43 



FIELD WORK. 



Under the modified method here presented the field work constitutes 

 the most delicate part of the tree analysis. The reliability of the tables 

 of growth calculated in the office for various groups of trees and the 

 deductions made from them depend not only upon the accuracy with 

 which the measurements of individual trees are taken, but also upon 

 the knowledge and skill employed in classifying the trees and describ- 

 ing the conditions under which they grow. 



The field work begins with a general description of the station. 

 Blank No. 1, given in the appendix, may be recommended for that 

 purpose. The geographical climate of a station is determined by its 

 latitude. Special attention must be given to ascertaining the physical 

 or local climate, for it has a direct effect upon the rate of growth and 

 quality of timber. The local climate depends upon the general con- 

 figuration, elevation, general trend of the valleys or mountains, nature 

 of soil, and proximity of sea. All these local features must be care- 

 fully noted. If the locality is provided with a meteorological station 

 the record of that station for average monthly temperature, for aver- 

 age monthly precipitation, and monthly means of relative humidity 

 should be procured for the greatest possible length of time. 



In most cases such climatic data can not be obtained, and that is why 

 it is advisable to carefully examine every local feature that may exert 

 au influence upon the temperature and humidity of the atmosphere. 



FOREST CONDITIONS OF STATION. 



In describing the forest conditions of the station typical forms should 

 be indicated, and, if possible, each typical form represented by one or 

 more sample areas. Such sample areas, besides having a statistical 

 value, furnish valuable information on which to outline the general 

 forest conditions surrounding the species under investigation. 



It is exceedingly desirable to procure trees for analysis from each 

 typical form of forest conditions of the station, especially so when the 

 •typical forms differ considerably from each other in soil and drainage 

 conditions or in the composition and density of the forest. The climate 

 being thus eliminated, it becomes more easy to determine the effect of 

 each of the various factors upon the rate of growth of the species. 



In many instances the timber investigator has little choice in select- 

 ing conditions for measuring trees, because the detailed measurement 

 necessary for analytical purposes requires the felling of the trees and 

 their being sawed up into logs, which operation is regulated by the 

 lumber camps. The operators of lumber camps usually confine them- 

 selves for each winter to limited forest areas, which seldom offer a wide 

 range of forest and other conditions. A station may comprise several 

 camps, each of which, of course, may represent distinct forest conditions. 

 But in most cases the timber investigator will have to connect his work 

 with the operations of the lumber camp, and direct his attention at 



