Wanted: Old wood for research
The annual rings of old pieces of wood or even logs are important pieces of the puzzle in climate and environmental research.
When a piece of wood or even an entire log comes to light in a gravel pit or construction site, it often ends up as worthless trash in the incinerator. For scientists, however, it can be worth its weight in gold. The annual rings of ancient wood can accurately reflect environmental and climatic conditions. Such unique archives offer the possibility of reconstructing growth conditions thousands of years ago. Tree-ring researchers at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL are therefore always on the lookout for such valuable wood.
Time and again, individual wood finds were reported to the researchers in the course of excavation work in Zurich. In close cooperation with tree-ring laboratories throughout Switzerland, the WSL scientists are now expanding their campaign "In search of old wood" systematically from.
First reports of finds across Switzerland
For example, in cooperation with the local forestry service in Celerina (GR), about 70 spruce and pine trees were recently recovered from a depth of about 8 meters. This find resulted in the course of the construction of a pumping station in the district of Maloja. First radiocarbon (14C) measurements in the Laboratory for Ion Physics at the ETH Zurich date the trees to about 3500 years BC.
Another 50 trees were recovered near Engi (GL) with the support of the local construction company during the construction of a flood protection embankment. This find was probably buried by a debris flow to a depth of approx. 5-7 m and preserved in the clay.
Near Aigle (VS), collaboration with the Swiss Holcim AG enabled the sampling of 28 subfossil oaks from a gravel pit. First dendrochronological measurements of the trees showed that they were included about 4300 years ago B.C.
More puzzle pieces wanted
"Every tree counts!" emphasizes Frederick Reinig. As a doctoral student at WSL, he is currently analyzing the 256 subfossil tree stumps found in 2013 in Zurich's Binz district. "This find, which is about 13,000 years old, is unique because of its size and age," Reinig explains.
However, to better understand the environmental conditions at the end of the last ice age, more wood samples are needed. Smaller finds or even single trees can be important pieces of the puzzle to close temporal gaps between previous measurements.
