| 1. |
- Alatalo, J. M., et al.
(author)
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Changes in plant composition and diversity in an alpine heath and meadow after 18 years of experimental warming
- 2022
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In: Alpine Botany. - Basel : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 132, s. 181-193
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Journal article (peer-reviewed)abstract
- Global warming is expected to have large impacts on high alpine and Arctic ecosystems in the future. Here we report effects of 18 years of experimental warming on two contrasting high alpine plant communities in subarctic Sweden. Using open-top chambers, we analysed effects of long-term passive experimental warming on a heath and a meadow. We determined the impact on species composition, species diversity (at the level of rare, common and dominant species), and phylogenetic and functional diversity. Long-term warming drove differentiation in species composition in both communities; warmed plots, but not control plots, had distinctly different species composition in 2013 compared with 1995. Beta diversity increased in the meadow, while it decreased in the heath. Long-term warming had significant negative effects on the three orders of phylogenetic Hill diversity in the meadow. There was a similar tendency in the heath, but only phylogenetic diversity of dominant species was significantly affected. Long-term warming caused reductions in forbs in the heath, while evergreen shrubs increased. In the meadow, deciduous and evergreen shrubs showed increased abundance from 2001 to 2013 in warmed plots. Responses in species and phylogenetic diversity to experimental warming varied over both time (medium (7 years) vs long-term (18 years)) and space (between two neighbouring plant communities). The meadow community was more negatively affected in terms of species and phylogenetic diversity than the heath community. A potential driver for the changes in the meadow may be decreased soil moisture caused by long-term warming.
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| 2. |
- Alatalo, Juha M., et al.
(author)
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Climate change and climatic events: community-, functional- and species-level responses of bryophytes and lichens to constant, stepwise, and pulse experimental warming in an alpine tundra
- 2014
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In: Alpine Botany. - : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 124:2, s. 81-91
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Journal article (peer-reviewed)abstract
- We experimentally imposed three different kinds of warming scenarios over 3 years on an alpine meadow community to identify the differential effects of climate warming and extreme climatic events on the abundance and biomass of bryophytes and lichens. Treatments consisted of (a) a constant level of warming with open top chambers (an average temperature increase of 1.87 A degrees C), (b) a yearly stepwise increase of warming (average temperature increases of 1.0; 1.87 and 3.54 A degrees C, consecutively), and (c) a pulse warming, i.e., a single first year pulse event of warming (average temperature increase of 3.54 A degrees C only during the first year). To our knowledge, this is the first climate change study that attempts to distinguish between the effects of constant, stepwise and pulse warming on bryophyte and lichen communities. We hypothesised that pulse warming would have a significant short-term effect compared to the other warming treatments, and that stepwise warming would have a significant mid-term effect compared to the other warming treatments. Acrocarpous bryophytes as a group increased in abundance and biomass to the short-term effect of pulse warming. We found no significant effects of mid-term (third-year) stepwise warming. However, one pleurocarpous bryophyte species, Tomentypnum nitens, generally increased in abundance during the warm year 1997 but decreased in control plots and in response to the stepwise warming treatment. Three years of experimental warming (all treatments as a group) did have a significant impact at the community level, yet changes in abundance did not translate into significant changes in the dominance hierarchies at the functional level (for acrocarpous bryophytes, pleurocarpous bryophytes, Sphagnum or lichens), or in significant changes in other bryophyte or lichen species. The results suggest that bryophytes and lichens, both at the functional group and species level, to a large extent are resistant to the different climate change warming simulations that were applied.
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| 3. |
- Bienau, Miriam J., et al.
(author)
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Snow cover consistently affects growth and reproduction of Empetrum hermaphroditum across latitudinal and local climatic gradients
- 2014
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In: Alpine Botany. - : Springer. - 1664-2201 .- 1664-221X. ; 124:2, s. 115-129
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Journal article (peer-reviewed)abstract
- Arctic ecosystems face strong changes in snow conditions due to global warming. In contrast to habitat specialists, species occupying a wide range of microhabitats under different snow conditions may better cope with such changes. We studied how growth and reproduction of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitat types differing in winter snow depth and summer irradiation, and whether the observed patterns were consistent along a local climatic gradient (sub-continental vs. sub-oceanic climates) and along a latitudinal gradient (northern Sweden vs. central Norway). Habitat type explained most of the variation in growth and reproduction. Shoots from shallow snow cover and high summer irradiation habitats had higher numbers of flowers and fruits, lower ramet heights, shorter shoot segments, lower numbers of lateral shoots and total biomass but higher leaf density and higher relative leaf allocation than shoots from habitats with higher snow depth and lower summer irradiation. In addition, biomass, leaf allocation and leaf life expectancy were strongly affected by latitude, whereas local climate had strong effects on seed number and seed mass. Empetrum showed high phenotypic trait variation, with a consistent match between local habitat conditions and its growth and reproduction. Although study areas varied strongly with respect to latitude and local climatic conditions, response patterns of growth and reproduction to habitats with different environmental conditions were consistent. Large elasticity of traits suggests that Empetrum may have the potential to cope with changing snow conditions expected in the course of climate change.
