Primary Producers 229 



^\' - 100 



o -o 

 DO cP 







FIGURE 5-31. Biomass and productivity o/Carex aquatilis in 

 Pond C, 1972, based on '"C uptake. 



Johnson (1970) and Billings et al. (1978) that during the summer peak of 

 aboveground graminoids at Barrow, 85 to 98% of the live vascular plant 

 biomass is made up of roots and rhizomes. Shaver and Billings (1975) state 

 that this high root-to-shoot ratio in arctic terrestrial plants is an effect of 

 low nutrient levels, low soil oxygen levels, and high soil moisture content. 

 All these factors act to decrease the effective uptake of water and nutrients 

 by a unit of root surface. 



This high ratio of root-to-shoot is also found in other aquatic plants 

 so it is not a unique feature of arctic plants. Westlake (1968) reports that 

 these ratios of roots to total biomass in a temperate reed swamp were 83% 

 for Phragmites, 85% for Equisetum, and 90% for Scirpus. 



Realistically, the root-rhizome weight we measured may be too high 

 as it is likely that too much dead material was included. For example, 

 Shaver et al. (1979) carefully dissected whole root systems from the tundra 

 and found that 62% of the plant was root and rhizome (small roots may be 

 lost). Dennis et al. (1978) consider that on the Barrow wet meadows there 

 is a subsurface standing crop (live) of 534 to 620 g m ' for an 

 aboveground maximum standing crop of 80 to 130 g. The aboveground 

 standing crop is up to twice this in the ponds (Table 5-7) so a value of 1000 

 to 1 200 g dry wt m " is reasonable for belowground living matter. 



Roots of Carex are found down to a depth of 25 cm in the sediment 

 but most are concentrated in the 10 to 20 cm layers; about 85% of the total 

 belowground biomass occurs in the top 10 cm (Shaver and Billings 1975). 

 These authors report that roots live for 5 to 8 years but can elongate only 

 for 2 to 3 years. In contrast to the above description, Arctophila has low 

 amounts of root biomass. By analogy to similar terrestrial plants (Shaver 

 and Billings 1975), such as Eriophorum, the roots likely live only 1 year. 



