|
 Research
Issues:
Paleoecology of Pacific Northwest Parks
(top of page)
Paleoecology of Pacific Northwest Parks:
Background:
Paleoecology is the study of the ecology of life systems of the past. The time depth of paleoecology spans the Earth's existence, while its spatial scale covers the globe. Because of its broad scale, paleoecology is integrative, and it unifies a great many other scientific disciplines. For its database, paleoecology is dependent on the evidence and record of past ecological conditions as these are preserved in the Earth's primary biochemical systems, these being atmospheric, mineral, and hydrologic. Paleoecology is concerned with understanding ecosystems and their components, including organisms, biotic communities, and environments, both their past and present forms. The methodology of paleoecology employs the techniques of many seemingly diverse scientific disciplines within all of the fields of the earth and biological sciences and their specialized subfields, such as geology, biology, limnology, oceanography, entomology, volcanology, pedology, paleontology, archeology, palynology, and tephrochronology, to name several, but always with the objective of investigating ecological processes and conditions of earlier times.
The prevailing environments found in today's Pacific Northwest parks are the products of hundreds of thousands of years of adjustments to changes in the Earth's primary biochemical systems, and the ecological conditions that developed consequential to these changes. As a result, present biotic communities and ecological relationships are not the same ones that prevailed during various time periods in the past, and may differ from those in the future. The three large wilderness parks of the Pacific Northwest, Mount Rainier, Olympic, and North Cascades, encompass steep environmental gradients that are manifested by biotic and climatic diversity, and great ecological complexity. At a local scale, each park reflects a different biogeographic history, while at a regional scale, the common environmental influences shared by the parks reflect broad-scale ecological events of the past. The Little Ice Age, for example, a climatic event that lasted from about A.D. 1300 to A.D. 1850, influenced glacier behavior in all three parks, yet little information exists about the extent of glaciers, individually or otherwise, that characterized this and other climatic events of the past.
Much of the scenery, landscape and ecology of the Pacific Northwest today is a product of dramatic environmental changes that spanned the past 30,000 years. These changes have generally been caused by climatic change, and in particular the effect climate has had on glacial cycles, biogeography, and sea level changes. The most prominent environmental changes are associated with the great ice ages. In the Pacific Northwest, the most recent ice age began about 30,000 years ago and ended only 11,000 years before present. It is known as the Fraser Glaciation and began with the growth of local alpine valley glaciers which peaked about 20,000 years ago. By 18,000 years ago a continental glacier began its advance into the North Cascades from Canada. Approximately 15,000 years ago the ice sheet grew to more than a mile thick and covered all but the highest peaks in the area, which stood as nunataks above the sea of ice and may have been refuges for some plants. Each of the three large parks experienced glacial periods in different ways. At North Cascades, nearly all of today's park area was covered by the Cordilleran Ice Sheet; at Olympic, the ice sheet flowed around the northern and eastern flanks of the range, severing for a time the genetic continuity of some floral and faunal populations, which set in place evolutionary changes according to principles of island ecology; Mount Rainier was unaffected by the ice sheet, but due to its great mass and elevation, it responded by enlarging its local alpine glaciers. Needless to say, during glacial periods, a great many biotic relationships between flora and fauna underwent changes.
While glacial periods were important, there were also interglacial periods characterized by greater warmth than even today's climate. Like glacial periods, the interglacial climates caused a change in the distribution of grassland, forest, and tundra communities, and in sea levels and shorelines. For example, animals that roamed Washington during the last ice age, such as mastodons and ground sloths, became extinct by about 10,000 years ago (Buechner 1953). In another example, the old-growth Douglas-fir forests that are so characteristic in the Pacific Northwest today did not appear until after about 6,000 years ago (Brubaker 1992). From study of fossil pollen, we know that the climate of this region warmed for several thousand years after the ice age. These studies further indicate that the modern climate may have been established about 4,500 years ago. After this time, glaciers are believed to have advanced and retreated three times, the most recent being the Little Ice age from A.D. 1300 1850. Plant and animal communities certainly adapted to the recent climate changes signaled by glaciers, but we have limited information on how the plant and animal communities in Mount Rainier, North Cascades, and Olympic National Parks have responded to climate change of the past.
