462 F. S. Chapin III et al. 



Atmosphere 



Rr = 40 



Pw = 202 



Rw = 38 



C= 40 



PNw= 164 



RC = 0.05 



Carnivore (0.001), . 



I I 



I I 



Herbivore (0.09)f- vV" 



I ' ' 



PRw = 31 I 



Rh= 1.2 



Live vascular 

 aboveground 



>f — 



Dead vascular 

 aboveground 



251 



PRo = 44 



Live vascular 

 belowground 



I I I 

 I I I 



P = 12 



M 



Rfui - 2 



PNm = 10 



Rn = 21 



18 



Live 

 moss 



PRm=16 



8 



347 



Dead vascular 

 belowground 



Invertebrate 



Eli I 



ganisms -L. 



[p 



Microorganisms 



Dead 

 moss 



1 



X 



30 



Litter 



• COo transfers 



. ^—Organic C transfers 



FIGURE 12-1. Carbon budget of the wet meadow vegetation type at the 



intensive study site to a depth of 20 cm. The number in each box is the pool 

 size of carbon for that compartment expressed in g C m'^ to a depth of 20 cm. We 

 assume that carbon constitutes 44% of organic material, the average measured at 

 another Alaskan tundra site (Chapin et al. 1979). The area of each box is propor- 

 tional to its compartment size. Values next to arrows indicate the annual carbon 

 fluxes between respective compartments (g C m~^ yr'J. Pv and Pm - net daytime 

 photosynthesis of vascular plants and moss, respectively; PNv and PN^ = net an- 

 nual carbon exchange between atmosphere and aboveground vascular plants and 

 mosses, respectively; Rb, Rd, Rh, Rc - respiration of vascular belowground, de- 

 composers, herbivores and carnivores, respectively; PRg, PRv, PRm - net annual 

 production of vascular belowground, vascular aboveground and mosses, respec- 

 tively; C - net carbon flux from atmosphere to community; A = net annual ac- 

 cumulation; E = export in runoff. Animal compartment sizes assume peak lem- 

 ming abundance to indicate maximal animal role. All other data were collected in 

 1970 and 1971, years of low lemming abundance. All values shown were obtained 

 independently by direct field measurements, extrapolated to an annual basis, and 

 corrected for light and temperature. Values for vascular plant and litter carbon 

 are calculated from Tieszen (1972b) and Dennis (1977), moss carbon from Oechel 

 and Sveinbjornsson (1978), and soil carbon from Flint and Gersper (1974). Refer- 

 ences for transfer values are given in Table 12-4. 



',^ 



