PAPERS BY MEMBERS 91 



REPRODUCTIOX BY LAYERIXG IX THE 

 BLACK SPRUCE. 



GEORGE D. FULLER 



During the summer of 1912 while conducting some eco- 

 logical studies along the Saguenay River. Quebec, attention 

 was directed to the process of forestation and reforestation 

 of slowly disintegrating granitic areas and where the rocky 

 surface was exposed to the full sweep of the wind. The re- 

 gion most closely examined consisted of granite hills about 

 Ha I Ha ! Bay with typical roches mountonnees contours and 

 elevations varying from 100 to 300 meters. In these exposed 

 situations the tree vegetation consisted largely of black 

 spruce. Picea mariana. Jack pine. Pinus Banksiana. the white 

 birch. Betula alba and the aspen. Populus tremuloides with 

 accasionally some white spruce, Picea canadensis and a few 

 other less abundant species. Many of the conifers exhibited 

 a growth-form apparently peculiar to such areas and finding 

 its highest specialization and most frequently occurrence in 

 the black spruce. 



Grown in swamps or thickets the black spruce is char- 

 acterized by an irregular narow cone of branches. This cone 

 was found to be even more slender in the sparse stand on the 

 granite surfaces but here were found in addition much longer 

 branches near the surface of the rock, forming a compact mass 

 of twigs, none rising more than 1-2 meter above the surface. 

 At least one half of the total foliage of the trees was usually 

 upon these prostrate branches. The same habit was evident 

 in Pinus Banksiana and to a less extent in Picea canadensis. 

 It seemed a decided advantage to trees rooted in the shallow 

 soil of the rock crevices as the exposure to excessive trans- 

 piration caused by high winds was much less, and fewer trees 

 were uprooted. The habit was confined to open stands. 



The mat of lichens and mosses which antedates the trees. 

 continued to thrive under and among the prostrate branches 

 and the resulting soil soon buried portions of the lower mem- 

 bers of the mass. This was apparently without results other 

 than somewhat more securely anchoring the trees in the case 

 of Pinus Banksiana but on the spruces roots were often pro- 

 duced from the buried branches and a circle of young trees 

 surrounded the parent. Should the tree be cut down its early 

 replacement was assured from this layering. 



Such reproduction by layering has recently been dis- 

 cussed by Cooper(l) who has also given complete citations 

 of the literature of the subject. The layering habit in Picea 

 mariana is mentioned by Louden (2) for specimens growing 

 under partial cultivation on the British Isles but its eflfect in 



