Advance of Norway spruce ( Picea abies) onto mafic Lommoltunturi fell in Finnish Lapland during the last 200 years

• Published in: Boreas
• Main Authors: Sutinen, Raimo, NÄrhi, Paavo, Middleton, Maarit, HÄnninen, Pekka, Timonen, Mauri, Sutinen, Marja‐Liisa
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2012
• Subjects: Lommoltunturi; Norway; Tundra; Lapland
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.2011.00238.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.2011.00238.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.2011.00238.x

As a result of global changes, shifts of alpine tree lines towards higher elevations have been recorded, but the role of the spatial variability of the snowpack and zonal‐pattern soil‐nutrient regimes is poorly understood. N orway spruce ( P icea abies ( L .) K arst) is best suited to fertile soils, and hence we applied soil physical‐chemical and snow measurements and the age chronology of N orway spruce along an elevational gradient (380–557 m a.s.l.) to address a vertical soil zonality hypothesis on mafic L ommoltunturi fell in F innish L apland. With regard to increasing elevation, we found an increase in soil N TOT , C TOT and Al , but a decrease in soil Ca , Mg and Ca : Al ratio as well as in electrical conductivity ( EC ). In addition, the snowpack was significantly thicker in low‐elevation forest than in the tree line and open tundra. In the 1840s, spruce established on low‐elevation soils with a Ca : Al ratio of 2.2. Starting from the 1920s a significant shift of spruce occurred such that it took 60 years to expand the tree line by 55 m in elevation. The spruce tree line has advanced, and the age distribution indicates new colonization of spruce in closed forest up to tundra. The poor soil Ca : Al ratio of 0.02 on tundra apparently is a constraint for spruce. Spruce forest is young (<165 years), and hence we argue that spruce has expanded onto formerly tree‐free sites of this mafic fell. This paper demonstrates that vertical soil zonality is a potential driver for the diffuse tree line of P icea abies on mafic F ennoscandian fells.