This study was conducted in a drained, exploited, and afforested Baltic bog Bagno Kusowo, located in North West Poland. The study aimed (i) to assess if human activity has a stronger impact on tree-ring width of Pinus sylvestris than climatic conditions in this transformed Baltic bog; (ii) to investigate how much the human modification of the ecosystem has influenced tree growth; (iii) to use this knowledge to reconstruct changes in the ecosystem further back in time, in the study area and its

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... mmediate neighbourhood. Wood samples for dendrochronological analyses were collected from 45 trees. Next, using classic dating methods and standard procedures (cross-dating methods, COFECHA program), chronologies were constructed (raw tree-ring width and residual chronologies: de-trended, autocorrelation removed, ARSTAN program). They formed a basis for further analyses: signature years, correlation and response function, as well as percentage growth change. The results of dendroclimatological analyses show weak increment-climate relationships and the analysis of weather conditions in the identified signature years did not detect any unambiguous relations with tree-ring width. However, results of the analyses indicate that the dominant factors affecting tree growth dynamics in the bog are changes in the hydrological system. Moreover, our results show many phases of human impact on environmental changes. Dendrochronological methods, combined with an analysis of old maps and other historical records, allowed us to reconstruct transformations of the ecosystem with a high resolution.