the boreal forest in canada provides a large volume of timber for canadians and other countries year after year and effective silviculture is the key to sustainable harvesting. site preparation can be a critical step in effective regeneration of sites, as it alters soil conditions and vegetative competition. the objective of this study is to be able to determine the difference in mean annual increment (mai) in terms of height growth and root collar width that mechanical site preparation has in jack pine regenerated stands. a total of six regenerated harvest blocks, three with site preparation and three without site preparation, that were a mix of four and five years old were studied within the lakehead forest around the city of thunder bay in the fall of 2017. the data collected (height in cm/yr. and root collar diameter in cm/yr.) from these plantations was analyzed using spss statistics, which provided descriptive statistics and a univariate anova. for the data to be significant, a 95% confidence level was required (p=0.05). the significance value for height and root collar diameter values between treatments was 0.824 and 0.755, respectively. this shows that the null hypothesis of this study was correct in that there was no significant increase in height in the site prepared sites from the non-site prepared sites. this could be due to a number of limitations involved with studying the boreal forest, and if this study was to be repeated, more consideration of these limitations could lead to different results.