Environmental conditions on coastal dunes greatly limit plant growth. Substrate instability, low nutrient and water availability, high winds and salinity are some of the factors that contribute to the low productivity of these... more
Environmental conditions on coastal dunes greatly limit plant growth. Substrate instability, low nutrient and water availability, high winds and salinity are some of the factors that contribute to the low productivity of these environ-ments (Pavlik, 1983; Gray, 1985; Lee & Ignaciuk, 1985; Maun, 1994). Only a few species are well adapted to such conditions and can grow successfully on these sites; American beachgrass, Ammophila breviligulata Fern., is one of these species. This pioneer grass is generally found on the eastern coast of North America and along the sandy and gravely shores of the St. Lawrence River and the Great Lakes (Fernald, 1950). It grows clonally through an exten-sive system of rhizomes, and sexual reproduction does not appear to be significant for the maintenance and growth of its populations (Maun, 1985). A. breviligulata plays an important role in dune fixation (Grandtner, 1977) through its deep rhizome system and its ability to form adventitious roots. These tw...
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Coastal sand dunes are extremely dynamic ecosystems, characterized by stark ecological succession gradients. Dune stabilization is mainly attributed to plant growth, but the establishment and survival of dune-inhabiting vegetation is... more
Coastal sand dunes are extremely dynamic ecosystems, characterized by stark ecological succession gradients. Dune stabilization is mainly attributed to plant growth, but the establishment and survival of dune-inhabiting vegetation is closely linked to soil microorganisms and to the ecological functions they fulfill. Fungi are particularly important in this context, as some interact intimately with plant roots, while others are critical to soil structure and nutrient availability. Our study aimed to describe wholly fungal diversity and community composition in a secluded coastal dune ecosystem at eight different stages of succession. We comprehensively sampled a relic foredune plain, which is part of an archipelago in the Gulf of Saint Lawrence (Québec, Canada), by collecting soils from 80 sites and measuring soil characteristics. Soil fungal communities were characterized by pyrosequencing, followed by taxonomic classification and assignment of putative roles. Even though we did not observe clear patterns in diversity, we were able to detect distinct taxonomic and community composition signatures across succession stages, which seemed to translate into variations in fungal life strategies. Our results show that a taxonomically and functionally diverse fungal community exists at each dune succession stage, even in the barren foredunes.
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Microbiology and Ecology
Cladina stellaris is a dominant lichen species of old-growth lichen-spruce woodlands in subarctic Québec, where the continuous lichen carpet persists for several decades in the absence of disturbance. The lichen carpet is, however,... more
Cladina stellaris is a dominant lichen species of old-growth lichen-spruce woodlands in subarctic Québec, where the continuous lichen carpet persists for several decades in the absence of disturbance. The lichen carpet is, however, vulnerable to caribou (Rangifer tarandus) disturbance under dry site conditions. Through grazing and trampling, large herds of migratory caribou reduce C. stellaris abundance and modify ground vegetation composition. Here, we have evaluated the age and growth performance of C. stellaris in relation to the recent activity of the George River Caribou Herd (GRCH). We measured the age, length, and growth rate of C. stellaris podetia in and near caribou trails in 15 lichen-spruce woodlands across the summer habitat. The age of lichens, used to evaluate the initial period of lichen recruitment following the decline of the GRCH, indicated that lichen recovery began in the early 1990s in heavily disturbed sites, whereas comparisons between the age structure of bo...
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ABSTRACT Over the last few decades, shrub species have expanded rapidly in open tundra environments due to climate change. Previous experimental studies in this environment have shown that nutrient addition and, to a lesser extent,... more
ABSTRACT Over the last few decades, shrub species have expanded rapidly in open tundra environments due to climate change. Previous experimental studies in this environment have shown that nutrient addition and, to a lesser extent, warming, had positive effects on shrub growth. However, the response of shrub species in open forested ecosystems such as lichen woodland is still largely unknown. The main objective of this study was to evaluate the performance of Betula glandulosa (Michx., dwarf birch) seedlings subjected to direct (warmer temperature, increased precipitation) and indirect (increased nutrient availability) effects of climate change in a lichen woodland (25 % tree cover). The study took place 10 km south of the subarctic treeline in western Québec (Canada). At the end of the second growth season, seedling leaf, woody stem and root biomass along with leaf area had increased significantly in response to nutrient addition. Moreover, seedlings exposed to nutrient addition had greater nitrogen, phosphorus and potassium concentrations in their leaves. Warming treatment also had a significant but weaker impact on leaf and woody stem biomass, while increase in precipitation had only a slight impact on seedling root biomass. Our results indicate that B. glandulosa response to simulated changes in the abiotic environment is similar to that observed in open tundra, suggesting that this species could also become more widespread in the forested ecosystems of the forest–tundra ecotone.
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... Acknowledgments. We thank Robyn Wethered and Harriet Eeley for their assistance in the field and in the lab, and Johan Kotze for commenting on early drafts. ... Lovejoy, TE, JM Rankin, RO Bierregaard Jr., KS Brown, LH Emmons, and ME... more
... Acknowledgments. We thank Robyn Wethered and Harriet Eeley for their assistance in the field and in the lab, and Johan Kotze for commenting on early drafts. ... Lovejoy, TE, JM Rankin, RO Bierregaard Jr., KS Brown, LH Emmons, and ME van der Voort. 1984. ...
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... and harvest strategies that are based on the ecology of the pole-size class need to be developed (Lawes and Obiri, 2003 ... 1). Scarp forest physiognomy is characterized by a poorly developedherb layer, a well-developed seedling and... more
... and harvest strategies that are based on the ecology of the pole-size class need to be developed (Lawes and Obiri, 2003 ... 1). Scarp forest physiognomy is characterized by a poorly developedherb layer, a well-developed seedling and sapling stratum, an open understorey and a ...
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... patches but on average is approximately 10% of the available stems ([Burgess et al., 2000], [Luoga et al., 2002] and [Obiri et al ... 1). Scarp forest physiognomy is characterized by a poorly developedherb layer, a well-developed... more
... patches but on average is approximately 10% of the available stems ([Burgess et al., 2000], [Luoga et al., 2002] and [Obiri et al ... 1). Scarp forest physiognomy is characterized by a poorly developedherb layer, a well-developed seedling and sapling stratum, an open understorey ...
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... A greenhouse experiment was conducted at the Kuujjuar-apik–Whapmagoostui Research Station of Centre d'études nordi-ques to ... japonicus, and Trisetum spicatum in response to mineral and organic fertilizer (white symbols: no... more
... A greenhouse experiment was conducted at the Kuujjuar-apik–Whapmagoostui Research Station of Centre d'études nordi-ques to ... japonicus, and Trisetum spicatum in response to mineral and organic fertilizer (white symbols: no organic fertilization; black symbols: with ...
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In order to ensure the sustainable development of the North, increased anthropogenic pressure on subarctic environments must be accompanied by appropriate restoration techniques. Locally adapted restoration guidelines need to rely on... more
In order to ensure the sustainable development of the North, increased anthropogenic pressure on subarctic environments must be accompanied by appropriate restoration techniques. Locally adapted restoration guidelines need to rely on sound ecological knowledge of the species used in restoration trials. We evaluate the tolerance (emergence and biomass production) of two coastal species (Leymus mollis and Trisetum spicatum) to sand burial, trampling, and drought, all major constraints to plant colonization in the ...