40470 Federal Register / Vol. 56. No. 157 / Wednesday, August 14. 1991 / Proposed Rules 



(D) Determine the dominance 

 threshold number — the number at which 

 50 percent of the total dominance 

 measure (i.e.. total cover) for the stratiun 

 is represented by one or more plant 

 species when ranked in descending 

 order of abundance (i.e., from most to 

 least abundant). 



(E) Simi the cover values for the 

 ranked plant species beginning with the 

 most abundant until the dominance 

 threshold number is immediately 

 exceeded; these species contributing to 

 surpassing the threshold number are 

 considered dominants, plus any 

 additional species representing 20 

 percent or more of the total cover of the 

 stratum; denote dominant species with 

 an asterisk on the appropriate data 

 form. 



(F) Designate the indicator status of 

 each dominant. 



(2) Bryophyte stratum (mosses, homed 

 liverworts, and true liverworts): 

 Bryophytes may be sampled as a 

 separate stratum in certain wetlands, 

 such as shrub bogs, moss-lichen 

 wetlands, and the wetter wooded 

 swamps, where they are abundant and 

 represent an important component of the 

 plant community. If treated as a 

 separate stratiun. follow the same 

 procedures as listed for herb stratum. In 

 many wetlands, however, bryophytes 

 are not abundant and should be 

 included as part of the herb stratiun. 



(3) Shrub stratum (woody plants 

 usually between 3 and 20 feet tall, 

 including multi-stemmed, bushy shrubs 

 and small trees below 20 feet): 



(A) Determine the percent areal cover 

 of shrub species within the entire plot 

 by walking through the plot, listing all 

 shrub species and estimating the percent 

 areal cover of each species. 



(B) Indicate the appropriate cover 

 class (T and 1 through 7) and its 

 corresponding midpoints (shown in 

 parentheses) for each species: T= <1% 

 cover (None); 1 = 1-5% (3.0); 2=6-15% 

 (10.5); 3 = 16-25% (20.5); 4 = 26-50% (38.0); 

 5 = 51-75% (83.0); 8=76-95% (85.5); 



7 = 96-100% (98.0). 



(C) Rank shrub species according to 

 their midpoints, from highest to lowest 

 midpoint; 



(D) Sum the midpoint values of all 

 shrub species. 



(E) Determine the dominance 

 threshold number — the number at which 

 50 percent of the total dominance 

 measure (i.e., cover class midpoints) for 

 the stratum is represented by one or 

 more plant species when ranked in 

 descending order. 



(F) Sum the midpoint values for the 

 ranked shrub species, beginning writh 

 the most abundant, until the dominance 

 threshold number is immediately 



exceeded; these species are considered 

 dominants, plus any additional species 

 representing 20 percent or more of the 

 total midpoint values of the stratum: 

 identify dominant species (e.g.. with an 

 asterisk) on the appropriate data form. 

 (G) Designate the indicator status of 

 each dominant. 



(4) Sapling stratum (young or small 

 trees greater than or equal to 20 feet tall 

 and with a diameter at breast height less 

 than 5 inches): Follow the same 

 procedures as listed for the shrub 

 stratimi or the tree stratum (i.e., plot 

 sampling technique), whichever is 

 preferred. 



(5) Woody vine stratum (climbing or 

 twining woody plants): Follow the same 

 procedures as listed for the shrub 

 stratiun. 



(6) Tree stratum (woody plants greater 

 than or equal to 20 feet tall and with a 

 diameter at breast height equal to or 

 greater than 5 inches): Determine the 

 basal area of the trees by individual and 

 by species within the 30-foot radius 

 sample plot Basal area for individual 

 trees can be calculated by measuring 

 diameter at breast height (dbh) with a 

 diameter tape and converting diameter 

 to basal area using the formula A = 

 pi(d)(d)/4 (where A = basal area, pi = 

 3.1416, and d = dbh). 



Do the following steps: 



(A) Locate and mark, if necessary, a 

 sample unit (plot) wnth a radius of 30 

 feet, or change the shape of the plot to 

 match topography, or increase size of 

 plot based on species area curve 

 assessment. 



(Note: A larger sampling unit may be 

 required when trees are large and widely 

 spaced.) 



(B) Identify each tree v«thin the plot, 

 measure its dbh (using a diameter tape), 

 compute its basal area, then record data 

 on the data form. 



[Note: Compute basal area using the 

 formula A = pi(d)(d)/4, where A = basal 

 area, pi = 3.1416, and d = dbh. To expedite 

 this calculation, use a hand calculator into 

 which the following conversion factor is 

 stored — 0.005454 for diameter data in inches 

 or 0.78535 In feet. Basal area in square feet of 

 an Individual tree can be obtained by 

 squaring the tree diameter and multiplying by 

 the stored conversion factor). 



(C) Calculate the total basal area for 

 each tree species by summing the basal 

 area values of all individual trees of 

 each species. 



(D) Rank species according to their 

 total basal area, in descending order 

 from the largest basal area to the 

 smallest. 



(E) Calculate the total basal area 

 value of all trees in the plot by summing 

 the total basal area for all species. 



(F) Determine the dominant trees 

 species; dominant species are those 

 species (when ranked in descending 

 order and cumulatively totaled) that 

 immediately exceed 50 percent of the 

 total basal area value for the "plot, plus 

 any additional species comprising 20 

 percent or more of the total basal area 

 of the plot; record the dominant species 

 on the appropriate data form. 



(G) Designate the indicator status of 

 each dominant (i.e., OBL, FACW, FAC. 

 FACU, or UPL). 



After determining the dominants for 

 each stratum, proceed to Step 10. 



Setp 10. Determine whether the 

 hydrophytic vegetation criterion is met 

 Complete the vegetation section of the 

 summary data sheet If the vegetation 

 fails to be dominated by these types of 

 species, the plot is usually not a 

 wetland, however, it may constitute 

 hydrophytic vegetation under certain 

 circiunstances (see list of exceptions). If 

 hydrophytic vegetation is present, 

 proceed to Step 11. 



Step 11. Determine whether the hydric 

 soil criterion is met. Locate the 

 observation area on a county soil survey 

 map, if possible, and determine the soil 

 map imit delineation for the area. Using 

 a soil auger, probe, or spade, make a . 

 hole at least 18 inches deep at the 

 representative location in each plant 

 community type. Examine soil 

 characteristics and compare if possible 

 to soil descriptions in the county soil 

 survey report or classify to Subgroup 

 following "Soil Taxonomy" (often 

 requires digging a deeper hole), or look 

 for regional indicators of significant soil 

 saturation. If soil has been plowed or 

 otherwise altered, which may have 

 eliminated these indicators, proceed to 

 the section on disturbed areas. Complete 

 the soils section on the appropriate data 

 sheet and proceed to Step 9 if conditions 

 satisfy the hydric soil criterion. Areas 

 having soils that do not meet the hydric 

 soil criterion are nonweUands. (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 

 floodplain soils, so that these hydric 

 soils are not misidentified as nonhydric 

 soils; see the "Atypical Hydric Soils" 

 discussion.) 



Step 12. Determine whether the 

 wetiand hydrology criterion is met 

 Record observations and complete the 

 hydrology section on the appropriate 

 data form. If the wetiand hydrology 

 criterion is met proceed to Step 13. If 

 tiie weUand hydrology criterion is not 

 met, the area is nonwetiand. 