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| 4. |
- Burli, S., et al.
(author)
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A common soil temperature threshold for the upper limit of alpine grasslands in European mountains
- 2021
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In: Alpine Botany. - : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 131, s. 41-52
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Journal article (peer-reviewed)abstract
- While climatic research about treeline has a long history, the climatic conditions corresponding to the upper limit of closed alpine grasslands remain poorly understood. Here, we propose a climatic definition for this limit, the 'grassline', in analogy to the treeline, which is based on the growing season length and the soil temperature. Eighty-seven mountain summits across ten European mountain ranges, covering three biomes (boreal, temperate, Mediterranean), were inventoried as part of the GLORIA project. Vascular plant cover was estimated visually in 326 plots of 1 x 1 m. Soil temperatures were measured in situ for 2-7 years, from which the length of the growing season and mean temperature were derived. The climatic conditions corresponding to 40% plant cover were defined as the thresholds for alpine grassland. Closed vegetation was present in locations with a mean growing season soil temperature warmer than 4.9 degrees C, or a minimal growing season length of 85 days, with the growing season defined as encompassing days with daily mean >= 1 degrees C. Hence, the upper limit of closed grasslands was associated with a mean soil temperature close to that previously observed at the treeline, and in accordance with physiological thresholds to growth in vascular plants. In contrast to trees, whose canopy temperature is coupled with air temperature, small-stature alpine plants benefit from the soil warmed by solar radiation and consequently, they can grow at higher elevations. Since substrate stability is necessary for grasslands to occur at their climatic limit, the grassline rarely appears as a distinct linear feature.
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| 5. |
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| 6. |
- Mondoni, Andrea, et al.
(author)
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Seed dormancy and longevity in subarctic and alpine populations of Silene suecica
- 2018
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In: Alpine Botany. - : Springer. - 1664-2201 .- 1664-221X. ; 128:1, s. 71-81
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Journal article (peer-reviewed)abstract
- Despite the strong environmental control of seed dormancy and longevity, their changes along latitudes are poorly understood. The aim of this study was to assess seed dormancy and longevity in different populations across the distribution of the arctic-alpine plant Silene suecica. Seeds of seven populations collected from alpine (Spain, Italy, Scotland) and subarctic (Sweden, Norway) populations were incubated at four temperature regimes and five cold stratification intervals for germination and dormancy testing. Seed longevity was studied by exposing seeds to controlled ageing (45 A degrees C, 60% RH) and regularly sampled for germination. Fresh seeds of S. suecica germinated at warm temperature (20/15 A degrees C) and more in subarctic (80-100%) compared to alpine (20-50%) populations showed a negative correlation with autumn temperature (i.e., post-dispersal period). Seed germination increased after cold stratification in all populations, with different percentages (30-100%). Similarly, there was a large variation of seed longevity (p(50) = 12-32 days), with seeds from the wettest locations showing faster deterioration rate. Subarctic populations of S. suecica were less dormant, showing a warmer suitable temperature range for germination, and a higher germinability than alpine populations. Germination and dormancy were driven by an interplay of geographical and climatic factors, with alpine and warm versus subarctic and cool autumn conditions, eliciting a decrease and an increase of emergence, respectively. Germination and dormancy patterns typically found in alpine habitats may not be found in the arctic.
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| 7. |
- Musauer Kessous, Igor, 1991, et al.
(author)
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Implementing spatial analyses to measure angiosperm biodiversity from the high-altitude grasslands of the Atlantic forest
- 2023
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In: Alpine Botany. - 1664-2201 .- 1664-221X. ; 133, s. 163-178
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Journal article (peer-reviewed)abstract
- Campos de altitude are high-altitude grasslands found in the mountain ranges of southeastern and southern Brazil, which are characterized by high species richness and endemism. Because of the difficulty in delimiting this vegetation type, measuring biodiversity patterns is challenging. Here, we compared the application of two methods using spatial data to estimate angiosperm diversity in campos de altitude: (1) filtering occurrence data by elevation, canopy height, location and keywords and; (2) the same as the first, however, adding a filter of “campos de altitude” in the vegetation type of the Flora e Funga do Brasil database. Also, we discuss conservation status, plant collections, endemism, vegetation data and similarity among 14 sites harboring campos de altitude. Our two resulting lists indicated between 1087 and 2398 angiosperm species and infraspecifictaxa in campos de altitude, mostly belonging to Asteraceae and Poaceae and endemic to Brazil. Extrapolations of species richness suggest a potential number of up to 4000 species. Of the taxa assessed for conservation status, 53–65% are threatened or near threatened. The flora of campos de altitude is more similar on closely located mountains rather than on mountains with similar geological characteristics and origin. We provide an editable list online destined to seek help from taxonomists to generate a more accurate species list, to support advances in knowledge on this unique tropical montane ecosystem.
