions on the foliar nutrition of old-growth European beech (Fagus sylvatica L.) stands: results of long-term serial analysis of macro- and micronutrients

Abstract Key message Long-term monitoring revealed nutrient- and site-specific changes of European beech foliar chemistry in correlation with meteorological conditions, underscoring shifts in beech nutrition due to climate change, thereby informing adapted sustainable forest management. Abstract Systematic long-term studies assessing the relevant macro- and micronutrients will improve our understanding of the complex interplay between climatic as well as site-specific factors and nutrient dynamics of European beech forests. Thus, we assessed the impact of meteorological conditions on the nutrition of old-growth European beech stands at a calcareous and an acidic site in central Germany. Foliar concentrations of six macronutrients and four micronutrients were analyzed over 13 years (2009–2021), and their association with meteorological conditions depending on the site was assessed using a linear mixed-effects model. The results revealed nutrient-specific and, for half of the nutrients, site-specific responses to meteorological variables, that is, mean annual temperature (MAT) and precipitation (MAP) of the current and/or the previous year. Within the MAT range of the observational period (7.4–10.3 °C), for nitrogen (calcareous site), phosphorus, magnesium, sulfur, copper, and zinc, a nonlinear relationship was observed, that is, the nutrient concentrations increased until a temperature optimum and decreased thereafter. In contrast, the concentrations of potassium (calcareous site), manganese, and iron increased and of calcium decreased with increasing temperature. MAP (351–723 mm) had an impact on the concentration of six nutrients (nitrogen, potassium, calcium, copper, iron, and zinc), but its effect was generally smaller than that of MAT. Our results indicate that the persistent deficiencies in foliar phosphorus (calcareous site) and sulfur (acidic site) may be aggravated with ongoing climate change. The findings may guide site-specific sustainable and ecosystem-oriented forest management strategies for the future.