High Alpine Areas Research Articles

Geomorphological disturbance affects ecological driving forces and plant turnover along an altitudinal stress gradient on alpine slopes

The altitudinal gradient is considered as a stress gradient for plant species because the development and fitness of plant communities tend to decrease as a result of the extreme environmental conditions present at high elevations. Abiotic factors are predicted to be the primary filter for species assemblage in high alpine areas, influencing biotic interactions through both competition for resources and positive interactions among species. We hypothesised that the relative importance of the ecological driving forces that affect the biotic interactions within plant communities changes along an elevation gradient on alpine debris slopes. We used multiple gradient analyses of 180 vegetation plots along an altitudinal range from ~1,600 to 2,600 m and single 100 m-bands in the Adamello-Presanella Group (Central Alps) to investigate our hypothesis; we measured multiple environmental variables related to different ecological driving forces. Our results illustrate that resource limitations at higher elevations affect not only the shift from competition to facilitation among species. A geomorphological disturbance regime along alpine slopes favours the resilience of the high-altitude species within topographic/geomorphological traps. An understanding of the ecological driving forces and positive interactions as a function of altitude may clarify the mechanisms underlying plant responses to present and future environmental changes.

Pollutants Capture the High Ground in the Himalayas

In high alpine areas once thought pristine, dust and soot appear to be accelerating glacier melting and may alter monsoon patterns.

Weathering rinds: Unlikely host clasts for evidence of an impact-induced event

Interhemispheric evidence of a cosmic impact 12.9ka is known now from North to South America, Europe and Eurasia, all data supporting a cosmic event derived from cores and from geological sections. Most databases supporting the impact hypothesis at the Younger Dryas Boundary (YDB) rely on high-temperature microspherules, melted minerals, cracked clasts, presence of nanodiamond, high-temperature scoria, high Fe/Ni ratios, pdf's, shock melted quartz, high 10Be/9Be ratios and occasional presence of platinum metals. Controversy over the impact, the so-called Black Mat enigma, and its relation to the Younger Dryas readvance at the end of the last ice age, is fueled by arguments over whether a single extraterrestrial impact might sustain a 1kyr-long downturn in insolation engendering a substantial increase in worldwide ice volume. New evidence in the form of impact microfeatures – extreme breccia, high crack propagation, thick carbon encrustations and partial to full shock-melted/contorted grains – in weathering rinds from the Western Alps, France, as documented here, adds to the growing body of evidence that the event was truly widespread, if not worldwide in effect. Whereas evidence of cosmic impacts may be erased by glacial and fluvial erosion in high alpine areas, such events as demonstrated herein are recorded as punctuated time-stratigraphic events in microcosm, preserved in weathered clasts.

Genus Berberis and Berberine HPLC: An Overview

The Indian Himalayan Region (IHR) is well known for richness and diversity of valuable but highly sensitive species of medicinal and aromatic plants. Among medicinal plants of the region, genus Berberis has gained an important place in different systems of medicine. This genus represents richness of species across IHR with wide ranging distribution from low lying sub-tropical to High alpine areas. The roots stem bark and fruits of various Berberis species in the region are well recognized for their alkaloid contents. Specifically the roots and stem bark of these species contain variety of isoqunoline alkaloids with berberine as a chief alkaloid. Berberine and its allied alkaloids are known to inhibit growth of microorganisms including fungi, protozoa and bacteria, and possess anti-tumor activity as well. In recent years, the global demand for these alkaloids and their derivatives has grown substantially. Its medicinal uses are reported Indian pharmaceutical codex and in different traditional medicines. Consequently pressure on wild populations has increased manifold, and a number of Berberis species have attained threatened status. All these features make the genus an important candidate for detailed investigation. Considering the above facts and realizing overall importance of the species. This articles briefly review, the pharmacologically, active isolated alkaloids and high performance liquid chromatography method of berberine alkaloid. This is an attempt to compile and documented information about above aspect need for further research and development.

