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Alpine Vegetation (alpine + vegetation)
Selected AbstractsComparisons of breeding systems between two sympatric species, Nastanthus spathulatus (Calyceraceae) and Rhodophiala rhodolirion (Amaryllidaceae), in the high Andes of central ChilePLANT SPECIES BIOLOGY, Issue 1 2009PHILIP G. LADD Abstract Alpine vegetation occurs over a wide range of ecological conditions. Thus, the breeding systems of alpine plants are likely to be diverse and vary from one geographical area to another. The reproductive characteristics of Nastanthus spathulatus (Calyceraceae) and Rhodophiala rhodolirion (Amaryllidaceae), species with contrasting floral morphology, were studied in the high Andes of Chile, which has a Mediterranean-type climate. Natural and supplemental open pollination, and cross pollination and self-pollination trials were carried out in the field. Flower visitors were quantified by field and video observations. Both species had high outcrossing properties, and Nastanthus was strongly self-incompatible. Rhodophiala could form some seed by self-pollination, but fruit and seed sets were much lower after self-pollination compared with outcrossing. The phenology and flower/inflorescence forms of these species supported the view that alpine flowers are comparatively long lived and that the floral display contributes to a large proportion of the plant biomass. Rhodophiala was well attended by a native bee species (Megachile sauleyi) that was appropriately sized for efficient pollination. Although no flower visitors were observed on Nastanthus and wind pollination was discarded experimentally, a high proportion of the flowers produced seeds under natural pollination. Therefore, the seed set was not severely pollen limited in these species. Including previously published information, breeding systems are now known for 12 species on this Mediterranean alpine site and current knowledge suggests an emphasis on outcrossing breeding systems. [source] A regional impact assessment of climate and land-use change on alpine vegetationJOURNAL OF BIOGEOGRAPHY, Issue 3 2003Thomas Dirnböck Abstract Aim, Assessing potential response of alpine plant species distribution to different future climatic and land-use scenarios. Location, Four mountain ranges totalling 150 km2 in the north-eastern Calcareous Alps of Austria. Methods, Ordinal regression models of eighty-five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land-use impacts on vegetation patterns in combination with climatic changes. Results, A regionalized GCM scenario for 2050 (+ 0.65 °C, ,30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 °C, ,30 mm August precipitation; + 2 °C, ,60 mm August precipitation) however, will bring about a severe contraction of the alpine, non-forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions, The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 °C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non-forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved. [source] Impacts of increased nitrogen supply on Norwegian lichen-rich alpine communities: a 10-year experimentJOURNAL OF ECOLOGY, Issue 3 2005ELI FREMSTAD Summary 1Species cover was tested during a 10-year fertilization experiment in the low-alpine Cetrarietum nivalis community and the middle-alpine Phyllodoco-Juncetum trifidi community in the Dovre mountains of south-central Norway. Nitrogen was added at 7, 35 and 70 kg N ha,1 year,1, with the highest dose corresponding to approximately 3.5 times the annual deposition in south-west Norway. 2Both communities are dominated by lichens (Cladonia spp. and Cetraria spp., respectively), have a patchy structure and are ,conservative' as regards species content. 3Lichens, which showed a decrease in cover and size, and after some years developed discoloured thalli, are the best organisms for monitoring changes in alpine vegetation that is exposed to increased nitrogen deposition. The most sensitive species in Cetrarietum nivalis appeared to be Alectoria nigricans and Cetraria ericetorum, but more abundant species (Cladonia mitis, C. stellaris and Cetraria nivalis) are likely to be more reliable indicators. Cetraria delisei seems to be a reliable indicator species for monitoring in Phyllodoco-Juncetum trifidi. 4Fertilization had no significant effect on the vascular plants (dwarf shrubs and a few graminoids) in either community, except for Festuca ovina, the cover of which increased slightly. 5Nitrogen pollution may affect oligotrophic, alpine communities differently, depending on their species composition and horizontal structure (patchiness). 6It is suggested that other factors, such as climate, soil properties and community structure, may be more important than long-range nitrogen pollution for determining species composition and species cover in many of the oligotrophic, alpine communities in southern Norway. However, in lichen-rich communities, critical loads have already been exceeded in the most polluted areas of south-west Norway. [source] Alpine flora dynamics , a critical review of responses to climate change in the Swedish Scandes since the early 1950sNORDIC JOURNAL OF BOTANY, Issue 4 2010Leif Kullman Reports about changes of alpine plant species richness over the past 60 years in the Swedish Scandes are reviewed, synthesized and updated with data from recent reinventories. Methodologically, this endeavour is based on resurveys of the floristic composition on the uppermost 20 m of four high-mountain summits. The key finding is that the species pool has increased by 60,170% since the 1950s and later. Some of the invading species are new to the alpine tundra, with more silvine and thermophilic properties than the extant alpine flora. Not a single species of the original flora has disappeared from any of the summits. This circumstance is discussed in perspective of widespread expectations of pending temperature-driven extinction of alpine species in an alleged future warmer climate. These progressive changes coincided with distinct warming (summer and winter) since the late 1980s. During a short cooler period (1974,1994), the species numbers decreased and the upper elevational limits of some ground cover species descended. Thus, discernible responses, concurrent with both warming and cooling intervals, sustain a strong causal link between climate variability and alpine plant species richness. Methodologically, plot-less revisitation studies of the present kind are beset with substantial uncertainties, which may overstate floristic changes over time. However, it is argued here that carefully executed and critically interpreted, no other method can equally effectively sense the earliest phases of plant invasions into alpine vegetation. [source] Long-term geobotanical observations of climate change impacts in the Scandes of West-Central SwedenNORDIC JOURNAL OF BOTANY, Issue 4 2004Leif Kullman In the context of projected future human-caused climate warming, the present study reports and analyses the performance of subalpine/alpine plants, vegetation and phytogeographical patterns during the past century of about 1 °C temperature rise. Historical baseline data of altitudinal limits of woody and non-woody plants in the southern Scandes of Sweden are compared with recent assessments of these limits at the same locations. The methodological approach also includes repeat photography, individual age determinations and analyses of permanent plots. At all levels, from trees to tiny herbs, and from high to low altitudes, the results converge to indicate a causal association between temperature rise and biotic evolution. The importance of snow cover phenology is particularly evident. Treeline advance since the early-20th century varies between 75 and 130 m, depending on species and site. Tendencies and potentials for further upshift in a near future are evident from the appearance of young saplings of all tree species, growing 400,700 m atop of the treeline. Subalpine/alpine plant species have shifted upslope by average 200 m. In addition, present-day repetitions of floristic inventories on two alpine mountain summits reveal increases of plant species richness by 58 and 67%, respectively, since the early-1950s. Obviously, many plants adjust their altitudinal ranges to new climatic regimes much faster than generally assumed. Nevertheless, plants have migrated upslope with widely different rates. This produces non-analogous alpine plant communities, i.e. peculiar mixtures of alpine and silvine species. The alpine region is shrinking (higher treeline), and the character of the remaining alpine vegetation landscape is changing. For example, extensive alpine grasslands are replacing snow bed plant communities. [source] | ||||||||||