72 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



practices known today. Standards geared to 

 either of these alternatives would have been 

 much higher. 



Unlike the 1945 survey, this survey was not 

 concerned with forest management practices. 

 Intent of ownership was considered only in a minor 

 way. Existence of sustained-^deld policies, or 

 management plans, and planned use of silvicultural 

 systems were not considered. Conditions on the 

 ground were appraised as they were found regard- 

 less of whether they resulted from accident, a 

 bountiful nature, or purposeful action of the 

 owner. The survey covered practically all large- 

 size private and public ownerships, and sampled 

 the medium and small piivate o\vnersliips. The 

 object was to obtain reasonably reliable data on a 

 regional basis. The term "recently cut lands" 

 relates to the fact that only cuttings made since 

 1947 were examined and, in the case of two or more 

 cuttings within that period, the most recent cut- 

 ting was used in most instances. 



Four Main Elements of Productivity 



The productivity index was designed to reflect 

 the combined effect of four of the most important 

 elements or factors that affect growth following 

 cutting. These are (1) existing stocking, (2) 

 prospects for stocking where present stocking is 

 deficient, (3) species composition, and (4) felling 

 age or the age of trees or stands at the time the 

 cutting occurred. In the field examination, each 

 of these elements was expressed on a rating scale 

 of to 100 with the latter figure representing a 

 standard of current attainability. The individual 

 ratings were combined into a single overall 

 productivity index. 



The standard for existing stocking referred to 

 the number of trees or seedlings per acre for a 

 particular site or forest type which met necessary 

 specifications. Any recently cut area with actual 

 stocking of 35 to 50 percent of the "normal" vield 

 table stocking for uncut sawtimber stands would 

 result in an upper level rating for stocking. 

 Standards for trees under sawtimber size represent 

 much smaller percentages of the better stocking 

 found in nature because of the natural tendency of 

 young stands to improve in stocking as they 

 mature. 



Standards for prospective stocking recognized 

 the probability of stocking by both natural 

 methods and by planting and were considered 

 only if stocking at the time of examination was 

 deficient. In prospective stocking, such factors 

 were considered as seed sources, seedbed condi- 

 tion, the presence or absence of inhibiting vegeta- 

 tion, topography, and planting plans. 



Species composition referred to the kind of 

 trees in the stand and included only commercial 

 species. Species were divided into two groups, 



(a) desirable, and (b) acceptable. If half or 

 more of the stand were in the desirable class, 

 composition was considered up to standard. If 

 none of the trees were in the desirable class, 

 composition was considered half of standard. 

 This recognized that acceptable species have some 

 value. 



The standard for felling age was the age at 

 which the timber stand involved would reach its 

 maximum mean annual growth. If cut prior to 

 that age, deductions from standard were made 

 because the full growth potential of the stand was 

 not realized. The felling age factor was applied 

 only to clear cutting and under rather restricted 

 conditions as explained in the section on Produc- 

 tivity of Recently Cut Lands. 



The information on the various elements was 

 obtained for each forest type that had been cut 

 wholly or in part since 1947 on each ownership 

 examined. Each such recently cut forest tvpe per 

 individual ownership was termed an "operating 

 area." The criteria and the standards for the 

 various elements were worked out regionally for 

 each forest type and important locality or site. 

 These are summarized in the appendix. The 

 various elements were combined for each operating 

 area into a productivity index by adding the 

 ratings for existing and prospective stocking (but 

 not to exceed an index of 100), multiplying their 

 result by the composition factor, and then multi- 

 plying by the felling age factor (if applicable). 



The productivity index scale of to 100 was 

 divided into three broad classes with adjective 

 descriptions of each class as follows: 0-39, lower; 

 40-69, medium; 70-100, upper. Each individual 

 operating area was assigned to one of three broad 

 classes, depending on the index rating for that 

 particular area. It was then possible to show the 

 proportion of total operating area by size or kind 

 of ownership, or other grouping in each of the 

 three broad productivity classes. This is the 

 manner in which most of the results are presented 

 in the subsequent description and tables. Thus, 

 a statement that 65 percent of the operating area 

 in the country was in the upper productivity class 

 means that 65 percent (areawise) of the forest 

 t3'pes on which there was recent cutting in the 

 individual ownerships examined had a produc- 

 tivity index rating between 70 and 100 percent of 

 what is considered reasonably attainable under 

 current conditions. In other words, results are 

 expressed, not in terms of productivity indexes 

 themselves, but in terms of proportion of operating 

 area in the various broad productivity classes. 



The Standards Could Be Higher 



Much judgment necessarily enters into a pro- 

 cedure such as just described. There is judgment 

 in the choice of the various elements of produc- 



