Winter Black Spruce Planting

A research project was initiated in February 2011 examining the possibility of winter planting black spruce (Picea mariana) when ground remained frozen, which could help enhance reforestation in the disturbed boreal wetland forest areas in northern regions of Alberta from oil and gas activities; specifically, it may help to address accessibility issues in wetlands. Objectives: (1) to test the survivability of winter-planting frozen black spruce container seedlings, relative to spring planting; and (2) to test the effectiveness of two planting depths for the winter planting survivability. Three planting treatments were designed and implemented in this study at a wetland area in Grande Prairie, Alberta: (1) winter planting to 4 cm (top of seedling plug is placed 4 cm below the soil surface), (2) winter planting to 8 cm, and (3) spring planting.

In Fall 2011, more than 94% seedlings had survived in all treatments, with a healthy height growth of 10-20 cm, so winter planting of frozen black spruce container stocks appears a feasible option for northern Alberta wetlands. 2012-13 measurements found a small fraction of seedlings (1.4-2.5%) died in all treatments and in both years (2012 and 2013), except winter-planting at 4 cm, which had a higher mortality rate of 5.7% (only in 2012) By 2013, 87% of winter planting at 4 cm seedlings remained alive; 94.1% for winter planting at 8 cm; and 94.8% for spring planting. Close to 50% of seedlings suffered extensive terminal dieback in 2011-12, with over 60% dieback in spring-planted seedlings and 37% and 40% for the winter-planting at 4 cm and 8 cm. Terminal dieback and mortality in 2012 increased significantly, likely due to dehydration and cold damage due to low snow cover during a extreme cold spell of -40⁰C in January 2012 and increased wind chill from a newly opened road. Seedlings on the east side, near the road, suffered most, and the spring-planted seedlings had higher damage, likely due to being taller and more exposed. All treatments experienced negative growth that year, but began growing again in 2012-2013. The winter plantings fared better than the spring plantings.