Climate-driven changes in pollinator assemblages during the last 60 years in an Arctic mountain region in Northern Scandinavia

Climate change is occurring more rapidly in the Arctic than elsewhere, and is predicted to have a large impact on biodiversity, since entire cold-adapted ecosystems are likely to disappear. Here, we highlight changes in the insect species richness and community composition of wild bees, butterflies and moths over 60 years in an area situated above the tree limit (Padjelanta National Park) in northern Sweden. Although there were changes in habitat availability, indicated by a significant decrease in the area of a glacier (from 22 km2 in 1898 to 7.5 km2 in 2009), and an increase in the area of birch forest in the National Park, we nevertheless found relatively moderate changes in the insect communities. Indeed, the observed number of species increased from 52 in 1944 to 64 in 2008. Remarkably, the mean number of butterflies and moths per site, but not wild bee species, increased significantly. Among the species that were recorded in both periods, the average altitude of 17 species had shifted downhill, 12 shifted uphill, and the altitude of the remaining 17 had not changed. While alterations in community composition were greater at the highest altitudes, changes in the insect community were smaller than expected, indeed much smaller than those reported from agricultural landscapes in North-West Europe. Interestingly, our results suggest that lower alpine altitudes (600–800 m a.s.l.) have become colonized by southern species, but also that high alpine areas (above 1,000 m a.s.l.) have recently become colonized by high alpine species previously absent from these sites, likely as a result of increasing habitat availability. We conclude that wild bee, butterfly, and moth communities in Arctic areas in northern Sweden are in flux, as a result of climate change and suggest that increased attention must be given to conservation planning in cold areas. In addition, we propose that monitoring programs should be established, because more pronounced climate-driven changes can be expected in the future.

A re-appraisal of nunatak survival in arctic-alpine phylogeography

A long standing and at times fervid debate in biogeography revolves around the question whether arctic and high alpine organisms survived Pleistocene ice ages on small island-like areas protruding above the ice-sheet, socalled nunataks, or whether they did so in peripheral nonglaciated refugial areas. A common picture emerging from a plethora of molecular phylogeographic studies in the last decade is that both in the Arctic and in temperate mountain ranges such as the European Alps nunatak survival needs to be only rarely invoked to explain observed genetic patterns (for a rare example see Stehlik et al. 2002). As two studies in this issue show, depreciation of the nunatak hypothesis is, however, not warranted. In this issue of Molecular Ecology Westergaard et al. (2011) investigate genetic patterns of two arctic-alpine plant species distributed on both sides of the Atlantic exclusively in areas that were mostly covered by ice-sheets during Pleistocene glacial advances. In both species, amplified fragment length polymorphism (AFLP) data identified divergent and partly genetically diverse groups east and west of the Atlantic. This suggests, for the first time in Arctic plants, in situ survival on nunataks. In an entirely different geographic setting and on a different geographic scale, Lohse et al. (2011, this issue) study the colonization of high alpine areas in the Orobian Alps, situated within and adjacent to a prominent peripheral refugial area (massif de refuge) in the Southern Alps of northern Italy, by dispersal-limited carabid ground beetles. Using explicit hypothesis testing and inference of ancestral locations in a Bayesian framework, stepwise colonization from two separate southern refugia is found to shape the genetic pattern of these beetles, but at the northern edge, populations survived at least parts of the last glaciation in situ on nunataks.

GENETIC DIFFERENTIATION AND SHELL MORPHOLOGY OF TROCHULUS OREINOS (WAGNER, 1915) AND T. HISPIDUS (LINNAEUS, 1758) (PULMONATA: HYGROMIIDAE) IN THE NORTHEASTERN ALPS.

Trochulus oreinos oreinos and T. oreinos scheerpeltzi are two land snail taxa endemic to the Northeastern Austrian Alps, which have been regarded as subspecies of the highly variable, widespread land snail T. hispidus. We analysed these three taxa morphologically and genetically to evaluate whether a delimitation between them is possible and, if so, to resolve their phylogenetic relationships. Shell morphological results revealed high similarity between the two T. oreinos taxa, and that they are clearly separated from T. hispidus. Additionally, the T. oreinos subspecies concur with respect to their habitat preferences, as they are both restricted to rocky high alpine areas, whereas the local form of T. hispidus is distributed over a wider altitudinal range in moist areas and scrubby perennial herb vegetation near water bodies. While the morphological and ecological results allow clear differentiation between T. hispidus and T. oreinos only, analyses of the mitochondrial cytochrome c oxidase subunit I and 16S rRNA genes revealed high sequence divergences between all three taxa, which indicates that they represent old lineages. The two T. oreinos taxa appear as distantly related sister groups, well separated from T. hispidus. Whether T. o. oreinos and T. o. scheerpeltzi should be considered as species cannot be decided at the current state of knowledge.

