The zone is characterized at all three sites by increasing percentages of Picea (10%), Cupressaceae ([is less than] 5%), Betula (30-65%), and Quercus ([is less than] 5% at Chase Pond and Main-a-Dieu Pond, 15% at Lac a Magie), sharp decreases in Alnus crispa and Cyperaceae to [is less than] 2% throughout most of the zone, and a decrease in Salix from [is less than] 5% to negligible values by the middle of the zone.
Although Alnus crispa pollen increases at all three sites during the Younger Dryas, the-low percentages (3-10%) and PARs ([is less than] 200 grains.
As with the forested sites, the peak in Alnus crispa pollen is attributed to long-distance transport (see discussion in Mayle et al.
Alnus crispa rises in this zone, and total herb pollen decreases.
Alnus crispa, Salix, Artemisia and Cyperaceae remain constant at low levels.
Alnus crispa increases gradually from 6000 to 4500 yr BP, reaching values up to 30%.
This maximum is largely due to the increase in Picea glauca PARs at this time and corresponds to the maximum of Picea glauca and Alnus crispa in the pollen percentage diagram (Fig.
Alnus crispa began to rise slowly, but it is less than clear whether it was growing locally.
Alnus crispa increased significantly at 6000 yr BP, indicating cooler and moister conditions, as suggested by Cwynar and Spear (1995).