Seedling response following different methods of mechanized site preparation

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University of New Brunswick


The findings of a study involving the response of black spruce (Picea mariana (Mill.) B.S.P.) paperpot tree seedlings, planted in 1980 on three sites in the Province of New Brunswick, are presented. Each of the areas chosen exhibited a different method of mechanically preparing the site. The mechanical scarifiers used were: the Cazes and Heppner (C & H) plough, the Model 3523 Letourneau crusher, and the shark finn barrels and chains. The study was designed in order to determine the effects of black spruce responding to different methods of site preparation. The sampling method involved a set of randomized sample plots established by the New Brunswick Department of Natural Resources in 1980. Height measurements were taken in years 1980, 81, 83, and 85. Other pertinent information was also collected from these visits including competition levels, brousing, slope, aspect and drainage classification. The results of the study show that as the disturbance to the site increased, the growth of black spruce decreased. The results of the study further showed a 54 percent reduction in total mean height growth. This was found by comparing a site prepared by a C & H plough to a site prepared with shark finn barrels and chains. There was also an increase in the frequency of brousing on the C & H ploughed site. The site prepared with the C & H plough had a 4 percent brouse level, while the sites prepared with a crusher or with shark finn barrels and chains had brouse levels of 0 and 0.5 percent respectively. The level of competition increased 67 percent between the three sites. The highest level of competition was on the C & H ploughed site. This level of competition was found to have greatly effected the growth of the seedlings. Therefore, matching the method of site preparation to the site and to the species reduces the problem of employing intensive site preparation methods on sites which do not require them. This, in turn, will maximize the productive nature of the site while also creating a more favorable environment in which the young tree seedlings are to grow. Key Words: black spruce, competition, seedling response, site disturbance, site preparation