Invasive insects threaten the resilience and sustainability of Canadian forests, but we lack a comprehensive national perspective on the extent of this vulnerability. We assessed Canadian forest exposure to invasive pests by quantifying host biomass intersecting with recent (1981–2010) and near-future (2021–2040) climate niches of 14 invasive insects. Of the 37 most abundant tree species in Canada, 24 were affected by at least one of the 14 focal pests. We combined spatial assessments of exposure and outbreak severity to create an integrated spatial portrait of vulnerability. Under current conditions, 3.2 billion tonnes of tree biomass could be exposed to at least one of these pests; this is projected to increase to 13.6 billion tonnes of biomass within two decades. Two vulnerability hotspots were identified: north-central British Columbia near the BC–Alberta border and the St. Lawrence Seaway near the U.S. border. To highlight the importance of surveillance and early eradication programs, we show that a re-invasion of the Asian longhorned beetle ( Anoplophora glabripennis) into Canadian forests would put six additional tree species and 3.1 billion tonnes of tree biomass at risk. This nation-wide view aims to support risk assessments, guide the prioritization of monitoring efforts, and inform adaptive forest management.

Measuring and modeling bird occupancy in managed forest landscapes can provide useful information for achieving sustainable forestry practices and for informing conservation. Occupancy models are useful tools to describe the habitat use of species and predict how changes in the habitat and landscape may affect future occupancy. Specifically, these models can help support changes in forest management practices to improve habitat quality for species, including species of conservation concern. We used occupancy modelling to quantify the habitat use of two species of conservation concern, Canada warbler (Cardellina canadensis) and olive-sided flycatcher (Contopus cooperi) in the managed Black Brook district forest in northwestern New Brunswick, Canada as case studies to demonstrate an approach for improving sustainability of forest management and improving outcomes for species including those of conservation concern. Bird observations were collected during the breeding season using autonomous recording units over multiple days in plots stratified by forest type and development stage. We extracted environmental variables from forest resource inventory, a digital elevation model, and LiDAR data and classified variables as informing composition, structure, and landscape. The landscape variables were made up of composition and structure variables measured at extents beyond the sampling area. The AIC supported model for Canada warbler included percentage of softwood (+), wetness (+), understory cover(+) and heterogeneity of canopy height (+). However, some of these relationships were weak, with 95 % confidence intervals that included zero. The AIC supported models for olive-sided flycatcher included percentage of softwood (+), understory(+), wetness(+), stand height variation(+) and heterogeneity at 6 m height (-), although none of the variables had 95 % confidence intervals excluding zero. Models for both species were able to effectively classify habitat suitability, and met the criteria for acceptable classification performance. For both species, none of the supported models included landscape level variables. We recommend monitoring areas where the occupancy is predicted to be the highest and uncertainty is lowest to improve identification of occupied habitat. This habitat should then be integrated into forest management planning to support the persistence of these species. Results from the models also suggest habitat features that can be created through forest management to increase the overall amount of good quality habitat for these species.

Measuring and modeling bird occupancy in managed forest landscapes can provide useful information for achieving sustainable forestry practices and for informing conservation. Occupancy models are useful tools to describe the habitat use of species and predict how changes in the landscape may affect future occupancy. Specifically, these models can help support changes in forest management practices to improve habitat quality for species, including species at risk. We used occupancy modelling to quantify the habitat use of two species at risk, Canada warbler (Cardellina canadensis) and olive-sided flycatcher (Contopus cooperi) in the managed Black Brook district forest in northwestern New Brunswick, Canada as case studies. Bird observations were collected using autonomous recording units over multiple days. We extracted environmental variables from forest resource inventory, digital elevation model, and LiDAR data. The AIC supported model for Canada warbler included percentage of softwood, wetness, understory cover and heterogeneity of canopy height. However, some of these relationships were weak, with 95% confidence intervals that included zero. Classification performance was excellent (AUC = 0.86). The AIC supported models for olive-sided flycatcher included percentage of softwood, understory, wetness, and stand height variation and decreasing heterogeneity at 6 m height, although none of the variables had 95% confidence intervals excluding zero. The classification performance for olive-sided flycatcher model was acceptable (AUC = 0.75). For both species, none of the supported models included landscape level variables. We recommend monitoring areas where the occupancy is predicted to be the highest to validate and improve current models, as well as to integrate these areas into overall conservation strategies to support the persistence of these species. In addition, we recommend using the models to support forest management that creates habitat in areas most likely to support these species. In general, our best path forward for improving outcomes for these species is to use the best available data and models to identify, conserve, and create habitat.

