Phosphorus nutrition of beech (Fagus sylvatica L.) is decreasing in Europe

- Key message
Foliar phosphorus concentrations have decreased in Europe during the last 20 years. High atmospheric nitrogen deposition and climate change might beresponsible for this trend. Continued decrease in foliar P concentrations might lead to reduced growth and vitality of beech forests in Europe.

- Context Increased forest soil acidification, atmospheric nitrogen deposition, and climate change have been shown to affect phosphorus nutrition of forest trees. Low foliar phosphorus levels and high nitrogen/phosphorus ratios havebeen observed in different European countries and have beenrelated to reduced growth in forests.

- Aims
We test the hypothesis that phosphorus concentrations of European beech (F. sylvatica L.) foliage are decreasing at the European scale.

- Methods
Foliar phosphorus concentrations in beech were monitored on the basis of the “International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests.” Here, data from 12 European countries,comprising 79 plots and a 20-year sampling period (1991–2010), were evaluated.- Results Foliar phosphorus concentrations ranged from 0.81to 1.66 mg g−1 dw (plot median of the 20-year sampling period). On 22 % of the plots, phosphorus concentrations were in the deficiency range of beech (Mellert and Göttlein 2012).On 62 % of the plots, the nitrogen/phosphorus ratio was above 18.9, which is considered to be disharmonious for beech. In addition, foliar phosphorus concentrations were significantly decreasing by, on average, 13 % from 1.31 to1.14 mg g−1 in Europe (p<0.001).- Conclusion Our results show that phosphorus nutrition of beech is impaired in Europe. Possible drivers of this development might be high atmospheric nitrogen deposition and climate change. Continued decrease in foliar phosphorus concentrations, eventually attaining phosphorus deficiency levels,