Understanding how reclamation practices influence plant community assembly and succession is an important step in developing realistic indicators and targets for reclamation of oil sands mine sites to upland forest ecosystems. We currently have a poor understanding of factors affecting plant community assembly and succession in reclaimed oil sands sites. Through synthesis of research completed over the last 24 years, we identify four key findings: (i) use of surface soil and forest floor material salvaged from mined areas increases plant species cover, richness, and diversity relative to the use of various other cover soil materials (such as clay subsoil); (ii) stockpiling of salvaged surface soils decreases the abundance of native plant propagules and delays early vegetation community development; (iii) differences in plant community composition between reclaimed and adjacent mature forests remain two decades after placing cover soils; however, differences are smaller with use of forest floor–mineral mix than peat–mineral mix; and (iv) plant community assembly is in progress but communities remain different to those found in natural undisturbed conditions. Our review identified critical knowledge gaps for further research to improve understanding of: (i) long-term (60 to 100 years) plant community composition in reclaimed oil sands sites; (ii) how residual forest patches near disturbed oil sands sites act as seed and propagule sources in newly reclaimed sites; (iii) plant community assembly processes in reclamation sites; (iv) the effect of micro-topographic heterogeneity on plant community development; and (v) how soil nutrient availability in different substrates influences plant community development over the long term. Ongoing support for selected existing studies and establishment of new studies focusing on plant community development through long-term monitoring are highly recommended.

This study examines light competition between aspen and spruce during the sequence of aspen development. Leaf area index and light transmission were measured or estimated for aspen stands from 2 to 125 years old. Light transmission was lowest at 15-25 years, and in some stands, transmission was less than 5% of above-canopy light. Hypothetical aspen stands with various stem configurations and heights were developed, and positions were identified that would meet or fail Alberta free-to-grow (FTG) standards. Light transmission was estimated at each position with the MIXLIGHT forest light simulator. Positions in canopy gaps or at the northern sides of canopy gaps had higher light. In general, however, there was little difference in available light between positions that met or failed FTG criteria. Stand density and size of aspen trees appears to be a better index to predict light transmission and spruce success in juvenile aspen stands than current FTG criteria.Key words: competition, free to grow, hardwood, spruce, light Cette étude porte sur la compétition pour la lumière entre le peuplier faux-tremble et l'épinette au cours de la période de développe-ment du peuplier faux-tremble. L'indice de la surface foliaire et la transmission de la lumière ont été mesurés ou estimés dans des peupleraies âgées de 2 à 125 ans. La transmission de la lumière a été la plus faible dans les peuplements de 15 à 25 ans, et dans certains peuplements, la transmission a été de moins de 5% par rapport à la lumière au-dessus des cimes. Des peupleraies hypothétiques représen-tant diverses configurations de tige et de hauteur ont été élaborées, et des positions ont été identifiées qui correspondraient ou non aux normes de tige libre de croître de l'Alberta. La transmission de la lumière a été estimée pour chaque position au moyen du simulateur de lumière sous couvert forestier MIXLIGHT. Les positions retrouvées dans les ouvertures du couvert ou du côté nord des ouvertures dans le couvert recevaient plus de lumière. De façon générale, cependant, il existe peu de différence au niveau de la lumière disponible entre les positions qui répondaient ou non aux normes de croissance sans concurrence. La densité du peuplement et la taille des tiges de peuplier semblent être un meilleur indice de prédiction de la transmission de la lumière et du succès de l'épinette dans les jeunes peupleraies que ne le sont les normes actuelles de croissance sans concurrence.

Quaking or trembling aspen (Populus tremuloides Michx.) forests occur in highly diverse settings across North America. However, management of distinct communities has long relied on a single aspento-conifer successional model. We examine a variety of aspen dominated stand types in the western portion of its range as ecological systems; avoiding an exclusive focus on seral dynamics or single species management. We build a case for a large-scale functional aspen typology based on existing literature. Aspen functional types are defined as aspen communities that differ markedly in their physical and biological processes. The framework presented here describes two "functional types" and seven embedded "subtypes": Seral (boreal, montane), Stable (parkland, Colorado Plateau, elevation and aspect limited, terrain isolated), and a Crossover Seral-Stable subtype (riparian). The assessment hinges on a matrix comparing proposed functional types across a suite of environmental characteristics. Differences among functional groups based on physiological and climatic conditions, stand structures and dynamics, and disturbance types and periodicity are described herein. We further examine management implications and challenges, such as human alterations, ungulate herbivory, and climate futures, that impact the functionality of these aspen systems. The functional framework lends itself well to stewardship and research that seeks to understand and emulate ecological processes rather than combat them. We see advantages of applying this approach to other widespread forest communities that engender diverse functional adaptations.

