two points along each transect in four of the five 

 ponds studied. The compass bearing of each transect 

 was also recorded. 



RESULTS: The initial results are presented in Table 2. 

 There appears to be a rough correlation between a 

 higher percent cover of H. aquatilis and a lower 

 percent cover of the associated species. However, it 

 was observed in the field that there is considerable 

 variation throughout a given pond as to the patchiness 

 of H. aquatilis and the other emergent plant species. 

 Nonetheless, the results appear to provide a reasonable 

 approximation of the relative abundance of each 

 species, at least in the areas bisected by the 

 transects. The method will allow for tracking changes 

 in the abundance of each species along the transects. 



The following difficulties regarding the line-transect 

 method for monitoring U. aquatilis should be discussed: 



i.) The method impacts the habitat; these impacts 

 result from wading in the ponds to establish and 

 read the transects. These impacts would not be 

 expected to seriously affect the major associated 

 emergent species, all of which are perennials with 

 sturdy root systems. However, the annual root 

 system and frail, submerged or floating habit of 

 H. aquatilis make the species easily susceptible 

 to physical disturbance. In addition, the bottom 

 substrates of the pond habitats are disturbed by 

 wading. 



ii.) The annual life history of H. aquatilis . and 

 the existence of seed banks (Lesica gt al. 1987) , 

 result in yearly fluctuations in population size 

 and areal extent. Annual differences in percent 

 cover as measured along the monitoring transects 

 may result in part from these fluctuations, which 

 in turn may be due to a variety of factors (i.e., 

 fluctuation in annual precipitation and 

 temperature averages, land use adjacent to 

 habitats) . The dependence of H. aquatilis on an 

 aquatic habitat that is highly influenced by these 

 variable physical factors will make it difficult 

 to determine the exact causes of population 

 fluctuations. 



To further assess these difficulties, it has been 

 proposed that these transects be re-read in 1989 and 

 1990. Data from three years will hopefully provide a 

 better understanding of these problems. In the 

 interim, repeated qualitative surveys of all known 

 populations have been recommended, to obtain population 

 size estimates and assess response to habitat 



