Water's 

 edge 



8m 



3m 



10m 



99 m 



Figure 6-2: The layout and dimensions of a typical vegetation transect. The figure illustrates the transect design 

 used at the Reference Station and Station II. Each dot is a sampling point for vegetation parameters (i.e., percent cover 

 and leaf area index). Asterisks (*) denote the sampling locations of pore water samples. 



of 65 sampling points at the Reference Station and 

 Station II and 75 sampling points at Station III. 



Percent Cover and Leaf Area Index 



Percent cover and leaf area index (LAI) were sampled 

 seasonally from June 1995 to December 1999, for a 

 total of 20 seasonal sampling dates. The three stations 

 were sampled one additional time in June 2000, but 

 only data for percent cover were acquired. However, 

 the Station III transect was partially destroyed by 

 livestock, and therefore percent cover data for that 

 date were not collected. 



A 0.25 m' quadrat subdivided into 100 cells was used 

 to estimate the percent cover of each species at each 

 sampUng point. CeUs with no vegetation and those 

 covered with water or wrack (dead plant material) were 

 considered bare area. LAI, a measure of plant foliage 

 density and distribution, was quantified at each 

 sampling point using a LAI-2000 Leaf Canopy 

 Analyzer (LI-COR, Lincoln, Nebraska). LAI provided 

 a non-destructive means of estimating foliage density 

 by measuring the amount of light attenuated within the 

 canopy. Each LAI measurement was an average of 

 three individual readings taken at a sampling point. 

 LAI readings for 1995 were not included in the 

 analyses due to complications with the measuring 

 technique at die beginning of die sampling period. 



Analyses 



Vegetation parameters were analyzed at two different 

 spatial scales (792 or 824 m" transects and 0.25 m" 

 quadrats interpolated to 0.25 m'grid cells). Large-scale 

 analyses averaged data over an entire transect and 

 utilized traditional methods, including graphs and 

 tables. Small-scale analyses were accomplished 

 through the use of a Geographical Information System 

 (GIS). The GIS allowed each sampUng point and 

 corresponding data to be geographically represented, 

 taking into account the spatial relationships between 

 vegetation parameters. Analysis at two different scales 

 was necessary because much of the heterogeneity 

 foiind at small scales was lost when the data were 

 averaged over an entire transect. Large-scale 

 obser\'ations were useful in that they indicated general 

 patterns and trends in vegetation parameters, such as 

 seasonal peaks and declines, but small-scale analyses 

 provided detailed information regarding changes in 

 vegetation species distribution and abundance. 



Large-Scale Analyses 



Total transect average percent cover for each species 

 was determined by adding together the percent cover 

 of each species at each sampling point and then 

 dividing by the total number of sampling points. Total 

 LAI was calculated in the same manner. These total 

 ntimbers provided an estimate of species percent cover 

 and LAI on a large-scale basis. 



Chapter Six •♦♦ 6-5 



