%0 Research article
%T Spatial tree age structure and fire history in two old-growth forests in eastern Fennoscandia
%A Wallenius, Tuomo
%A Kuuluvainen, Timo
%A Heikkilä, Raimo
%A Lindholm, Tapio
%D 2002
%J Silva Fennica
%V 36
%N 1
%R doi:10.14214/sf.557
%U https://silvafennica.fi/article/557
%X Two near natural old-growth forests, one dominated by Picea abies and  the other by Pinus sylvestris, were studied for their fire history, and  spatial patterns of trees and tree ages. The spatial tree age structure  and the disturbance history of the forests were examined by drawing age  class maps based on mapped and aged trees and by dating fires based on  fire scars, and by using spatial analyses at tree scale. The tree age  structures of the Picea and Pinus dominated forests were different,  mainly due to differences in fire history and sensitivity of the  dominant tree species to fire. Fire histories and tree age structures of  both sites have probably been affected by human in the ancient past.  However, in the Picea dominated site, the fires had been severe, killing  most of the trees, whereas in the Pinus dominated site the severity of  fires had been more variable, leaving some Pinus and even Picea trees  alive. In the Pinus dominated site, the tree age distribution was  multimodal, consisting of two Pinus cohorts, which were established  after fires and a later Picea regeneration. The Picea dominated site was  composed of four patches of different disturbance history. In the  oldest patch, the tree age distribution was unimodal, with no distinct  cohorts, while a single cohort that regenerated after severe fire  disturbances dominated the three other patches. In both sites the  overall spatial patterns of living and dead trees were random and the  proportion of spatially autocorrelated variance of tree age was low.  This means that trees of different age grew more or less mixed in the  forest without forming spatially distinct regeneration patches, even in  the oldest patch of Picea dominated Liimatanvaara, well over 200 years  after a fire. The results show that detail knowledge of disturbance  history is essential for understanding the development of tree age  structures and their spatial patterns.