YIELD TAELSS 57 



c. Forecast Tables. 



These have also been termed Yield Tables. They state (fore- 

 cast) that if, for instance, the stand is cut over to a diameter limit 

 of 12", there will be a growth sufficient to make 3000 ft. b. m. in 

 twenty-five years. They are ba.sed on the stand of timber left after 

 cutting and its estimated growth, the assumption being that a certain 

 number of trees die (estimated) and that the forest continues to 

 reproduce as in the past, and that the composition in mixed forests 

 continue as at present. 



Since these tables are based on the present, more or less acci- 

 dental conditions of the wild woods they apply only for the im- 

 mediate locality and for the immediate future.* 



d. Other Studies in the Timber. 



These involve chiefly the behavior of the important species of 

 trees on the property. 



T. Behavior of trees, notably : 



a. Tolerance. 



b. Site requirements, chiefly as to soil, and in mountains as to 

 exposure and altitude. 



c. I'ehavior of principal species in mixture. 



d. Reproduction, frequency of seed years, abundance of seed- 

 ing, etc. In hardwoods, also, the sprouting. 



These facts as gathered at the first X'aluation Survey are, of 

 necessity, merely beginnings. The behavior of trees in any locality 

 is not learned in one year, and experience must accumulate. 



For this reason such a line of inquiry is treated briefly and 



♦Tables of this kind, though evidently worked out with a great deal of 

 care, have not given us very satisfactory or convincing data. The following 

 figures are taken from four different publications. The growth per acre and 

 year of a stand cut to 12" d. b. h, is as follows: 



Spruce (East) cut takes 2490 ft. per acre, growth -is 103 ft. 



Loblolly (S. C.) cut takes 6190 ft. per acre, growth is 73 ft. 



Pine (Ark.) cut takes 6060 ft. per acre, growth is 150 ft. 

 while according to recent studies the growth of Loblolly in Maryland on 

 Site If, or average lands, is over 400 ft. per acre and year. Here a fast 

 growing species in a warm climate is expected to grow only 75% as much 

 timber as another stand of slow grooving stuff on a cold site, and this in 

 spite of nearly double the growing stock on the land. 



