A hierarchical classification system of Iceland's
watersheds and rivers is presented. The classification
is based on Iceland's substrate, climate, water, biota,
and human cultural influences. The geological formations
of Iceland are very different in character depending on
their age and formation history. Three major types of
formations occur: Tertiary, Plio-Pleistocene, and
Pleistocene. These formations have different
hydrological characters and different landscapes. There
are also large differences in the climate within Iceland.
Four major river types are found in Iceland: spring-fed
rivers in Pleistocene areas, direct runoff rivers in
Plio-Pleistocene areas, direct runoff rivers in Tertiary
areas and wetland heath rivers in Tertiary areas. Eleven
biogeoclimatic regions occur in Iceland, each having a
different watershed type.
The classification together with life history theory
can explain the distributions, abundances, and life
history strategies of Icelandic salmonids. Oceanic
conditions must also be considered to explain the life
history patterns of anadromous populations. When the
freshwater and marine habitat is stable, the life history
patterns of individuals in a population tend to be
uniform, one life history form being most common. In an
unstable environment many life history forms occur and
the life span of one generation is long. The properties
of the habitat can further explain which life history
types are present. In the most stable and favorable
rivers of Iceland resident life history forms are more
common.
Such a classification of a river habitat greatly
aids the understanding of the habitat and how it enables
and constrains the salmonid populations within it.
Consequently adaptations in life histories are better
understood and conservation, utilization, and management
of these valuable natural resources are made more
coherent and efficient. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37370 |
| Date | 17 May 1990 |
| Creators | Gudjonsson, Sigurdur |
| Contributors | Warren, Charles E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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