The significance of oceans and seas on climate and phytogeography
has been well documented. The effects of smaller bodies
of water, i.e. lakes, has been much less intensively studied.
Of prime importance to the phytogeographer specializing in these regions
is the unique interactions between lakes, climate, and plant distribution;
which have been shown to create, in association with other factors,
an extremely varied and interesting flora.
Lakes Baikal and Superior, the world's largest freshwater lakes,
provide an interesting opportunity for documenting the effects of large
lakes upon climate and examining the effects of this on plant distribution.
The comparison of phytogeographical conditions, in view of the global
position of these two lakes, can serve to illustrate certain effects
attributable to the limnoclimate, topography, overall species distribution,
and many other factors involved in the vegetation of the areas at Lakes
Baikal and Superior.
Purpose of this paper:
Lakes, in particular, large lakes, have an area which is climatically
directly affected by the body of water. The focus of this
study is upon the phytogeographic similarities and variations of these
climatic influence areas at Lakes Baikal and Superior. The
purpose of this paper is to (1) show the phytogeographic conditions
of the Lake Superior and Lake Baikal areas, and examine some of the
main influences on this phytogeography, e.g., mainly macro- and microclimate
in this paper, but also geology, topography, soils, and human influence,
and (2) to compare the occurrence of some important plant
taxa and plant communities in the two areas, and suggest reasons for
their differences and similarities. The specific tool of
measurement used for analysis will be the locus and ecology of plant
communities and species within these areas. Because the
vegetation communities of the areas are exceedingly plastic and varied,
i.e., complex, and because the influences of various forces on these
communities are also extremely complex, it will be necessary to generalize,
and to use representative species, genera, and vegetation associations,
rather than cover a large number of variants individually.
This paper is not intended to be a comprehensive study; however, it
is intended to show that there is a great need for further work regarding
The occurrences of plants at Lakes Baikal and Superior is dependent
on many individual parameters of climate, soil, competing vegetation,
disturbance, and countless others; hence it is not possible to fully
explain in detail why the floras of these areas appear as they do in
relation to each other. However, based on the specific examples
observed and documented in the literature, it is possible to draw upon
several general observations and make a few conclusions.
The first observation is that Lakes Baikal and Superior, like
other large water bodies, have a marked influence on the surrounding
climate, and that many of these climatic enhancements can strongly affect
plant growth and distribution.
The second is that a large number of plants do follow closely
the presence of the lakes: some are conspicuously absent from the lake
areas; some make range extensions toward the lakes; some follow only
the shorelines at the lakes; some are disjunct from distant locations
at the lakes, and some are endemic and found nowhere else.
A third observation is that both Lake Baikal and Lake Superior
are located to a large extent in the northern forests, and within this
circumboreal formation, a large number of plants and plant communities
have been shown to be identical in species or genera.
The final of these observations is that the occurrence of plants
at the lakes does not necessarily follow a regular pattern; while many
areas such as islands and the rocky shores of Lake Superior have been
found to be areas of disjunct or rare species, similar areas nearby
may have normal vegetation patterns. In addition, there
may be features unrelated to limnoclimate which are sufficient phytogeographical
"magnets" for rare species, such a feature is Ouimet Canyon near Lake
Based on the observations above, inductive logic points toward
the following: Lakes Baikal and Superior, both with very large
surface areas, volumes, and depths, have a marked limnoclimatic effect
on the surrounding areas. This limnoclimate greatly changes
the normal climate in the area in which it occurs, and thus appear as
climatic "islands" distinct from their surroundings. These
areas have very special phytoclimatic conditions which allow a number
of plants to survive which are normally found elsewhere, while at the
same time allowing many of the typically boreal or northern species
to remain. In these areas, variations in local conditions
of climate, soil, topography, disturbance, vegetation, and others determine
how strong the limnoclimatic factor will affect the occurrence of species
and communities. Therefore, the occurrence of specific vegetation
types, while somewhat predictable is not entirely predictable.
It seems evident, then, that the limnoclimatic influence areas
of Lake Baikal and Lake Superior share many climatic and phytogeographical
processes unique to large lakes and to the boreal forest, as well,
the two areas share a great many identical species and genera.
. They are also different in several aspects, and these
differences give important clues to the controls on plant distribution
in such areas. Further study of this area of phytogeography
would be helpful in documenting these similarities and differences,
and explore further the reasons for these, as well as perhaps helping
to unite the human inhabitants of these areas as well.