Northern Asian forests

Forests in northern Asia had fewer trees at the peak of the last Ice Age compared with their modern counterparts.

Credit: US National Oceanic and Atmospheric Administration

Earth's climate both influences and is influenced by vegetation. It is therefore important to understand past variations in vegetation cover. A recent study finds that the density of trees in forests during peak conditions of the last Ice Age — the Last Glacial Maximum — was moderately lower than in today's forests.

Fossil pollen grains can be used to infer the types of past vegetation. Pavel Tarasov from Free University, Germany and colleagues¹ used an extensive compilation of data on modern and fossil pollen collected from various locations in northern Asia in order to reconstruct the tree density during the Last Glacial Maximum. They first calculated modern tree density using remotely sensed as well as pollen data. The relatively robust agreement between estimates based on the two methods and the quantitative relationship between them allowed the authors to use data on fossil pollen to estimate what the tree density in northern Asia could have been around the Last Glacial Maximum. The results indicate that during that period, areas that are forested at present were much more open with lower vegetation density.

These findings support moderately low tree cover density, but not a complete absence of trees and substantial reduction in northern Asia as had been suggested earlier, during the peak of the last Ice Age.