Description

To determine the differences in tree regeneration after fire and logging, lowland black spruce stands burned (by crown fire) and logged (by clearcut) 6 to 13 years ago in southeastern Manitoba were investigated. Black spruce regeneration was the most abundant on both burned and logged sites, with jack pine as the main associate on burned sites and tamarack and trembling aspen as main associates on logged sites. Other tree species were rarely found on either burned or logged sites. A continous recruitment pattern was observed on both burned and logged sites for black spruce, with a higher number of black spruce seedlings recruited each year on burned sites. As a result, seedling stocking and density was significantly higher on burned sites. When compared to the regeneration standard of Manitoba, all burned sites were considered satisfactory while two of the nine logged sites were unsatisfactory. Advanced regeneration was found insignificant to post-disturbance (either fire or logging) forest recovery. The total height and the 1995 height growth of black spruce seedlings were significantly higher on logged sites, which was caused, at least in part, by the inherent difference in site quality (measured by site index) between burned and logged sites. Relative annual height growth (expressed as % of mean annual height growth) was higher at age £ 5 and lower at age ³ 6 on burned sites when compared to logged sites where it increased linearly with age. The ratio of the 1995 height growth of logged sites to that of burned sites decreased from 165 % to 135 % when total height approached 1 m. These differences in early height growth pattern suggested that black spruce seedlings of burned sites may have encountered more competition from understory plants.