decreased each year for the vegetative types of Transect C, except 
for the “buggy trail" type, where an increase in 1955, resulting 
from the activities of the investigators, caused an overall increase 
for the transect. These large openings were total measurements 
(table II), and had the variations occurring from year to year been 
measured as a 5-percent sample, the changes would not have been 
statistically significant. 
| Large openings on Transect A represented, for the most part, 
shallow, relatively permanent ponds that probably resulted from 
muskrat “eat-outs” 10 years earlier. Large openings on Transect C 
represented lack of vegetation. 
Changes in the proportions of the various species of plants 
also occurred (figures 2-9). Decrease in nonvegetated ground was 
brought about by the encroachment of saltmeadow cordgrass, which 
increased in coverage each year in almost all of the vegetative 
types. In almost all cases the loss of coverage by other species 
was wholly or partly made up by increases of saltmeadow cordgrass. 
Olney's three-square decreased in extent of coverage from 1954 to 
1955 wherever it occurred, except on Transect C. From 1955 to 1956 
it increased beyond its 1954 coverage. The probabilities of these 
increases being chance occurrences are as follows for the designated 
transect: 
A Saltmeadow cordgrass - Olney's 
three-square type 1% level (49 samples) 
(Continued) 
11 
