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The resilience (measured as changes in functional group representation and species composition) of bryophyte communities found in the younger-aged (“matrix”) forests surrounding old-growth remnants was examined in two different forest types, warmer, drier (Nimpkish) versus cooler, wetter (Sayward), on Vancouver Island, British Columbia. Bryophytes were sampled within 10 m × 2 m belt transects (species composition only) and using 10 cm × 30 cm microplots (composition and abundance) in two age classes of matrix forest, clearcuts (age 7–20 years), and second-growth (age 25–49 years) as well as in remnant old-growth forest stands (age >300 years). The cover of all bryophytes was diminished and more patchily distributed in younger-aged stands; however, the richness and frequency of bryophyte functional groups showed different responses in the two younger age class forests. Disturbance-associated species exhibited both higher richness and frequency in clearcut plots and higher richness in second-growth plots. In comparison, the richness of species associated with old-growth was largely unchanged in younger-aged forests compared with old-growth forests; however, the frequency of occurrence of species associated with old-growth was significantly reduced in younger-aged forests. The cooler, wetter forests exhibited greater resilience, as the difference in species composition between second-growth and old-growth stands was less than that between second-growth and old-growth stands in the warmer, drier forests. The greater difference in second-growth species composition in the warmer, drier forests was attributed mainly to the persistence of disturbance-associated species. Les auteurs ont examiné la résilience (mesurée à partir des changements de la représentation des groupes fonctionnels et de la composition en espèces) des communautés de bryophytes dans des forêts plus jeunes (« matrice ») entourant des vestiges de forêts surannées dans deux types de forêts différents, chaud et sec (Nimpkish) versus plus frais et plus humide (Sayward), sur l’île de Vancouver, en Colombie Canadienne. Ils ont échantillonné les bryophytes sur des transects de 10 m × 2 m (composition en espèces seulement) en utilisant des microparcelles de 10 cm × 30 cm (composition et abondance) dans deux classes d’âge de la forêt matricielle, dans les coupes à blanc (âge 7–20 ans) et en régénération (âge 25–49 ans), ainsi que dans des peuplements de forêt surannée résiduelle (âge >300 ans). On observe une couverture plus morcelée de l’ensemble des bryophytes dans les peuplements de jeune âge, cependant la richesse et la fréquence des groupes fonctionnels de bryophytes montrent différentes réactions dans les deux classes de forêts plus jeunes. Les espèces associées aux perturbations montrent à la fois une plus grande richesse et une plus grande fréquence dans les parcelles coupées à blanc et une plus grande richesse dans les parcelles en régénération. En comparaison, la richesse en espèces associée aux forêts surannées demeure largement inchangée; cependant, la fréquence de présence des espèces associées aux forêts surannées se voit significativement réduite dans les forêts plus jeunes. Les forêts plus fraîches et plus humides affichent une résilience plus importante, puisque la composition en espèces entre les forêts en régénération et les peuplements surannés est moindre que celle observée entre les forêts en régénération et les peuplements surannés des forêts plus chaudes et plus sèches. Les auteurs attribuent la plus grande différence en espèces des peuplements en régénération avec les forêts plus chaudes et plus sèches surtout à la persistance des espèces associées aux perturbations. [ABSTRACT FROM AUTHOR]

Aim Non-vascular epiphytes have been largely ignored in studies examining the biotic and abiotic determinants of spatial variation in epiphyte diversity. Our aim was to test whether the spatial patterning of species richness, biomass and community composition across geographic regions, among trees within regions, and among branches within trees is consistent between the vascular and non-vascular components of the temperate rain forest flora. Location Coastal lowland podocarp-broadleaved forests on the west coast of the South Island of New Zealand. Methods We collected single samples (30 × 25 cm) from 96 epiphyte assemblages located on the inner branches of 40 northern rata ( Metrosideros robusta) trees. For each sample, branch characteristics such as branch height, branch diameter, branch angle, branch aspect, and minimum and maximum epiphyte mat depth were recorded. The biomass for each individual epiphyte species was determined. Results Northern rata was host to a total of 157 species, comprising 32 vascular and 125 non-vascular species, with liverworts representing 41% of all species. Within epiphyte mats, the average total organic biomass of 3.5 kg m−2 of branch surface area consisted largely of non-living biomass and roots. Vascular and non-vascular epiphytes showed strikingly different spatial patterns in species richness, biomass and composition between sites, among trees within sites, and among branches within