Reports on establishing an ex situ site for ‘beautiful’ vavilovia (Vavilovia formosa) in Armenia

Vavilovia (Vavilovia Fed.) is one of the five genera in tribe Fabeae and consists of only one species, ‘beautiful’ vavilovia (Vavilovia formosa (Stev.) Fed.). The main centre of distribution is the Central and Eastern Caucasus, with a disjunct distribution among high alpine areas in the region, extending as far as West Turkey, Lebanon and Iran. In Armenia, in situ studies on Vavilovia started in the late 1930s. In July and August 2009, three expeditions were conducted to two locations: two to the Ughtasar Mountain and one to the Geghama Mountains. The first expedition to Ughtasar resulted in fresh plant collections and soil analysis for one of the sites. The expedition to Geghama established the existence of Vavilovia in the region of Lake Aknalitch. The second expedition to Ughtasar provided immature fruits and seeds. Collected plant material was transplanted into the Flora and Vegetation of Armenia plot of the Yerevan Botanic Garden established in 1940. Today, along with other plants the plot contains more than 200 species of wild relatives of cultural plants from 130 genera, including indiginous species of tribe Fabeae such as Vavilovia. The transplanted plants will continue to be monitored to see if the plants go on to successfully flower and set seed or whether further sites, possibly at higher altitudes might need to be tested to meet the long term conservation requirements of this iconic legume. These co-ordinated efforts provide a good example of an ex situ conservation strategy for Vavilovia formosa, which, if successful will improve access and utility for the whole legume research community.

SnowSlide: A simple routine for calculating gravitational snow transport

Knowledge about lateral snow transport processes is essential for the description of the spatial distribution of snow and therefore for the distribution of water on the lands surface. While numerous snow hydrological models are accounting for wind induced snow transport, they are mostly neglecting gravitational snow transport processes. This leads to unrealistic calculations of snow cover distributions in high Alpine regions effecting the subsequent prediction of individual components of the water and energy cycles at the land surface. “SnowSlide” as presented here is a fast and parsimonious model component allowing for the calculation of gravitational snow transport processes in an integral way. The functionality and performance of SnowSlide is demonstrated a) for artificial land surfaces and b) for two winter periods at the Watzmann massif in south‐east Germany. It is shown that the integration of SnowSlide into the snow‐hydrological model “SnowModel” is significantly improving the prediction of spatially distributed snow patterns in high Alpine areas and therefore generating more realistic descriptions of Alpine water and energy balances.

Multicriteria GIS modeling of wind and solar farms in Colorado

The majority of electricity and heat in Colorado comes from coal and natural gas; however, renewable energy sources will play an integral role in the state’s energy future. Colorado is the 11th windiest state and has more than 250 sunny days per year. The objectives of this research are to: 1) determine which landcover classes are affiliated with high wind and solar potential; and 2) identify areas that are suitable for wind and solar farms using multicriteria GIS modelling techniques. Renewable potential (NREL wind speed measurements at 50 m above the ground and NREL annual insolation data), landcover, population density, federal lands, and distance to roads, transmission lines, and cities were reclassified according to their suitability. Each was assigned weights based on their relative importance to one another. Superb wind classes are located in high alpine areas. Unfortunately, these areas are not suitable for large-scale wind farm development due to their inaccessibility and location within a sensitive ecosystem. Federal lands have low wind potential. According to the GIS model, ideal areas for wind farm development are located in northeastern Colorado. About 41 850 km 2 of the state has model scores that are in the 90–100% range. Although annual solar radiation varies slightly, inter-mountain areas receive the most insolation. As far as federal lands, Indian reservations have the greatest solar input. The GIS model indicates that ideal areas for solar development are located in northwestern Colorado and east of Denver. Only 191 km 2 of the state had model scores that were in the 90–100% range. These results suggest that the variables used in this analysis have more of an effect at eliminating non-suitable areas for large-scale solar farms; a greater area exists for suitable wind farms. However, given the statewide high insolation values with minimal variance, solar projects may be better suited for small-scale residential or commercial projects.

