Survey of the vascular plants of Alert (Ellesmere Island, Canada), a polar desert at the northern tip of the Americas

Abstract

Long-term monitoring is critical to guide conservation strategies and assess the impacts of climatic changes and anthropogenic activities. In High Arctic ecosystems, information on distribution and population trends of plants is dramatically lacking. During two field expeditions in 2018 and 2019, we conducted a systematic floristic survey together with opportunistic collecting in the polar desert surrounding Alert (Nunavut, Canada) to update past vascular plant inventories. We recorded 58 species, of which 54 species were recorded over the last seven decades, and four species that are additions to the local flora (Draba pauciflora R. Brown, Festuca edlundiae S.G. Aiken, Consaul, & Lefkovitch, Festuca hyperborea Holmen ex Frederiksen, and ×Pucciphippsia vacillans (T. Fries) Tzvelev). With the addition of 19 species that were previously reported but not found in our survey, we estimate the species richness in the study area at 77 species.

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

“…A total of 264 vegetation plots were sampled. Of the 77 vascular plant species ever recorded in the study area (Desjardins et al 2021a), 58 were found during this study, as well as five cryptogams (biological soil crust, blue-green algae, lichen, macrofungus, and moss). Among the 58 vascular species, 54 were found within the vegetation plots while four rare species were found only through opportunistic sampling (i.e., collected along marked trails and while traveling within the study area, outside of vegetation plots), namely Carex aquatilis Wahlenberg var.…”

“…Canonical Correspondence Analysis (CCA) was used to identify primary relationships between cover data and environmental variables (Legendre and Legendre 2012). Environmental variables included: (1) Normalized difference vegetation index (NDVI) computed from the pan-sharpened multispectral satellite picture of the study area, (2) elevation from the Canadian Digital Elevation Model (DEM) (Natural Resources Canada 2015), ( 3) slope derived from the DEM using ArcGIS, (4) distance to the nearest perennial snowbank derived from the habitat map (Desjardins et al 2021a), ( 5) location with respect to a perennial snowbank (binary state with 1 indicating location below a snowbank and 0 location above or beside a snowbank); this binary variable was added since the distance to the nearest perennial snowbank may not fully capture the effect of snowbanks, considering that sites spatially close to a snowbank but located upslope or besides the snow patch do not actually benefit from melt water that flows downslope, (6) distance to the nearest lake or pond derived from the habitat map and from the Topographic Data of Canada -CanVec Series (Natural Resources Canada 2017), ( 7) distance to the nearest river derived from Topographic Data of Canada -CanVec Series (Natural Resources Canada 2017), and (8) distance to the nearest ocean shore derived from Topographic Data of Canada -CanVec Series (Natural Resources Canada 2017). These eight environmental variables were not collinear, as shown by the variance inflation factor (VIF; regclass package in R software, R Core Team 2020) being <10.…”

“…Isostatic rebound following deglaciation raised the marine limit to 135 m above sea level (England 1976) and uncovered many beds of marine silts and clays mixed with masses of recent marine shells (Bruggemann and Calder 1953). A more detailed description of the study area can be found in Desjardins et al (2021a).…”

“…The systematic vegetation survey was carried out from 28 July to 24 August 2018, and from 3 July to 2 September 2019. A random stratified design was used, based on a habitat map described in Desjardins et al (2021a). The habitat map was constructed from a multispectral satellite picture of the study area (40cm resolution pan-sharpened multispectral picture from WorldView-2/3; taken on 2 and 13 August 2015) and consisted of six classes, including snow/water and five broad vegetation gradients classified into habitat types: barren ground, xeric, xeric-mesic, mesic, and wetland.…”

“…In order to fill geographic gaps in data coverage in Canada (Bjorkman et al 2020) while improving harmonization of data collection and monitoring (Christensen et al 2020), a systematic, plot-based survey of vascular plants was conducted at Alert (Ellesmere Island, Nunavut, Canada) in 2018-2019 by Desjardins et al (2021a). This survey estimated the total number of vascular species at 77 in the Alert region and recorded no introduced species.…”