NOTE ON PROLIFERATIVE POWER OF PINUS sp. 



N. M. Grier, Ph. D. 



Near Lakehurst, N. J. is the proving ground of the Chemical 

 Warfare Service, U. S. A. It consists of a large tract of 

 exceptionally sandy loam covered mostly with a growth of 

 conifers {pinus rigida, principally echinata, sylvestris), but 

 with occasional oaks, chestnuts, sassafras, etc., intermingled. 

 Most of this tract has been re-forested within 40-50 years, 

 while in this part of New Jersey, forest fires are by no. means 

 infrequent. 



Judged by the age of oak saplings, a fire had occurred in 

 one part of this tract within the last 4 years. Its effect had been 

 to completely destroy the undergrowth and residual humus 

 and to kill all other kinds of trees but the conifers, whose 

 charred bark indicated the severe heat. A succeeding flora, 

 principally of huckelberry, bracken, commoner grasses had 

 obtained a thriving footing, while the stumps of the destroyed 

 trees supported luxuriant outgrowths. Examination of the 

 trunks of the conifers showed, that previous to the fire, extensive 

 self-pruning had taken place, indicating the density of shade 

 in the woods at one time, the trees branching about 10 feet 

 from the ground. A large number of these branches had 

 been burned quite short, while many of the higher ones had been 

 killed. 



It will be remembered that the branching habit of conifers 

 is a radial one — the trunk might be compared to the hub of a 

 wheel, the whorls of branches to the spokes. Also in old trees 

 these whorls are usually some distance apart from each other. 

 The fire, however, had elicited an elaborate response from the 

 trunks — something which seemed unusual to the writer in view 

 of the common impression of the conservative habits of conifers. 

 While thickest at the top of the trees (in fact, very thick), 

 there appeared between the older whorls, in regions of the trunk 

 never branched before and as near the ground as 3 feet, new 

 and healthy whorls of branches. This proliferation also occurred 

 around the stumps of burnt off branches in all directions 

 above, below, and to the sides. 



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