Information on past adaptations of plant and animal communities would be invaluable to understanding the prevailing ecological conditions in today's parks. Reconstruction of past climates and vegetation patterns would also aid in the interpretation of the entire history of human involvement in the landscape, beginning with precontact, indigenous populations over 10,000 years ago. Compilation of these data would provide park managers with a measure or baseline of past environmental conditions that could be used to predict future changes and to develop management of strategies that address the significant ecological challenges that have been predicted for the future.
Park Focus:
Mount Rainier National Park
North Cascades National Park
Olympic National Park
Research Needs:
What were climate patterns in the three parks over the last 10,000 - 30,000 years? Can detailed climatic reconstructions be completed from pollen records or tree cores for the three parks or for specific watersheds in each of the parks?
How have vegetation communities (forests and meadows) changed over the last 10,000 to 13,000 years?
How did treeline fluctuate, during the Holocene, in the three parks?
How have the frequency and extent of disturbances, such as fire and wind throw, in forest communities, changed during the Holocene? Is the fire frequency pattern estimated through charcoal analysis different from estimates based on tree ring analysis?
How have ecological conditions changed in the lakes over the last 6,000 to 13,000 years?
Development of a radiocarbon chronology for both terrestrial and aquatic Quaternary depositional environments.
Available Resources:
NPS curation facilities and other repositories (such as museums), that house specimens of natural and cultural remains, both present and extinct.
A diatom calibration set is available for the Cascade Mountain Ecoregion. (Eilers, J.M., P.R. Sweets, D.F. Charles, K.B. Vache. 1998. E&S Environmental Chemistry, Inc. Corvallis, Oregon)
Four or five sediment cores will be available for subsampling from lakes in North Cascades National Park by October 2000. The estimated age of these cores ranges from 6,000 to 9,600 years.
References of Interest:
Brubaker, L. B. 1992. Climate change and origin of old-growth Douglas-fir forests in the Puget Sound Lowland. In Implications of climate change for Pacific Northwest forest management, Department of Geography Publication Series, Occasional Paper No. 15, University of Waterloo.
Buechner, H. K. 1953 Some biotic changes in the State of Washington during 1853-1953. Research Studies of the State College of Washington 21, Pullman, WA.
Dunwiddie, P. W. 1983. Holocene forest dynamics on Mount Rainier, Washington. Ph.D. dissertation. University of Washington, Seattle, WA.
Gavin, D. G. and L. B. Brubaker. 1999. A 6000-year soil pollen record of subalpine meadow vegetation in the Olympic Mountains, Washington, USA. Journal of Ecology 87(1): 105-122.
Graumlich, L. J. and L. B. Brubaker 1986. Reconstruction of annual temperature (1590-1979) for Longmire, Washington, derived from tree rings. Quaternary Research, 25: 223-234
Heine, Jan. 1999. Glacier advances near mount rainier at the last glacial/interglacial transition. University of Washington, Seattle. Presented at the Northwest Scientific Association, Tacoma, Washington, March 24-27, 1999. The theme, A Century of Resource Stewardship and Beyond: Mount Rainier National Park 100th Anniversary Symposium.
MacLachlan, J. S. and L. B. Brubaker. 1995. Local and regional vegetation change on the northeastern Olympic Peninsula during the Holocene. Canadian Journal of Botany 73: 1917-1924.
Sigafoos, Robert S. and E.L. Hendricks. 1972. Recent Activity of Glaciers of Mount Rainier, Washington. Botanical Evidence of Glacier Activity. An investigation of the chronology of terminal and lateral moraines of eight glaciers at Mount Rainier, Washington. US GPO. Washington, D.C. 24pp.
Sugita, S., 1990 Palynological records of forest disturbance and development in the mountain meadows watershed, Mt. Rainier, Washington. Ph.D. Dissertation. University of Washington, Seattle, WA.
Back to Research Issues
(top of page)
|
