METHODS 
Allegedly, the feeding activity of nutria reduces stands of 
vegetation to openings. The method of measuring vegetation was, 
therefore, designed primarily to measure openings in the vegetation. 
Transects were marked at 100-foot intervals with bamboo poles. Each 
pole established a station where the vegetation was sampled by means 
of a 5-foot line intercept. Along each sample line intercept, the 
extent in inches of clumps or patches of vegetation and of interven- 
ing open spaces was measured at ground level. Species of plants 
forming the clumps or patches of vegetation intercepted were listed 
in order of abundance. Thus, a 5 percent sample of the whole tran- 
sect was obtained. Scientific names of the plant species are given 
in table I. 
This method sampled both large openings and the small spaces 
between clumps or patches of vegetation and gave an index to species 
of-plants as well. Many of the open spaces resulted from natural 
patterns of growth of the vegetation, but some resulted from the 
activity of nutria and other animals. An opening lacked the plant 
species that formed the usual vegetation characterizing marsh assoc- 
jations. Thus, an open area may have been devoid of vegetation or 
it may have supported those plant species, usually annuals, which 
invade openings. 
In addition to sampling all open spaces, the total extent of 
large openings was measured along two transects. A large opening had 
a minimum diameter of 4 feet along the transect. 
