75 



Ihis gives lor Oxalis an inlensily ol assimilalioii of ahoul O.r. mg. 

 per 50 cm.-, al 18", and for 1 hour. Bul since llic CO., pressure 

 is in reality ahoul 40% higher (see p. 71), Ihc actua) assimilalion 

 according lo lig. 5, becomes about O..;,-^, mg. And al moic favour- 

 abie moments it runs up lo 1 mg. and över. In Slrlhiri,, Ihc in 

 erease is nol (juile so greal. 



1'lioto. tlio aiitlior 



Fig. 7. Vegetation of Oxalin Acefosella at tbe .southern side of a licpfh in th« 



Ulagap-bog. 



Whal this involves for the foresl-vegelalion in ils enlirely is 

 obvious. The higher CO.^ pressure is certainly an importanl con 

 dition for Ihe exislence of Ihe shade-planls under less favourai)le 

 condilions of lighl. The shade Hora however slaniis in man\ 

 places on Ihe limil of the minimum of exislence. and liiorcfore 

 depends on cerlain climalic condilions lo a niuch grealer exlenl 

 Ihan Ihe sun Hora. Windy and dry summers have an unfavour 

 able elTecl by diminishing the available supplies of (U)., ; during 

 rainy summers on the other hand Ihe supply of lighl sinks. so 

 Ihat the shade plants die much more (juickly than wouid olhetwise 



