1,649 research outputs found

    Arctic Plants, Ecosystems and Strategies

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    Reviews and develops a perspective of what is known about the structure, function, and adaptive strategy of arctic tundra ecosystems, with emphasis on plants, the primary biological producers of an ecosystem. The short-term change in plant arrays following disturbance of the natural assemblage, due to ecological succession, is poorly understood in the tundra. Distribution and migrations of tundra flora give insight into Pleistocene events and evolutionary strategies, one clue to which is frequently of polyploidy. Implicit in understanding tundra dynamics or vegetation associations is study of topographic microrelief, soils and thaw depths, as well as description of the flora. Progress is noted in knowledge of the structure and function of vegetation in arctic ecosystems: the morphological adaptation, carbohydrate cycle, chlorophyll content, physiologic processes in adaption to severe environments such as photosynthesis, respiration, light saturation, photoperiodic requirements and temperature tolerance

    Ion-exchange properties and swelling capacity of leaf cell wall of Arctic plants

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    Ion-exchange (number of functional group) properties and swelling capacity of leaf cell walls of plant species Betula nana, Salix polaris, Dryas octopetala and Cassiope tetragona from Western Spitsbergen Island were investigated. It was found out that cell wall of Arctic plants is cation exchanger which has similar functional groups (amine groups, carboxyl groups and phenolic OH-groups) with cell wall of boreal plants. In all investigated species, the highest percentage in the structure of the cell wall was recorded for the carboxyl groups of hydroxycinnamic acids and phenolic OH-groups, which are part of phenolic compounds. In comparison with species from other climatic zones leaf cell wall of arctic plants has in 2–3 times higher amount of ion exchange groups of all types as well as the higher values of swelling coefficients. It was proposed that the high values of the ion-exchange capacity and swelling coefficient of the cell wall of all studied species contribute to greater water flow system by the apoplast and enhance the metabolic processes in the cell wall of plants at high latitudes

    Plant phenology and seasonal nitrogen availability in Arctic snowbed communities

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    Thesis (M.S.) University of Alaska Fairbanks, 2006This study was part of the International Tundra Experiment (ITEX) and examined the effects of increased winter snow depth and decreased growing season length on the phenology of four arctic plant species (Betula nana, Salix pulchra, Eriophorum vaginatum, and Vaccinium vitis-idaea) and seasonal nitrogen availability in arctic snowbed communities. Increased snow depth had a large effect on the temporal pattern of first date snow-free in spring, bud break, and flowering, but did not affect the rate of plant development. By contrast, snow depth had a large qualitative effect on N mineralization in deep snow zones, causing a shift in the timing and amount of N mineralized compared to ambient snow zones. Nitrogen mineralization in deep snow zones occurred mainly overwinter, whereas N mineralization in ambient snow zones occurred mainly in spring. Concentrations of soil dissolved organic nitrogen (DON) were approximately 5 times greater than concentrations of inorganic nitrogen (DIN) and did not vary significantly over the season. Projected increases in the depth and duration of snow cover in arctic plant communities will likely have minor effects on plant phenology, but potentially large effects on patterns of N cycling

    Onset of autumn senescence in High Arctic plants shows similar patterns in natural and experimental snow depth gradients

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    Predicted changes in snow cover and temperature raise uncertainties about how the beginning and the end of the growing season will shift for Arctic plants. Snowmelt timing and temperature are known to affect the timing of bud burst, but their effects on autumn senescence are less clear. To address this, researchers have examined senescence under natural and experimental environmental gradients. However, these approaches address different aspects of plant responses and the extent to which they can be compared is poorly understood. In this study, we show that the effect of snowmelt timing on the timing of autumn senescence in High Arctic plants is the same between a natural and an experimental gradient in three out of four studied species. While the two approaches mostly produce comparable results, they give in combination greater insight into the phenological responses to predicted climate changes. We also showed that a short warming treatment in autumn delayed senescence by 3.5 days in Dryas octopetala L., which is a 10% extension of the growing season end for this species. Warming treatments have commonly been applied to the whole growing season, but here we show that even isolated autumn warming can be sufficient to affect plant senescence.Peer reviewe

