Introduction 
The approach of the Biome studies of the 
International Biological Program centers around 
the ecosystem concept. We view the soil, the 
vegetation, the microorganisms, and the various 
animal species as parts of an integrated natural 
system. Their interactions, as influenced by 
climate, landforms, and other ‘‘abiotic’’ factors, 
produce the natural ecosystems that we know 
(grassland, forest, desert, etc.). The tundra eco- 
system is dominated by the low winter tempera- 
ture; short, cool growing season, and (at least on 
the coastal plain of northern Alaska) flat topo- 
graphy and presence of permafrost (perennially 
frozen ground) close to the surface. 
The vegetation that grows under these con- 
ditions is characteristically low in stature and 
dominated by grasses and grass-like sedges. The 
variety or diversity of both plant and animal 
species is low. Marked seasonality of ecosystem 
function is an obvious and important feature of 
tundra. A simplified view of ecosystem organiza- 
tion at Prudhoe Bay is shown in Fig. 1. 
Our approach to the study of the tundra 
ecosystem involves: 
1. Identification of the plant, animal, and 
soil organisms that make up the system, and 
their distribution in space (e.g., across major 
landforms) and time. 
2. Measurement of the climatic and other 
abiotic variables that influence the system. 
3. Description of the functioning of the 
plant, animal, and soil elements of the system 
(e.g., plant production, caribou grazing, lemming 
reproduction). 
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4. Study of the interactions between the 
major ecosystem processes of primary produc- 
tion, consumption by animals, and decomposi- 
tion and mineral nutrient cycling. 
An important tool of ecosystem research is 
the ecological model. The model is a formaliza- 
tion of our biological understanding of the 
system. Specific biological processes or inter- 
actions are described by one or a set of logical 
and mathematical expressions; the entire system 
may be regarded as a set of simultaneous inter- 
actions. The ability of these expressions to 
mimic the real system offers a test of our 
biological understanding of the systems and 
identifies gaps and weaknesses. Completed 
ecological models may provide some degree of 
predictive power in answering ‘What would 
happen if ...’” questions. 
The scope and intensity of research at Prud- 
hoe Bay has not been sufficient for the construc- 
tion of a “‘whole system” ecological model; 
however, models have been constructed for par- 
ticular biological processes (e.g., caribou graz- 
ing), and data collected at Prudhoe Bay will be 
used to test models developed through more 
intensive research at Barrow. Thus, Prudhoe Bay 
data are being used to test the generality of 
results obtained at Barrow and other inter- 
national tundra sites. Another purpose of this 
volume is to present observations and data 
gathered by Tundra Biome scientists so that the 
region can be better known to future investiga- 
tors, the industry, and others involved in activ- 
ities at Prudhoe Bay. 
