228 



TIMBER RESOURCES FOR AMERICAS FUTURE 



The Elements Adopted 



TJie most useful measure of productivity on any 

 cutover area would be the current and future an- 

 nual or periodic growth in terms of board-feet and 

 cubic feet by species or species groups. Since re- 

 liable methods of forecasting growth directly on 

 some cutovers and on the large scale required for 

 national siu've^'s are not available, less direct 

 means were used. Tlierefore, certain elements or 

 specific conditions of cutover areas, directly af- 

 fecting growtli, wei'e chosen as a basis for apprais- 

 ing productivity. 



The major elements considered most directly 

 related to current and prospective growth on cut- 

 over areas and which could be measured on the 

 ground were chosen for study. These elements 

 were (a) existing stocking, (b) prospective stock- 

 ing, (c) species composition, and (d) effect of fell- 

 ing age with relation to maturity. Concentration 

 on these four elements left out of consideration 

 other elements of forest management sucli as ad- 

 herence to sustained-yield policies, existence of 

 wTitten forest management plans, and any silvi- 

 cultural systems or methods found in effect. Thus 

 the study does not appraise the status of manage- 

 ment. 



Adoption of these elements also omits any direct 

 measure or recognition of the intent to practice 

 forestry on any ownership or the degree of effort 

 expended to create a given set of conditions on a 

 cutover area. On the basis of the four elements, 

 the end result of the cutting is subjected to meas- 

 urement and appraisal wliether it be accomplished 

 by accident or by carefully designed effort. This 

 differs basically from the Reappraisal Report con- 

 cept which rated forest practices on a combination 

 of standards for cutover areas and degree of for- 

 estry effort expended on the entire ownership. 



Existing Stocking 



Growth of forest stands varies with stocking, 

 hence a measure of stocking on the ground is 

 essential to appraisal of current and future pro- 

 ductivity. In its sixnplest terms, stocking is ex- 

 pressed in numbers of trees per acre. For piuposes 

 of this survey, existing stocking consisted of trees 

 on the ground immediately after cutting plus 

 those wliich had l)ecome established between tlie 

 time of cutting and the titne of examination. 



But not all trees on the ground are usable 

 even if of merchantable size, because of defects 

 or because they consist of noncommercial species. 

 Thus, cull trees were eliminated from the stocking 

 count as were trees of commercial species over- 

 topped by larger cull trees. Trees with low vigor 

 or other damage due to disease, insects, or animals 

 were also eliminated from the stocking count by 

 adoption of standards describing permissible limits 

 of damage or by observation of the examiner wliere 

 this indicated that such trees would not survive. 



Hence, a "crop tree" concept w^as adopted which 

 limited the count of existing stocking to those trees 

 of commercial species found cru-rently or potenti- 

 ally productive. The crop tree concept was ap- 

 plied to trees of all sizes beginning with well- 

 established seedlings. , 



For each forest type or subtype, and where 

 deemed important by site or geographical area 

 within a type, stocking standards were drawn up 

 showing the nuxriber of crop trees per acre of each 

 size class considered to constitute standard or 100 

 percent stocking. Field procedures were devised 

 by which any distribution of tree sizes found on a 

 recently cut area could be translated into a per- 

 centage of tlie standard stocking. Thus, the size 

 of crop trees did not influence the stocking rating. 

 The same rating derived from a given number of 

 large trees could be attained by their equivalent 

 consisting of a larger number of small trees. 



In developing standards, the basic references- 

 used were normal yield tables and other technical 

 sources of information showing averages of the 

 higher levels of stocking found in natural, uncut 

 stands. Such high levels of stocking are usually 

 referred to as "normal" stocking, and this mean- 

 ing of the term is used in subsequent discussion. 

 Stocking standards were derived by reducing 

 normal stocking to the averages found on recently 

 cut areas of ownerships judged to be well managed. 



For trees of sawtimber size, the standards for 

 100 percent stocking of recently cut lands repre- 

 sented from 50 percent to 70 percent of normal 

 stocking, depending upon forest type and locality. 

 However, 70 percent of the stocking standard was 

 needed to qualify for the upper level of stocking. 

 Thus, any recently cut area with 35 to 50 percent 

 of normal stocking in trees of sawtimber size 

 would qualify for the upper productivity level 

 provided standards for other elements were met. 



For seedling and sapling trees, the standards 

 I'epresented much lower percentages of normal 

 stocking. For most forest types, standards for 

 crop trees ranging from established seedlings to 

 trees one inch in diameter were set at 1,000 per 

 acre. For a few types, 500 to 750 established 

 seedlings were accepted as 100 percent stocking. 

 Stocking standards always required many more 

 small trees than large ones. For example, on the 

 Douglas-fir type of Oregon and Washington, 750 

 crop trees per acre less than 2 years of age and 58 

 trees per acre in the 24-inch diameter class both 

 represented 100 percent stocking. Yet "normal" 

 stocking of trees in very young stands of Douglas- 

 fir exceeds 4,000 trees per acre. 



Reasons for adopting standards so much lower 

 than normal for small trees are based on a well- 

 recognized tendency for young forest stands of 

 varying stocking to reach or approach normal 

 stocking as they grow older. Thus, young, under- 

 stocked stands will tend to reach or approach 

 normal stocking in later years. On the basis of 



