The Canadian Field-Naturalist (E-Journal)
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Effects of prescribed fire on a drought-stressed Trembling Aspen (Populus tremuloides) stand
No full textA small stand of drought-stressed Trembling Aspen (Populus tremuloides) near Saskatoon, Saskatchewan, Canada, was surveyed before and after a prescribed fire. A headfire in grass understorey fuel caused near complete mortality of established stems and of all aspen saplings. In the second and third years post-fire, only limited establishment of saplings was observed. Woody encroachment by aspen into grassland is challenging to control in the Aspen Parkland ecoregion; our results indicate that combining prescribed burning with secondary stress from drought conditions can enhance the fire effects
"The Ecological Buffalo: on the Trail of a Keystone Species" by Wes Olson, photography by Johane Janelle, 2022 [book review]
Full text linkHabitat, dispersal, and distribution of the rare Orange-fruit Horsegentian (Triosteum aurantiacum E.P. Bicknell; Caprifoliaceae) in northern Nova Scotia, Canada
No full textWhy some plant species are rare and how rare species persist are foundational questions in community ecology. In 2015 we repeated a 2006 survey of three river valleys in rural Antigonish County, northern Nova Scotia, Canada, which support populations of the rare herb Orange-fruit Horse-gentian (Triosteum aurantiacum E.P. Bicknell) to see how the populations had changed over a decade and to learn more about why the plant remains rare. Our survey confirms previous observations that Orange-fruit Horse-gentian is largely restricted to the understorey of hardwood and mixedwood stands, on bare ground within and near river floodplains, often with White Ash (Fraxinus americana L.). Predictive maps based on geographic information system modelling led to the discovery of new occurrences of the species along the three original rivers and along a fourth river, including a dense cluster in mature hardwood forest, which had not previously been considered habitat. Measurements of photosynthetic capacity using pulse-amplitude modulation (PAM) fluorometry showed significant stress on horse-gentian plants growing in full sunlight or light shade compared with plants beneath closed canopy confirming this plant is shade-adapted. Late-autumn observations of potential consumers of horse-gentian fruit suggest that White-tailed Deer (Odocoileus virginianus) may be the primary long-range disperser of seeds. Hence, this species may remain rare in northern Nova Scotia because its optimal habitat (mature, closed-canopy forest with open understorey and calcium-rich soil) is rare and distributed in disjunct patches (mostly along floodplains) and seed dispersal is limited by the range size of the deer.La question de pourquoi quelque d’espèces de plantes reste rares et comment ils survivent en face de la compétition sont primordial en écologie. En 2015, nous avons répétées un levé de 2006 de la population de Triosteum aurantiacum Bicknell, une plante herbacée rare qui pousse dans les vallées de trois rivières dans la Comté d’Antigonish, au nord de Novelle Ecosse, pour vérifier la grandeur de la population après neuf ans et comprendre pourquoi l’espèce reste rare. Notre levé a confirmé que l’habitat de T. aurantiacum est presque limitée au sous-bois des peuplements feuillus et mixtes, sur sol nu, dans ou près des plaines inondables des rivières, et fréquemment associé avec Frêne blanc (Fraxinus americana L.). Des populations de T. aurantiacum dans les vallées de deux rivières s’augmentent, mais une troisième semble d’être en déclin. L’espèce ne se rencontre le long de deux autre rivières. Néanmoins, les cartes prédictives basées sur SDG ont facilitées la découverte des nouveaux sous-populations de T. aurantiacum le long des trois rivières originales et aussi le long d’une quatrième rivière, ça incluant un bouquet dense des plantes dans une forêt des feuillus matures, précédemment négligé. Comme mesurée par fluorimétrie, la capacité du photosynthèse de T. aurantiacum poussant en plein soleil ou sous un ombre légère est réduite considérablement comparé à des plantes sous un ombre lourde. Des observations en automne de consomption des fruits de T. aurantiacum suggèrent que Cerf de Virginie (Odocoileus virginianus) peut être le disperseur des semences primaire à longue distance. Donc, Triosteum aurantiacum peut reste rare parce-que leur habitat optimal (la forêt mature avec l’ombre lourde, sous-étage ouvert et sol riche en calcium) est lui-même rare, et distribué en carrés dissociés (la plupart des plaines inondables des rivières) et le dispersion des semences est limités par le taille de l’aire de répartition de Cerf de Virginie.
