The proposed use of pit and mound topography in conifer plantations: converting Cawthra Mulock’s coniferous plantations to mixed-species forest

Abstract

Forest managers have been increasingly interested in hastening the conversion of coniferous plantations to uneven-aged, mixed-species forest in an effort to increase native biological diversity and improve forest resilience. Studies investigating broadleaf recruitment are predominantly focused on the variation of understory light environments created by canopy gap openings. Although improved light availability contributes significantly to seedling growth, there are other physical and chemical alterations produced within treefall gaps that are often overlooked in tree regeneration studies. Treefalls are typically accompanied by uprooting, which leads to the creation of two important properties in understory environments: (1) the change in soil profile, and (2) the presence of pit and mound topography. The increased structural complexity of the forest floor, following treefall, has been found to greatly benefit germination and seedling growth of a diversity of tree species. The construction of pit and mounds has shown to be a successful strategy for improving species establishment and species richness in wetland systems, peatlands, and open-field habitats. However, the use of pit and mound topography within coniferous plantations to enhance broadleaf seedling growth and survivorship, remains unexplored. The proposed research will examine the effects of pit and mound topography, light intensity, and the effects of added biochar on the growth and survival of broadleaf seedlings in a coniferous plantation. The results can be applied to the management of coniferous plantations throughout Ontario. The results will also contribute to a better understanding of the regeneration niches of ecologically important northern temperate tree species.