Permanent Sample Plots. 39 



include them, if necessary, in the future. Plots on the same section or 

 those within one-half mile of each other, when not separated by private 

 land, should be designated by the same major plot arable numeral. 



ESTABLISHMENT. 



Withdrawal. — Formal withdrawal is usually not necessary* but the fol- 

 lowing form should be used in writing to the Ranger on whose district 

 the plots are located. 



Comers and Boundaries. — All corners** should be either of very durable 

 wood or of some semi-durable species which has been seasoned for some 

 time or creosoted. Forest Order No. 23, Part 4, should be followed with 

 following changes : 



In marking corners the letter "S" should be used instead of the letter 

 "R", so as to indicate a silvicultural area. Each plot should be designated 

 by a serial letter in addition to the arabic number of the major plot, i. e., 

 the marking S-2-B-4 indicates corner number 4 of reproduction plot 

 number B of major sample plot number 2. 



All plot corners should be set 2 feet in the ground where possible; the 

 smaller stakes should be driven in until firm. 



MEASUREMENTS. 



Diameter. — All merchantable species having an average diameter at 

 breast height, outside the bark, of an even 4.0 inches or over should be 

 measured and numbered. All stumps should be measured outside the bark 

 and their diameters and location placed upon the map of the plot. 



All trees whose crowns extend for at least half of their width into the 

 plot should be measured and mapped. 



All diameter measurements should be recorded to the nearest tenth of 

 an inch, the first measurement being taken 4.5 feet from the ground or 

 six inches above the copper nail with which the number tag is fastened, 

 and the second taken at right angles to it : both figures should be recorded 

 separately. Where a measurement can not be taken at breast height it 

 should be taken at the nearest practical point above and below and an 

 average obtained ; where a fork occurs below breast height each fork 

 should be numbered and recorded separately; where the fork is too high 

 for this the main stem of the tree should be measured below and where the 

 swelHng (from the fork) is not appreciable. Care must be taken that 

 swellings or small limbs are not measured on the opposite side of the tree 

 from which the caliper man is standing. Notes should be made of any 

 irregularities in the form of the tree which visibly affects the figures 

 obtained such as large burns, deep scars, swellings, etc. In using the 

 calipers they should be always held at right angles to the bole of the tree 

 for both of the readings. The first diameter reading should be taken 

 directly over the copper nail so that the trees diameter (at that point) 

 divided by two will appear directly above the nail i. e., for a reading of 20 

 inches the 10 inch mark on the calipers should appear directly above the 

 nail. The points 4' and 4' 6" above the ground at which the number is 

 placed and the diameted measurements are taken should always be mea- 

 sured, preferably wath the 51 inch calipers. 



Height. — All trees having a diameter breast high of 4 inches or over 

 outside the bark should have their heights recorded with the Klaussner 

 hypsometer; the distance from the tree to the instrument should in all 



*Any conflicts with mineral locations, special or other uses. Forest Homestead 

 applications, etc., should be avoided. 



*Where the danger from fire is great the plot corners should be surrounded by 

 large mounds of earth or rocks or both. 



