SAMPLE PLOTS IN SILVICULTURAL RESEARCH 45 



An indelible pencil is most convenient for marking cores, as it 

 makes a permanent mark on moist wood. 



Recently, the use of phloroglucin has been advocated as an aid in 

 counting annual rings on increment cores (70). Phloroglucin stains 

 the lignin. As the lignin is more dense in the late summer wood, 

 the stain causes the annual rings to stand out. Phloroglucin is 

 used in an approximately 5-percent aqueous solution. The stain 

 is intensified if hydrochloric acid also is used, in a solution contain- 

 ing 2 parts of water to 1 part of concentrated acid. The two fluids 

 may be mixed and used together; better results are obtained, how- 

 ever, by immersing the cores for a short time in a test tube of phloro- 

 glucin and then placing them in a tube of acid. Drying the cores 

 in advance does not interfere with this practice. Cores that have 

 been dried do absorb more of the stain, unless they are slightly 

 moistened with water before being stained. Phloroglucin is equally 

 efficacious on stumps, if poured or lightly brushed into a groove 

 cut along the radius on which it is proposed to count the rings. 



So far as is possible, increment cores should be preserved. An 

 excellent means of carrying cores in the field and of filing them is 

 to place them lengthwise in the folds of corrugated paper. Increment 

 cores taken in the general forest survey in Sweden were preserved by 

 inserting each core in a paper tube, one end of which was closed by 

 flattening and stapling, The tubes were made of several turns, or 

 layers, of paper and so were stiff enough to endure ordinary han- 

 dling without becoming bent. A printed form on each tube permitted 

 the entry of a record identifying the core. Pencil boxes are satis- 

 factory for small cores that are not subject to warping. Test tubes 

 that can be corked are sometimes used. 



The use of the increment borer, like the use of nails and the 

 scraping of bark, on some species of pine may cause pitch soaking of 

 the wood or start a flow of resin that will attract insects. Full 

 information as to how increment borings ultimately affect trees, 

 although badly needed, is not yet available. On a permanent plot 

 the fewest possible borings should be made. If there appears to be 

 danger of damage to the tree, the hole may be filled with a i/^-inch 

 wooden dowel that fits it exactly. The dowel should be driven into 

 the hole until the outer end is flush with the cambium. It is believed 

 that within a short time after this treatment the opening will be 

 closed by a callus. A record should be kept of the trees that are 

 bored for any purpose. 



The increment borer should be kept sharp at all times. In the 

 field, minor nicks and slight dullness can be corrected by careful 

 use of a small rat-tail file. Such sharpening should not, however, 

 be depended upon entirely. After about 100 or 200 borings, accord- 

 ing to the character of the wood on which it is used, the borer should 

 be sent to a competent machinist for sharpening (62), 



STUMP DIAMETER 



It is sometimes necessary to estimate the diameters of felled trees 

 from stump measurements. A study of butt taper of similar trees 

 in a similar situation will show the relationship between the diam- 

 eter at breast height and the diameter at any stump height. Such 

 a study should be made in all cases in which ordinary accuracy is 

 required. It should be remembered, however, that stump measure- 



