346 POLAR PROBLEMS 



to six weeks is the vegetation, except lichens on cHff faces, exposed 

 to sunlight. The ground thaws to a depth of a few inches only on a 

 few cloudless days about midsummer and even then is saturated 

 with ice-cold water in which the root hairs of plants are physiolog- 

 ically inactive. 



These influences are detrimental to plant life and make it prac- 

 tically impossible for higher plants to complete their life cycles. A 

 plant would be unlikely to reach the flowering state and would have 

 no chance of maturing its seeds. Even in the Arctic summer, with 

 its eight to ten weeks' growing season, plants have to "rush" their 

 life cycle, often flowering before the snow is off the ground and even 

 then finding the summer too short for sexual reproduction. The 

 low means of the Antarctic winter, which fall as low as -35° C. on some 

 coasts, are probably no more detrimental to plant life than means of 

 zero. Antarctic mosses which are frozen solid for ten or eleven months 

 grow vigorously for the rest of the year. 



Other Causes 



In addition to these principal causes there are contributory factors 

 in the poverty of Antarctic plant life. The chief sites for plant growth 

 are small islets and rocky coasts. In such places winds help to clear 

 the snow, but they are chiefly cold, dry winds blowing out of the Ant- 

 arctic anticyclone and are detrimental to plant growth by their active 

 promotion of transpiration.^ Lack of soil has been suggested as an 

 adverse influence, but it cannot be of first importance, since many 

 places that are devoid of vegetation have several inches of soil well 

 impregnated with bird guano. On comparable sites in the Arctic 

 vegetation w^ould be luxuriant. A few samples of soil from South 

 Victoria Land proved on analysis to be alkaline owing to the accumu- 

 lation of carbonates and zeolites and the absence of organic acids, but 

 they were not valueless for plant growth. In several of the samples 

 wheat was grown in Australia and showed rapid germination and 

 unusual vigor. 



Apart from climatic influences the greatest enemy of plant life 

 is found in the penguin. In spring and summer myriads of these 

 sea birds occupy every site which is at all favorable to plants. Nothing 

 escapes their insatiable curiosity or fails to prove attractive to their 

 beaks. Any plant which had gained a footing on a penguin rookery 

 would stand a poor chance of survival. 



5 Carl Skottsberg: On the Zonal Distribution of South Atlantic and Antarctic Vegetation, Geogr. 

 Journ., Vol. 24, 1904, pp. 655-663. 



