356 



REICHLE, DINGER, EDWARDS, HARRIS, AND SOLLINS 



TABLE 4 



CARBON DIOXIDE EXCHANGE RATES FOR TREE SPECIES 

 OCCURRING IN THE TULIP POPLAR FOREST 



Mean net photosynthesis 



Species 



mgC0 2 dm" 2 hr 



mg CO, g"' hr" 



Liriodendron tulipifera 6.5 



Quercus albat 5.2 



Quercus borealis maximal 5.5 



Quercus macrocarpa% 6.5 



A cer saccharu m % 4.6 



8.1 



•Net daytime C0 2 uptake for all species was calculated from ratios of maximum net photosynthetic rate measured 

 for Liriodendron in situ to maximum net photosynthetic rate reported in the literature for other species. 

 tKramer and Decker (1944). 

 JWuenscher and Kozlowski (1970). 



TABLE 5 



NET CARBON DIOXIDE UPTAKE AND DARK 



RESPIRATION FOR MAJOR VEGETATIONAL COMPONENTS 



IN THE TULIP POPLAR FOREST 



•All values on dry weight basis. 



C0 2 uptake (10.5 g/g) and dark respiration (1.0 g/g) rates, estimated for 

 associated overstory species was used to calculate total carbon dioxide flux for 

 this component. 



Net CO2 uptake per 24-hr period over the entire growing season is calculated 

 to be 11.3 g/g of foliage, using 70 mg/g net C0 2 intake for L. tulipifera and 

 subtracting respirational losses. This estimate compares to values of 14.5 g/g and 

 8.9 g/g for white oak and scarlet oak, respectively, in the Brookhaven 

 forest (Botkin, Woodwell, and Tempel, 1970). Multiplication of C0 2 uptake per 

 gram of leaf by leaf biomass (Table 2) yielded a daytime C0 2 uptake for yellow 

 poplar equivalent to 3100 g/m 2 (Table 5). Uptake by associated overstory 

 species became 801 g/m 2 . Dark respiration by these components resulted in loss 

 of 382 g/m 2 . Carbon dioxide uptake and release by understory species were 

 considered as being proportional to the leaf biomass of this component, yielding 

 an annual C0 2 uptake and dark respiration of 5 33 g/m and 52 g/m 

 respectively. 



