Biology Reference
In-Depth Information
Figure 8.5
Quaternary pollen diagram from Crider's Pond, Pennsylvania. Modifi ed from
Ritchie 1987. Used with permission from Cambridge University Press, Cambridge.
len zones denote intervals characterized by particular pollen types and the
inferred climate. Zone 1, for example, indicates the cold, moist climate of a
boreal forest, with representative
Abies
,
Picea
, and
Betula
; zone 2, a warm,
dry hypsithermal interval, with pine maximum; and zone 3, the cool, moist
conditions for a deciduous forest, with
Acer
,
Castanea
,
Fagus
, and
Quercus
.
There may be supplemental diagrams for fungal spores, seeds, diatoms,
phytoliths, macrofossils (e.g., pine needles), bryophytes, and insect re-
mains. Modern pollen rain studies are made to better associate a particular
spectrum with the arrangement and quantitative representation of plants in
a modern community (Gosling and Bunting 2008; Minckley et al. 2008).
For example, at Sicamous Creek Lake in British Columbia,
Abies lasiocarpa
,
which constitutes 50 percent of the vegetation, is 10 percent of the pollen
rain (Minckley and Whitlock 2000); and on southern Vancouver Island,
needles document the presence of
Abies
where the pollen is 1-2 percent
(Heinricks et al. 2002). These and other techniques provide ever-improving
estimates about the composition and spatial arrangement of Quaternary
vegetation and the implied paleoenvironments based on spore and pol-
len diagrams (Delcourt and Delcourt 1991; Birks 1993; Birks and Gordon
1985). Even so, the diagrams refl ect mostly major changes in the dominant
vegetation. To prevent interpretations from exceeding the sensitivity of the
method, a wide array of ancillary information must be incorporated from
a knowledge of the structure, ecology, and composition of local communi-
ties, catastrophic events, glacial geology, isotope records, water chemistry,
