both questions is NO, normal conditions are 

 assumed to be present. Proceed to Step 6. 



Step 6. Determine random starting points 

 and random directions for three 200-foot line tran- 

 sects in each area that meets or may meet the hydric 

 soil criterion. {Note: More than three transects may 

 be required depending on the standard error 

 obtained for the three transects.) There are many 

 ways to determine random starting points and ran- 

 dom transect direction. The following procedures 

 are suggested: 



1) Starting point - Superimpose a grid over 

 an aerial photo or map of the study area. Assign 

 numbers (1, 2, 3 ...N) to each vertical and hori- 

 zontal line on the grid. Starting points for a transect 

 are selected by using a table for generating random 

 numbers or other suitable method. The fu^t select- 

 ed digit represents a line on the horizontal axis; the 

 second, the vertical axis. The intersection of the 

 two lines establishes a starting point 



2) Transect direction - At a starting point, 

 spin a pencil or similar pointed object in the air and 

 let it fall to the ground. The direction that the pencil 

 is pointing indicates the direction of the transect. 

 Proceed to Step 7. 



Step 7. Lay out the transect in the esta- 

 blished direction. If the transect crosses the hydric 

 soil boundary (into the nonhydric soil area), bend 

 the line back into the hydric soil area by randomly 

 selecting a new direction for the transect following 

 the procedure suggested above. Mark the approxi- 

 mate location of the transect on a base map or aerial 

 photo. Proceed to Step 8. 



Step 8. Record plant data (e.g., species 

 name, indicator group, and number of occurrences) 

 at interval points along the transect. At the starting 

 point and at each point on 2-foot intervals along the 

 transect, record all plants that would intersect an 

 imaginary vertical line extending through the point. 

 If this hne has no plants intersecting it (either above 

 or below the sample point), record nothing. 



Identify each plant observed to species (or other 

 taxonomic category if species cannot be identified), 

 enter species name on the Prevalence Index Work- 

 sheet, and record all occurrences of each species 

 along the transect. For each species listed, identify 

 its indicator group from the appropriate regional list 

 of plant species that occur in wetlands (i.e., OBL, 



FACW, FAC, FACU, and UPL; see p/5 )• Plant 

 species not recorded on the lists are assumed to be 

 upland species. If no regional indicator status and 

 only one national indicator status is assigned, apply 

 the national indicator status to the species. If no 

 regional indicator status is assigned and more than 

 one national indicator status is assigned, do not use 

 the species to calculate a prevalence index. If the 

 plant species is on the list and no regional or nation- 

 al indicator status is assigned, do not use the spe- 

 cies to calculate the prevalence index. For a transect 

 to be valid for a prevalence calculation, at least 80 

 percent of the occurrences must be plants that have 

 been identified and placed in an indicator group. 

 Get help in plant identification if necessary. {Note: 

 Unidentified plants or plants without indicator stat- 

 us are recorded but are not used to calculate the 

 prevalence index.) Proceed to Step 9. 



Step 9. Calculate the total frequency of occur- 

 rences for each species (or other taxonomic catego- 

 ry), for each indicator group of plants, and for all 

 plant species observed, and enter on the Prevalence 

 Index Worksheet. The frequency of occurrences of 

 a plant species equals the number of times it occurs 

 at the samphng points along the transect. Proceed to 

 Step 10. 



Step 10. Calculate the prevalence index for the 

 transect using the following formula: 



PIi = 



where 



Fo + 2Ff^ + 3Ff + 4Ffu + 5Fu 

 Fo + Ffw + Ff + Ffu + Fu 



PIj = Prevalence Index for transect i; 



Fq = Frequency of occurrence of obligate wetland 



species; 

 Ff^ = Frequency of occurrence of facultative 



wetland species; 

 Ff = Frequency of occurrence of facultative 



species; 

 Ffu = Frequency of occurrence of facultative 



upland species; 

 Fu = Frequency of occurrence of upland species. 



After calculating and recording the prevalence index 

 for this transect, proceed to Step 11. 



48 



