Upland forest I White Oak. Blackgum, White Ash, 

 Hickories, Winged Elm, Loblolly Pine) 



Sycamore • Sweetgum - American Elm 



Upland Forest 



River Channel 



First Bottom (Terrace) 



Second Bottom (Terrace) 



Upland 



Figure 21. The correspoiKJence between alluvial floodplain microtopography and forest 

 cover types. (A) = river channel; (B) = natural levee (front); (C) = backswamp or 

 first terrace flat; (D) = low first terrace ridge; (E) = high first terrace ridge; (F) 

 = oxbow; (G) = second terrace flats; (H) = low second terrace ridge; (I) = high second 

 terrace ridge; (J) = upland. The vertical scale is exaggerated. 



Figure 22. Microtopographic relief on a 

 snail blackwater creek floodplain (Lower 

 Three Runs Creek, Barnwell County, SC). 

 Areas of similar elevation are similarly 

 marked. Arrows indicate channels which 

 are always filled with water. Quadrat is 

 100 m on a side. (After Hay 1977.) 



and the zonal classification system (Table 

 10). Trees in the almost constantly inun- 

 dated Zone II may survive with roots 

 partially inundated as much as 90% of the 

 time and die only when inundation is 

 permanent. On the other hand, upland 

 (Zone VI) trees not so adapted to maintain 

 themselves during flooding may begin to 

 show signs of stress if constantly inunda- 

 ted as little as 2% of the time (dogwood 

 and black cherry) and die as the flooding 

 interval increases to 12% to 17% of the 

 time. 



Dominance Types and Their Distribution 



Based upon field observation and 

 studies in the four-state study area, we 

 have classified bottomland hardwoods on 

 floodplains into 75 dominance types organ- 

 ized by zones (Tables 11-14). Although 

 Zones I (open water) and Zone VI (uplands) 

 are relevant, they are not presented other 

 than to introduce the nature of Zone I 

 species. 



Each table organizes the dominance 

 types for each zone by topographic setting 

 or uses other features to aid field iden- 

 tification. The reader should review 



38 



