PRIiLI-MINARY REPORT OF KXPURIMENTS IN PENNSYLVANIA 299 



ture to predict that they will be potent factors in shaping the future 

 course of many vital forest practices in the State, and their range of 

 usefulness and applicability may extend to neighboring States. 



A better perspective of the field of forest experimentation may prob- 

 ably be obtained by classifying the experiments as follows: (i) Politi- 

 cal, (2) managerial, (3) technical. 



The political or social experiments concern themselves with the 

 human or economic side of forestry. They embrace some of the most 

 interesting and original of all the experiments, and pertain primarily to 

 forestry education, forest legislation, forest recreation, and social serv- 

 ice. The managerial experiments inquire into the business aspect of 

 forestry and cover such subjects as the organization of the personnel, 

 the size of State forests, the subdivision of forests, the differentiation 

 of stands, methods of disposal of forest products, the development of 

 road systems, and methods of ascertaining the growing stock. The 

 technical experiments investigate primarily the problems of forest crop 

 production. The latter outnumber all others, and among them are 

 some of the most essential to present-day forest practice. It would be 

 impossible to treat in a single paper all of the experiments in either of 

 the three classes ; hence I have elected to discuss representative experi- 

 ments in the field of forest production. 



No phase of forest production embraces more instructive and essen- 

 tial experiments than that of seeding and planting. To date 1.029 

 plantations have been established on State forests and 150 have been 

 reinforced. They cover an aggregate area of 19.425 acres and embrace 

 many indigenous and exotic species, which occur in both mixed and 

 pure stands on a large number of different sites. 



The principal exotic species planted in the past are European larch, 

 Scotch pine, and Xorway spruce. At the end of the spring planting 

 season of 1918 the following number of each had been set out on State 

 forests : 



Number of 

 Species trees planted 



European larch 682,142 



Scotch pine 2,954,059 



Norway spruce 4.547.753 



Additional exotic trees have been planted, but on a far less extensive 

 scale than the three foregoing species. A\'estern yellow pine. Douglas 

 fir, western white pine, and Japanese larch have been given a fair and 

 comprehensive trial, having been planted in different parts of the State 

 on a wide range of situations. Some of the other exotic species set out 



