Comparison of pollen and conifer stomates as indicators of alpine treelinein northwestern Canadian lake sediments

We compare fossil pollen and stomate assemblages in 29 lake sediment surfac e samples from mountainous regions in northwestern Canada to characterize t he relationship between modern vegetation, and pollen and stomate depositio n. Modern pollen spectra were dominated by arboreal taxa originating from l ower elevation sites. Pinus pollen frequently reached 30% of the pollen sum , regardless of elevation. Alpine-tundra vegetation has lower pollen abunda nce, even in the alpine-tundra zone, where it dominates the sparse vegetati on cover. Fossil stomates were observed in all but one site where trees cur rently exist in the vicinity of the lake, while no stomates were found in t he sediments from alpine-tundra sites. The highest concentration of stomate s occurred in lake sediments from closed-canopy forested areas. Our data su ggest that different boreal forest types may be differentiated based on pol len assemblages and that the presence of stomates clearly distinguishes veg etation zones dominated by arboreal vegetation from alpine-tundra zones whe re trees are not present.