CiiAi". I] THE FORMATIONS 165 



direct rays of the sun, and should therefore necessarily assume about the same 

 temperature as the soil. Care was also taken that the seedling-trees experimented 

 vvitli, and which stood in the forest-nursery at Mariabrunner, should be under 

 xternal conditions at least approximately similar to those of the difl'erent parts 

 Df the crowns of trees in the forest. 



AVERAGE 'AMOUNT OF TRANSPIRATION FROM JUNE i TO 

 END OF NOVEMBER (after Von Hohnel). 



(The figures represent gr.inis of water lost on loo grams dry weiglit of foliage or needles.') 



iirch 67-987 



Jme 61-519 



^sh 56689 



^ornbeam 56-251 



ieech 47-246 



Corway maple .... 46-287 



ycamore 43'577 



'omnion elm 40'73 1 



Pedunculate and sessile oak . . 28-345 



Turkey oak 25.333 



Common maple .... 24-683 



Spruce 5-847 



Scots pine 5-S02 



Silver fir . . . . . 4-402 



Black pine ..... 3-207 



Von Hohnel came to the conclusion regarding the amount of water used by 



hectare' of beech high-forest 115 years old, that 'according to various 



ssuniptions it amounts to 3.587,000-5,380,000 kilograms of water during the 



egetative season. A beech wood, fifty to sixty years old, during the six months' 



getative season transpired 2,330,900 kilograms per hectare, and a beech-pole 

 ood, thirtj' to forty years old, transpired in the same period 680,000 kilograms.' 



Since the total rainfall, roughly speaking, during the whole year amounted to 

 000,000 kilograms, it corresponded excellently with the results of tiie transpira- 

 m obtained in the experiment -. 



Besides the few trees tliat arc hygrophiloits during the vegetative season, 

 id alone occur in Central Europe, there arc also some that are markedly 

 'rophilous, in fact some that will thrive on the driest desert-soil. It may 

 rove to be one of the most interesting tasks for future botanical travellers 

 i investigate the conditions of life of these markedly xerophilous trees, 

 r example those that appear in great variety in dry savannahs and in 

 epical deserts. 



The depth of their root-system renders it possible for trees to thrive in 



ras ivlicre long seasons of dronght accompanied by great heat recur 



-iodically, as in the Mediterranean countries, in Cisgangetic India, 

 id in the Soudan. The incorrectness of the opinion frequently held, 



at forest for its proper development requires atmospheric precipitations 

 all seasons of the year, but especially during the vegetative season, 



satisfactorily shown hy the occurrence of forest in regions with hot 



y seasons. 



It is neither frequent atmospheric precipitation nor a rainy vegetative 



' 2-47 acres. - Von Hohnel, op. cit., p. 290. 



