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Definitions for Waterlogging Tolerance Rating 



Most Tolerant . Those species that are capable of living from seedling 

 to maturity in soils that are waterlogged almost continually year after 

 year except for short durations during droughts. The soils are typi- 

 cally anaerobic in character but are less so where the water is moving. 

 Some species in this group adapt by producing soil water roots that 

 oxidize their rhizosphere, accelerate anaerobic metabolism but at a 

 controlled rate and tolerate the toxic compounds typical of highly 

 reduced waterlogging soils. 



Highly Tolerant . Those species capable of living from seedling to matu- 

 rity in soils that are waterlogged for 50 to 75 percent of the year. 

 Waterlogging typically occurs during the winter, spring and 1-3 months 

 of summer. 



Moderately Tolerant . Those species capable of living from seedling to 

 maturity in soils waterlogged about 50 percent of the time. Waterlog- 

 ging typically occurs in portions of the winter, spring, and early 

 summer. 



Weakly Tolerant . Those species that are capable of living from seedling 

 through maturity in soils that are temporarily waterlogged for durations 

 of 1-4 weeks and usually accounting for 10 percent of the growing 

 season. 



Least Tolerant . Those species that are capable of living from seedling 

 through maturity in soils that are occasionally waterlogged for dura- 

 tions of a few days only, usually accounting for less than 2 percent of 

 the growing season. 



Definitions for NWI Status Descriptions 



Obligate Wetland (OBL) . Occur almost always (estimated probability 

 >99 percent) under natural conditions in wetlands. 



Facultative Wetland (FACW) . Usually occur in wetlands (estimated proba- 

 bility 67 to 99 percent), but occasionally found in nonwetlands. 



Facultative (FAC) . Equally likely to occur in wetlands or nonwetlands 

 (estimated probability 34 to 66 percent) . 



Facultative Upland (FACU) . Usually occur in nonwetlands (estimated pro- 

 bability 67 to 99 percent), but occasionally found in wetlands (esti- 

 mated probability 1 to 33 percent) . 



Obligate Upland (UPL) . Occur in wetlands in another region, but occur 

 almost always (estimated probability >99 percent) under natural condi- 

 tions in nonwetlands in the region specified. If a species does not 

 occur in wetlands in any region, it is not on the National List . 



A positive (+) or negative (-) symbol was used with the Faculta- 

 tive Indicator categories to define more specifically the regional 



