5. POLAR ECOSYSTEMS 



Polar Flora and Vegetation 



The polar tundra with a perma- 

 frost base, as found in the high 

 arctic and antarctic, is one of the 

 most fragile types of world vegeta- 

 tion. As with any ecosystem, the 

 living components in the tundra — 

 the microorganisms, plants, and an- 

 imals — are in delicate balance with 

 their environment; any change in 

 the environment will result in some 

 changes in the composition and rela- 

 tionships of the living components. 

 Since the number of different types 

 of living organisms in the polar 

 tundra are much fewer than in other 

 ecosystems, even small changes often 

 cause drastic changes in the composi- 

 tion and relationships of the living 

 organisms. For example, depression 

 by heavy vehicles, overgrazing, or 

 trampling by animal herds or humans 

 at certain times of the year can result 

 in complete local destruction of the 

 tundra vegetation. (See Figure IX-15) 

 Recovery to the original vegetation, 

 if it occurs at all, takes at least 100 

 years. 



In the arctic, economic develop- 

 ment has already begun and is likely 

 to increase significantly in the future. 

 It is very important that the effects 

 of these developments on the fragile 

 tundra be studied by trained scien- 

 tists so that an assessment may be 

 made as changes take place. In the 

 antarctic, the only threat to the tun- 

 dra is from base construction and 

 tourism; these threats have thus far 

 been moderated by the provisions 

 and recommendations of the Antarc- 

 tic Treaty relating to conservation of 

 antarctic fauna and flora. 



Because it appears to be much sim- 

 pler than the biological systems of 

 the temperate and tropical regions, 

 the polar tundra offers unique oppor- 

 tunities for studying problems in- 

 volving the interrelations between 



the environment and the living or- 

 ganisms. This simplicity in appear- 

 ance results from the lack of large 

 trees, which in other regions make 

 for a distinct multi-level system (the 

 ground, the herb layer, the shrub 

 layer, and several tree-top layers) 

 with many different types of dwelling 

 places for other organisms. In the 

 polar regions, the levels are few, 

 and thus there are fewer complica- 

 tions involved in studying any one 

 of them. Despite this relative sim- 

 plicity, however, it does not neces- 

 sarily follow that the processes or 

 interrelations within the tundra are 

 any easier to understand than those 

 in a temperate or tropical forest. 



Recent Developments in 

 Polar Studies 



In the antarctic, except for areas 

 of the northern Antarctic Peninsula, 

 the tundra is the most depauperate 

 type, composed entirely of nonflower- 

 ing plants, mostly lichens, mosses, 

 and algae. Even where this tundra is 

 present, it is very spotty, dependent 

 primarily on the availability of water 

 in a land where desert conditions 

 prevail and where most of what 

 water there is is unavailable to plants 

 because it is frozen into snow and 

 ice. 



The more humid northern Antarc- 

 tic Peninsula and the sub-antarctic 



Figure IX-15 — A SECTION OF THE TUNDRA BIOME 



The photograph shows a section of tundra or marshy plain near Point Barrow, 

 Alaska. The land is characterized by a lack of trees and an upper surface that is 

 spongy and uneven due to the freezing and thawing of the poorly drained land. 

 The picture shows polygons that are 15 to 25 feet across, a result of winter freezing. 

 Beneath the surface, at depths ranging from a few inches to several feet, is the 

 permafrost, or permanently frozen soil, that is the ultimate limit to plant root growth. 



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