Jack pine establishment in Ontario: 5-year comparison of stock types ± bracke scarification, mounding, and chemical site preparation

Abstract

Field experimentation was begun in 1984 to assess performance of jack pine (Pinus banksiana Lamb.) (2 + 0 bareroot and FH408 Japanese paperpot) in relation to mechanical site preparation, including Bracke scarification with and without supplementary mounding, and site preparation using Roundup® herbicide. Twenty treatments encompassed 4480 trees in 40-tree plots split equally between bareroot and paperpot stock. The study site, about 200 km north of Sault Ste. Marie, Ontario, had deep silt loam soil. After 3 growing seasons, survival was significantly higher among bareroot than among paperpot stock, but survival no longer differed significantly (P < 0.05) between stock types 2 years later. In years 4 and 5, the rate of increase in mean total height of bareroot stock was 11% less than that of paperpot stock, though bareroot stock was 40 and 4.7 cm greater in mean total 5th-year height and 5th-year height increment, respectively. Paperpot stock needed mechanical site preparation more than did bareroot stock. By the end of year 5, positive responses of survival and growth to mounding had become clear in both stock types; however, although mound size had little or no effect on survival or total height, mean stem volume was significantly (P < 0.01) greater on 20-L vs. 10-L mounds. Fifth-year mean stem volume was also significantly (P < 0.01) greater on mineral-on-organic (M/O) than on mineral-on-mineral (M/M) mounds. Chemical site preparation had no effect on relative growth rates beyond year 3. Indices that combined survival with total height or stem volume after 5 years show the significant (P < 0.01) superiority of: 20-L vs. 10-L mounds, M/O vs. M/M mounds, and chemical vs. no-chemical site preparation.