Epsilon Archive for Student Projects

Abstract

Successful establishment of conifer seedlings is critical for reforestation, yet the effects of fertilization and mechanical site preparation on early seedling performance remain poorly understood. This field study investigates the effects of Silvivo, an organic nitrogen-based fertilizer treatment, on Pinus sylvestris seedlings over one growing season in northern Sweden. Seedlings were planted in June and harvested in October across four treatment groups — one control and three treatment combinations incorporating Silvivo and mechanical site preparation. Survival, total biomass, root collar diameter, and root-to-shoot ratio were measured to assess growth and establishment. Ectomycorrhizal (ECM) fungal community composition was characterized using ITS metabarcoding.
The Silvivo amendment increased total biomass and root collar diameter across treatments, and improved seedling survival in plots without mechanical soil preparation. Root-to-shoot ratio was only marginally affected when seedlings were grown in mounded soil. There was shift in ECM fungal community composition in response to the fertilizer treatment, but this shift was not significant. The observed growth and survival responses, despite the limited ECM community responses, suggests that the changes in the ECM community may not be the primary driver of the seedling response to Silvivo during the first growing season. These findings indicate that organic nitrogen fertilization may improve early establishment metrics in Pinus sylvestris, particularly when mechanical site preparation is not utilized, and highlight the importance of site preparation method when evaluating fertilizer efficacy in boreal reforestation.