CARBON FLOW AND STORAGE IN A FOREST ECOSYSTEM 



355 



TABLE 3 



CARBON FLUX TO THE FOREST FLOOR BY LITTERFALL 

 AND CARBON STANDING CROP* 



*Litterfall collected over a 3-year period in 20 plastic tubs (0.15 m 2 ) placed at 

 random within a 500 m 2 plot. Mean litter standing crop determined from monthly 

 samples through 1 year. Carbon values were determined on randomly selected 

 litterfall and litter standing-crop samples. 



tBy Walkley— Black procedure as described by Jackson (1958). 



JThe conventional 58% carbon value is generally accepted by soil biologist as 

 the average percent carbon in soil organic matter (Jackson, 1958). 



multiplied by the ratio of the mean maximum net photosynthetic rate reported 

 for these species to the mean maximum rate obtained for yellow poplar of 6.5 

 mg dm hr or 8.1 g g hr . This product was considered to be the annual net 

 daytime C0 2 uptake for the species in question, corrected for variations due to 

 fluctuations in environmental factors similar to those impinging on yellow 

 poplar in the ecosystem being studied. Total dark respiration for these was 

 estimated in a similar fashion, using annual dark CO2 losses for yellow poplar 

 and the appropriate gaseous exchange ratio (Table 4). The mean of net daytime 



