Development of opinion-based generic reforestation regimes and their application in vegetation management and water modelling in the Upper and Lower Foothills of Alberta

Abstract

The operational forestry practices employed by Millar Western Forest Products Ltd. in the Upper and Lower Foothills of Alberta, Canada integrate a broad range of tools to plan, implement, and manage post-harvest site regeneration of pure and mixedwood boreal forests. Following tree harvesting, mechanical site preparation is often used to improve microsite conditions to promote conifer seedling establishment or natural regeneration. Chemical and mechanical site preparation and stand tending control competing vascular weed species. To meet forest regeneration commitments, incorporating knowledge gained from forestry experimentation, long-term field data and iterative deterministic modelling into modified management approaches is employed to formulate appropriate vegetation management strategies. These strategies consider and balance multiple biodiversity (e.g., habitat supply modelling), physical environmental (e.g., streamflow), and societal (e.g., industrial fibre requirements) needs relative to a regenerated vegetation complex. From this experience and understanding, the Company developed a series of generic establishment regimes (GERs), which prescribe detailed silvicultural activities to achieve site-regenerated vegetation complexes in alignment with higher-level forest management planning. An outcome of the GER formulation was the development of corresponding plant community assembly diagrams (PCADs), which describe vegetation complexity and permit calculation of total biomass relative to the time series of silvicultural activities within each GER. In turn, these allow forest planners to model biological, physical, and societal factors, while taking into consideration specific stand growth trajectories based on impacts of silvicultural activities on vegetation biomass and species composition. The GERs and PCADs help formulate vegetation complexes over time and are used to guide the behaviour of a vegetation growth model used in conjunction with a hydrologic simulation model. Résumé :Les pratiques forestières utilisées par la compagnie Millar Western Forest Products Ltd. dans les hauts et les bas contreforts en Alberta, Canada, comprennent une large gamme d'outils aidant à planifier, implanter et gérer la régéné-ration des sites après la récolte des forêts boréales mixtes et à une seule espèce. À la suite de la récolte, le site est couvent préparé mécaniquement pour améliorer les conditions afin de faciliter l'établissement de semis de conifères ou la régénéra-tion naturelle. La préparation chimique et mécanique du site et les soins sylvicoles contrôlent l'apparition d'espèces de plantes nuisibles vasculaires. Pour rencontrer les engagements de régénération de la forêt, il a fallu incorporer des connaissances acquises d'expériences en foresterie, des données à long terme prises sur le terrain ainsi qu'une modélisation déter-ministe itérative dans les approches de gestion modifiées; cela a permis d'établir des stratégies appropriées de gestion de la végétation. Ces stratégies tiennent compte et équilibrent de m...