Influence of Site Preparation on Natural Regeneration and Understory Plant Communities within Red Pine Shelterwood Systems

Abstract

The effects of four site preparation treatments on natural red pine (Pinus resinosa) regeneration and understory plant community composition were examined within a red pine shelterwood in northern Minnesota. Site preparation treatments were applied after shelterwood establishment cuttings and included underburning (B), herbicide (H), mechanical mulching (M), and M + H treatments. Natural red pine regeneration densities were greatest in M only and M + H treatments, whereas there was no statistical difference in red pine regeneration between H, M, and untreated control areas 5 years after treatment application. Ordination and indicator species analysis of the understory communities revealed distinct understory assemblages corresponding to each treatment. Diervilla lonicera and Pteridium aquilinum were significant indicators of burned communities, whereas Maianthemum canadense and Rubus strigosus and red pine were significant indicators of the H only and M + H treatments, respectively. Overall, densities of shrub species did not change after B, whereas reductions in shrub densities were observed for all other treatments. Findings from this work indicate that viable site preparation treatments exist for securing natural red pine regeneration within shelterwood systems, thus providing an alternative or supplement to artificial regeneration efforts in regions with low risk of shoot blight infection.