40472 Federal Register / Vol. 56. No. 157 / Wednesday, August 14, 1991 / Proposed Rules 



wetland hydrology. In this way, the 

 boundary of areas meeting the hydric 

 soil criterion is further refined by field 

 observations. In map units where only 

 part of the unit is hydric (e.g., 

 complexes, associations, and 

 inclusions], locate hydric soil areas on 

 the ground by considering landscape 

 position and evaluating soil 

 characteristics of the hydric soil portion 

 or for properties caused by weUand 

 hydrology. 



(Note Some hydric soils, especially organic 

 soils, have not been given a series name and 

 are referred to by common names, such as 

 peat, muck, swamp, marsh, wet alluvial land, 

 tidal marsh, Sulfaquents, and Sulflhemists; 

 these areas are also considered hydric soil 

 map units and should appear on the county 

 lists of hydric soil map units. Certain hydric 

 soils are mapped with nonhydric soils as an 

 association or complex, while other hydric 

 soils occur as inclusions in nonhydric soil 

 map units. Only the hydric soil portion of 

 these map units should be evaluated for 

 hydrophytic vegetation.) 



In areas where hydric soils are not 

 easily located by landscape position and 

 soil characteristics (morphology], a soil 

 scientist should be consulted. 



(Caution: Become familiar with hydric soils 

 that do not possess good hydric field 

 indicators, such as red parent material soils, 

 some sandy soils, and some floodplains soils, 

 so that these hydric soils are not 

 misidentified as nonhydric soils. See 

 "Atypical Hydric Soils" discussion.) 



(Note: If the project area does not have a 

 soil map, hydric soil areas must be 

 determined in the field to use the point 

 intercept sampling method. Consider 

 landscape position, such as depressions, 

 drainageways, floodplains, and seepage 

 slopes, and either classify the soil or look for 

 field indicators of hydric soil, then delineate 

 the hydric soil areas accordingly. If the 

 boundary of the hydric soil areas cannot be 

 readily delineated, one should use the 

 quadrat sampling procedure.) 



After establishing the boundary of the 

 area in question, proceed to Step 5. 



Step 5. Consider the following: 



(1] Is the area presenUy lacking 

 hydrophytic vegetation or hydrologic 

 indicators due to annual, seasonal, or 

 long-term fluctuations in precipitation, 

 surface water, or ground water levels? 



(2) Are hydrophytic vegetation 

 indicators lacking due to seasonal 

 fluctuations in temperature (e.g., 

 seasonality of plant growth]? 



If the answer to either of these 

 questions is Yes or uncertain, and the 

 area meets the description of one of the 

 exceptions in this manual, proceed to 

 the appropriate section of tiiis manual. If 

 the answer to both questions is NO, 

 proceed to Step 6. 



Note: In some cases, normal climatic 

 conditions, such as snow cover or frozen 



soils, may prevent an accurate assessment of 

 the wetland criteria; one must use best 

 professional judgment to determine if 

 delaying the wetland delineation is 

 appropriate. 



Step 6. Determine random starting 

 points and random directions for three 

 200-foot line transects 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 random 

 transect direction. The following 

 procedures are suggested: 



(1] Starting point — Starting points for 

 the transects are selected randomly 

 along the perimeter of the area to be 

 examined. Determine the approximate 

 perimeter length and select three 

 random numbers (from a table for 

 generating random numbers or other 

 suitable method]; these random numbers 

 indicate the position of the starting 

 points for the three transects; pick a 

 point along the perimeter to begin 

 pacing off the distance to the starting 

 points. 



(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 

 established 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 procediu-e 

 suggested above. Mark the approximate 

 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. Only individual plants wi\h 

 stems located in the subject area (i.e., 

 soil type] should be recorded. At the 

 starting point and at each point on 2-foot 

 intervals along the transect, record all 

 individual plants that would intersect an 

 imaginary vertical line extending 

 through the point. Count each individual 

 plant only once per sample point; each 

 individual of a single species counts as a 

 separate plant for the tally (e.g., three 

 individuals of red maple count as three 

 hits for red maple at that single point). If 

 this imaginary line 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 Worksheet, and 

 record all occurrences of each species 

 along the transect. For each species T 

 listed, identify its indicator group from 

 the appropriate regional list of plant 

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

 FACW, FAG. FACU, and UPL]. 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 calcuilate a prevalence 

 index. If the plant species is on the list 

 and no regional or national indicator 

 status is assigned, do not use the species 

 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. Unidentified 

 plants or plants writhout indicator status 

 are recorded but are not used to 

 calculate the prevalence index. Proceed 

 to Step 9. 



Step 9. Calculate the total frequency 

 of occurrences for each species (or other 

 taxonomic category], 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 occiu-s at the 

 sampling points along the transect 

 Proceed to Step 10. 



Step 10. Calculate the prevalence 

 index for the transect using the 

 following formula: 



PIl = 



iFo -I- 2Ffw + 3Ff + 4Ffu + 5Fu 

 Fo+Ffw+Ff+Ffu+Fu 



where 



PIi= Prevalence Index for transect i; 



Fo=Frequency of occurrence of obligate 



wetland (OBL) species: 

 Ffw = Frequency of occurrence of facultative 



wetland (FACW) species; 

 Ff= Frequency of occurrence of facultative 



(FAC) species; 

 Ffu = Frequency of occurrence of facultative 



upland (FACU) species; 

 Fu= Frequency of occurrence of upland (UPL) 



species. 



After calculating and recording the 

 prevalence index for this transect, 

 proceed to Step 11. ^ 



Step 11. Repeat Steps 5 through 10 for 

 two other transects. After completing 

 the three transects, proceed to Step 12. 



Step 12. Calculate a mean prevalence 

 index for the three transects. To be 



