Seedling growth and water use of boreal conifers across different temperatures and near-flooded soil conditions

Abstract

To test the hypothesis that seedling growth and water use increase with soil temperature and improved soil aeration and vary with species, we evaluated the above- and below-ground growth and water use of seedlings of four northern boreal conifer species: black spruce ( Picea mariana (Mill.) B.S.P.), white spruce ( Picea glauca (Moench) Voss), tamarack ( Larix laricina (Du Roi) K. Koch), and lodgepole pine (Pinus contorta Dougl. ex Loud.) grown under different temperature and near-flooded soil conditions. Seedlings were grown in specialized pots that maintained the water table level at either 15 cm (high water table treatment: very wet) or 30 cm (low water table treatment: moderately wet) below the soil surface, and whole-seedling transpiration was assessed. Soil temperature (5, 10, or 20 °C) was controlled with a water bath surrounding the pots. Although some species were sensitive to the high water table treatment, soil temperature was the driver of seedling growth and water use. We ranked the ability of the seedlings of the species to tolerate the cold soil conditions examined as black spruce > lodgepole pine > tamarack > white spruce. The ranking of the ability to tolerate near-flooded conditions was tamarack and lodgepole pine > black spruce > white spruce.