CARBON FERTILIZATION EFFECTS IN A SIMULATED ECOSYSTEM 333 



4000 



3000 



E 

 u 



< 



111 



DC 

 < 

 _l 

 < 



to 



< 



2000 



1000 



All species 

 762-m elevation 

 1.6-m soil depth 

 _£_ , Normal 

 _2_ , + 50% 



20 40 60 80 



YEARS SINCE CLEAR-CUT 



Fig. 2 Simulated change in total basal area per 10- by 10-m plot during the 

 first 100 years of succession following clear-cutting for forest stands whose 

 trees had normal and 50% greater than normal annual diameter increments. 

 Shown are the mean and 95% confidence intervals for 100 replicates in each 

 treatment. 



more southerly latitudes. One expects this elevation to be a sensitive zone for a 

 New England forest. Since none of the species is at its optimum, any 

 environmental change might have a strong effect on any species, and 

 perturbations might produce more pronounced effects here than elsewhere. 



Experiments were carried out at four levels of treatment: 10, 20, 50, and 

 100% increase in annual individual tree growth. The predicted effect on total 

 basal area for 50% increase during the first 100 years of secondary succession is 

 shown in Fig. 2. Although the total basal area of the treated forest is 

 significantly greater than the normal forest during the first and second and later 

 decades, there is no significant difference for the third, fourth, and fifth decades. 

 At the end of 100 years, the ratio of the treated to normal means is 1.4 : 1.0; 

 however, with 95% confidence this ratio could be anywhere between 1.15 : 1.0 