1. 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 understorey 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 to environmental variation (i.e. environmental fit). 2. We measured morphological (specific leaf area: SLA, specific root length: SRL) and chemical traits (Leaf and Root N, P, K, Mg, Ca) of five forest understorey vascular plant species at 78 sites across Canada. A total of 261 species-by-site combinations spanning similar to 4300km were sampled, capturing important abiotic and biotic environmental gradients (neighbourhood composition, canopy structure, soil conditions, climate). We used multivariate and univariate linear mixed models to identify drivers of ITV and test the association of between-site ITV with environmental fit. 3. Between-site ITV of leaf traits was primarily driven by canopy structure and climate. Comparatively, environmental drivers explained only a small proportion of variability in root traits: these relationships were trait specific and included soil conditions (Root P), canopy structure (Root N) and neighbourhood composition (SRL, Root K). Between-site ITV was associated with increased environmental fit only for a minority of traits, primarily in response to climate (SLA, Leaf N, SRL). 4. Synthesis. By studying how ITV is structured along environmental gradients among species adapted to a wide range of conditions, we can begin to understand how individual species might respond to environmental change. Our results show that generalisable trait-environment relationships occur primarily aboveground, and only accounted for a small proportion of variability. For our group of species with broad ecological niches, variability in traits was only rarely associated with higher environmental fit, and primarily along climatic gradients. These results point to promising research avenues on the various ways in which trait variation can affect species performance along different environmental gradients.

Considering intraspecific trait variability (ITV) in ecological studies has improved our understanding of species persistence and coexistence. These advances are based on the growing number of leaf ITV studies over local gradients, but logistical constraints have prevented a solid examination of ITV in root traits or at scales reflecting species' geographic ranges. We compared the magnitude of ITV in above- and below-ground plant organs across three spatial scales (biophysical region, locality and plot). We focused on six understorey species (four herbs and two shrubs) that occur both in disturbed and undisturbed habitats across boreal and temperate Canadian forests. We aimed to document ITV structure over broad ecological and geographical scales by asking: (a) What is the breadth of ITV across species range-scale? (b) What proportion of ITV is captured at different spatial scales, particularly when local scale disturbances are considered? and (c) Is the variance structure consistent between analogous leaf and root traits, and between morphological and chemical traits? Following standardized methods, we sampled 818 populations across 79 forest plots simultaneously, including disturbed and undisturbed stands, spanning four biophysical regions (similar to 5,200 km). Traits measured included specific leaf area (SLA), specific root length (SRL) and leaf and root nutrient concentrations (N, P, K, Mg, Ca). We used variance decomposition techniques to characterize ITV structure across scales. Our results show that an important proportion of ITV occurred at the local scale when sampling included contrasting environmental conditions resulting from local disturbance. A certain proportion of the variability in both leaf and root traits remained unaccounted for by the three sampling scales included in the design (36% on average), with the largest amount for SRL (54%). Substantial differences in magnitude of ITV were found among the six species, and between analogous traits, suggesting that trait distribution was influenced by species strategy and reflects the extent of understorey environment heterogeneity. Even for species with broad geographical distributions, a large proportion of within-species trait variability can be captured by sampling locally across ecological gradients. This has practical implications for sampling design and trait selection for both local studies and continental-scale modelling. A plain language summary is available for this article.

The relationships between site quality indices (SQI) (estimated height at age 50) of black spruce and Jack pine and site characteristics were investigated over a large territory in the boreal forest of Quebec. The relationships with degree-days (DD) and parent material, which are considered as permanent site factors, were significant for both species. Linear regressions with these two parameters as independent variables explained about 40% of the variability in site quality indices for black spruce and Jack pine. The addition of soil chemistry and biological data to this model indicated a significant contribution of exchangeable Mg concentrations or Al:CEC molar ratios in the forest floor and lichen cover to the prediction of site quality indices. Inclusion of these variables increased the model R2 up to 60% for both species. Whether these variables reflect permanent site conditions or conditions related to the history of the sites is unknown.