Erratum to:

DOI 10.1007/s10353-016-0437-x

In the version originally published online, the legends to the two parts of Fig. 1 did not match the figures. Part a shows the FEV1 in liters and part b the FEV1 in per cent. Moreover, the legend to Fig. 2 belongs to Fig. 4 and vice versa. The article has been updated in the meantime.