Ice age forest spruces up ecology record

Sand-mining operations in Michigan have uncovered a true forest primeval—a 10,000-year-old spruce woods buried in sand.

A logger slices into a 10,000- year-old spruce tree. Michigan Technological University

The trees probably died after being flooded by retreating glaciers at the end of the last ice age, says Kurt S. Pregitzer, a forest ecologist from Michigan Technological University in Houghton, who led the forest excavation.

Sand and water quickly buried and preserved the forest. The trees, some up to 145 years old when they died, were still standing when the forest was discovered. Many sported bark and twigs. Spruce needles, pinecones, and mosses blanketed the floor.

The researchers cut cross-sections from the 140 standing trees. All were spruce, but pollen from the forest floor and surrounding lakes indicates pines and hardwood trees nearby.

The same conditions that favored the ancient spruce forest seem to occur today in the far north and at high altitudes where forests are expanding, say the researchers in the Feb. 21 Journal of Ecology. The team hopes that analysis of the tree-ring record from the spruces will tell more about the climate at the time the forest died.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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