Feathermoss seedbeds facilitate black spruce seedling recruitment in the forest-tundra ecotone (Labrador, Canada)

As climate warms, conifers are expected to expand their ranges into alpine tundra where ecological factors such as seedbed availability, and post-dispersal seed and seedling predation may control local recruitment. Seedbed composition may influence microhabitat, nutrients, physical structure, and predation level and, therefore, affect the success of conifer recruitment, thereby providing the template for future expansion. In the boreal forest, seedbed—seedling competition dominates such that seedbed removal increases black spruce recruitment. In the harsher climate of the Mealy Mountains boreal forest—tundra ecotone (Labrador, Canada) the Stress gradient hypothesis (SGH) predicts that facilitation may dominate seedbed—seedling interactions. This study investigated potential mechanisms of seedbed facilitation (temperature, water, nutrients, physical protection) in three conifer seedbeds (Pleurozium schreberi, Cladonia spp., bare soil) and examined whether seed predation and/or seedling herbivory varied among seedbeds over three years. Seed emergence was low overall (