Plant-soil feedbacks in boreal tree species

Abstract: Plant-soil feedback (PSF) is important for understanding how plants influence the composition and abundance of soil biota and nutrients and how this affects plant growth. The plant economic spectrum (PES) also plays a role. This study is a two-stage experiment that aims to determine the roles of plant traits and biotic and abiotic soil properties on PSF. Soil was collected from two sites in Sweden consisting of replicated monocultures of different tree species. Soil in each plot is considered to be “trained” by the planted species. A glasshouse experiment was set up with a live and sterilization-inoculation experiment using four boreal tree species (Betula pendula, Picea abies, Pinus contorta, and Pinus sylvestris). In the live experiment, seedlings were planted on live soil from each species and in the sterilization-inoculation experiment each species was planted on combinations of sterile soil and live soil inoculum. Biomass was taken and used to calculate PSF for each species. In the live experiment, B. pendula had significantly higher biomass than the other species which follows the predictions made based off the PES. P. contorta had positive PSF, although not significantly different, and the other species had negative PSF which was unexpected as it was predicted that all species would exhibit negative PSF. In the sterilization-inoculation experiment, soil inocula did not have a significant effect on PSF but some species had a significant species-soil origin interaction. This rejected the third hypothesis as it was predicted that soil inocula would follow the same patterns as the first experiment. This research has implications for the forestry industry as it can inform better on tree species choice and more sustainable forestry practices.