REPRODUCTION OF BLACK SPRUCE (PICEA MARIAXA) 



By W. H. Kenety 



Superintendent Forest Experiment Station, Cloquct, Minn. 



One of the trees which is economically very important in Minnesota, 

 Wisconsin, and Canada is the black spruce (Picea mariana). This 

 tree up to the present time has been the source of the greater part of 

 the paper pulp manufactured into news paper in these states and parts 

 of Canada. 



It is doubtless generally known that black spruce is confined almost 

 entirely to sites, the vegetative ground cover of which is moss, known 

 under the terms of sphagnum moss, peat moss, etc., and composed 

 largely of species of Lycopodium. 



Black spruce is found as a dominant type on two sites which are 

 very different in some respects, one being the spruce swamps and 

 muskegs of Minnesota, Wisconsin, and adjacent parts of Canada, and 

 the other the rocky outcrops of rock, so prevalent in northeastern 

 Minnesota. In a study of black spruce the writer's attention was 

 attracted by the similarity of the type of vegetation and the very 

 dissimilar topographic and soil features of these two situations. Both 

 sites where black spruce prevailed had a cover of moss, and this 

 feature was so pronounced that a sort of symbiotic relationship between 

 the moss and the spruce was suggested. A study was made of the 

 ecological conditions in a spruce swamp where data were secured daily 

 throughout one growing season, from June 1 to November 1. Soil 

 temperatures taken throughout the season at depths of 6 inches, 12 

 inches, and 24 inches revealed the fact that the temperature of the 

 first foot of soil did not get above 32° F. until the first week of June. 

 Ice was found in many places in the swamp within a foot of the 

 surface until the middle of July. The mean temperature of the soil 

 from June 1 to November 1 was 46.1°. The soil was warmest in 

 September and the upper 6 inches rarely reached a temperature of 

 50°. Determination of the soil moisture based on the dry weight of 

 the soil showed that throughout the season the soil was nearly satu- 

 rated, no determination giving less than 80 per cent moisture. Under 

 these trying conditions it can be easily understood that the germination 

 and establishment of any spruce seed in this sort of a situation is 

 almost an impossibility. This is substantiated by the fact that no 



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