Insect seed and cone predation reduces reproductive potential of treeline conifers across northern Canada

Aim: Altitudinal and latitudinal treeline ecotones have not consistently responded to climate warming the in direction and/or magnitude as predicted by climate alone, suggesting that non-climatic mechanisms (e.g., biotic interactions) are also mediating treeline range dynamics. Through a collaborative research approach, we assessed environmental conditions associated with insect cone granivory and how this biotic interaction may govern the reproductive potential, and therefore range dynamics, of spruce-dominated treelines across northern Canada. 
Location: Ten boreal forest treelines, tundra and alpine, from Yukon to Newfoundland and Labrador, Canada
Taxa: White spruce (Picea glauca (Moench) Voss), Black spruce (Picea mariana (Mill.) B.S.P.), Strobilomyia spp., Megastigmus spp.
Methods: Treeline sites were assessed for presence and magnitude of pre-seed dispersal granivory by insects, and viability of available seed was determined. We quantified stand density metrics, organic layer dept...