New observations and records for Umbilicaria (Umbilicariaceae) in Bolivia

Based on extensive new collections, a key to and a list of 11 species of the lichen genus Umbilicaria in Bolivia are provided, and their diversity, altitudinal distribution, biogeographical affinity and reproductive strategies are discussed. Umbilicaria africana, U. aprina, U. cinereorufescens, U. decussata, U. dendrophora, U. leprosa and U. vellea are reported from Bolivia for the first time. The Umbilicaria species of Bolivia belong to several biogeographical elements: an “international” high altitude group of species (4000–5500 m) found in most alpine or Arctic areas of the world (U. aprina, U. cinereorufescens, U. decussata, U. dendrophora, U. nylanderiana, U. vellea), and a central Andean endemic element (U. calvescens, U. leprosa, U. haplocarpa) which completely dominates at lower altitudes (2500–4000 m). In addition the mainly Southern Hemispheric U. africana is abundant in the high alpine areas. A two-phase scenario is suggested where the ancestor of the endemic element colonized and evolved in the Andes while the mountain chain was still fairly low, while the international element is a comparatively recent addition.

Combination of Numerical Dating Techniques Using 10Be in Rock Boulders and 14C of Resilient Soil Organic Matter for Reconstructing the Chronology of Glacial and Periglacial Processes in a High Alpine Catchment during the Late Pleistocene and Early Holocene

Glacier fluctuations and paleoclimatic oscillations during the Late Quaternary in Val di Rabbi (Trentino, northern Italy) were reconstructed using a combination of absolute dating techniques (14C and 10Be) and soil chemical characterization. Extraction and dating of the stable fraction of soil organic matter (SOM) gave valuable information about the minimum age of soil formation and contributed to the deciphering of geomorphic surface dynamics. The comparison of 10Be surface exposure dating (SED) of rock surfaces with the 14C ages of resilient (resistant to H2O2 oxidation) soil organic matter gave a fairly good agreement, but with some questionable aspects. It is concluded that, applied with adequate carefulness, dating of SOM with 14C might be a useful tool in reconstructing landscape history in high Alpine areas with siliceous parent material. The combination of 14C dating of SOM with SED with cosmogenic 10Be (on moraines and erratic boulders) indicated that deglaciation processes in Val di Rabbi were already ongoing by around 14,000 cal BP at an altitude of 2300 m asl and that glacier oscillations might have affected the higher part of the region until about 9000 cal BP. 10Be and 14C ages correlate well with the altitude of the sampling sites and with the established Lateglacial chronology.

Hydrologic Effects of NDVI Time Series in a Context of Climatic Variability in an Upstream Catchment of the Minjiang River1

Abstract: Increasing regional vegetation activity has been frequently found especially in middle and high latitude and alpine areas, but the effects of which on regional hydrology is still highly uncertain. The Upstream Catchment of Minjiang River is a large mountainous catchment covering 22,919 km2 with a diverse vegetation distribution pattern, including alpine group (A), subalpine group (SA), and temperate and subtropical group (T/ST). The Seasonal Mann‐Kendall test, a nonparametric trend test method, detected consistent upward trends in all groups in monthly accumulated growing degree days (AGDDM) time series from 1982 to 2003, but no significant trend in mean monthly precipitation (MMP) time series in any group. The alpine group had a significant (p = 0.024) upward trend in monthly Normalized Difference of Vegetation Index (NDVI) time series from 1982 to 2003, in contrast, the SA and T/ST groups had decreasing (although not significant) trends. AGDDM plays more important role than MMP in affecting NDVI change in alpine areas, indicating temperature was the main climatic driver. In contrast, water was the main driver for the T/ST group, as indicated by the significant correlation between NDVI and MMP and a weak correlation with AGDDM. Correlation coefficients of NDVI and river flow varied with seasons, mostly negative, especially during the growing season (April to October). A significant (p = 0.025) correlation was found only in August, indicating that an increase in peak‐NDVI decreased high flow significantly. TI‐NDVIc, which was developed in an attempt to track the vegetation change at the catchment scale, accounted for more than 40% of the evapotranspiration increase (r2 = 0.43).

Impact of infrastructure on habitat selection of wolverines Gulo gulo

Abstract Compared to the other northern large carnivores, wolverines Gulo gulo are thought to be the most sensitive species with regard to habitat changes and human disturbance. Nowadays wolverines in Scandinavia are found in remote high alpine areas, and we investigated whether human development through presence of infrastructure has relegated them to these areas. We analysed wolverine habitat selection and the impact of infrastructure in two study areas in Norway using compositional analysis. We found that alpine tundra with low human development was important for wolverines to locate their home ranges. Human development formed a more important factor for home range location than did habitat, because habitat selectivity was much higher in undeveloped habitats than in developed habitats. Within their home ranges, wolverines used alpine shrubland and forest, irrespective of human development. The sympatric distribution of wolverines with wild and semi-domestic reindeer Rangifer tarandus indicates that wol...

