Control of Tundra Plant Allocation Patterns and Growth 185 



shoot growth is primarily a consequence of high rates of maintenance 

 respiration and translocation to roots. 



The evolutionary response of plants to the nutrient-limited environ- 

 ment is to limit production to the formation of a small amount of tissue 

 that is well supplied with nutrients and highly effective metabolically. 

 This would explain the apparent paradox of relatively high nitrogen and 

 phosphorus concentrations in leaves of plants that respond dramatically 

 to nitrogen and phosphorus fertilizers, in contrast to graminoid crop 

 plants where nutrient deficiency is evident in foliar nutrient analysis. 



Rapid upward translocation early in the season supports rapid shoot 

 growth when radiation is most favorable for photosynthesis. Net down- 

 ward translocation begins six weeks after growth commences, a full 

 month before onset of obvious leaf senescence. The belowground carbo- 

 hydrate and nutrient reserves appear to exceed levels required for growth 

 in any given season and may allow the graminoids to successfully survive 

 intensive lemming grazing and to regrow even after successive clippings. 



