ECOLOGY AND SILVICULTURE 345 



positive results, since the conditions which prevailed at the time of 

 cutting and subsequently are only to be inferred from more or less 

 debatable evidence. Still, by comparing the results of the studies on 

 areas having certain constant features, this method may throw light 

 on a few general considerations, and these may be all that are imme- 

 diately essential to the needs of a practice which could not yet use 

 more detailed findings, however reliable. 



Accordingly, an observational study of past cuttings was undertaken 

 by the Forest Service in 1915. The phases of the study were, briefly, 

 (1) an enumeration, measurement, and classification of the significant 

 forest vegetation of each cutting studied, usually of quarter acre 

 sample plots; (3) a collection of all the facts and inferences ob- 

 tainable by observation as to the period since cutting, the composi- 

 tion of the original stand, the modifying action of various agencies 

 since the cutting, etc. In general it was aimed to make each of the 

 plots studied tell what the forest was like before cutting, how the 

 cutting afifected composition and density, what came up as dominant 

 young growth, what are its chances for success, and what method of 

 cutting would have given better results, and why.^ 



In compiling the field data, the aggregate number per acre of trees 

 of all the species was given separately for each class, and the per- 

 centage which each species formed of the total for the class was shown. 

 It was hoped that by such comparisons between plots similar in certain 

 respects, resemblances in the character of the reproduction could be 

 discerned which would justify tentative deductions as to cause and 

 effect. As a matter of fact, the variety of conditions found was such 

 that the 45 plots studied in 1915 represent fully half as many 

 distinct sets of conditions. The field data, therefore, are sufficient 



''The form on which the field notes were compiled shows a^ separate tally for 

 "original stand" and "present stand," on an acre basis. The composition of the 

 original stand before cutting and the size of its trees was inferred by combining 

 "holdovers," or trees left in logging, with the stumps, reducing all to a probable 

 diameter, breasthigh, at time of cutting. In very old cuttings "the species of some 

 of the trees cut could not always be determined beyond question from the stumps, 

 and it is possible that in some cases a few smaller or more perishable stumps had 

 entirely disappeared or been covered by soil and humus. Since most of the cuttings 

 were less than 20 years old, however, there was probably not very great inaccuracy 

 from this source. The present stand was separated into "holdovers" and second 

 growth; the latter, in turn, was divided into "Class I" trees, those in the upper crown 

 cover, or which, through tolerance or position, seemed likely to survive for some 

 time, and "Class II" trees, those which would never take an important place in the 

 stand. There was a further distinction between "advance growth," or seedlings 

 \vhich struck root in the original stand before the cutting and "subsequent reproduc- 

 tion," or seedlings and sproats which sprang up after the cutting. 



