A vegetation classification approach is needed that can describe the diversity of terrestrial ecosystems and their transformations over large time frames, span the full range of spatial and geographic scales across the globe, and provide knowledge of reference conditions and current states of ecosystems required to make decisions about conservation and resource management. We summarize the scientific basis for EcoVeg, a physiognomic‐floristic‐ecological classification approach that applies to existing vegetation, both cultural (planted and dominated by human processes) and natural (spontaneously formed and dominated by nonhuman ecological processes). The classification is based on a set of vegetation criteria, including physiognomy (growth forms, structure) and floristics (compositional similarity and characteristic species combinations), in conjunction with ecological characteristics, including site factors, disturbance, bioclimate, and biogeography. For natural vegetation, the rationale for the upper levels (formation types) is based on the relation between global‐scale vegetation patterns and macroclimate, hydrology, and substrate. The rationale for the middle levels is based on scaling from regional formations (divisions) to regional floristic‐physiognomic types (macrogroup and group) that respond to meso‐scale biogeographic, climatic, disturbance, and site factors. Finally, the lower levels (alliance and association) are defined by detailed floristic composition that responds to local to regional topo‐edaphic and disturbance gradients. For cultural vegetation, the rationale is similar, but types are based on distinctive vegetation physiognomy and floristics that reflect human activities. The hierarchy provides a structure that organizes regional/continental vegetation patterns in the context of global patterns. A formal nomenclature is provided, along with a descriptive template that provides the differentiating criteria for each type at all levels of the hierarchy. Formation types have been described for the globe; divisions and macrogroups for North America, Latin America and Africa; groups, alliances and associations for the United States, parts of Canada, Latin America and, in partnership with other classifications that share these levels, many other parts of the globe.

Victoria Island in Canada’s western Arctic is the eighth largest island in the world and the second largest in Canada. Here, we report the results of a floristic study of vascular plant diversity of Victoria Island. The study is based on a specimen-based dataset comprising 7031 unique collections from the island, including some 2870 new collections gathered between 2008 and 2019 by the authors and nearly 1000 specimens variously gathered by N. Polunin (in 1947), M. Oldenburg (1940s–1950s) and S. Edlund (1980s) that, until recently, were part of the unprocessed backlog of the National Herbarium of Canada and unavailable to researchers. Results are presented in an annotated checklist, including keys and distribution maps for all taxa, citation of specimens, comments on taxonomy, distribution and the history of documentation of taxa across the island, and photographs for a subset of taxa. The vascular plant flora of Victoria Island comprises 38 families, 108 genera, 272 species, and 17 additional taxa. Of the 289 taxa known on the island, 237 are recorded from the Northwest Territories portion of the island and 277 from the Nunavut part. Thirty-nine taxa are known on the island from a single collection, seven from two collections and three from three collections. Twenty-one taxa in eight families are newly recorded for the flora of Victoria Island: Artemisia tilesii, Senecio lugens, Taraxacum scopulorum (Asteraceae); Crucihimalaya bursifolia, Draba fladnizensis, D. juvenilis, D. pilosa, D. simmonsii (Brassicaceae); Carex bigelowii subsp. bigelowii, Eriophorum russeolum subsp. albidum (Cyperaceae); Anthoxanthum monticola subsp. monticola, Bromus pumpellianus, Deschampsia cespitosa subsp. cespitosa, D. sukatschewii, Festuca rubra subsp. rubra, Lolium perenne, Poa pratensis subsp. pratensis (Poaceae); Stuckenia filiformis (Potamogetonaceae); Potentilla × prostrata (Rosaceae); Galium aparine (Rubiaceae); and Salix ovalifolia var. ovalifolia (Salicaceae). Eight of these are new to the flora of the Canadian Arctic Archipelago: Senecio lugens, Draba juvenilis, D. pilosa, Anthoxanthum monticola subsp. monticola, Bromus pumpellianus, Deschampsia cespitosa subsp. cespitosa, Poa pratensis subsp. pratensis and Salix ovalifolia var. ovalifolia. One of these, Galium aparine, is newly recorded for the flora of Nunavut. Four first records for Victoria Island are introduced plants discovered in Cambridge Bay in 2017: three grasses (Festuca rubra subsp. rubra, Lolium perenne, and Poa pratensis subsp. pratensis) and Galium aparine. One taxon, Juncus arcticus subsp. arcticus, is newly recorded from the Northwest Territories. Of the general areas on Victoria Island that have been botanically explored the most, the greatest diversity of vascular plants is recorded in Ulukhaktok (194 taxa) and the next most diverse area is Cambridge Bay (183 taxa). The floristic data presented here represent a new baseline on which continued exploration of the vascular flora of Victoria Island – particularly the numerous areas of the island that remain unexplored or poorly explored botanically – will build.

Most spatial modelling of climate change impacts on permafrost has been conducted at half-degree latitude/longitude or coarser spatial resolution. At such coarse resolution, topographic effects on insolation cannot be considered accurately and the results are not suitable for land-use planning and ecological assessment. Here we mapped climate change impacts on permafrost from 1968 to 2100 at 10 m resolution using a process-based model for Ivvavik National Park, an Arctic region with complex terrain in northern Yukon, Canada. Soil and drainage conditions were defined based on ecosystem types, which were mapped using SPOT imagery. Leaf area indices were mapped using Landsat imagery and the ecosystem map. Climate distribution was estimated based on elevation and station observations, and the effects of topography on insolation were calculated based on slope, aspect and viewshed. To reduce computation time, we clustered climate distribution and topographic effects on insolation into discrete types. The modelled active-layer thickness and permafrost distribution were comparable with field observations and other studies. The map portrayed large variations in active-layer thickness, with ecosystem types being the most important controlling variable, followed by climate, including topographic effects on insolation. The results show deepening in active-layer thickness and progressive degradation of permafrost, although permafrost will persist in most of the park during the 21st century. This study also shows that ground conditions and climate scenarios are the major sources of uncertainty for high-resolution permafrost mapping

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An ecological vegetation classification approach has been developed in which a combination of vegetation attributes (physiognomy, structure, and floristics) and their response to ecological and biogeographic factors are used as the basis for classifying vegetation types. This approach can help support international, national, and subnational classification efforts. The classification structure was largely developed by the Hierarchy Revisions Working Group (HRWG), which contained members from across the Americas. The HRWG was authorized by the U.S. Federal Geographic Data Committee (FGDC) to develop a revised global vegetation classification to replace the earlier versions of the structure that guided the U.S. National Vegetation Classification and International Vegetation Classification, which formerly relied on the UNESCO (1973) global classification (see FGDC 1997 Grossman and others 1998). This document summarizes the development of the upper formation levels. We first describe the history of the Hierarchy