Effects of woody debris and cover soil types on soil properties and vegetation 4–5 years after oil sands reclamation

Abstract

Woody debris is a critical component of natural forests, with an important function in land reclamation to control erosion and enhance diversity and function of newly developing ecosystems. Combined with cover soils, woody debris can play a significant role in plant community development, as cover soil is a source of inexpensive and ecologically adapted propagules. As we develop woody debris application as a land reclamation tool, its impacts on cover soils over time need to be documented. This study assessed how woody debris volume, types (Picea mariana, Populus tremuloides), and size influenced soil properties, and vegetation structure and composition in forest floor‐mineral mix (FFM) and peat‐mineral mix (PMM) cover soil types 4–5 years after oil sands reclamation. Soil chemical and physical properties were significantly affected by cover soil types, whereas no woody debris effects were evident. FFM cover soil was associated with greater vegetation cover, plant species richness, composition, and woody plant density than PMM. Nonmetric multi‐dimensional scaling and multi‐response permutation procedures revealed plant community compositional differences only for cover soil types. Presence of early‐to‐late and mid‐to‐late seral species 4–5 years after reclamation in FFM and PMM indicated community development trajectories were following typical early successional processes of boreal forests of the region. Woody debris type, size, and volume application had small or no impact on vegetation development. Although FFM cover soil was more effective than PMM, further long‐term research to evaluate impacts of woody debris on vegetation development would be important to affirm its use for reclamation.