Growth and Nutrition of Black Spruce Planted on Cutover Upland Raw Humus in Quebec

As part of a larger study of the nitrogen cycle in a stand of upland black spruce north of Baie Comeau, on the north shore of the St. Lawrence River, Quebec, a portion of the 65-year-old stand was clearcut (fig. 1) and planted with wilding trees (fig. 2) , 4 to 6 years of age, collected along the side of the road (Weetman, 1964, 1967). The stand was known to be nitrogen deficient. The foliar nitrogen concentration in current needles sampled in the fall was less than one percent. This stand has responded in diameter and height growth to urea applications. It was anticipated that black spruce trees planted in the cutover would also be nitrogen deficient. In 1961, when these treatments were carried out, a phosphorus deficiency was also anticipated. However, our present knowledge of black spruce nutrition indicates that this is not the case. Nitrogen deficiencies were anticipated on this site because it has a podzol profile in a deep outwash sand mixed with till and capped with four to six inches of mossy, fibrous and inactive raw humus. The C/N ratio of this humus is 55/1. It was thus originally anticipated that mineral nitrogen released by decomposition would be immobilized by microbial activity.

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Author(s): Gordon F. Weetman

Publication: Tree Planters' Notes - Volume 18, Number 4 (1967)

Volume: 18

Number: 4