Abstract
White spruce (Picea glauca) holds ecological and economic significance as a key conifer species in Canada. Given the susceptibility of white spruce to droughts induced by climate warming and the diverse silvicultural demands related to growth and cold resistance, the assisted migration of white spruce emerges as a crucial and impactful solution. However, the repercussions of climate warming extend beyond drought stress, as they also exacerbate threats from insects and pathogens. Among these threats, the eastern spruce budworm (Choristoneura fumiferana) stands out as a significant menace to white spruce. Historically, it has led to substantial losses in white spruce populations. And the needle terpenes concentration plays a significant role in the chemistry defense of white spruce against eastern spruce budworm. Notably, there exist substantial research gaps regarding the impact of migration from varying distances on the terpene content of white spruce needles.
The aim of this study was to investigate the impact of migration from varying distances on the terpene content of white spruce needles and explore the factors influencing the terpene content of white spruce needles in transplants. This study collected foliar monoterpene and sesquiterpene concentration and fungal endophyte abundance from white spruce trees in six genotype origins spanning five provinces in Canada and 9 genotype origins inside Alberta. The findings revealed that larger-scale and longer-distance assisted migration of white spruce, the factors influencing the needle terpene content are the latitude and longitude of the genotype origin, with a notable positive correlation observed between needle endophytic fungi and terpene content, demonstrating significant specificity. Conversely, in the intra-provincial migration of white spruce, the key influencing factor is the elevation of the genotype origin. Therefore, the result of this research implies a comprehensive consideration of afforestation objectives and chemical defense against the eastern spruce budworm when making plans.