%0 Research article
%T Tree mortality after prescribed burning in an old-growth Scots pine forest in northern Sweden
%A Linder, Per
%A Jonsson, Peter
%A Niklasson, Mats
%D 1998
%J Silva Fennica
%V 32
%N 4
%R doi:10.14214/sf.675
%U https://silvafennica.fi/article/675
%X Tree mortality and input of dead trees were studied after a prescribed  burning in a forest reserve in northern Sweden. The stand was a  multi-layered old-growth forest. The overstorey was dominated by Scots  pine (Pinus sylvestris L.) and the understorey consisted of mixed Scots  pine and Norway spruce (Picea abies L. Karst.). Ground vegetation was  dominated by ericaceous dwarf-shrubs and feathermosses. The stand has  been affected by six forest fires during the last 500 years. The  prescribed burning was a low intensity surface fire that scorched almost  90% of the ground. Tree mortality for smaller pines and spruces  (DBH < 10 cm) was over 80% in the burned parts of the reserve. For  larger pines, 10–50 cm DBH, mortality showed a decreasing trend with  increasing diameter, from 14% in class 10–20 cm DBH to 1.4% in class  40–50 cm DBH. However, pines with DBH ≥ 50 cm had a significantly higher  mortality, 20%, since a high proportion of them had open fire scars  containing cavities, caused by fungi and insects, which enabled the fire  to burn inside the trunks and hollow them out. The fire-induced  mortality resulted in a 21 m3 ha–1 input of dead trees, of which 12 m3  ha–1 consisted of trees with DBH ≥ 30 cm. An increased mortality among  larger trees after low-intensity fires has not previously been described  in Fennoscandian boreal forests, probably owing to a lack of recent  fires in old-growth stands. However, since large pines with open fire  scars were once a common feature in the natural boreal forest, we  suggest that this type of tree mortality should be mimicked in forestry  practices aiming to maintain and restore natural forest biodiversity.