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Forest development after land reclamation in the oil sands mining region of northern Alberta, Canada was assessed using long-term monitoring plots from both reclaimed and natural forests. The metrics of ecosystem development analyzed included measures of plant community structure and composition and soil nutrient availability. Early seral reclamation plots were grouped by site type (dry and moist-rich) and age categories, and these were compared with mature natural forests. There were few significant differences in ecosystem metrics between reclamation site types, but natural stands showed numerous significant differences between site types. Over time, there were significant changes in most plant community metrics such as species richness and cover of plant community groups (e.g., forbs, shrubs, and non-native species), but these were still substantially different from mature forests 20 years after reclamation. Available soil nitrogen did not change over time or by reclamation site type but available soil phosphorus did, suggesting that phosphorus may be a more suitable indicator of ecosystem development. The significant temporal changes in these reclaimed ecosystems indicate that studies of ecosystem establishment and development on reclaimed areas should be conducted over the long-term, emphasizing the utility of monitoring using long-term plot networks. OPEN ACCESSForests 2015, 6 2110

Boreal forests in northern Alberta have a growing anthropogenic footprint due to a rapidly growing oil sands mining industry. Although land reclamation is a necessary aspect of responsible industrial development, these activities nearly always affect higher order landscape components such as the broader landform, and its hydrology and biogeochemistry. Recent anthropogenic impacts are then believed to result in new environmental conditions and obstacles under which the boreal forest is developing, potentially leading to irreversibly different environments that could be characterized as novel ecosystems. Reflecting an emerging trend across the field of restoration ecology, these novel ecosystems are not necessarily undesirable. Instead, they are an unavoidable consequence of pervading anthropogenic effects on natural ecosystems. It is our view that successful reclamation outcomes can still be derived so long as policy and regulatory requirements are afforded the necessary scope and economic flexibility to account for the development of hybrid and novel ecosystems among highly disturbed mine sites. Hence, this analysis seeks to situate current and anticipated challenges affecting the reclamation of boreal forest following oil sands mining by describing (i) how regulatory criteria shape reclamation practices and targeted end goals and (ii) how these approaches embody latest trends and priorities in the area of restoration ecology.Key words: land reclamation, equivalent land capability, boreal forest, oil sands, novel ecosystems. Résumé :Les forêts boréales du nord de l'Alberta subissent une empreinte anthropique croissante due à l'expansion rapide de l'industrie des sables bitumineux. Alors que la réhabilitation des sites est un aspect essentiel d'un développement industriel responsable, ces activités affectent presque toujours des composantes majeures du paysage telles que son relief, son hydrologie et sa biogéochimie. On suppose que les impacts anthropiques récents créent des conditions environnementales et des obstacles nouveaux pour le développement de la forêt boréale, ce qui pourrait mener à des environnements irréversiblement différents qui pourraient être qualifiés d'écosystèmes nouveaux. Reflétant une tendance émergente en écologie de la restauration, ces nouveaux écosystèmes ne sont pas nécessairement indésirables. Ils sont plutôt une conséquence inévitable des effets anthropiques invasifs sur les écosystèmes naturels. Nous sommes d'avis que la réhabilitation des sites peut encore donner de bons résultats dans la mesure où on accepte que les exigences politiques et réglementaires aient l'ampleur et la flexibilité économique nécessaires pour prendre en compte le développement d'écosystèmes hybrides et nouveaux dans des sites miniers hautement perturbés. Ainsi, cette analyse vise à identifier les défis actuels et anticipés de la réhabilitation de la forêt boréale à la suite de l'exploitation des sables bitumineux en décrivant (i) la manière dont les critères réglementaires influencent les pratiques...

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