subsequent population response. Additional data regarding the 

 actual dates of drying, as well as other climatic factors, are 

 needed to more closely determine the nature of these observed 

 fluctuations. 



The line transect results revealed an increase in July water 

 depth in ponds 020 and 027 between 1988 and 1989. An increase in 

 percent cover of H. aquatilis and Carex vesicaria, and a decrease 

 for Glvceria borealis, was also recorded over this two-year 

 interval. Alternatively, July water depths in ponds 009 and 013 

 did not fluctuate much between the two years, and the percent 

 cover of H. aquatilis and C. vesicaria remained approximately the 

 same during this interval (G. borealis was not encountered along 

 the transects in the latter two ponds) . These results also 

 suggest that year-to-year fluctuations in water depth and rate of 

 drying are important in determining the abundance of aquatic 

 plant species. A third year of transect data will be useful in 

 evaluating whether these observed trends are consistent. 



V. TRANSPLANT EXPERIMENTS 



During 1989, soil plugs for transplant experiments were obtained 

 from two ponds containing dense populations of H. aquatilis . The 

 transplants were placed in four ponds that appeared to be 

 suitable habitat for H. aquatilis . but that had not been observed 

 to support the species. 



STUDY SITES: The ponds from which soil plugs were taken are 

 occurrence numbers 007 and 049; the locations of these 

 populations are indicated in an earlier status report (Shelly 

 1988) . The plugs from population 007 were placed in two ponds 

 near Flathead National Forest Rd. #10161 (Lake County) : 



A.) T24N R17W Section 6, SE^NW^SW^; 955.8 m (3135'). 

 B.) T24N R18W Section 1, NEJjSE^; 942.1 m (3090'). 



The locations of these transplant sites are shown on p. 48. 



The plugs from population 049 were placed in two ponds near 

 Flathead National Forest Rd. #10566 (Missoula County) : 



C.) T19N R17W Section 12, NWJjSE^NW^; 1295.7 m (4250'). 

 D.) T19N R17W Section 12, SW^SE^NW^; 1291.2 m (4235'). 



The locations of these transplant sites are shown on p. 43. 



METHODS: At each of the "donor" ponds, soil plugs were taken 

 from areas where dense populations of H. aquatilis had been 

 observed during peak growth and flowering times (mid-July) . The 

 plugs were obtained by pressing a #10 tin can into the pond 

 sediments to a depth of approximately 9-13 cm. The areas of the 

 ponds where the plugs were collected were moist, but not under 

 water. The presence of H. aquatilis seeds was verified in the 



