by Marie-Claude Boileau | 25 July 2023
Published in Forests 14(6): 1124. https://doi.org/10.3390/f14061124
The soil microbiome plays major roles in the below-ground processes and productivity of forest ecosystems. Atmospheric nitrogen (N) deposition is predicted to increase globally and might create disturbances in soil microbial communities, essentially by modifying soil chemistry. However, the impacts of higher N deposition on the soil microbiome in N-limited northern forests are still unclear. For 16 years, we simulated N deposition by adding ammonium nitrate at rates of 3 and 10 times the ambient N deposition directly into soils located in three bioclimatic domains of the eastern Canadian forest (i.e., sugar maple–yellow birch, balsam fir–white birch, and black spruce–feather moss). We identified changes in the microbial communities by isolating the DNA of the L, F, and H soil horizons, as well as by sequencing amplicons of the bacterial 16S rRNA gene and the fungal ITS region. We found that long-term increased N deposition had no effect on soil microbial diversity, but had moderate impacts on the composition of the bacterial and fungal communities. The most noticeable change was the increase in ectomycorrhizal fungi ASV abundance, potentially due to increased tree root growth on fertilized plots. Our work suggests that, in N-limited northern forests, extra N is rapidly mobilized by vegetation, thus minimizing impacts on the soil microbiome.
by Marie-Claude Boileau | 24 July 2023
https://doi.org/10.2737/NRS-GTR-P-211-paper39
Improving financial revenues from partial cuts in sugar maple (Acer saccharum) stands at the northern edge of the species’ range involves harvesting trees that have reached their financial maturity size (i.e., the diameter at which their monetary value is greatest and beyond which there is no further gain). To establish the lumber value of each tree at the sawmill, a sample of 171 trees were measured, felled, bucked into logs, and sawn into boards. We estimated their value changes over 10 years using data from a network of permanent sample plots. The most vigorous and best quality maples started losing value at a diameter at breast height of 36 cm. Those belonging to the lowest grade and containing a potential sawlog increased in value, but only marginally. The low value of these trees makes the profitability of forest management challenging at the northern edge of sugar maple’s range.
by Marie-Claude Boileau | 24 July 2023
https://doi.org/10.2737/NRS-GTR-P-211-paper18
Yellow birch (Betula alleghaniensis Britt.) is the second most harvested hardwood species in Quebec. Hardwood stands harboring this species are likely to yield high value products, and their proximity to inhabited regions facilitates a more intensive silviculture. Yet, little is known about the effects of silvicultural treatments such as commercial thinning on stands composed mostly of yellow birch. We set up an experiment in a 41-year-old yellow birch stand that arose after a clearcutting in 1971. The experimental design comprises four treatments: a control (no intervention); and light, moderate, and heavy commercial thinnings. After 5 years, results show that the thinnings had no significant effect on the net growth in basal areal of the stand. The treatments mostly led to an increase in the proportion of yellow birch and crop trees in the stand following the harvest targeting aspens and other less desired species. The smaller diameter trees near the trails showed the highest diameter growth response to the thinnings.
by Audrey Verreault | 19 July 2023
Brief explanation of the ecoforestry inventory program in the forests of southern Québec. The document aims to inform owners of private forests of the importance of this inventory and its possible implications.
by Claire Morin | 13 July 2023
The sparse knowledge about Nunavik birdlife limits our ability to ensure the recovery of some species or their maintenance at viable population levels. Nunavik is home to the majority of breeding pairs of Golden Eagles (Aquila chrysaetos) in eastern North America. However, since 2011, with the exception of one population survey conducted in the Ungava Bay area, this vast territory has been the subject of very few eagle (and other raptor) inventories, even though it has many rock faces that are suitable for this species. This report presents the results of a 2022 Hudson Bay inventory conducted by a joint team from the Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP) and the Canadian Wildlife Service of Environment and Climate Change Canada (CWS). The inventory highlighted the widespread use of this area by Golden Eagles, with a total of 163 nests located, of which 133 (81.5%) were new nesting sites for the species. The inventory also provided new information on the nesting of other birds of prey: the peregrine falcon (Falco peregrinus), rough-legged hawk (Buteo lagopus), gyrfalcon (Falco rusticolus), merlin (Falco columbarius) and osprey (Pandion haliaetus). The inventory was also intended to collect data for the northern component of the Atlas of Breeding Birds of Québec. The resulting nesting indices allowed us to extend the known nesting area of various species. This was the case for Tundra Swan (Cygnus columbianus), Long-tailed Duck (Clangula hyemalis), Red-throated Loon (Gavia stellata) and Rock Ptarmigan (Lagopus muta), which were found further south than their known breeding range in mainland Québec, as well as for American duck (Mareca americana), Killdeer (Charadrius vociferus) and American bittern (Botaurus lentiginosus), which, conversely, were found further north than their known range. Harlequin Duck (Histrionicus histrionicus) was particularly numerous, with 163 individuals counted, many of them on rivers not previously known to support this duck. Other species at risk were the Rusty Blackbird (Euphagus carolinus), Bank Swallow (Riparia riparia), Lesser Yellowlegs (Tringa flavipes), and Red-necked Phalarope (Phalaropus lobatus). The efforts made during this ornithological inventory represent one of the most important multi-species knowledge acquisition projects ever conducted at these latitudes.
