Biotic and abiotic effects on temperate tree range expansion at the boreal - temperate ecotone

Abstract

The broad-scale effects of climate change on the distribution of species around the planet are relatively well understood, however our predictive powers of how species ranges will shift and re-organise are hampered by species’ interactions with one another and their environments. An investigation into seedling emergence constraints of four northern temperate tree species beyond their realised geographical niche was conducted using the available literature and experimental manipulation of natural systems. Two iterations of the field experiment (2015/16 & 2016/17) allowed for development and evaluation of experimental design, particularly vertebrate herbivore exclosure design. Climatic variables were largely unimportant drivers of model species’ ability to successfully emerge at experimental sites across Newfoundland, whereas biotic interactions impacted species-specific emergence, depending on reproductive strategies. Seed predation and canopy composition were among the most important biotic drivers of model species’ emergence success.