: Throughout much of the northern temperate and boreal forests of Canada, intensifying silviculture to enhance fibre production is of increasing interest. However, some oppose the application of intensive silviculture, citing possible negative effects on biodiversity. Using fifth-year post-harvest data from the NEBIE Plot Network in Ontario, Canada, we studied the relationship between plant diversity, silviculture intensity, and contemporary climate. Neutral, linear (positive and negative), exponential (positive and negative), quadratic (concave up and concave down), cubic, and higher-order models were fit to the data. Here we discuss the potential influence of climate and silviculture on observed biodiversity patterns. As well, we address their effects on regional species pools, succession, hierarchical structure, invasibility by exotic species, and species resilience. Résumé : Pour une bonne partie de la forêt boréale et tempérée nordique du Canada, l'intensification de la sylviculture pour augmenter la production de bois suscite de plus en plus d'intérêt. Cependant, certains s'opposent à l'utilisation de la sylviculture intensive craignant de possibles effets négatifs sur la biodiversité. En utilisant des données prises 5 ans après la récolte du NEBIE Plot Network (Ontario, Canada), nous avons étudié les liens entre la diversité végétale, l'intensité de la sylviculture et le climat actuel. Des modèles neutre, linéaires (positif et négatif), exponentiels (positif et négatif), quadratiques (concave vers le haut et vers le bas), cubique et d'ordre supérieur ont été ajustés aux données. Dans cet article, nous discutons de l'influence potentielle du climat et de la sylviculture sur les patrons de biodiversité observés. Nous discutons également de leurs effets sur les assemblages régionaux d'espèces, la succession, la structure hiérarchique, l'envahissement par des espèces ...

In the past two decades, forest management has undergone major paradigm shifts that are challenging the current forest modelling architecture. New silvicultural systems, guidelines for natural disturbance emulation, a desire to enhance structural complexity, major advances in successional theory, and climate change have all highlighted the limitations of current empirical models in covering this range of conditions. Mechanistic models, which focus on modelling underlying ecological processes rather than specific forest conditions, have the potential to meet these new paradigm shifts in a consistent framework, thereby streamlining the planning process. Here we use the NEBIE (a silvicultural intervention scale that classifies management intensities as natural, extensive, basic, intensive, and elite) plot network, from across Ontario, Canada, to examine the applicability of a mechanistic model, ZELIG-CFS (a version of the ZELIG tree growth model developed by the Canadian Forest Service), to simulate yields and species compositions. As silvicultural intensity increased, overall yield generally increased. Species compositions met the desired outcomes when specific silvicultural treatments were implemented and otherwise generally moved from more shade-intolerant to more shade-tolerant species through time. Our results indicated that a mechanistic model can simulate complex stands across a range of forest types and silvicultural systems while accounting for climate change. Finally, we highlight the need to improve the modelling of regeneration processes in ZELIG-CFS to better represent regeneration dynamics in plantations. While fine-tuning is needed, mechanistic models present an option to incorporate adaptive complexity into modelling forest management outcomes.

We assessed 27 indicators of plant diversity, stand yield and individual crop tree responses 25 years post-treatment to determine long-term trade-offs among conifer release treatments in boreal and sub-boreal forests. This research addresses the lack of longer-term data needed by forest managers to implement more integrated vegetation management programs, supporting more informed decisions about release treatment choice. Four treatments (untreated control, motor-manual brushsaw, single aerial spray, and complete competition removal) were established at two jack pine (Pinus banksiana Lamb.) sites in Ontario, Canada. Our results suggest that plant diversity and productivity in boreal jack pine forests are significantly influenced by vegetation management treatments. Overall, release treatments did not cause a loss of diversity but benefitted stand-scale yield and individual crop tree growth, with maximum benefits occurring in more intensive release treatments. However, none of the treatments maximized all 27 indicators studied; thus, forest managers are faced with trade-offs when choosing treatments. Research on longer term effects, ideally through at least one rotation, is essential to fully understand outcomes of different vegetation management on forest diversity, stand yield, and individual crop tree responses.

In Ontario, forest management planning requires that legal obligations to sustain forest composition and pattern, wildlife habitat, and other values are met, while at the same time addressing, for example, wood supply needs, costs, forest access, and stakeholder concerns. One of the latter is pressure to reduce herbicide use. Stand-level effects of vegetation management alternatives have been documented, but how these effects scale up to the landscape-level and affect the achievement of social, ecological, and economic objectives embedded in forest management plans (FMPs) remains uncertain. We applied nine modelling scenarios in the context of approved FMPs to explore the potential landscape-level effects of replacing herbicide use with an alternative (brush saw) for two large forests in northeastern Ontario. Results of non-spatial and spatial modelling over 60 years suggested that although herbicides are applied to only 25% to 34% of the harvested area in these forests, reductions in use would affect: (i) overall wood supply, with 14% to 44% less conifer and 6% to 17% less hardwood available; (ii) habitat supply, with less habitat for species preferring recent disturbances and more habitat for species preferring mature and older forest; (iii) costs, with wood transportation cost increasing by 16% to 20% and increased spending on silviculture; (iv) size and distribution of cutblocks and disturbance patches, with more small patches; and (v) the extent of the active road network, which would increase.

Between April 2000 and March 2007, the Canadian Ecology Centre – Forestry Research Partnership funded, directed, or catalyzed approximately 145 projects. Most of these focused on knowledge and data acquisition, providing a solid foundation for a series of sensitivity and gap analyses to determine whether a long-term goal of enhancing productivity on 6 forest management units in Ontario was achievable, and more importantly, sustainable. A research strategy provided the focus for knowledge and data acquisition and the partnership facilitated integrated research, development, transfer, and implementation. Here we provide an overview of this effort, which is expected to position forest managers of the 6 forests to apply an adaptive management process to increase understanding of the response of their forests to various forest management policies and practices in the future. The strategy and approach described could be useful to other jurisdictions aiming to more closely integrate forest research and operations as well as those interested in implementing adaptive management. Key words: forest ecology, forest economics, forest inventory, forest management

The effect of climate change on forest dynamics is likely to increase in importance in the forthcoming decades. For this reason, it is essential to predict the extent to which changes in temperature, precipitation, and atmospheric CO₂ might affect the development of forest ecosystems and successional pathways. The gap model ZELIG-CFS was used to simulate the potential long-term effects of climate change on species-specific annual change in mean basal area and stand density under two scenarios of representative concentration pathways (RCP), 4.5 and 8.5, for the boreal forest region of Ontario, Canada, where mean temperature, precipitation, and atmospheric CO₂ are expected to increase. Forest ecosystems in this boreal region included pure and mixed stands of black spruce (Picea mariana [Mill.] B.S.P.), paper birch (Betula papyrifera Marsh.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana Lamb.), trembling aspen (Populus tremuloides Michx.), white spruce (Picea glauca [Moench] Voss), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamifera L.). Simulation results under climate change generally predicted a decline in the basal area and stand density for black spruce, balsam fir, jack pine, and white spruce, but an increase for paper birch, trembling aspen, American larch, and balsam poplar. However, the extent of change differed regionally among species. Forest composition is expected to change over the long term. Simulation results indicated that shade-intolerant deciduous and conifer species will increase their dominance over the 100-year time horizon. This transition toward the increasing presence of deciduous forests is likely explained by more favorable temperature conditions for their growth and development.