Internal structure of an alpine rock glacier based on crosshole georadar traveltimes and amplitudes

ABSTRACTRapid melting of permafrost in many alpine areas has increased the probability of catastrophic rock slides. In an attempt to provide critical structural information needed for the design and implementation of suitable mitigation procedures, we have acquired low frequency (22 MHz) cross‐hole radar data from within a fast‐moving rock glacier, an important form of alpine permafrost. Since the ice, rock and pockets of water and air found in the underground of high alpine areas have very different dielectric permittivities and electrical conductivities, the radar method was well‐suited for investigating the structure and state of the rock glacier. Our interpretation of the radar velocities and attenuations was constrained by geomorphological observations, borehole lithological logs and the results of a surface seismic survey. The radar data revealed the existence of a discontinuous 7–11 m thick ice‐rich zone distinguished by high velocities (0.14–0.17 m/ns) and low attenuations (0.04–0.09 m−1) and a thin underlying ice‐free zone characterized by moderate velocities (0.11–0.12 m/ns) and low attenuations (0.04–0.09 m−1). Beneath these two zones, we observed a prominent band of high velocities (0.14–0.17 m/ns) and moderately high attenuations (0.10–0.20 m−1) associated with unconsolidated glacial sediments and numerous large air‐filled voids, which in the past were probably filled with ice. At greater depths, the variably dry to water‐saturated sediments were represented by generally lower velocities (0.08–0.10 m/ns) and higher attenuations (0.16–0.24 m−1). The bedrock surface was represented by an abrupt ∼0.03 m/ns velocity increase. We speculate that the disappearance of ice, both laterally and with depth, occurred during the past one to two decades.

A dendroarchaeological re-examination of the “Messiah” violin and other instruments attributed to Antonio Stradivari

The “Messiah” violin is considered by many to be the finest work by Antonio Stradivari and one of the most valuable musical instruments in existence. Questions were recently raised concerning its authenticity on stylistic and historical grounds, especially in light of conflicting sets of tree-ring dates for the spruce top of the violin. To resolve this controversy, we analysed the tree rings on the “Messiah” and those found on five other instruments constructed in the same general period, dating these against a regional chronology that integrated 16 alpine tree-ring chronologies from five countries. We conclusively dated both the “Archinto” (1526–1686) and “Kux”/“Castelbarco” (1558–1684) violas against the regional chronology. We could not directly date the “Messiah” against the regional master chronology, but found that its tree rings dated well against both the “Archinto” and “Kux”/“Castelbarco” violas. Our results strongly suggest that the tree rings of the “Messiah” violin date between 1577–1687, dates that support the attribution to Antonio Stradivari and the label date of 1716. We hypothesize the wood used to make the “Messiah” came from a low-elevation tree growing distant from the high alpine areas, whereas the wood used to make the two violas likely came from an intermediate, mid-elevation location.

A dendroarchaeological re-examination of the “Messiah” violin and other instruments attributed to Antonio Stradivari

The “Messiah” violin is considered by many to be the finest work by Antonio Stradivari and one of the most valuable musical instruments in existence. Questions were recently raised concerning its authenticity on stylistic and historical grounds, especially in light of conflicting sets of tree-ring dates for the spruce top of the violin. To resolve this controversy, we analysed the tree rings on the “Messiah” and those found on five other instruments constructed in the same general period, dating these against a regional chronology that integrated 16 alpine tree-ring chronologies from five countries. We conclusively dated both the “Archinto” (1526–1686) and “Kux”/“Castelbarco” (1558–1684) violas against the regional chronology. We could not directly date the “Messiah” against the regional master chronology, but found that its tree rings dated well against both the “Archinto” and “Kux”/“Castelbarco” violas. Our results strongly suggest that the tree rings of the “Messiah” violin date between 1577–1687, dates that support the attribution to Antonio Stradivari and the label date of 1716. We hypothesize the wood used to make the “Messiah” came from a low-elevation tree growing distant from the high alpine areas, whereas the wood used to make the two violas likely came from an intermediate, mid-elevation location.

