88 A STUDY OF FOREST CONDITIONS 



fields, vary considerably from those of original growth, 

 almost justifying their separation into a different type or 

 subtype. Two variations of the oldfield growth are found, 

 hardwood and pine. The hardwoods come in on abandoned 

 fields more slowly than the pine. They are usually of the 

 poorer species, such as sassafras, hackberry, pliim, and the 

 inferior oaks, and it is only after many years that a stand 

 of the better species, such as yellow poplar, white oak, and 

 hickory becomes established. Black locust comes in nat- 

 urally and is one of the most valuable and fastest growing 

 trees in this type, but it is liable to serious damage by fire 

 and insects. 



Where seed trees are near enough, old fields usually 

 seed up with loblolly and shortleaf. These grow faster 

 than the hardwoods and form a much denser stand. Their 

 relative proportion in mixture varies according to the 

 available seed trees and to the quality and moisture con- 

 tent of the soil, the loblolly preferring the deeper, moister 

 soil. These old fields are frequently used for pasturage, 

 and the grass is burnt off to improve the range. As a 

 result the pines are often sadly injured and the soil im- 

 poverished. 



Mississippi Flood Plain. — ^All the bottoms and swamps 

 lying between the Mississippi River and the "cliffs," or 

 loess hills, are subject to overflow or woiild be overflowed 

 were they not protected by the levees. The most extended 

 areas lie about the mouths of the larger rivers, such as the 

 Big Black and Homochitto, where water from the Mis- 

 sissippi often backs up these streams for many miles, flood- 

 ing the country on either side. The greater part of this 

 area is submerged only in times of high water, but much 

 of the low swamp land is under water the greater part of 

 the year. 



The soils of these overflowed lands are alluvial deposits 

 of sandy loam, varying to clay loam. Where a stream 

 carrying sediment overflows its banks, the water begins 

 at once to lose its velocity and deposit the sediment. The 

 coarser and heavier particles of its suspended matter are 

 deposited near the streams, while the finer particles are 



