Mortality dynamics in an old-growth stand of beech (Fagus sylvatica) in Southern Sweden

Sammanfattning: Mortality patterns were assessed in an old growth beech stand in southern Sweden. Aprevious inventory of 1200 trees in 1996 was used as a base for an inventory in 2006.Mann-Whitney U test was used to compare statistical distribution between living anddead trees of those inventoried in 2006. Dendrochronological reconstruction wasapplied for assessment of the temporal patterns of mortality. The mortality rate was18% in ten years, affecting mainly larger diameter classes >40cm dbh. During thestudy period, 6.9 % of the total amounts of living trees became high stumps, fromwhich 45% subsequently died. In understory trees, growth reactions and scars relatedto tree falls and canopy damage increased by over 80 % between the 1970’s and the1990’s, suggesting an increasing disturbance rate over this period. The causes of deathcould not be attributed to disturbances by themselves, but rather to a combination offungal infection (mainly Fomes fomentarius) and wind in most cases. The mortalitylevel found in this beech population is rather high compared to other studies inEuropean deciduous forest. Since the age of the stand is near the reported maximumof the species, mortality is likely to be high in the future. Damaged beech trees thatsurvive a long time (over ten years) provide unique substrate for species assemblages,constituting a desirable feature for conservation.