Stability and Fragility in Arctic Ecosystems
Keywords: Active layer
AbstractThe conclusions reached in this paper, concerning the "Fragile Arctic" are the following: 1) Two definitions of ecological stability are in use, and it is essential to keep them separate and explicitly stated. "Type-l stability" is the condition of non-oscillation, or nearly non-oscillation and steady state found in certain tropical situations, the result of continued evolution toward greater economy of energy and involving high information content and low production/biomass ratio. This type of stability is highly vulnerable to serious perturbation, to which it cannot adapt. Such systems may thus be called "fragile" and they are found in the tropics and perhaps in certain parts of high latitude systems, such as lakes, subarctic forests and perhaps the tundra vegetation itself. "Type-2 stability" is the condition of ability to absorb serious perturbation and return to a stable state, usually the status quo ante. This involves system oscillation, smaller information content, higher production/biomass ratios, and lesser economy of energy use. This type is found in mid and high latitudes, in which the physical environment itself oscillates considerably. 2) In tundra environments, extreme ecosystem simplicity in the animal communities leads to extreme oscillation, and it is suggested that such oscillations can be tolerated only if the geographic scale is large, which it is in the Arctic. 3) "Thermokarst", or damage to tundra terrain by damage to, or removal of, the active layer, is a serious hazard which is well understood and can be easily avoided. It is upon this that the "fragile Arctic" reputation is founded. 4) Oil in arctic sea water constitutes a serious hazard, probably more serious than in warmer waters.