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Rare moss diversity and distribution patterns are described for the province of Alberta. Multivariate analyses were used to elucidate the distribution patterns of the rare mosses in relation to environmental factors, in comparison with those of the common mosses. Hierarchical clustering of species occurrence among Alberta ecoregions resulted in 11 species groups having similar distributions and four ecoregion groups with similar species composition. Rare and common mosses show comparable distributions at the geographic scale of ecoregions; the analyses did not provide support that rare mosses respond to environment factors differently than common mosses. The rare mosses are more narrowly distributed among the species and ecoregion groups than are common species. The most important environmental variables determining species distributions are mean annual temperature and growing degree days. Other important factors determining moss distribution are mean elevation, annual rainfall, and mountain landscape. Diversity patterns are shown to vary widely among the ecoregions and to differ between rare and common species. Rare species are especially diverse in the Rocky Mountains, which support 81% of the province's known rare moss flora and reflect a complex of diverse landscapes for moss colonization. Only 40% of known rare species in Alberta are found in non-mountainous regions. Key words: mosses, rare species, diversity, distribution, Alberta. La diversité et les modèles de distribution des mousses rares sont décrits pour la province de l'Al-berta. Des analyses multivariées sont utilisées pour élucider les modèles de distribution des mousses rares en relation avec les facteurs environnementaux, en comparaison avec ceux des mousses communes. Le regroupement hiérarchique de la présence des espèces parmi les écorégions de l'Alberta a donné lieu à onze groupes d'espèces ayant des distributions similaires et à quatre groupes d'écorégions ayant une composition d'espèces similaire. Les mousses rares et communes présentent des distributions comparables à l'échelle géographique des écorégions ; les analyses n'ont pas permis de confirmer que les mousses rares réagissent aux facteurs environnementaux différemment des mousses communes. Les mousses rares sont distribuées plus étroitement parmi les groupes d'espèces et d'écorégions que les espèces communes. Les variables environnementales les plus importantes qui déterminent la répartition des espèces sont la température annuelle moyenne et les degrés-jours de croissance. Les autres facteurs importants qui déterminent la répartition des mousses sont l'altitude moyenne, les précipitations annuelles et le paysage montagneux. Les modèles de diversité s'avèrent varier considérablement parmi les écorégions et différer entre les espèces rares et les espèces communes. Les espèces rares sont particulièrement diversifiéesdansles Rocheuses, qui abritent 81 % de la floredemousses rares connues de la province et reflètent un complexe de divers paysages pour la colonisation des mousses. Seulement 40 % des espèces rares connues en Alberta se trouvent dans des régions non montagneuses. [Traduit par la Rédaction] Mots-clés : mousses, espèces rares, diversité, distribution, Alberta., Introduction Rare species are an important component of plant biodiversity in many regions and understanding their biological attributes and distribution patterns is often imperative for their conservation and management (Soderstrom [...]

Peatlands with ground surfaces near the water table may be sensitive to disturbances that reduce this distance to water. Shrubby rich fens (SRF) in northern Alberta, Canada, are restricted to the wettest landscape positions and are characterized by brown mosses and stunted trees on weakly consolidated and saturated substrates. In situ oil sands exploration (OSE) practices have established thousands of drilling pads to explore for deeply buried bitumen deposits, with many located on peatlands. In the development of OSE pads on peatlands, the vegetation layer is removed, eliminating the functionally important hummock‐hollow surface topography. We examined the spontaneous regeneration of bryophytes and vascular plants and surface microtopography on SRF, 7 and again 14 years after pad abandonment. In both sampling years, drilling pad surfaces were closer to the water table (mean pad elevation 2012 = 3.3 cm, 2019 = 5.6 cm) and had minor topography compared to adjacent reference habitat. We found, however, over the 7 years, that for both drilling pads and reference habitat, bryophyte and vascular plant richness decreased, and most species declined in frequency. Furthermore, for pads and reference habitat, density of tree seedlings decreased, and expansion of hummock‐forming mosses was limited. Findings suggest that drilling pads and their natural counterparts on SRF may be prone to episodic reductions in plant diversity and ecosystem retrogression, likely resulting from prolonged surface saturation during summers with high rainfall. Because of their wet landscape positions and environmental vulnerability, SRF are likely the peatland habitats slowest to recover following OSE pad construction. [ABSTRACT FROM AUTHOR]

