342 



FORESTRY INVESTIGATIONS f. S. DKI'AKTMKNT OF AGRICULTURE. 



and 5.G7 are the lowest numbers for tlie corresponding constituents, the highest being 3.40 and 

 Ki.HO, respectively. Here again we have two trees of about tin; same age, under apparently the 

 same conditions of growth, tapped at the same time and abandoned for the same length of time 

 before felling, and yet differing very widely from each other. It is difficult to conceive why tap- 

 ping should have affected the heartwood of these two trees in such a strikingly different manner. 

 If the assumption is made that the tapping had drained both trees equally, wliat explanation can 

 be given for the fact that within one year of abandonment one tree is very rich in turpentine while 

 tbe other has less than one-fourth as much? 



Comparison of irees ~>'2 and 53 irith (iO nd til. Compare 53 and 61. Here we have two trees 

 both very rich in turpentine, but while 53 had five years of rest after tapping, 61 had only one 

 year. Had the tapping forced the trees to pour out their oleoresiu previously stored up in the 

 heart, we should expect to find in the time of rest the prime factor for the tree in resuming its 

 natural condition; but, on the contrary, results of analysis show that time of abandonment before 

 felling is of little importance. While we can have a tree very rich in turpentine within live, 

 years after tapping, we can also have trees rich and poor even within one year, and trees almost 

 totally deprived of turpentine in the heartwood within five years after tapping. 



Conqxirixon of 1 with X. These two trees had never been tapped, and yet neither is rich in 

 turpentine. No. '2 contains about twice as much turpentine as No. 1, the difference becoming 

 smaller as we go up the tree. The highest numbers for 2 are 1.93 and 14.19 for T and it, respec- 

 tively, the lowest 0.86 and 5.89, with an average of about 1 and 7. We can say that there is as 

 much difference between untapped trees as there is between trees that have been tapped. 



Average analyses. The average analyses cover 16 trees. Thirteen trees furnish four sets of 

 analyses of tapped trees and 3 trees furnish one set of untapped. The results obtained are 

 summarised in the following table: 



These results show a pretty constant average number for turpentine in tapped trees. The 

 heartwood of untapped trees is poorer in both volatile oil and rosin than that of tapped trees. 

 And here again it is worthy of notice that time of abandonment is of little importance to tapped 

 trees. The trees that had been abandoned for one year are fully as rich as those that had five 

 years to recover from tapping. 



Comparison of tapped mth untapped trees. If now the heartwood of tapped trees be compared 

 with that of untapped, one is at a loss as to what conclusions should be drawn from so few 

 analytical data. It is remarkable that the two richest trees and tbe poorest tree are among those 

 that had been tapped. Of the remaining 19 trees, there is no difference between the 14 tapped 

 and 5 untapped. Whatever differences are found among bled trees are equally found among 

 those that have not been tapped. 



Indeed, from the study of the results of analyses the writer is of the opinion that the difference 

 in untapped trees is due to the same cause as the difference in trees that have been tapped. As 

 stated above, the cause of the difference among tapped trees can not be traced directly to 

 tapping; it ought to be looked for, rather, in the condition of the trees previous to tapping. 



The difference between trees 52 and 53 can be explained on the following hypothesis: 53 had 

 been a rich tree from early growth and had a large amount of turpentine stored up in the heart- 

 wood; 52 for some reason or other had very little stored away. When the two trees were sub- 

 jected to tapping they gave up whatever turpentine they had in the sapwood and whatever they 

 could produce from season to season, till at the end of four years the production became too small 

 in amount and too poor in quality. The trees were then abandoned. But tree No. 53 had its 

 oleorcsin in the heartwood untouched, while No. 52 had hardly any before tapping, and for the 

 same unknown cause did not store away any in the heartwood after the tree had been abandoned. 