A model for optimal mycorrhizal colonization along altitudinal gradients

Mycorrhizal associations are generally favourable for vascular plants in nutrient-poor conditions. Still, non-mycorrhizal plants are common in high arctic and alpine areas, which are often poor in nitrogen and phosphorus. The relative proportion of mycorrhizal plants has been found to decrease along with increasing altitude, suggesting that the advantage of the mycorrhizal symbiosis may change along an altitudinal gradient. This may be related to the environmental factors that possibly constrain the amount of photosynthesized carbon to be shared with mycorrhizal fungi. We propose a simple optimization model for root colonization by fungal symbionts and analyze the advantages of mycorrhizas in relation to the nutrient use efficiency of photosynthesis (PNUE), the kinetics of nutrient uptake and the soil nutrient levels. Our model suggests that mycorrhizas are not usually favoured at low PNUE values. At low nutrient levels, mycorrhizas may be advantageous if they have a lower threshold concentration of nutrient uptake (xmin) compared to non-mycorrhizal roots. If mycorrhizal roots have a higher maximum capacity of nutrient uptake (Vmax), mycorrhizas can be favourable for the host plant even at relatively low nutrient concentrations and at relatively low PNUE. Consequently, the possible patterns along altitudinal gradients essentially depend on PNUE. If the soil nutrient concentration is constant and PNUE decreases, the advantage of mycorrhizal symbiosis declines independently of the nutrient uptake kinetics. If PNUE remains constant and the soil nutrient concentration decreases along with increasing altitude, the emerging colonization pattern (either increasing, decreasing or intermediate) depends on the nutrient uptake kinetics. Additionally, if both PNUE and the soil nutrient concentration decrease, several patterns may emerge, depending on the nutrient uptake kinetics.

Stable isotope analysis for characterization of pollutants at high elevation alpine sites

Variations in the abundance of stable isotope of sulfur, nitrogen and carbon in sulfate, nitrate and organic carbon, respectively, were studied in snow and air samples from high-alpine sites. Their suitability as a tool for characterizing the source regions which contribute to the pollution of the high-alpine areas was investigated. The contributions of different sources to a specific receptor site are generally unknown and depend on emission patterns and meteorological conditions. Measured isotope ratios reflect the actual superposition of the distinct source types under the assumption that no major isotope fractionation occurs during transport and deposition and that post-deposition isotope effects can be excluded. In order to study the relationship between source region and isotopic pattern, daily high-volume samplings of the atmospheric aerosol at Sonnblick (Austrian Alps, 3106 m asl) were combined with twice-daily backtrajectories and evaluated statistically. In addition, vertical snow profiles taken in pits at various locations in the Alps were analyzed. For their interpretation, a so-called snow calendar was constructed which relates specific snow strata to the dates of the respective precipitation events. Furthermore, the isotope ratios of hydrogen and oxygen in the snow samples were used to support the meteorological information. Main findings of the investigations are regional patterns of δ 34S in airborne sulfates, the seasonality of nitrogen isotope composition in nitrates, and a pronounced isotopic difference in nitrates and sulfates of pre-industrial and modern origin, respectively. This study was part of EUROTRAC subproject ALPTRAC.

Effect of elevation on sexual reproduction in alpine populations of Saxifraga oppositifolia (Saxifragaceae).

Self-compatibility in high arctic and alpine areas is regarded as an adaptation to low pollinator abundance. However, high genetic variability as a consequence of outcrossing is, with regard to population persistence, favorable in highly stochastic environments such as tundra habitats. To evaluate these contradictory scenarios, I performed in situ pollination experiments to examine the breeding system of the predominant outcrosser Saxifraga oppositifolia in ten populations at two different elevations in the Swiss Alps. Pollinator limitation was detected at both elevations, but fruit set in naturally pollinated flowers was only slightly less at the higher elevation. Increased pollinator limitation at high compared with low elevation thus could not be demonstrated in this experiment. Hand-crossings yielded equal mean proportion seed set at both elevations, and so did hand-selfings. This constant pattern of the breeding system in S. oppositifolia indicates selective factors that lead to the maintenance of a high level of outcrossing even in high-elevation populations. Based on sex allocation models, it was expected that a high ovule number should be selectively advantageous in a plant-pollinator system where chance visitation or selfing play important roles. However, female reproductive offer in terms of ovule number per flower did not change from low to high elevation. Since neither increased pollinator limitation nor increased seed set in selfed flowers was found at high compared with low elevation, the prerequisites for testing the hypothesis were not given. This study contradicts the hypothesis that inimical environmental factors in alpine or arctic habitats necessarily select for increased selfing rates in a preferentially outcrossing species like S. oppositifolia.