Future climate changes and the Coleoptera fauna of the Great Lakes Region.
Anthropogenic change, especially the
build-up of greenhouse gases, will probably force some major climate
changes in all parts of the world, and the Great Lakes Region will be
included. Current Global Circulation Models suggest substantial
modification of eastern North American climates. The whole of the Great
Lakes catchment basin, including the headwaters of adjacent catchment
basins will likely experience a 4°C average temperature increase during
summer months (June, July, August) under a doubled carbon dioxide scenario
(expected by 2050 - 2100). Average Winter (December, January, February)
increases will be more extreme. The western half of the Great Lakes
watershed, and adjacent catchments will have an 8°C, increase and the
eastern half of the Great Lakes basin and adjacent catchments a 7°
increase (Canadian Climate Modelling Group, 1993, pers. comm.).
The implications for such changes are
remarkable, but unfortunately they are also relatively unpredicatable. One
potential scenario is shown. The degree of change is unprecedented over
such a short time-frame. The closest comparison, although this was several
magnitudes slower than the predicted future change, were the conditions
experienced at the Laurentide ice margin during the Late Pleistocene
amelioration. At that time there was a widespread extirpation of certain
species throughout the region. The twenty-first century warming will cause
another extirpation event, but the prediction of what species may vanish
is complicated by anthropogenic influences. Human land clearance, demands
for water with draw- downs on aquifers, rivers and lakes, as well as
regional flooding where new dams are constructed for water redistribution
will have significant impacts. Add to these the unknown consequences of
genetic manipulation of species, or more conventional chemical and
biochemical spraying to conserve food and forest resource crops, and the
outcome is extremely unpredictable. Current government cutbacks in museum
curation programmes, the implied lack of importance attached to taxonomy
and the training of new personnel engaged in nomenclatural classification,
means that there is a very real chance that we will never know just what
species have been extirpated or become extinct.
However, this anthropgenically-forced
climatic event could allow us to establish how far, and how fast, species
can move in the short-term warming experiment that awaits. Detailed
baseline studies must be carried out as soon as possible with the aim of
discovering the limits of what species are where today, and research
councils must be committed to long-term collecting and curation programmes
which must last throughout the twenty-first century. The following
programme was verbally suggested at the Ontario Ecology-Ethology
Conference at St. Catherines, Ontario (Morgan 1990b).
At least two collecting programmes should
be created. A small and relatively cheap programme would involve a census
of what Coleoptera species are present at specific elevations on selected
mountains in the New England states and in Québec, New Brunswick and
western Newfoundland, perhaps six mountains in all. This would establish a
vertical thermal gradient for all the species recorded, coupled with
ancillary ecological and climatic data. A second, larger, experiment would
involve the establishment of 15 regional collecting areas, at 100 km
distances, from southernmost (Point Pelee) to northernmost (Cape Henrietta
Maria) Ontario. Here detailed collecting conducted on perhaps a five-year
interval basis would keep track of Coleoptera across ecotonal boundaries
in the province. This transect is practically south to north across
Ontario. The ecotonal boundaries and isotherms tend to cross the province
from east to west. Continuous, discontinuous and sporadic permafrost areas
are represented on this transect. Northern Ontario represents the furthest
south that lowland permafrost and tundra is found in North America. The
southernmost location is well into the Carolinian zone, and the mixed
hardwood and Boreal forests of eastern North America are also well
represented in the central parts of the province. The logistics involved
in both of these collecting programmes are outside the scope of this
paper, but they are suggested as a realistic means of assessing the nature
of future changes in the Coleoptera fauna. If Coleoptera are indeed good
biological indicators of rapid climate change then details of their
movements should help to point the way to what is happening in this
portion of the mid-continent. |