CRITERIA FOR RATING PRODUCTIVITY 



INTRODUCTION 



In making the field ratings for productivity of 

 recently cut lands, the existing stocking, prospects 

 for future stocking, species composition, and felling 

 age practiced thereon were measured and recorded 

 in terms of specific criteria or guides. Because re- 

 gional foresters of the Forest Service were assigned 

 responsibility for conducting the surveys, detailed 

 criteria and field manuals were prepared for each 

 of the administrative regions of the Forest Service 

 according to the methods outlined in the section 

 Productivity of Recently Cut Lands, p. 225. The 

 reader will also find in that section the reasons for 

 procedural steps and the concepts basic to the 

 standards presented here. 



The purpose of the following pages is to preserve 

 and to make public the major standards used in 

 the 1953 survey. To avoid repetition of definitions 

 and procedures common to several regions or 

 types, and to reduce space devoted to tabular 

 presentations, the criteria used for rating pro- 

 ductivity are summarized and condensed for type 

 gi'oups within the several Timber Resource Re- 

 view regions or combinations of them. Volumin- 

 ous material on the mechanics of procedure, such 

 as the coding system used to record field data and 

 the sampling procedures followed, has been 

 omitted. Also, some of the minor guides, im- 

 portant locally, have been omitted. 



The subject matter under consideration is tech- 

 nical and highly complex. Technical readers in- 

 terested in the procedures and standards for a 

 given forest type in a particular locality should 

 obtain a copy of the field manual from the appro- 

 priate regional forester and also a copy from the 

 Chief Forester of the basic plan entitled "Task 

 VIII, Productivitv of Recentlv Cut Lands — Julv 

 1953." 



DEFINITION AND EXPLANATION OF 

 TERMS 



The definitions and explanations that were 

 applied in all regions and in all forest type groups 

 are summarized below. Important exceptions and 

 additions to meet local conditions are given in the 

 criteria for the regions and type groups in which 

 they occur. 



Crop Tree 



Only crop trees were counted in the field 

 sampling to estimate stocking. "Crop trees" were 

 defined as trees of desirable or acceptable species 

 as specified in the individual type-group descrip- 

 tions and which by local experience have proved 

 their abilit}" to produce commercial wood products 

 on the site under examination and, if below com- 

 mercial size, show capability of growth to mer- 

 chantability by reason of their form, vigor, 

 crown position, and freedom from injury, disease, 

 and parasites. Only mature specimens or those 

 capable of making good growth at the time of 

 examination qualified as crop trees. Ability of 

 a young tree to survive a period of suppression 

 and eventually develop into a crop tree did not 

 qualify it to be counted. 



Effect of Felling Age 



Effect of felling age is the reduction of produc- 

 tivity that results from clear cutting or very heav}- 

 cutting in stands before the culmination of mean 

 annual growth for the class of products removed. 

 It is expressed as that percentage of the mean 

 annual growth at culmination reached by the 

 stand at the age when clear cut. Thus, if a given 

 species culminates mean annual growth at 120 

 years with a mean annual growth of 200 volume 

 units, but was cut at 80 years when mean annual 

 growth was 150 units, allowance for this effect of 

 felling age reduced the productivity rating by 

 25 percent. 



Effects of felling age were recognized for two 

 general classes of products depending upon plu- 

 rality of the volume cut: (a) Large products and 

 high-quality products such as saw and veneer 

 logs, and (b) small, relativel3' lower quality 

 products such as cordwood. Products that did 

 not fit this classification, such as Christmas trees, 

 corral poles, fencing material, and transmission 

 poles, were assumed to have reached maturity 

 at the age cut, and felling-age effect was not con- 

 sidered. Also, no reduction for felling age was 

 made either for stands or individual trees whose 

 removal did not have a material effect in reducing 

 growth. Examples: (a) Injured and diseased trees 

 or stands, (b) trees in the suppressed crown classes, 



" Assembled by Leonard I. Barrett, Philip A. Briegleb, Gordon G. Mark, and Arthur L. Roe. 



671 



