Researchers study ancient Lake Saimaa shorelines exposed by low water

The Natural Resources Institute Finland (Luke) is using Lake Saimaa’s exceptionally low water levels to investigate past dry periods, the public broadcaster Yle reports.

Exposed tree trunks and root systems along the shores may provide evidence of previous low water levels. In some cases, trees have grown below the current shoreline, indicating the water was once even lower.

Samuli Helama, a senior researcher at Luke, said the findings could reveal lake level fluctuations dating back hundreds or even 1,500 years, helping compare historical dry periods with current climate change.

Most of the root systems under study are likely pine, as the species tolerates varied conditions and decays slowly.

Researchers are asking local residents, cottage owners, and boaters to report suitable root systems for study. Reports will first be mapped, after which researchers will contact some submitters to collect samples, pending permission from water cooperatives.

Samples are cut with a chainsaw into disc-shaped sections, revealing growth rings that are measured under a microscope. These are compared with existing tree-ring data from Lake Saimaa, where a 1,500-year tree chronology has already been established.

Helama described tree rings as “barcodes” that allow researchers to build a timeline by matching patterns, identifying which trees grew simultaneously.

The project spans multiple years, with no prior known similar research on ancient shorelines in Finland.