Subfossil forest in Leusden, the Netherlands, died around 12,750 years ago due to abrupt climate change

Today a team of scientists presents the results of tree ring research of 167 trees that were excavated in 2016 during a nature development project at the Den Treek-Henschoten Estate in Leusden (Netherlands). The find of this approximately thirteen thousand year old subfossil forest received a lot of media attention in March 2017, because it is a unique find for the Netherlands. About 15 comparable sites are known within Europe. The study of the pines fits in with research into climate change in the latter part of the last ice age (14,700 to 11,700 years ago). This exceptional period provides climate researchers with a laboratory for studying the effects of climate change in our time.

Excavation of the subfossil forest, Leusden, the Netherlands
©RCE
Researchers creating a cross-section of a tree for dating research.

Hunter-gatherers

The trees found, 165 pines and 2 birches, are part of two different forest stocks that grew at different times.

Using the 14C dating method it was possible to date both series accurately. The oldest series lived between about 13,475 and 13,390 years ago and the youngest between 12,995 and 12,745 years ago. A comparison with temperature data for this period - based on research on Greenland ice cores - shows that local forest development can be explained by relatively rapid processes of warming and cooling. The demise of the forest from Leusden at ca 12,745 years ago can be unequivocally associated with a very abrupt drop in temperature around 12,850 years ago, the start of the so-called Younger Dryas Climate Event.

The research provides a unique insight into the environmental changes that the hunter-gatherers in this area had to deal with at the time. In just a few generations, a large and open forest area turned into a tundra. Vast expanses of large amounts of dead pines provided a tangible reminder of this profound change for those who were able to radically change their way of life. It was not until a thousand years later, at the beginning of the Holocene, that birch and pine came back.

Notes

The results of the research will be presented during a press conference on November 3, at 2 p.m. at the Landgoedkantoor of Landgoed Den Treek-Henschoten, Treekerweg 11a, Leusden (Netherlands). Please register via d.muller@cultureelerfgoed.nl. Afterwards the site can be visited and you can discuss the results with a delegation of the researchers. The annual meeting of the Palynologische Kring in advance (from 10 a.m.).

On November 3, it will be announced that the research has recently become available in open access: Environmental changes in the late Allerød and early Younger Dryas in the Netherlands: a multiproxy high-resolution record from a site with two Pinus sylvestris populations - ScienceDirect.