Modern Pollen Spectra From the Western Interior of Canada and the Interpretation of Late Quaternary Vegetation Development

Abstract

SUMMARY The pollen spectra obtained from 127 lake sediment surface samples from the western interior of Canada are examined. Principal components biplots and discriminant analysis are used to investigate the correspondence between modern pollen rain and major vegetation zones in the study area. It is demonstrated that the major vegetation zones in the western interior of Canada can be distinguished on the basis of their modern pollen rain. Principal components biplots and discriminant analysis are also used to compare late Quaternary fossil pollen assemblages from lakes located near the southern and northern periphery of the modern boreal forest with the modern pollen spectra. The results suggest that the late Pleistocene and early Holocene pollen spectra from the southern and northern periphery of the boreal forest lack modern analogues in the western interior of Canada. The northern and southern boundaries of the boreal forest were located north of their modern positions during the mid Holocene. Vegetation developed and responded to mid Holocene climatic change at different rates at the two sites. Modern vegetation conditions were established at both sites between 5000 B.P. to 3000 B.P. Vegetation has remained relatively stable during the last three thousand years.

Lake Area Variability Across a Climatic and Vegetational Transect in Southeastern Alberta

“…Figure 3 suggests that such a low stand occurred during a period when the P-PET index was negative. This would have made the region too arid to support a forest, and so the no-analogue pollen spectra most likely represent parkland rather than forest, in agreement with MacDonald and Ritchie (1986).…”

“…2,4) were initially interpreted as birch forest and mixed wood forest respectively (Lichti-Federovich, 1970). MacDonald and Ritchie (1986) reinterpreted this pollen diagram using a modern-analogues based approach, noting that while the analogues for these zones are poor, they most strongly resemble parkland pollen spectra. A core from the lake contains sedimentological evidence for a pronounced low water stand from 8700-6290 BP (Schweger and Hickman, 1989).…”

A Partial Bison (Bison cf. B. latifrons) Skeleton from Chuchi Lake, and its Implications for the Middle Wisconsinan Environment of Central British Columbia

“…In contrast, the pollen assemblage from Unit 1 is most similar to modern northern boreal forest assemblages (MacDonald and Ritchie, 1986). However, in Unit 1, pollen percentages from the shrub Shepherdia canadensis, and the herbs Gramineae and Artemisia are anomalously high compared to modern analogues from the northern boreal forest region (MacDonald and Ritchie, 1986). Because Artemisia is not a high pollen producer, its moderate pollen percentage indicates its presence in the local flora.…”

“…Compared with other modern lake-sediment pollen assemblages from British Columbia, Alberta and Yukon (MacDonald and Ritchie, 1986), that of Tezzeron Lake is typical of subalpine forest spectra which corresponds to the forest region of this area as defined by Rowe (1972). In contrast, the pollen assemblage from Unit 1 is most similar to modern northern boreal forest assemblages (MacDonald and Ritchie, 1986).…”

Pollen deposition in the boreal forest of west-central Canada

“…A number of studies have described late-Wisconsinan pollen stratigraphy in the western interior of Canada (summarized in Ritchie 1976Ritchie , 1987Ritchie and Yarranton 1978;MacDonald and Ritchie 1986). In these studies, pollen assemblages preserved in lake sediments and peat were used to reconstruct past vegetation.…”