Pollen whiskers, rational limits and cryptic refugia: Determining the local presence of spruce on lateglacial landscapes of eastern Canada

•Pollen limit for the presence of spruce refined using stomates and macrofossils.•Spruce is present when the relative abundance of spruce pollen is as low as 8%.•Stomates are more reliable than macrofossils for identifying the presence of spruce.•Spruce may contribute as little as 4% pollen and be present on the landscape.

The 20% spruce isopoll has traditionally been used to identify the range limit of spruce in eastern North America. Using plant macrofossils and stomates in a network of 25 lateglacial-aged sites throughout Nova Scotia, we identified sites where spruce was locally present but contributed as little as 4% to the pollen rain. Our data suggest that 8% pollen abundance is a more reasonable limit that consistently indicates the local presence of trees. Using 8% to define the presence of spruce, we find that the number of sites likely to contain spruce increases from 3 to 11 as compared to using the 20% isopoll. The resulting increase in the estimated distribution of spruce leads to a reduction in the apparent migration lags and migration rates of spruce into the region. Reducing the error in distribution histories will provide better-constrained estimates of climate change and its impact on the local vegetation.