The supra-long Scots pine tree-ring record for Finnish Lapland:: Part 1, chronology construction and initial inferences

This paper reviews the development of the current 'supra-long' pine chronology for northern Finnish Lapland. In the forest-tundra ecotone region of northern Finnish Lapland over 250 samples from living Scots pines (Pinus sylvestris L.) and over 1700 samples of subfossil pines have been collected for dendrochronological studies. In addition. over 1400 subfossils have been sampled from the forested area of Finnish Lapland. The goal of the research was to build a more than 7000-year long continuous pine ring-width chronology. The construction of the chronology is now completed. The intensive phase of the data collection and chronology building lasted about 10 years, 1989 to 1999. The major part of the Finnish Lapland master curve was constructed several years ago, but it was extremely difficult to bridge the c. 300-year gap, prior to 165 BC between the 'absolute' younger part of the chronology and the 'floating' older part. The crucial samples were identified and assembled in the chronology in early 1999, and there is now an unbroken pine chronology about 7500 years long constructed from the subfossil forest-limit pines of northern Finnish Lapland. The severe growth depression centred on 330 BC is likely to have been caused by increased wetness. A brief summary is presented of inferred tree-line changes from the location of the samples.