Wooded rich fens (WRF), characterized by high variation in surface topography and numerous plant species organized along microtopographic gradients, are abundant in continental western Canada. In regions where in situ oil sands exploration (OSE) prevails, however, winter operations eliminate the surface vegetation and mechanically flatten the exposed peat. This results in saturated or flooded soils during the growing season and eliminates plant species dependent on naturally elevated microhabitats, with implications for peatland recovery. In northeastern Alberta, we redeveloped hummock topography on replicate WRF after OSE by extracting blocks of frozen peat from peatland surfaces in the winter. Peat mounds and adjacent unmounded flattened areas were left to regenerate naturally and were sampled four to five summers later. Mounds facilitated the colonization of many peatland plants not adapted to waterlogged soils. For bryophytes, mean richness and diversity of liverworts, Sphagnum, and true mosses were higher in mounded plots than in unmounded plots. For vascular plants, woody plants (trees and shrubs) had higher richness, cover, and diversity (trees only) in mounded plots. Peat mounding may be effective for stimulating vegetation development on OSE-degraded WRF. All mounds, however, will require lateral expansion by hummock-forming mosses to provide the habitat volume required for development of large woody plants. Key words: microtopography, oil sands exploration, peatland restoration, Sphagnum, wooded rich fen. Les tourbieres boisees minerotrophes (TBM) sont abondantes dans la region continentale de l'ouest du Canada. Elles sont caracterisees par une grande variation topographique de surface et la presence de nombreuses especes vegetales distribuees le long de gradients microtopographiques. Cependant, dans les regions oU l'exploration des sables bitumineux (ESB) domine, les operations hivernales eliminent la vegetation de surface et aplanissent mecaniquement la tourbe qui est exposee. Cela entrarne la saturation ou l'engorgement des sols durant la saison de croissance et elimine les especes vegetales qui dependent de microhabitats naturellement sureleves, ce qui a des repercussions sur la recuperation des tourbieres. Dans le nord-est de l'Alberta, nous avons recree la topographie de hummocks dans plusieurs TBM apres l'ESB en extrayant des blocs de tourbe gelee a la surface de tourbieres en hiver. On a laisse les monticules de tourbe et les zones aplanies adjacentes sans monticules se regenerer naturellement et un echantillonnage a ete realise quatre a cinq etes plus tard. Les monticules ont facilite la colonisation de plusieurs plantes des tourbieres qui ne sont pas adaptees aux sols gorges d'eau. Dans le cas des bryophytes, la diversite et la richesse des hepatiques, des sphaignes et des vraies mousses etaient en moyenne plus grandes dans les places echantillons avec des monticules que sans monticules. Dans le cas des plantes vasculaires, la richesse, le recouvrement et la diversite (arbres seulement) des plantes ligneuses (arbres et arbustes) etaient plus eleves dans les places echantillons avec des monticules. La creation de monticules de mousses peut etre efficace pour promouvoir le developpement de la vegetation dans les TBM degradees a la suite de l'ESB. Cependant, une expansion laterale des monticules par les mousses qui forment les hummocks sera necessaire pour fournir le volume d'habitat requis pour le developpement de grosses plantes ligneuses. [Traduit par la Redaction] Mots-cles : microtopographie, exploration des sables bitumineux, sphaignes, restauration des tourbieres, tourbiere boisee minerotrophe., Introduction Peatlands are critically important wetland ecosystems because of the numerous functional and biological roles that they have on landscapes (Vitt 2006; Minayeva et al. 2017). Peatlands account for approximately [...]

Frullania stylifera (R.M. Schust.) R.M. Schust. (Frullaniaceae) is newly reported for Canada. The species grows closely appressed to the bark of trees and shrubs and was recently documented from two areas of mature forest at Buffalo Point First Nation in extreme southeastern Manitoba, Canada. These localities represent a northern range extension for the species on the continent and include two new phorophyte hosts for North America. Features used to distinguish F. stylifera from other known species of Frullania in Manitoba are provided. [ABSTRACT FROM AUTHOR]

Epiphytic mosses and liverworts contribute substantially to the bryophyte diversity of circumpolar boreal forests but are susceptible lo altered growing conditions after forest harvesting. Management practices that retain some trees after harvest may enhance epiphyte survival; however, the effectiveness or this emerging method needs lo be assessed. We examined the survival, composition, and nearest neighbour relationships of epiphytic bryophytes on trembling aspen (Populus tremuloides Michx.) across a range (10%-100%) of dispersed green-tree retention 5 years after harvest in boreal mixed- wood forest. Growth of the forest floor moss Hylocomium splendens (Hedw.) Schimp. in B.S.G. was used as an indicator of changes in moisture availability for epiphytes following harvesting. Epiphyte richness and abundance increased with canopy retention and were positively correlated with local abundance of coniferous trees. Positive associations among neighbouring species in intact forest demonstrated that interspecies relationships form naturally. However, there was a shift in species composition after harvesting and fewer interspecific associations with declining retention. These trends were accompanied by reduced Hylocomium splendens growth, which implies that moisture may be an important driver of epiphyte response. Although different levels of canopy retention were similarly capable of maintaining some epiphytes, the loss of species associated with intact forest will require consideration of alternative management practices for their conservation. Key words: corticolous, Hylocomium splendens, liverwort, moss, poikilohydric. variable retention. Les mousses et les hepatiques epiphytes contribuent subsiantiellement a la diversite des bryophytes des forets boreales circumpolaires, mais sont sensibles aux modifications des conditions de croissance, suite aux operations forestieres. Les methodes d'amenagement qui conservent certains arbres apres la recolte peuvent ameliorer la survie des epiphytes; cependant, on doit evaluer l'efficacite de ces methodes en emergence. Les auteurs ont examine la survie, la composition et les relations avec les voisins les plus rapproches des bryophytes epiphytes sur le peuplier faux-tremble (Populas tremuloides Michx.) pour l'ensemble d'une aire (10% a 100%) comportant des arbres vivants conserves et disperses, 5 ans apres la recolte dans une foret boreale mixte. Ils ont utilise la croissance d'une mousse du parterre forestier, l'Hylocomium splendens (Hedw.) Schimp, in B.S.G., colome indicatrice des modifications de la disponibilite de l'humidite pour les epiphytes, suite a la recolte des arbres. La richesse et l'abondance des epiphytes augmentent avec la retention de la canopee et montrent des correlations positives avec l'abondance localisee de coniferes. Les associations positives avec les especes avoisinantes dans la foret intacie demontrent que des relations interspecifiques se forment nalurellement. Cependant, on observe un deplacement de la composition en especes apres la recolte et moins d'associations interspecifiques avec une diminution de la retention. Ces tendances s'accompagnent d'une reduction de la croissance de l'Hylocomium splendens, ce qui implique que l'humidite pourrait etre un agent causal important de la reaction des epiphytes. Bien que differents degres de conservation de la canopee peuvent etre egalement aptes a maintenir certaines epiphytes, la perte d'especes associees aux forets intactes necessitera la definition de methodes alternatives d'amenagement pour leur conservation. Mots-cles: corticole, Hylocomium splendens, hepatiques, mousse, poikilohydrique, retention variable. [Traduit par la Redaction], Introduction Forest management practices that retain a greater volume of standing trees after harvest are gradually becoming more widely accepted in place of traditional clearcut methods in North American and [...]

