SAMPLE PLOTS IN SILVICULTURAL RESEARCH 



43 



AGE 



Tree ages are determined by counting annual rings on increment- 

 borer cores or on stumps. Borings for the purpose of determining 

 age and diameter growth are usually made at breast height (8). 



The increment borer, with extractor, and a device for measuring 

 increment cores are shown in plate 3, B. 



If the total age of a tree is sought, account must be taken of the 

 time required by the tree to reach the height at which the rings are 

 counted. The length of this period may be determined from stem 

 analyses of reproduction of the same species growing under the same 

 conditions. In order to hold this correction to the minimum, incre- 





FIXED 

 CROTCH KNOT 



FRONT VIEW OF SLIP KNOT 



TO SWING BOARD 



SLIP 



TIGHTENING 



KNOT- 



LONG LOOSE 

 HANGING END 



A PULL ON THIS END 

 OR A STRAIGHTENING 

 OF THE SLIP KNOT AL- 

 LOWS THE CLIMBER 

 TO LOWER OR RAISE 

 HIMSELF 



SWI NG BOARD 



LONG LOOSE END 



BACK VIEW OF SLIP KNOT 



TO SWING BOARD 



LONG LOOSE 

 HANGING END 



Figure 



-Swing for tiiking measurements on standing trees. 



ment borings for the determination of total age should be made as 

 near the ground line as possible. On hillsides borings may some- 

 times be made on the downhill side of the tree at the root collar, and 

 total age thus determined directly. For some species, true age can- 

 not be ascertained dependably even by this method ; e.g., seedlings of 

 longleaf pine (P. palustris) remain in the " grass stage " for a 

 period that may exceed 20 years, and that cannot be exactly ascer- 

 tained in a given case by any method now known. Badly suppressed 

 small seedlings of tolerant species, also, may make so little diameter 

 growth over a period of many years that their growth rings cannot 

 be counted except with the use of a low-power microscope. 



It should be borne in mind that eccentricities of growth may make 

 a single boring in a tree unreliable as an indicator of the diameter 



