Both snow goose and muskrat graze preferentially on the fleshy rhizome of Scirpus olneyi. They 

 often graze in one area until virtually all their available food source is gone, producing an eatout 

 (Lynch et al. 1947; O'Neil 1949). Eatouts degrade the marsh surface, destroy soil continuity, 

 produce excessive amounts of litter, and change species composition and the structure and 

 percentage of cover. Very little Scirpus olneyi has been found during the first 2 years after eatouts 

 in study areas at Rainey Sanctuary. 



Standing Crop 



Standing crop from four stations shows several patterns. First, both downstream stations have 

 significantly higher (TBD= 1750, TBU= 1O40 gm/m 2 ) maximum standing crops than do upstream 

 stations (BID= 1340, BIU= 775 gm/m 2 ) (Table 2). Second, Toms Bayou stations have slightly 



Table 2. Summary of standing crop data. 



a Average multiplied by 10=g dry weigh t/m 2 . 



Abbreviations: See Table 1 for site abbreviations. Other = live plants which are not listed by 

 name; Spartina = Spartina patens; Scirpus=Scirpus olneyi; Total =total biomass of living plants. 



136 