Site moisture is an important component of the forest landscape for maintaining biodiversity, including forest‐floor bryophytes. However, little is known about its role in shaping understorey responses to harvesting.We investigated the influence of site wetness, determined using a remotely sensed, topographic depth‐to‐water (DTW) index, on responses of bryophyte cover, richness, diversity and composition to variable retention harvesting (comparing: 2% [clear‐cut], 20% and 50% dispersed green tree retention and uncut controls [100% retention]) in three boreal forest cover‐types (broadleaf, mixed and conifer forests) in western Canada. The DTW index provides an approximation of DTW at or below the soil surface and was derived from wet‐areas mapping based on discrete Airborne Laser Scanning data acquired over an experimentally harvested landscape located in north‐western Alberta, Canada.The effectiveness of leaving retention (vs. clear‐cutting) for conserving bryophyte communities depended on site wetness, as indicated by DTW, with the specifics varying among forest types. In broadleaf forests, bryophyte cover and richness were generally low and not much affected by harvesting but drier sites had higher richness and a few more unique species. In mixed and conifer forests, leaving retention (vs. clear‐cutting) on wetter (vs. drier) sites was more effective for conserving bryophyte cover, wetter sites had higher total species richness and more species were exclusive to wetter sites.Synthesis and applications. Site wetness, as indicated using the remotely sensed topographic site wetness index "depth‐to‐water" mediates bryophyte responses to variable‐retention harvests. Specifically, our results suggested that in conifer and mixed forests it would be more beneficial to target wetter sites for retention patches or dispersed retention whereas in broadleaf forests there might be a slight advantage to targeting drier sites. Our study demonstrates that this tool could be used to inform management decisions around leaving dispersed or patch retention. Site wetness, as indicated using the remotely sensed topographic site wetness index "depth‐to‐water" mediates bryophyte responses to variable‐retention harvests. Specifically, our results suggested that in conifer and mixed forests it would be more beneficial to target wetter sites for retention patches or dispersed retention whereas in broadleaf forests there might be a slight advantage to targeting drier sites. Our study demonstrates that this tool could be used to inform management decisions around leaving dispersed or patch retention. [ABSTRACT FROM AUTHOR]

Fabronia ciliaris (Fabroniaceae, Bryophyta) was recently discovered in the Great Lakes-St. Lawrence forest region in southeastern Manitoba. This collection represents the first record of the species in Canada and the northernmost extent of the species in North America. [ABSTRACT FROM AUTHOR]

An assessment of bryophyte species growing on an Ordovician dolomite escarpment in the Interlake region of Manitoba known as Marble Ridge revealed a diverse flora composed mostly of circumboreal floristic elements. Two liverwort families (including three species) and four moss species are reported for Manitoba for the first time: the liverworts Alhalamia hyalina (Sommert.) Hatt. (Cleveaceae), Mannia fragrans (Balbis) Frye et Clark (Aytoniaceae), and Mannia sibirica (K. Müll.) Frye et Clark (Aytoniaceae) and the mosses Brachythecium collinum (Schleich, ex C. Müll.) Schimp. in B.S.G., Grimmia teretinervis Limpr., Schistidium frigidum H. H. Blom, and Seligeria donniana (Sm.) C. Müll. An annotated summary of these and other bryophyte species documented at the site is provided. The diversity of encountered bryophytes can mostly be attributed to the moist and shaded microclimatic conditions on the escarpment and the large number of microhabitats the escarpment supports. This study represents one of few accounts of bryophytes in the region and highlights the importance of this particular geologic formation in supporting a number of species that are expected to be regionally uncommon. [ABSTRACT FROM AUTHOR]