174 F. S. Chapin III et al. 



0.6 



Owl Mound 



o 



c 

 a> 

 u 

 c 

 o 

 o 



o 



■g. 



o 



0.0 



Temperate 

 Plant 



Dupontia ftsheri 



FIGURE 5-15. Estimated compart- 

 mentalization of phosphorus into 

 various classes of compounds in 

 shoots of a temperate plant (Bieleski 

 1973) and Dupontia fisheri from 

 three microsites. Ester-P includes 

 inorganic-P and was determined by 

 a weak acid extraction (Ulrich and 

 Gersper 1978). Lipid was measured 

 (McCown 1978) and assumed to con- 

 tain the same proportion of phos- 

 pholipid as cold-acclimated winter 

 wheat seedlings (de la Roche et al. 

 1972). Phosphorus in DNA is as- 

 sumed to be constant in Dupontia 

 and 40% greater than that observed 

 in temperate grasses (Bieleski 1973). 

 The phosphate contained in RNA 

 was determined by subtraction. 



0.036 



FIGURE 5-16. Seasonal course of ribulose diphosphate 

 carboxylase activity per unit nitrogen in leaves o/ Dupon- 

 tia fisheri, Carex aquatilis and Eriophorum angustifoli- 

 um. (Calculated from Tieszen 1975, Chapin et al. 1975.) 



