CLIMATE AND WATER RELATIONS 



165 



150- 



130- 



110- 



0>9O 



> 70 

 V 



SO 



^130 



c 



110 



9Q 



70- 



50- 



30- 



JASONDJF MAMJJASONDJFMAMJ 



1 1 I I 1 ' I I I I I I 1 I I I I I J ! 1 1 L 



Pinus cembra 



Loiseleuria procumbens 



Picea zxczlsa 



needles begin to drop ^ — — 



Rhododendron ferr. 



ISO 

 130 

 110 

 ■90 

 70 

 -50 

 -130 

 110 

 ■90 

 70 

 50 

 30 



T 1 r 1 1 1 1 1 1 1 1 1 1 1 1 1 : 1 1 1 1 1 I r 



J ASONDJFMAMJ JASOTJDJFMAMJ 



Fig. 8. Natural (circles) and sub-lethal water content (solid line) in percentage of dry 

 weight of several sub-alpine plant species without snow cover at the Patscherkofel 

 in winter. (From Larcher, 1957). 



In winter the dehydration of needles of grown up spruce trees [Picea 

 excelsa) approached the critical hinit more than that of the adult pine trees 

 especially if we take the beginning of the dropping of their needles as an 

 injury. 



Tables 



Injury delay of cut-off leaves and twigs exposed to the open air in February and March 

 (Pisek and Berger, 1938) and drought stress (actual as per cent sub-lethal deficit) 

 (Hofler, Migsch and Rottenburg, 1941 ; Larcher, i960) in the natural habitat 



