GENERAL CONDITIONS 63 



fields were hewn out of the swamp with cheap slave labor. Altho 

 these clearings were subject to destructive floods about once in 

 three years the heavy yields from the fertile alluvial soil in the 

 two good years tended to offset the loss of the flood year. In 

 these old fields cottonwood and ash usually preempted the best 

 drained sites while red gum took the second choice. The latter 

 is, however, far more abundant numerically because its toler- 

 ance permits it to grow well in dense, pure stands. Live oak is 

 another species which keeps to relatively high ground if there 

 may be said to be any such thing in a river bottom. Holly, 

 mahogany and lignumvitae are seldom found in abundance but 

 occur scattered sparingly on the better drained portions under- 

 neath the other trees. The following subtypes include the 

 principal composition combinations which occur commonly: 



Pure cypress. 



Cypress and tupelo gum. 



Pure red gum. 



Mixed white ash and cottonwood. 



Hardwood hammock (in southern Florida). 



Bottomlands are not favorable places for forest fires so that 

 this kind of damage is at a minimum. Likewise destructive in- 

 sects and fungi are not abundant, whether because fires have not 

 weakened the timber or because the frequent floods tend to keep 

 them in check has not been yet determined. Beyond a heart 

 rot in cypress — called " peck " — all the bottomland tree 

 species are unusually free from defects. 



The rapidity of growth on the better drained sites is truly 

 remarkable. Individually the intolerant species like cotton- 

 wood and ash attain the largest diameter and greatest height but 

 in yield per acre the more tolerant red gum and cypress lead. 

 The results of growth investigations of the leading species are 

 summarized below: 



