|Thursday, July 08|
An examination of pattern-process relationships at a model krummholz-island treeline in Newfoundland, Canada
* Anna Crofts, Université de Sherbrooke, Canada
Carissa Brown , Memorial University
Alpine treelines - ecotones in which forests transition to alpine ecosystems - display a variety of spatial patterns ranging from abrupt lines to diffuse zones of increasingly small, deformed, and/or clustered trees. These spatial patterns may have direct and/or indirect implications to tree species’ responsiveness to climate warming. Recent studies have reported a link between spatial pattern and treeline responsiveness, with some spatial patterns rarely observed to advance (e.g., krummholz-island treelines). An increased understanding of mechanisms driving different spatial patterns may increase our ability to explain variability in treeline response. Krummholz-island treelines are characterized by stunted, deformed individuals that are clustered into islands surrounded by dissimilar vegetation. The formation of this spatial pattern is hypothesized to be driven by two mechanisms: 1) establishment is limited by the availability of safe sites, which are thought to be positively associated with tree islands, and 2) dieback of established individuals constrains tree stature. To examine the generality of these mechanisms, we paired a seedling transplant experiment with an observational study examining tree stature at a krummholz-island treeline in central Newfoundland. Despite observing changes in microclimatic conditions with distance from tree islands, there were no trends in seedling survival. Seedling survival was high, regardless of transplant position, suggesting that establishment at this treeline is not limited by the number of safe sites. Moreover, we observed no trends in tree height suggesting that dieback is not constraining tree stature. Our results suggest that the hypothesized mechanisms driving krummholz-island spatial patterns are not limiting a response to climate warming at this alpine treeline.
Alpha diversity patterns of arboreal bryophytes and lichens along a temperate to boreal elevation gradient at Mont Mégantic National Park, Québec
* Christina Rinas, Université de Sherbrooke, Canada
R. Troy McMullin, Canadian Museum of Nature
François Rousseu, Université de Sherbrooke
Mark Vellend, Université de Sherbrooke
Understanding the processes of community assembly along environmental gradients has important implications for predicting future ecological responses to environmental change. Here we report patterns of alpha diversity for arboreal macrolichens and bryophytes along an elevation gradient and lateral gradients (around a tree bole influenced by inclination or aspect) of sugar maple and balsam fir trees at Parc National du Mont Mégantic. For lichens on firs, alpha diversity increased as elevation increased. In contrast, for bryophytes on maples, alpha diversity was more responsive to the lateral gradient, with greater diversity on the upper surfaces of inclined tree boles. Finally, the alpha diversity of lichens on maples showed a weaker, negative relationship with inclination. Our results indicate that the important predictors of arboreal cryptogam diversity vary more among tree species (maple vs. fir) than focal taxa (lichens vs. bryophytes). Patterns are likely due to different effects of water, temperature, and competition among bryophytes and lichens.
Bryophyte Communities in Quercus garryana Ecosystems on South East Vancouver Island: Preliminary Mesohabitat Assessment
* Daniel Tucker, University of Alberta, Canada
Catherine La Farge, University of Alberta
Quercus garryana ecosystems are threatened Mediterranean-like sites that occur in a limited range on the west coast of North America. This ecosystem has higher plant diversity and rarity than any other in British Columbia, and the less than 10% remaining are relicts due to habitat loss, fragmentation, and degradation. The bryophyte component remains understudied, and identification of habitat associated communities could provide a more accurate picture of ecosystem health at remaining sites. We used floristic habitat sampling and multivariate analyses to determine bryophyte diversity and community composition among three prominent mesohabitats (meadows, outcrops, Quercus garryana epiphytes) in five intact sites. We found that total species richness was highest in meadows (67), high in outcrops (63), and lowest on Quercus garryana (40) and included 11 provincially rare species. Alpha diversity and mean transformed abundance classes were significantly lower in the Quercus garryana mesohabitat versus meadows and outcrops. Multi-response permutation procedure indicated the Quercus garryana epiphytic community as statistically unique, whereas there was no significant difference between meadow and outcrop mesohabitat communities. Several species were identified as indicators for each mesohabitat type. Observations were compiled with micrographic images as a special project using the citizen science application iNaturalist. This study of Quercus garryana ecosystems from southeastern Vancouver Island, B.C., provides a preliminary mesohabitat assessment for bryophytes in this rare and threatened heterogeneous ecosystem. These baseline results can help identify priority sites for restoration based on habitats associated with bryophyte species diversity.
