1. Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. 2. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577-587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our...

Temperate tree species are expected to expand their distribution into the boreal forest in response to climate change. However, it is becoming increasingly clear that many species will experience significant setbacks in capacity to migrate due to a series of unfavourable conditions impacting their recruitment success, and thus their ability to colonize new locations. We quantify the relative influence of a series of factors important for tree seedling recruitment at range margins: propagule dispersal, substrate...

1.There is mounting evidence that species diversity increases the temporal stability of forest growth. This stabilising effect of diversity has mainly been attributed to species differences in their response to fluctuating environmental conditions. Interactions among individuals could also contribute to the stabilising effect of diversity by increasing the mean and reducing the variance of tree growth, however, this has never been directly demonstrated. 2.We used tree‐ring width chronologies from temperate and boreal mixed stands of...

1. Although anthropogenic edges are an important consequence of timber harvesting, edges due to natural disturbances or landscape heterogeneity are also common. Forest edges have been well-studied in temperate and tropical forests, but less so in less productive, disturbance-adapted boreal forests. 2. We synthesized data on forest vegetation at edges of boreal forests and compared edge influence among edge types (fire, cut, lake/wetland; old vs. young), forest types (broadleaf vs. coniferous) and geographic regions. Our...

1. Even-aged silviculture based on short-rotation clearcuts had severely altered boreal forests. Silvicultural alternatives (e.g., continuous cover or retention forestry) has the potential to restore and protect the habitats and functions of boreal forests. These alternatives are however often restricted to structurally complex old-growth forest, which are particularly threatened by anthropogenic disturbances. Increasing the use of alternatives to even-aged silviculture in early-successional stands could help recruit more structurally complex forests, with characteristics closer to the...

Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale-dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (Odocoileus virginianus) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided...

The ability of tree species to track their climatic niche at rates comparable to global warming is concerning, particularly if they are constrained by local adaptation. If a species is locally adapted at its range margin it could be beneficial for range expansion as it ensures that the genotypes colonizing new areas are the fittest because environmental conditions are more similar to the current ones. In trees, local adaptation can slow range expansion when climate...

Intraspecific trait variability (ITV) provides the material for species adaptation to environmental changes. To advance our understanding of how ITV can contribute to species adaptation to a wide range of environmental conditions, we studied five widespread understory forest species exposed to both continental-scale climate gradients, and local soil and disturbance gradients. We investigated the environmental drivers of between-site leaf and root trait variation, and tested whether higher between-site ITV was associated with increased trait sensitivity...

Wetlands and predation in boreal ecosystems play essential roles throughout the breeding season for bird assemblages. We found a positive association of beaver activity and a negative influence of American red squirrels (Tamiasciurus hudsonicus) on bird assemblages. We used a multispecies hierarchical model to investigate whether bird communities differ between two major wetland habitats in boreal Canada: beaver ponds and peatland ponds. In addition to including variables such as forest cover and latitude, we adopted...

1. Functional responses in habitat selection occur when individuals adjust their selection of habitat features as a function of the availability of those features. Functional responses in habitat selection are generally assumed to be fitness-rewarding tactics and are used to guide conservation actions. Fitness consequences of functional responses, however, have rarely been evaluated. 2. Eighty-three caribou were followed with GPS collars to establish the link between functional responses in habitat selection and adult female survival,...

sequencesfungal ITS sequencesSoil chemical analysesSoil chemical analysessoilchar.csvfunguild resultsfunguild.csvdescription of samplescarsample.csvR codeR_code

Measuring individual fitness empirically is required to assess selective pressures and predict evolutionary changes in nature. There is, however, little consensus on how fitness should be empirically estimated. As fitness proxies vary in their underlying assumptions, their relative sensitivity to individual, environmental, and demographic factors may also vary. Here, using a long-term study, we aimed at identifying the determinants of individual fitness in bighorn sheep (Ovis canadensis) using seven fitness proxies. Specifically, we compared four-lifetime...

Trophic interactions in multiprey systems can be largely determined by prey distributions. Yet, classic predator–prey models assume spatially homogeneous interactions between predators and prey. We developed a spatially informed theory that predicts how habitat heterogeneity alters the landscape-scale distribution of mortality risk of prey from predation, and hence the nature of predator interactions in multiprey systems. The theoretical model is a spatially explicit, multiprey functional response in which species-specific advection–diffusion models account for the response...

1.Differences between species in their response to environmental fluctuations cause asynchronized growth series, suggesting that species diversity may help communities buffer the effects of environmental fluctuations. However, within-species variability of responses may impact the stabilizing effect of growth asynchrony. 2.We used tree ring data to investigate the diversity-stability relationship and its underlying mechanisms within the temperate and boreal mixed woods of Eastern Canada. We worked at the individual tree level to take into account the...

Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-age structures. It creates small openings in large areas and often generates a more homogenous forest structure (fewer large leaving trees and defective trees) that differs from old-growth forest. In this study, we evaluated whether this type of harvesting has an impact on genetic diversity of sugar maple (Acer saccharum Marshall). Genetic diversity among seedlings, saplings and mature trees was compared between selection...

Due to climate change, the ranges of many North-American tree species are expected to shift northward. Sugar maple (Acer saccharum Marshall) reaches its northern continuous distributional limit in north-eastern North America at the transition between boreal mixed-wood and temperate deciduous forests. We hypothesized that marginal fragmented northern populations from the boreal mixed-wood would have a distinct pattern of genetic structure and diversity. We analyzed 18 microsatellite loci variation in 23 populations distributed along three latitudinal...

Aim Non-climatic constraints on species northern range boundaries are often overlooked in attempts to predict climate-induced range shifts. Here, we examined the effects of habitat availability and fire disturbance on the distribution of eastern white cedar (Thuja occidentalis L.) at the northern boundary of its range. Location North-western Quebec, Canada (46-51° N and 74-79° W) Methods We used forest inventory data (n=4,987) to characterize white-cedar habitat based on edaphic and topographic conditions at sampled sites...

A combination of wildfires and defoliating insect outbreaks play an important role in the natural successional dynamics of North American boreal forests, which, in the long term, change the post-disturbance composition and structure of forest stands. After stand-replacing disturbances (mainly wildfires), early successional hardwoods typically dominate the affected areas in boreal forests. Provided sufficient time following disturbances, the increasing recruitment of mid- to late-successional softwoods as well as the mortality of hardwoods gradually change forest...

1. As soils store more carbon (C) than the Earth’s atmosphere and terrestrial biomass together, the balance between soil C uptake in the form of soil organic matter and release as CO2 upon its decomposition is a critical determinant in the global C cycle regulating our planet’s climate. Although plant litter is the predominant source of C fueling both soil C build-up and losses, the issue of how litter chemistry influences this balance remains unresolved....