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| 8. |
- Trunschke, Judith, et al.
(author)
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Plasticity of flower longevity in alpine plants is increased in populations from high elevation compared to low elevation populations
- 2017
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In: Alpine Botany. - : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 127:1, s. 41-51
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Journal article (peer-reviewed)abstract
- Flower longevity is an adaptive trait, optimized to balance reproductive success against the costs of flower maintenance. The trait is highly plastic in response to pollination success, and numerous studies report increased flower longevity in high elevation environments, where diversity, abundance, and activity of pollinators are low. However, few studies have experimentally investigated how flower longevity varies with pollination intensity within and among populations. We studied flower longevity of six alpine species under three pollination intensity treatments (hand-pollination, natural pollination, pollinator exclusion) at 1600 m vs. 2600 m a.s.l. at the Furka Pass, Central Swiss Alps. We hypothesized, (1) that flower longevity is generally increased in population at high elevation, and (2) that the increase in flower longevity when pollination fails is stronger in populations at high elevation compared to low elevation. Hand-pollination did not decrease flower longevity in any of the studied populations and rarely increased natural seed production suggesting no pollination limitation at both elevations. This was supported by similar pollinator visitation rates, pollinator efficiency, and pollination effectivity. Pollinator exclusion significantly increased flower longevity, but only in populations of three species at low elevation, whereby in all populations of the six species at high elevation, indicating a higher plasticity of flowers in populations at high elevation compared to populations from lower elevation. We suggest that the higher plasticity of flower longevity in alpine populations is of advantage in their unpredictable pollination environment: Increased flower longevity compensates for low pollination in unsuitable periods guaranteeing a minimum reproduction, while the capacity to senescence rapidly after successful pollination saves redundant floral costs in suitable periods.
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| 9. |
- Wehn, Solvi, et al.
(author)
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Alpine vegetation along multiple environmental gradients and possible consequences of climate change
- 2014
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In: Alpine Botany. - : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 124:2, s. 155-164
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Journal article (peer-reviewed)abstract
- Alpine plant communities are being subject to climate change, resulting in the need for plants to adapt to new conditions. In this study, we investigated changes in vascular plant diversity along a coast-inland gradient in central Norway. At four different mountains, species were registered in 100 m(2) plots, laid out from the forest line to the summit. In addition, plots were grouped into snow cover duration (short, medium, and long) and aspect (North, South, East, and West). We documented richness and spatial turnover of species and functional groups (trees and tall shrubs, dwarf shrubs, herbs, graminoids, and seedless plants) along the different gradients using glm and RDA. Thereafter, we included variables from climate scenario models in the derived glm's to estimate how species richness and the distribution of these groups could be impacted by future climate change. Our results show that there are significant changes in species and functional groups along the regional gradient. Further, also local variation due to altitude and snow cover duration influenced species distribution and composition. Predictions of future vegetation showed an increase in species richness compared to present, with most changes occurring in areas of long and medium snow cover duration. We predicted the main changes to occur at lower altitudes. Here, dwarf shrubs and graminoids were expected to increase the most in number of species, whereas species of trees and tall shrubs were expected to increase the most in proportion.
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| 10. |
- Bi, Cheng, et al.
(author)
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Experimental grazer exclusion increases pollination reliability and influences pollinator-mediated plant-plant interactions in tibetan alpine meadows
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In: Alpine Botany. - 1664-2201.
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Journal article (peer-reviewed)abstract
- 1. Co-flowering plant species often interact through shared pollinators, with effects ranging from positive (facilitation) to negative (competition). It remains unclear how this variation relates to variation in floral density, floral trait distinctiveness, and local environmental conditions. We studied the effect of grazer exclusion, a proposed local management strategy, on pollinator-mediated plant-plant interactions in heavily degraded alpine meadows of the Qinghai-Tibet Plateau. 2. We studied the effect of experimental grazer exclusion on plant reproduction and pollinator-mediated reproductive interactions quantified through pollen transfer networks. We also explored potential mechanisms of pollinator-mediated interspecific pollen transfer and its effect on plant reproductive fitness, including local floral abundance and floral trait distinctiveness among co-flowering species. 3. Grazer exclusion led to greater pollen deposition onto stigmas. The overall quantitative effects of pollinator-mediated interspecific interactions on the receptor species were mainly positive (facilitative) or neutral (with no detectable effect). The frequency of positive relative to negative quantitative effects for pairwise donor-receptor pairs tended to increase after grazer exclusion. Plants with floral traits similar to those of local ‘hub species’ appeared to benefit from pollinator-mediated interactions. 4. Our results suggest an overall positive effect of excluding grazers during the plant growing season on plant reproduction. Facilitative species interactions predominate in harsh environments such as the alpine, and the benefits of pollinator-mediated interactions among plants seemed to exceed the cost of conspecific pollen loss associated with pollinator sharing. This suggest that species invasions into alpine plant communities, an expected consequence of climate change, may not necessarily have negative effects on the reproduction of resident plant species.
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