Habitat fragmentation and its role on bryophyte diversity: a study in the boreal forest
* Enrique Hernández-Rodríguez, Université du Québec en Abitibi-Témiscamingue (UQAT), Canada
Juan C. Villareal, Herbier Louis-Marie, Université Laval, Québec
Nicole J. Fenton, Université du Québec en Abitibi-Témiscamingue (UQAT)
The habitat fragmentation (HF) process is one of the principal drivers of biodiversity loss all over the world. A consequence of HF is a change in the landscape configuration, with effects on biodiversity that could be different from the habitat loss. The boreal forest in Quebec has experienced fragmentation by anthropogenic and natural disturbances that may put at risk its stability and resilience. Bryophytes (liverworts and mosses) are one of the principal biological components of this forest occupying a wide variety of microhabitats. Due to their susceptibility to environmental changes, they are an ideal study group to evaluate HF. The objectives of this study are 1) to assess HF effect on bryophyte diversity (α and β) and their community composition, and 2) to know what the landscape configuration and composition features influence the diversity patterns and community assembly. Around 100 landscapes with a gradient of conditions (e.g., trees species composition, age, and size of forest stands) were analyzed. Preliminary results show a variation in the alpha and beta diversity of forest stands from the landscapes studied. This variation in the diversity of bryophytes could be explained by differences in the quantity of habitats, the quality of the stands, and their spatial arrangement in the landscapes. This study will improve HF knowledge considering an integral vision of the landscape configuration of the boreal forest. This research will provide information about how landscape configuration could help to keep the biodiversity and quality of the forest in a sustainable forest management context.
Heathland vegetation ecology relies on specific symbiotic fungi
* Jill Kowal, Royal Botanic Gardens, Kew, Great Britain
Jeffrey G. Duckett, The Natural History Museum, London
Katie J. Field, University of Sheffield
Grace Hoysted, University of Sheffield
Silvia Pressel, Royal Botanic Gardens, Kew
Laura M. Suz, Royal Botanic Gardens, Kew
Martin I. Bidartondo, Royal Botanic Gardens, Kew; Imperial College London
Background: Heathlands are protected habitats supporting numerous endangered plants and animals. Heathland soils are acidic, nutrient-poor, mainly sand and peat, and fluctuate between extreme dry and wet conditions. To access soil nutrients, vascular plant roots and liverwort rhizoids form mutualistic symbioses with fungi exchanging nutrients for photosynthates between the mycobionts and their hosts. As such, symbiotic fungal communities contribute to heathland plant survival, nutrient cycling and carbon sequestration. Objectives: To investigate diversity and function of heathland plants’ fungal symbionts to understand heathland belowground ecology and thus improve habitat restoration and conservation strategies for the delivery of ecosystem services. Methods: Through multidisciplinary approaches combining molecular identification, cytology, isotope tracing and cultivation experiments, we examined root and rhizoid fungal colonisation and identified the fungi of both common and rare heathland plants, including: the heathers Calluna vulgaris and Erica tetralix, the dominant grass Molinia caerulea, the rare lycophyte Lycopodiella inundata, and the liverwort Cephalozia bicuspidata, plus the encroaching trees, Pinus sylvestris and Betula spp. We also conducted isotope tracing experiments to assess mutualistic status between partners and tested the liverworts as carriers of fungal inoculum for heather establishment. Results: Heathland plants maintain specific mycorrhizal or mycorrhizal-like associations with different fungal clades despite the proximity of other symbiotic fungi in adjacent vegetation. Using liverworts as bio-fertilisers for Ericaceae sharing mycorrhizal fungi offers a practical source of fungal inoculum for restoring heathlands. Conclusion: Understanding the mutual preferences between heathland plants and their fungal symbionts is critical for protecting and managing this rare and endangered habitat.
