672 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



and (c) trees or overstory stands impeding under- 

 stories having potentially higher value. 



Seed Trees 



Seed trees were required to have a full, healthy 

 crown and reasonable prospects of surviving for 

 a sufficient time to bear at least one full crop 

 of seed. 



Forest Types 



The forest type groups adopted by the nation- 

 wide forest survey (see Definitions, p. 630) were 

 used as the basic types in compiling results. 

 However, criteria were prepared by the regional 

 task groups for local types as considered import- 

 ant. These local types were keyed to the most 

 appropriate type group for compilation purposes. 

 For this reason, criteria will appear in the following 

 pages for types not listed in the major type 

 groups. For example, in the Middle Atlantic 

 Region only the white pine type of the type group 

 white-red-jack pine exists on ihe ground. Hence, 

 stocking standards were prepared only for the 

 local white pine type. Basis for type classification 

 was the species composition just prior to the most 

 recent cutting. 



Species Classification 



For each forest type recognized in the regional 

 criteria, the principal tree species encountered 

 are listed as "desirable," "acceptable," or "non- 

 count," depending on their rate of growth, 

 susceptibility to injury and parasites, and the 

 utility of their products in comparison with that 

 of associated species. Classification of minor 

 species of relatively little importance not listed 

 in the criteria was determined by the field exam- 

 iners as encountered. 



Established Seedlings 



Healthy seedlings of desirable or acceptable 

 species that have completed one growing season, 

 and that meet crop tree specifications, are desig- 

 nated as "estabHshed," unless specified otherwise 

 in the individual criteria. 



Clear Cuttings 



Clear cuttings are defined as cuttings that re- 

 move all of the trees or all or substantially all 

 of the trees that are merchantable for the products 

 being harvested, and that result in elimination 

 of most of the original overstory. In the East, 

 when 80 percent or more of such merchantable 

 volume was removed, the area was considered 

 clear cut. 



PROCEDURES FOR EASTERN 

 UNITED STATES 



In the eastern part ot the countr}', including 

 North Dakota, Oklahoma, and Texas, the pro- 

 ductivity classification of recently cut lands was 

 derived from numerical ratings based on tallies of 

 sample plots distributed throughout the cutover 

 areas. 



The existing stocking was tallied on concentric 

 circular plots, a Koo-acre plot being used for trees 

 up to the 6-inch d. b. h. class, and K-acre plots 

 used for trees in the 6-inch d. b. h. class and larger. 

 The "desirable" and "acceptable" species were 

 recorded by these two categories, and ratings of 

 existing stocking were read from stocking tables 

 prepared from the standards for the type. 



If this step shows that 50 percent or more of the 

 stocking was in desirable species, no correction was 

 made for composition. If less than 50 percent 

 was in desirable species, the rating was reduced by 

 applying a composition factor. In order not to 

 reduce existing stocking by more than half because 

 of substandard composition, no factor under 0.5 

 was used. 



If the plot was not fully stocked, prospective 

 stocking was calculated bj" various methods based 

 on the standards for the particular forest type. 

 Generally, the prospective stocking rating was 

 based on: (1) the available seed source — either 

 from seed trees on the cutover area and/or from 

 an adjacent uncut stand that contained seed- 

 bearing trees, and (2) the condition of the seed- 

 bed, existence of slash, cull trees, weed trees, 

 or herbaceous growth on the plot that would 

 inhibit establishment or growth of trees. The 

 effects of grazing, rodents, deer browsing, etc., 

 were included in the final numerical estimate for 

 prospective stocking. 



Figures for existing and prospective stocking 

 were added to obtain a value for total stocking. 

 The maximum value recorded for stocking was 100 

 percent. If the stand was cut heavily, i. e., more 

 than 80 percent of the volume in merchantable 

 sizes for the products harvested was removed, and 

 the trees were cut at ages younger than the age of 

 culmination of mean annual growth for the class of 

 product harvested, the rating was reduced by 

 apphnng a felling-age factor. In even-aged stands, 

 average age was used as the felling age to ascertain 

 the factor. In uneven-aged stands, a weighted 

 average factor was calculated. The final pro- 

 ductivity estimate was the product of stocking 

 percentage, the composition factor, and the felling- 

 age factor. 



Sample Calculation of Productivity 



a productivity estimate was calculated on a 

 field worksheet for each plot. The estimate for a 

 given forest type on an ownership was the average 

 of all plots in the cutover part of the type. To 



