Environmental Problems

Phenomena that significantly interfere with the structure and function of ecosystems over a major portion of the lifetime of the longest-lived organisms can generally be classed as environmental problems. Widespread concern regarding the prospect of large-scale resource development in the Arctic was first expressed over 30 years ago in the early to mid-1970s. Human activities and concomitant environmental problems are presently more extensive within the tundra biome than in the past. Large portions of the region are faced with widespread threats ranging from oil and gas development to wilderness recreation. Direct human effects on Arctic ecosystems may be even more imperative than climatic change in the next few decades. These effects include disturbance associated with, for example, resource exploitation and altered grazing regimes due to changing patterns of reindeer husbandry. Recent models acknowledge that land management policies (for instance, fire suppression, reindeer husbandry) have as much or more effect on northern vegetation and soils as expected changes in climate, but human land-use is still underrepresented in most models.

Perhaps the greatest overall threat to Arctic ecosystems is climatic warming, generally predicted to be particularly pronounced in polar regions. Belowground stores of carbon in the Arctic are enormous and threaten to exacerbate climatic warming if methane and carbon dioxide are released through the warming of soils and permafrost. Assuming a doubling of atmospheric CO2, and no constraints on migration of species, it has been calculated that the Arctic tundra area would decrease by 20-32% due to northward expansion of the boreal forest. This would profoundly affect, for example, geographic ranges and habitat conditions for herbivorous ungulates such as caribou, muskoxen, and elk, and other grazing animals. Such changes would, in turn, manifest potentially serious consequences for indigenous and nonnative herders and hunters. Arctic vegetation and soils have often been considered particularly susceptible to disturbance, that is, "fragile," but fragility is ill defined and perhaps, with use, has come to be an oversimplification. In fact, a limited number of species provide forage for a vast number of animals. The implications of these plant-animal links indicate that the elimination of one or more of dominant species could result in profound changes in the structure and function of Arctic ecosystems, especially those of the High Arctic. In this sense these systems are fragile.

A major challenge for the scientific community is to predict how vegetation composition will respond to these various environmental changes and what the consequences for Arctic ecosystems will be. Even moderate warming is likely to cause a massive increase in thermokarst (subsidence of surface due to thawing), particularly in ice-rich permafrost regions such as northern Alaska and northwest Siberia. If this occurs, one can expect an increase in the numbers of small and large patches with exposed soils. Stimulation of plant reproduction by increased temperatures would likely be most significant in these disturbed areas, and transient responses of both plants and animals to environmental change would become more important. Even without a warming climate, the extent of disturbed surfaces—including thermokarst triggered by mechanical impacts—is likely to increase as development continues. It has been suggested that anthropogenic habitat loss will prevent many species from colonizing new habitats when their former habitats become unsuitable in the course of climatic warming.

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