Vegetation classification and ecology of barrens and heathlands in Nova Scotia
* Jeremy Lundholm, Saint Mary's University, Canada
Caitlin Porter, Atlantic Canada Conservation Data Centre
Sean Basquill, Nova Scotia Department of Lands and Forestry
Michael Buckland-Nicks, Environment and Climate Change Canada
Amy Heim, Saint Mary's University
Nova Scotia’s barrens are culturally iconic and ecologically important, with distinct vegetation and associated environmental drivers. Following Canadian vegetation classification standards, we describe a recently released plant community classification for these ecosystems. We sampled 331 releve plots from 173 barren sites across their geographical range in Nova Scotia. Plot data included: vascular plant, bryophyte and lichen species abundances, plant community structure, humus form and depth, mineral soil structure and chemistry, and 19 other environmental variables. We used multivariate ordination and clustering statistics to determine key environmental drivers and to classify Nova Scotia barrens vegetation. Our study inventoried 595 species of vascular plants, bryophytes and lichens. The classification describes 22 distinct community types, of which most are low shrublands with dominant species from the Ericaceae. Moisture regime, wind and salt spray exposure are among the most important factors explaining variations in the species composition, structure and distribution of plant communities on barrens in Nova Scotia. The factors that maintain open barrens vegetation in this largely forested region include climatic limits to soil development and tree growth, wildfire, and past land use. The classification allows estimation of a species pool for each community, and combined with aerial imagery, can help resolve the spatial context for barrens vegetation dynamics. Similar information can be used to help assess the vulnerability of barrens communities to anthropogenic impacts, including climate change. Sampling barrens stratified by classified communities also improves understanding of the relationships between plant traits and species persistence in these environments.
Moss diversity in plant communities associated with a penguin rookery on Deception Island, Maritime Antarctica
* Angélica Casanova-Katny, Laboratorio de Ecofisiología Vegetal y Cambio Climático y Núcleo de Estudios Ambientales (NEA), Facultad de Recursos Naturales, Universidad Católica d, Chile
Cristóbal Araneda , Laboratorio de Micología y Micorrizas, Departamento de Botánica, Facultad de Cs. Naturales y Ocean., Universidad de Concepción
Miguel Angel De Pablo, Unidad de Geología. Departamento de Geología, Geografía y Medio Ambiente. Facultad de Ciencias. Universidad de Alcalá
Marc Oliva, Departamento de Geografía, Facultad de Geografía e Historia, Universitat de Barcelona
Sebastian Doetterl, Soil Resources, Institute of Terrestrial Ecosystems, ETH Zurich, Zurich, Switzerland
Laura Farías, Depto. Oceanografía; Universidad de Concepción. Centro de Ciencia del clima y la resiliencia (CR)2 y Instituto Milenio de socio-ecología costera
Francisco Fernandoy, Laboratorio de análisis isotópico - LAI, Facultad de Ingeniería, Universidad Andrés Bello.
Josefa Binimelis, Laboratorio de Micología y Micorrizas, Departamento de Botánica, Facultad de Cs. Naturales y Ocean., Universidad de Concepción
Catalina Marin, Laboratorio de Micología y Micorrizas, Departamento de Botánica, Facultad de Cs. Naturales y Ocean., Universidad de Concepción
Beatriz Díez, Depto. Genética Molecular y Microbiología, Facultad de Ciencias Biológicas Investigadora Adjunta Center for Climate and Resilience Research (CR)2; Inv
In order to determine the influence of a penguin rookery on the diversity of vegetation on Deception Island, we studied the composition of bryophytes of a transect of approximately 2 km between Irízar Lake and the penguin rookery (Pygoscelis antarcticus) of La Descubierta point. A total of new 39 vegetation carpets formed mainly by bryophytes were detected, distributed in three main sectors, next to Irízar Lake, in Vapour Col and at La Descubierta point. The bryophytes correspond to 15 moss species and only 2 liverworts, with 11 moss families represented. Two mosses, Sanionia uncinata (31) and Politrychastrum alpinum (9), were found to dominate the moss carpets, being also the most frequent species. In addition, we found a new site on the island where the moss Bryum orbiculatifolium is present, which grows directly associated with the penguin rookery. In addition, we also observed that there are 5 species of mosses common to the three sectors, with other 5 species growing only in the penguin area that are significantly different than the other two sectors. Soil analysis show elevated contents of soil nitrogen in the penguin rookery compared to the surrounding area. Vascular plants were not detected in the entire study site. We argue that these sites are in states of early colonization where biota is marked by the presence of pioneer mosses that grow around penguin colonies, influenced likely by nutrient input through deposited guano as well as climate warming affecting the Antarctic Peninsula.