trees, which could not be explained by the branch structural characteristics we measured. The two plant groups had no significant association in community composition ( r = 0.04, P = 0.08). However, the species richness of vascular plant seedlings was strongly linked to the presence/absence of lichens. Main conclusions Non-vascular plants contributed substantially to the high species richness and biomass recorded in this study, which was comparable to that of some tropical rain forests. High variability in community composition among epiphyte mats, and very low correlation with any of the environmental factors measured possibly indicate high levels of stochasticity in seed or spore colonization, establishment success or community assembly among branches in these canopy communities. Although we found some evidence that vascular plant seedling establishment was linked to the presence of lichens and the biomass of non-living components in the epiphyte mats, there was no correlation in the spatial patterning or determinants of species richness between non-vascular and vascular plants. Consequently, variation in total epiphyte biodiversity could not be predicted from the measurement of vascular plant diversity alone, which highlights the crucial importance of sampling non-vascular plants when undertaking epiphyte community studies. [ABSTRACT FROM AUTHOR]

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A letter to the editor is presented related to the mutation of codon 82 β in homozygous condition in a thalassemia major patient of North Indian family originating from Pakistan, along with its antenatal diagnosis.

Responses in bryophyte communities following volcanic disturbance are not well understood. The eruption of Mount St. Helens on 18 May 1980 deposited large amounts of tephra (aerially transported volcanic ejecta) on nearby forests in southwestern Washington and presented an opportunity to examine bryophyte succession, with a focus on mosses. We examined changes in moss community over 36 years following this disturbance, using permanent plots located in old-growth conifer forests. We used an experimental design where we removed the tephra from some of the plots shortly after the eruption. Initial dramatic decreases in total bryophyte cover, moss species richness, and diversity in plots with intact tephra were followed by increases by 2016. Community profiles also shifted through time but were somewhat site-specific. Moss community change was related to changes in vascular plant species and was driven by changes in a few key moss species with distinct growth strategies. Bryophyte change through time was most pronounced in the plots buried by tephra, but differed among sites. Overall, total bryophyte cover had recovered, reaching our estimate of pre-disturbance levels at all sites after 36 years, but trajectories of change differed among sites, demonstrating the importance of idiosyncratic site factors and the dynamics of the vascular plant species. Key words: moss, Mount St. Helens, succession, tephra, volcanic disturbance. Les réactions des communautés de bryophytes à la suite de perturbations volcaniques ne sont pas bien comprises. L'éruption du Mont St. Helens le 18 mai 1980 a déposé de grandes quantités de téphra (éjectas volcaniques transportés par voie aérienne) sur les forêts voisines du sud-ouest de l'Etat de Washington et a été l'occasion d'examiner la succession des bryophytes, en mettant l'accent sur les mousses. Les auteurs ont examiné l'évolution des communautés de mousses sur une période de 36 ans à la suite de cette perturbation en utilisant des parcelles permanentes situées dans des forêts âgées de conifères. Ils ont utilisé un plan expérimental dans lequel certaines des parcelles avaient été débarrassées du téphra peu après l'éruption. Les premières baisses spectaculaires de la couverture totale de bryophytes, de la richesse et de la diversité des espèces de mousses dans les parcelles où le téphra était intact ont été suivies d'augmentations jusqu'en 2016. Les profils communautaires évoluaient aussi au fil du temps, mais ils étaient plutôt spécifiques à chaque site. L'évolution des communautés de mousses était liée aux changements des espèces de plantes vasculaires et était déterminée par des changements de quelques espèces de mousses clés ayant des stratégies de croissance distinctes. L'évolution des bryophytes au fil du temps était plus prononcée dans les parcelles touchées par le téphra, mais elle variait d'un site à l'autre. Dans l'ensemble,lacouverturetotaledebryophytess'était rétablie, atteignant leur estimation des niveaux d'avant perturbation sur tous les sites après 36 ans, mais les trajectoires de changement différaient selon les sites, ce qui démontre l'importance des facteurs idiosyncrasiques des sites et de la dynamique des espèces de plantes vasculaires. [Traduit par la Rédaction] Mots-clés: mousse, Mont St. Helens, succession, téphra, perturbation volcanique., Introduction Temporal changes in bryophyte (moss and liverwort) communities following different types of disturbances remain inadequately understood for temperate and boreal coniferous forests, despite a number of studies examining bryophyte [...]

