Impact of forest drainage after clearcutting on black spruce growth in a boreal forest

The objective of this study was to retrospectively evaluate, with the help of stem analysis, the growth increases of natural and planted black spruce (Picea mariana (Mill.) BSP) seedlings in 39 drainage networks located in Quebec public boreal forest and drained operationally after cutting. The ecological conditions of the sites have been described using the forest ecosystem classification for the Clay Belt of eastern Ontario. A significant effect of the drainage on 9-year periodic growth in diameter and height of natural black spruce seedlings, varying with distance from the ditch and ecological conditions, was observed. Stocking of natural black spruce seedlings was sufficient to insure the reconstruction of a forest stand both on the treated sites and on the control sites. The 5-year height growth increment of planted black spruce seedlings was weaker than that of the natural seedlings, which were located on the same sites, and it varied with distance from the ditches.