mardi 10 février 2026

The temperate forest phyllosphere and rhizosphere microbiome: a case study of sugar maple

The temperate forest phyllosphere and rhizosphere microbiome: a case study of sugar maple
Enea M, Beauregard J, De Bellis T, Faticov M and Isabelle Laforest-LapointeFrontiers in Microbiology  - 14 January 2025 
To prevent sugar maple from declining in the face of global change, it will be crucial to gain a better understanding (1) of its capacity to shift north in pace with climatic changes and (2) of the contributions of surrounding microbial communities in this process. ... sugar maple assembles diverse and species-specific root and leaf microbiomes, with potential impacts on tree growth, immunity, and survival. First, the origin of the soil on which sugar maple grows appears to play a key role. Despite improved regeneration under colder temperatures, which corresponds to current northern range limit climatic conditions, sugar maple survival and biomass after transplants are up to 50% higher on soil from the center of its range. This suggests that this tree species is highly dependent on root biotic interactions (e.g., in the rhizosphere with arbuscular mycorrhizae) for successful establishment in a newly available niche or in adaptation to climate change, irrespective of the physico-chemical properties of the soil. Second, sugar maple leaves have also been the focus of several studies on tree-microbe interactions in the phyllosphere, demonstrating that the local abiotic environment of trees drives leaf microbial colonization (Laforest-Lapointe et al., 2016a; Wallace et al., 2018).  

Tonia De Bellis, Isabelle Laforest-Lapointe, Kevin A. Solarik, Dominique Gravel, Steven W. Kembel - Ecology - 12 April 2022
We collected sugar maple seeds from across the species current range, then planted them in temperate and mixedwood/transitional forests (current range) and in the boreal region (beyond range but predicted future range in response to climate change). ... Variation among sites and regions were the main drivers of the differences in host microbial communities, whereas seed provenance did not play a large role ....  Along the latitudinal gradient, we (1) observed reductions in mycorrhizal diversity that can negatively impact maple establishment; (2) and revealed reductions in fungal leaf pathogens that can have opposite effects. Our results highlight the need for an integrated approach including the examination of various microbial taxa on different plant compartments to improve our understanding of plant range shifts and plant–microbe interactions.

lundi 9 février 2026

dimanche 4 janvier 2026

Densité et succès reproducteur de la grive des bois (Hylocichla mustelina) dans les parcs nationaux d’Oka et du Mont-Saint-Bruno

Densité et succès reproducteur de la grive des bois (Hylocichla mustelina) dans les parcs nationaux d’Oka et du Mont-Saint-Bruno
Marc-André Villard, Thierry Grandmont, Mathieu Lemay and René Charest - Le Naturaliste canadien - Volume 148, Number 1, Spring 2024
La grive des bois (Hylocichla mustelina) a été désignée espèce menacée au Canada en 2012. De 1970 à 2021, ses effectifs auraient chuté de 75 % au Canada et de 84 % au Québec. La présente étude visait à déterminer le statut de l’espèce dans 2 parcs nationaux de la région de Montréal. En 2021 et en 2022, 88 nids ont été trouvés dans le parc national d’Oka, contre 10 au parc national du Mont-Saint-Bruno (2022). La densité de nids était nettement inférieure à Mont-Saint-Bruno (0,03/ha versus 0,10/ha), possiblement en raison du surbroutement de la végétation par le cerf de Virginie (Odocoileus virginianus). Les taux de survie des nids variaient d’un parc à l’autre et d’une année à l’autre (Oka : 68,2 % en 2021 et 27,6 % en 2022 ; Mont-Saint-Bruno : 68,9 %). La cause principale d’échec des nids était la prédation. Le taux de parasitisme par le vacher à tête brune (Molothrus ater) était plus élevé à Mont-Saint-Bruno (25 % versus 1,9 %). À Oka, la prédation des nids était plus forte chaque année le long du sentier le plus fréquenté, ce qui suggère un effet négatif du taux de passage des visiteurs sur le succès des nids.

The Wood Thrush (Hylocichla mustelina) was listed as Threatened in Canada in
2012. Between 1970 and 2021, its numbers are estimated to have declined by
75% nationally, and by 84% in the province of Québec. The aim of the present
study was to document the status of this species in two national parks in the
Montréal region. Eighty-eight nests were found in Oka National Park (parc
national d’Oka, 2021 and 2022 combined), and 10 in Mont-Saint-Bruno National
Park (parc national du Mont-Saint-Bruno, 2022). Nest density was substantially
lower at the Mont-Saint-Bruno site (0.03/ha versus 0.10/ha), possibly due to
overbrowsing by white-tailed deer (Odocoileus virginianus). Nest survival rate
varied as a function of location and year: Oka: 68.2% in 2021 and 27.6% in
2022; Mont-Saint-Bruno: 68.9%. The main cause of nest failure was predation.
The rate of brood parasitism by brown-headed cowbird (Molothrus ater) was
higher at Mont-Saint-Bruno (25% versus 1.9%). In Oka, nest predation was
higher along the most heavily used trail in both study years, suggesting a
negative impact of trail use by visitors on nest success.