The effects of stem density and nutrient status on size inequality and resource allocation in lodgepole pine and white spruce seedlings
Lodgepole pine (Pinus contorta Loudon) and white spruce (Picea glauca (Moench) Voss) seedlings were grown at three densities (900, 2200, and 4000 stems/m2) in fertilized and unfertilized soil. Pine was grown for 111 days and spruce for 120 days. For both the pine and spruce, the mean weight of shoots, roots, and total plant was significantly greater and the root to shoot ratio was lowest in the fertilized and low density treatments. For the spruce, the fertilized treatment had significantly higher size inequality (as measured by the Gini coefficient) for shoot, root, and total mass. For lodgepole pine, only the inequality in root size was greater with fertilization. For the spruce, inequality in shoot, root, and total mass was lowest in the high-density conditions. In the pine, there was little relationship between size inequality and stem density. Compared with the spruce, the pine had greater biomass allocation to roots in poor growing conditions.