    Biological Features and Processes of the Circumpolar World

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    This site considers the flora and fauna of the northern regions, which are unique because their environments are extreme and finely balanced. It looks at the major factors involved in the biological evolution of circumpolar ecosystems, such as cold temperatures and low precipitation, lack of solar energy during much of the year, a rich marine environment along an extended coastline, constant and ongoing changes in the northern environment, and the recent emergence of the region from the last ice age. The site suggests that in order to understand the living Arctic and Subarctic, we need to consider the fact that all living things are part of a system, depend on solar energy, and can thrive only in the presence of liquid water, and that the Arctic and Subarctic environments are comparatively new. Educational levels: High school, Undergraduate lower division

    Microclimate relationships of intraspecific trait variation in sub-Arctic plants

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    Within-species trait variation is a substantial part of plant functional diversity. However, this intraspecific trait variation (ITV) is rarely investigated in relation to a key characteristic of the Arctic and alpine ecosystems: fine-scale microclimatic heterogeneity. Here, we quantified the influence of microclimate (soil moisture, snow and local temperatures) on plant functional traits, specifically on ITV. We focused on six widespread northern latitude vascular plant species, and measured four traits: plant height, leaf area, leaf dry matter content (LDMC) and specific leaf area (SLA). We related ITV to field and remotely sensed microclimate data from 150 study plots within six study grids. The grids were located within a 76-m altitudinal belt in three environments: the tundra, tundra-forest ecotone and mountain birch forest in Kilpisjarvi, northwestern Finland. We compared the range of trait values between this local trait dataset (n = 5493) and global trait databases (n = 10 383). We found that information in the local dataset covers a relatively large portion of the trait ranges in global databases. The proportion varies among traits and species; the largest portion was 74% for variation in leaf area of Vaccinium uliginosum, and the lowest was 19% for LDMC of Betula nana. We found that ITV in height was mostly related to local temperatures, whereas SLA and LDMC were more related to soil moisture and snow conditions. However, species showed contrasting relationships with the microclimate drivers. We conclude that microclimate profoundly shapes ITV in northern latitude plants and that even a very compact geographic area can contain a large amount of ITV. The influence of the microclimatic conditions varies among functional traits and species, which indicates that plastic response or adaptive potential of the species to climate change may also vary across species, but that necessary variation may often be present within local plant populations.Peer reviewe

    Detection and Attribution of Long-Term Vegetation Changes in Northern Alaska

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    Climate change is impacting terrestrial ecosystems world-wide and the Arctic is particularly vulnerable as it is warming faster and with greater magnitude than other regions. Understanding the responses of arctic plants species to abiotic factors is crucial to predicting the impact climate change will have on the Arctic because plants play critical roles in carbon exchange, energy balance, and trophic interactions. Using data from long-term research sites in Barrow and Atqasuk, Alaska, the purpose of this thesis was to investigate how arctic plants respond to 17-19 years of experimental warming, establish the relative strengths of various abiotic factors in predicting the response of plant traits over time, and examine evidence that climate change will significantly affect plants as the region continues to warm. Plants typically responded to longterm experimental warming with increased inflorescence heights, increased leaf lengths, and accelerated reproductive phenologies, while reproductive efforts responded less consistently. Further analysis revealed that responses to experimental warming tended to dampen during warmer years. Though mostly non-significant, several abiotic factors showed trends over time consistent with regional warming patterns observed in the Barrow area including increasing air and soil temperatures, earlier snowmelts, delayed freeze-ups, drier soils, and increasing thaw depths. Several plant species showed significant trends toward increasing inflorescence heights and reproductive efforts over the same time period. Of the abiotic factors examined, air and soil temperatures yielded the greatest predictive capabilities as these factors were consistently correlated with the greatest number of traits across sites. Unlike other traits, the reproductive efforts of many species were best predicted using temperatures during the year prior to flower burst. When we compared experimental warming responses with trends in abiotic factors and traits over time we found strong evidence that climate change will likely cause significant shifts 5 in the growth and reproductive efforts of at least seven plant species at these sites. This study illustrates the value of long-term monitoring coupled with experimentation and lays the groundwork for future studies examining the ecosystem consequences of climate change on the Barrow region
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