Following the appointment of the new Cabinet, the Forest Sector now reports to the ministère des Ressources naturelles et des Forêts, while the Wildlife and Parks Sectors report to the ministère de l'Environnement, de la Lutte aux changements climatiques, de la Faune et des Parcs. Adjustments will be made to the website over time.

Seedling response to simulated browsing and reduced water availability: Insights for assisted migration plantations

Published in Forests 12(10): 1396. https://doi.org/10.3390/f12101396

To facilitate forest transition to future climate conditions, managers can use adaptive silvicultural tools, for example the assisted translocation of tree species and genotypes to areas with suitable future climate conditions (i.e., assisted migration). Like traditional plantations, however, assisted migration plantations are at risk of failure because of browsing by ungulate herbivores. The ability of seedlings to tolerate browsing could also be hampered by low water availability, as is expected under climate change. Using a greenhouse experiment with five eastern North American tree species, we evaluated the effects of simulated winter browsing and reduced water availability on the growth (total biomass, shoot:root ratio), survival, and chemical composition (nitrogen, total phenolics, flavonoids) of seedlings. We compared seedlings from three geographic provenances representing three climate analogues, i.e., locations with a current climate similar to the climate predicted at the plantation site at a specific time (here: current, mid-century and end of the century). We hypothesized that seedlings would allocate resources to the system (shoots or roots) affected by the most limiting treatment (simulated browsing or reduced water availability). Additionally, we evaluated whether the combination of treatments would have an additive or non-additive effect on the growth, survival and chemical composition of the seedlings. Quercus rubra seedlings reacted only to the water reduction treatment (changes in biomass and N concentration, dependent on geographic provenance) while Pinus strobus reacted only to the simulated browsing treatment (biomass and chemical composition). We also observed non-additive effects of reduced water availability and simulated browsing on Prunus serotina, Acer saccharum and Thuja occidentalis. In general, shoot:root ratio and investment in chemical defense did not vary in response to treatments. The regrowth response observed in Q. rubra and A. saccharum suggests that these species could tolerate periodic browsing events, even when water availability is reduced. More information is required to understand their long-term tolerance to repeated browsing events and to harsher and more frequent water stress. We highlight the importance of species-specific growth and allocation responses that vary with geographic provenance, which should be considered by managers when planning climate-adapted strategies, such as assisted migration.

Contemporary status, distribution, and trends of mixedwoods in the northern United States

Published in Canadian Journal of Forest Research 51(7): 881-896. https://doi.org/10.1139/cjfr-2020-0467

As interest in managing and maintaining mixedwood forests in the northern United States (US) grows, so does the importance of understanding their abundance and distribution. We analyzed Forest Inventory and Analysis data for insights into mixedwood forests spanning 24 northern US states from Maine south to Maryland and westward to Kansas and North Dakota. Mixedwoods, i.e., forests with both hardwoods and softwoods present but neither exceeding 75%–80% of composition, comprise more than 19 million hectares and more than one-quarter of the northern US forest. They are most common in the Adirondack – New England, Laurentian, and Northeast ecological provinces but also occur elsewhere in hardwood-dominated ecological provinces. These mixtures are common even within forest types nominally categorized as either hardwood or softwood. The most common hardwoods within those mixtures were species of Quercus and Acer, and the most common softwoods were species of PinusTsuga, and Juniperus. Although mixedwoods exhibited stability in total area during our analysis period, hardwood saplings were prominent, suggesting widespread potential for eventual shifts to hardwood dominance in the absence of disturbances that favor regeneration of the softwood component. Our analyses suggest that while most mixedwood plots remained mixedwoods, harvesting commonly shifts mixedwoods to either hardwood- or softwood-dominated cover types, but more specific information is needed to understand the causes of these shifts.

Is the annual maximum leaf area index an important driver of water fluxes simulated by a land surface model in temperate forests?

Published in Canadian Journal of Forest Research 51(4): 595-603. https://doi.org/10.1139/cjfr-2020-0126

In land surface models, vegetation is often described using plant functional types (PFTs), a classification that aggregates plant species into a few groups based on similar characteristics. Within-PFT variability of these characteristics can introduce considerable uncertainty in the simulation of water fluxes in forests. Our objectives were to (i) compare the variability of the annual maximum leaf area index (LAImax) within and between PFTs and (ii) assess whether this variability leads to significant differences in simulated water fluxes at a regional scale. We classified our study region in southwestern Quebec (Canada) into three PFTs (evergreen needleleaf, deciduous broadleaf, and mixed forests) and characterized LAImax using remotely sensed MODIS-LAI data. We simulated water fluxes with the Canadian Land Surface Scheme (CLASS) and performed a sensitivity analysis. We found that within-PFT variability of LAImax was 1.7 times more important than variability between PFTs, with similar mean values for the two dominant PFTs, deciduous broadleaf forests (6.6 m2·m−2) and mixed forests (6.3 m2·m−2). In CLASS, varying LAImax within the observed range of values (4.0–7.5 m2·m−2) led to changes of less than 2% in mean evapotranspiration. Overall, LAImax is likely not an important driver of the spatial variability of water fluxes at the regional level.

Granular calcite: A new cultural practice to improve the physicochemistry of the peat substrate, growth and morphophysiological quality of white spruce seedlings in forest nurseries

Published in Land 10(7): 661. https://doi.org/10.3390/land10070661

Growing Picea glauca seedlings poses many challenges for forest nursery managers, including reaching the target height at the end of the first growing season (1 + 0) and the homogeneity and uniformity of seedling growth. To increase growth and morphophysiological quality of white spruce seedlings (1 + 0), emphasis was placed on improving the physicochemistry of the acidic peat substrate by replacing silica with granular calcite as a covering material. The objective of our study is to compare the effects of silica and calcite on the physicochemistry of the peat substrate, as well as on growth and mineral nutrition of white spruce seedlings (1 + 0) under forest nursery conditions. Three treatments were used to cover the cavities of large white spruce seedlings produced in containers: silica (29 g/cavity; control treatment), calcite (24 g/cavity) and calcite + (31 g/cavity). At the end of the first growing season, the two calcite treatments significantly increased the total dry mass (28%), roots (27%) and shoot (29%) dry masses and height (24%) compared to silica treatments. Average calcium concentration and content of calcite treatments were significantly higher than that of silica treatment.