Vascular plant communities in the polar desert of Alert (Ellesmere Island, Canada): Establishment of a baseline reference for the 21st century

Abstract

The startling warming of the Arctic is driving important environmental changes, but vegetation responses have been spatially heterogeneous and difficult to predict. In this context, establishing new ecological baselines and initiating monitoring schemes are essential. We conducted systematic plot-based surveys in the polar desert surrounding Alert (Nunavut, Canada). We aimed at (1) identifying distinct plant communities, (2) characterizing community attributes, including diversity and abundance, as well as environmental variables associated with each community, and (3) establishing a georeferenced baseline with permanent field markers allowing robust resurveying. We used hierarchical clustering to categorize cover values of vascular plant species, cryptogams, and ground substrates from 1,320 quadrats (1 m 2 each) surveyed in 264 vegetation plots. Five plant communities were identified, with one community associated with each of the barren and mesic habitats, and three communities associated with wetlands. The mean biotic covers were generally higher at Alert (13-98%) compared to other polar deserts in the Canadian Arctic Archipelago. A total of 250 quadrats from 50 vegetation plots were permanently marked, and a database describing all plots is available online. This study improves our understanding of High-Arctic plant communities and establishes an important vegetation monitoring reference at the northernmost permanently inhabited settlement on Earth. RésuméLe réchauffement sans précédent de l'Arctique entraîne des changements environnementaux importants, mais les réponses de la végétation sont spatialement hétérogènes et difficiles à prédire. Dans ce contexte, l'établissement de nouvelles bases de référence écologiques et la mise en place de programmes de suivi sont essentiels. Nous avons effectué des relevés systématiques par quadrats dans le désert polaire entourant Alert (Nunavut, Canada). Nous avions pour objectifs (1) d'identifier les communautés végétales distinctes, (2) de caractériser les attributs de chaque communauté, y compris la diversité et l'abondance, ainsi que les variables environnementales associées à chacune et (3) d'établir une base de données géoréférencée avec des quadrats marqués de façon permanente permettant un rééchantillonnage rigoureux. Nous avons utilisé une analyse de groupement hiérarchique pour catégoriser les valeurs de recouvrement des espèces végétales vasculaires, des cryptogames et des types de substrats de 1320 quadrats (1 m 2 chacun) étudiés dans 264 parcelles de végétation. Cinq communautés végétales ont été identifiées, une associée aux habitats arides, une associée aux habitats mésiques, et trois associées aux habitats humides. Les recouvrements biotiques moyens étaient généralement plus élevés dans les communautés à Alert (13 à 98%) que dans celles d'autres déserts polaires de l'archipel Arctique canadien. Au total, 250 quadrats répartis dans 50 parcelles de végétation ont été marqués avec des clous, et une base de données détaillée décrivant toutes les parcelles est ...

Algorithms and Predictors for Land Cover Classification of Polar Deserts: A Case Study Highlighting Challenges and Recommendations for Future Applications

“…For example, the forb-dominated barren, the driest vegetation class, had the furthest mean distance from a snowbank (Table S2). In addition, we found that distance to snowbanks emerged as the most important predictor of sedge-dominated wetland, thus confirming Desjardins et al [75], who had demonstrated at the same site an association between this community and perennial snowbanks. To our knowledge, snowbanks were never previously used as a predictor of vegetation classification in the Arctic.…”

“…We obtained ground references for seven land cover classes: forb-dominated barren, forb-dominated tundra, grass-dominated wetland, sedge-dominated wetland, mossdominated wetland, water, and snow. The five plant communities were identified in Desjardins et al [75] and are described in Table 1. Briefly, we conducted stratified random plot-based surveys during the summers of 2018 and 2019, with survey locations adjusted so that plots were located within homogeneous vegetation patches.…”

“…Such confusions can be explained because the above pairs are composed of the same plant species but with an ascending percentage of coverage. Similarly, errors occurred due to a retrogression from one community to another (e.g., from grass-dominated wetland to forb-dominated tundra, the latter characterized by a high number of dead stems of Alopecurus magellanicus Lamarck) or due to the presence of mixed communities (e.g., grass-dominated and sedge-dominated wetlands were sometimes intermingled within the same lush patches of vegetation) [75]. Some misclassifications between the vegetation classes could also be related to soil humidity.…”

Vegetation biomass and topography are associated with seasonal habitat selection and fall translocation behavior in Arctic hares

“…The region is part of the polar desert biome (Bliss 2000 ). Plant communities mostly consist of herbaceous and low shrub species, mosses, and lichens (Desjardins et al 2021a , 2021b ; Government of Canada 2018 ). The area surrounding CFS Alert is rugged with hills, small lakes, and ponds.…”

Plant communities on inselbergs in Burkina Faso

“…[ 29 ]. IndVal assesses the strength of the association between a single species and several groups of relevés, each group representing a plant community [ 30 ], and is given by the indicator species analysis [ 24 ].…”