 
Distribution and habitat use of Canada Goose (Branta canadensis) during spring and fall migration along the James Bay east coast
Full text linkCanada Goose (Branta canadensis) is the main waterfowl harvested by Cree hunters in James Bay. Environmental changes that could affect the number, distribution, and migration patterns of geese have occurred along James Bay’s east coast in the last 50 years, including isostatic rebound, climate warming, and hydroelectric development. We determined the spring and fall distribution of Canada Geese along the James Bay east coast in 2018 and identified habitats associated with the greatest goose densities. We conducted four helicopter surveys between Waskaganish and Chisasibi, two each during spring and fall. The main goose concentrations were between Eastmain and Wemindji in both seasons. In spring, goose densities increased with the percentage of salt marshes whereas in fall, the highest densities were in areas with the greatest proportion of tidal flats and turbid water. We did not find any relationships between Common Eelgrass (Zostera marina L.) beds and the distribution of Canada Geese although it was an important habitat for geese in the 1970s. Our observations are consistent with surveys conducted in the 1990s that found limited use of eelgrass beds by migrating geese. This suggests that geese may be using alternative habitats during migration following the decline of eelgrass beds reported by Cree land users and confirmed by ground surveys and remote sensing. Changes in distribution and habitat use of goose flocks along the James Bay east coast are probably a consequence of habitat changes, natural and human disturbances, and the increasing number of moult migrant temperate breeding Canada Goose (Branta canadensis maxima).La bernache du Canada (Brenta canadensis) est la principale espèce de sauvagine récoltée par les chasseurs Cris de la Baie James. Depuis les 50 dernières années, de nombreux changements environnementaux ont affecté la Baie James et possiblement le nombre, la distribution et les modes de migration des bernaches cette région. De précédents inventaires aériens ont été conduits au début des années 1970, avant le développement des projets hydroélectriques dans la région boréale du Québec, sur le territoire Cri de Eeyou Istchee, puis au début des années 1990, une fois les travaux hydroélectriques partiellement achevés. Les objectifs de notre étude étaient de déterminer la distribution actuelle des bernaches du Canada au printemps et en automne le long de la côte est de la Baie James et d’identifier les habitats associés avec les plus grandes densités de bernaches. Nous avons réalisé deux séries d’inventaires en hélicoptère au printemps et en automne 2018, entre Waskaganish et Chisasibi. Au cours des deux saisons, nous avons observé les plus grandes concentrations de bernaches entre Eastmain et Wemindji. Au printemps, la densité de bernache augmentait avec la proportion de marais salés alors qu’en automne, on trouvait les plus grandes densités dans les sections avec les plus grandes proportions de zones intertidales et d’eau turbide. Les herbiers de zostère (Zostera marina) n’expliquaient pas la distribution actuelle des bernaches, ce qui confirme les observations des communautés Cries selon lesquelles la zostère est devenue moins disponible pour les bernaches. La modification des habitats, les perturbations naturelles et d’origine humaine, ainsi que l’augmentation du nombre de bernaches résidentes effectuant des migrations de mue (B. c. maxima) ont probablement conduit à des changements de l’utilisation des habitats de la Baie James par les groupes en migration
"Ring of Fire: High-Stakes Mining in a Lowlands Wilderness" by Virginia Heffernan, 2023 [book review]
No full textMinutes of the 145th Annual Business Meeting (ABM) of the Ottawa Field-Naturalists’ Club, 10 January 2024 (draft)
Full text linkFirst known observations of migratory Army Cutworm Moth (Euxoa auxiliaris) in the southern Canadian Rocky Mountains
Full text linkArmy Cutworm Moth (Euxoa auxiliaris) migrates long distances to mountain talus slopes where they aggregate in prodigious numbers over summer. Composed of ~70% lipid and ~25% protein at the height of summer, the moths attract Grizzly Bear (Ursus arctos horribilis) to talus slopes in certain mountain ranges in the contiguous United States to forage at aggregations. We present the first known observations of migratory Army Cutworm Moths aggregating on talus slopes in the southern Canadian Rocky Mountains of British Columbia and Alberta. Because this is a potential food resource for the bears, managers may wish to evaluate suitable moth habitat
The carcass zone: salmon contribution to tree rings in old‑growth Sitka Spruce (Picea sitchensis) throughout coastal British Columbia
Full text linkThe contribution of Pacific salmon to riparian forest biodiversity is widely recognized, yet the direct influence on coniferannual growth rings is less well-established. I examined broad spatial and temporal trends (1945–1999) in ring width, basal area increments (BAI), and nitrogen signatures in heartwood rings of 282 old-growth riparian Sitka Spruce (Picea sitchensis;average age ~300 years) from 79 watersheds in three regions of coastal British Columbia. Several large yearly fluctuations in salmon biomass entering streams were positively but weakly correlated with tree growth, lagged one to four years. General linear models indicate that tree age and salmon carcass proximity were the major growth predictors, while tree distance to stream and riparian slope were not significant. Average annual BAI (marginal means) in carcass zones were 80%, 150%, and 55% higher than adjacent control sites on the Mainland, Mid-coast Islands, and Haida Gwaii, respectively. Nitrogen isotope signatures (δ15N) in heartwood rings ranged from –8.6‰ to 8.0‰ and were about 3‰ higher in carcass trees than control trees. Total nitrogen (TN) ranged from 0.03% to 0.15% and was largely independent of salmon carcass occurrence. Bivariate plots (δ15N against TN) indicate a geographical clustering of elevated TN in Haida Gwaii watersheds, lower δ15N and TN in the Mid-coast Islands, and elevated δ15N and TN in watersheds with exceptionally high salmon carcass transfer and bear activity. These cumulative data robustly quantify accentuated conifer growth from salmon-derived nutrients in riparian zones that are largely independent of climatic influences and tree age