The temperate rainforest on the Olympic Peninsula represents a biome that is characterized by unusually high epiphyte biomass and accompanying canopy soils. These canopy communities form thick mats that play important ecological roles: increasing ecosystem nutrient capital, fostering abundant invertebrates, and enhancing moisture retention. Little is known about the physical properties and microenvironmental conditions of these mats. We investigated seasonal patterns in temperature and moisture of canopy soils and compared them to O- and A-horizon terrestrial soils. Temperature tended to fluctuate more in canopy soils than in terrestrial soils. During the 4 months of highest precipitation, canopy soils also showed higher maximum saturation levels than terrestrial soils. Both soil types displayed sharp 'dry-downs' during the summer dry season, which contrasts with results from similar research in a tropical cloud forest, where only canopy soils dried significantly during the dry season. In the late summer in the Olympic Rainforest, canopy soils remained dry until the first rainfall, whereas terrestrial soils began to rehydrate a month earlier, possibly through hydraulic redistribution. Regional climate models predict increased winter precipitation but drier summers for this area. Our results suggest that extended summer droughts may increase canopy drying, which may have negative impacts on epiphyte communities. Key words: temperate rainforest, arboreal soil, epiphyte mats, canopy. Resume : La foret temperee ombrophile de la Peninsule Olympic represente un biome caracterise par une biomasse epiphyte particulierement abondante, accompagnee de sols de canopee. Ces communautes de la canopee forment des coussins epais jouant des roles ecologiques importants : augmentation de la reserve en nutriments de l'ecosysteme, encouragement d'une abondante proliferation d'invertebres, augmentation de la retention de l'humidite. On connait peu de chose au sujet des proprietes physiques et des conditions micro environnementales de ces coussins. Les auteurs ont examine les patrons saisonniers de la temperature et de l'humidite des sols de canopee avec celles des horizons O et A des sols terrestres. La temperature a tendance a fluctuer plus fortement dans les sols de canopee que dans les sols terrestres. Au cours des 4 mois les plus pluvieux, les sols de canopee montrent egalement un maximum de saturation plus eleve que les sols terrestres. Les deux types de sol montrent une nette dessiccation au cours de la saison seche estivale, ce qui contraste avec les resultats de recherches similaires conduites dans la foret tropicale ombrophile, ou seuls les sols de canopee sechent significativement au cours de la saison seche. A la fin de l'ete, dans la Peninsule Olympic, les sols de canopee demeurent secs jusqu'a la premiere pluie, alors que les sols terrestres commencent a se rehydrater un mois plus tot, possiblement par redistribution hydraulique. Les modeles climatiques regionaux predisent une augmentation des precipitations hivernales, mais des etes plus secs pour cette region. Les resultats suggerent que la prolongation de la duree des secheresses estivales pourrait augmenter la dessiccation de la canopee, ce qui pourrait avoir des impacts negatifs sur la communaute epiphyte. [Traduit par la Redaction] Mots-cles: foret ombrophile temperee, sol arboricole, coussins d'epiphytes, canopee., Introduction Old-growth temperate forests of the western slopes of the Olympic Mountains host extremely high epiphyte biomass and diversity (Franklin and Dyrness 1988; Kirk and Franklin 1992), supporting communities that [...]