relationship between the distribution of plant species and the frequency 

 and duration of flooding in the lower White River Valley, Arkansas. 

 Using flood frequency and duration, he defined four species associations 

 on the White River floodplain, each of which had a distinctly different 

 tolerance to inundation. He concluded that based on plant species- 

 flooding relationships, plant communities could be used as a basis to 

 transfer flooding parameters to ungauged streams. 



Plant Community Organization 



The concept of community structure has been debated for decades. 

 Clements (1916) first described communities as discrete, self -organizing 

 entities that could be considered as discrete organisms. Gleason (1917) 

 disagreed with Clements' organismal concept and proposed a hypothesis 

 relating to the individualistic occurrence of plants. His hypothesis 

 has developed into the continuum concept, which indicates that plant 

 species distribution is determined by the species' response to its envi- 

 ronment. Whittaker (1967) and Mcintosh (1980) later developed Gleason' s 

 ideas, expanding on the continuum concept. They maintain that since 

 plant species adapt differently, no two occupy the same zone. This 

 results in a continuum of overlapping species associations, each 

 responding to subtly different environmental factors (e.g., water, soil 

 pH, nutrients, and solar radiation). A continuum can be described for 

 each factor in various increments or zones. 



Zonation simply describes the different levels of an environmental 

 gradient to which a species is responding. The reason zonation is so 

 obvious in some ecosystems is that environmental gradients are 



