Primary Producers 231 



(1978b) estimates of partitioning of carbon in terrestrial plants, the annual 

 aboveground production of Carex in the pond is 140 to 180 g C m \ root 

 production is equal to the aboveground (140 to 180), while the respiration 

 is 308-396 g C m", mostly in the roots, rhizomes, and stem bases. The 

 total respiration above was estimated from a measure of total net shoot 

 uptake of CO2 minus the production above- and belowground (Tieszen 

 1978b). This amount of respiration is higher than the 20 to 50 g C m ' we 

 have measured for the entire pond (Chapters 4 and 8). Because of the 

 discrepancy, our estimate must be taken as the best available but not 

 necessarily the correct value. 



The above estimates are for the plant stands. To estimate production 

 on the basis of a square meter of the entire pond, the estimates were 

 multiplied by 0.3. 



Arctophila fulva production is quite low in the ponds we studied but 

 can be much higher in ponds where the grass has completely overgrown the 

 whole pond. From the data in Table 5-7, the aboveground production in 

 Pond J was around 20 g dry wt m "^ (7.2 g C) in 1971 or 1.5 g C m ' on a 

 whole pond basis. In Pond L, where A. fulva covered the whole surface, 

 the production was 150 g dry wt m" (54 g C). Root production is 

 unknown but if, as suspected, this plant grows new roots each year, then 

 the underground production will be 30 to 40 g dry wt m "^ (11 to 14 g C) in 

 the stands of Pond J and a similar proportion for Pond L. In the ponds we 

 are concentrating on in this report. Ponds A, B, C, and J, Arctophila is not 

 important relative to Carex even though it does produce more than the 

 phytoplankton. 



Nutrient Content 



The nutrient contents of Carex were determined as a part of a transect 

 study of sites that extended from the driest tundra into the ponds (Tieszen, 

 Mandsager, and Vetter unpublished data). After collection, the plant parts 

 were separated into three groups (see Table 5-8), dried at 60 to 70°C for 1 

 to 2 days, pulverized with a Wiley Mill and then taken to the University of 

 Alaska for analyses (details of methods in Van Cleve and Viereck 1972). 

 Nitrogen was determined by titration of the ammonia released from a 

 Kjeldahl digestion of the plant material. Phosphorus was determined by 

 the molybdenum blue method on a perchloric acid digest while all the 

 cations were measured by atomic absorption. 



The nutrient content of Carex in these ponds (Table 5-8) and also in 

 the terrestrial plants is as high or higher than that of non-cultivated plants 

 from temperate areas (Harner and Harper 1973). This suggests "that 

 tundra plants have adapted to a nutrient-poor environment by producing a 

 relatively small biomass with high nutrient content . . ." (Chapin et al. 

 1975). In the transects, one set of plants from a wet polygon did contain 



