294 CAIN, DE OLIVEIRA CASTRO, PIRES, AND DA SILVA 



C curves. The Castanhal sampling was continued to 3.5 hectares and 179 

 species. The three curves at the 1 -hectare point and two of them at the 2- 

 hectare point are running about 24 species apart, with the Mucambo flora 



192 



160- 



128 



96 



64 



32 



10 



12 



14 



16 



18 



20 



1000 square meters 



50 



40- 



i5 30- 



C/) 



20 



10 



<1 1-2 2-4 4-8 8-16 16-32 32-64 64128 



Density 



Fig. 1-2. — Fig. 1. Species-area curves for samples of terra firme rain forest 

 in region of Belem, Para. — Fig. 2. Frequency of species of given densities on a 

 2-hectare sample plot of terra firme rain forest at Mucambo, Belem, Para. 



the richest and the Castanhal flora intermediate. These appear to be para- 

 bolic curves and are not becoming asymptote, although there certainly is a 

 finite number of species within a given forest type. 



On the Mucambo plot we found (using our revised list of carefully meas- 



