The paper presents the first physicochemical and microbiological studies conducted in the northern area of Svalbard (Spitsbergen). Ten sediment samples were collected from the bottom of the longest fjord in the region, Wijdef jorden. Bottom sediments from ten lakes located along the shores of Wijdefjorden and Woodfjorden were also sampled. Organic matter content (LOI), water content, temperature, pH, and salinity of the sediments were determined. The quantity of aerobic bacteria cultured on various growth media at 4 ° C, 14 ° C, and 37 ° C ranged from 10 2 to 10 6 cfu/g of wet sediment mass, depending on the type of sampling station (fjord or lake). The number of bacteria did not co rrelate with organic matter content. Out of the 37 bacterial strains isolated from Wijdefjorden, 48% and 70% revealed ureolytic and proteolytic activity, respectively. The proportion of freshwater strains with ureolytic and proteolytic activity was 32% and 55%, respectively. Antibiotic resistance testing indicated that bacterial strains from the bottom sediments of the lakes were resistant to 8 antibiotics (out of the 18 investigated). Possible sources of this resistance are discussed. Using 16S DNA analysis, bacterial isolates from the lakes were identified as Pseudomonas sp., whereas frequently occurring strains in bottom sediment of the fjord were Pseudoalteromonas sp.
An early Permian (late Artinskian–Roadian) cladid crinoid (Catacrinidae gen. et sp. indet.) is reported for the first time from the V ø ringen Member of the Kapp Starostin Formation of Spitsbergen. The specimen is partly articulated and preserves a considerable part of its stalk and a complete cup, but only the proximal portions of its arms. Thus, it cannot be identified with any degree of certainty at the generic level. Despite this, our finding is important as it constitutes one of the youngest records of catacrinid crinoids to date and considerably extends the palaeogeographic distribution of this group.
Hansbreen, a medium size tidewater glacier in Southern Spitsbergen (Svalbard) is one of the most intensively studied glaciers in the Arctic. This work presents new digital elevation models of its surface and basal topography based on data collected during GPS/GPR campaigns conducted in the spring seasons of 2005 and 2008, as well as on other recent topographic/bathymetric sources. The mean thickness of the glacier is calculated as 171 m and its volume is estimated to be 9.6 (±0.1) km 3 . The main feature of the bedrock morphology is a vast depression that is overdeepened below sea level and extends as far as 11 km upstream from the glacier front. This depression is divided into four individual basins by distinct sills that are related to the main geological/tectonic features of the area. The bedrock morphology affects considerably the glacier’s surface topography. The influence of bedrock and surface relief on the subglacial drainage system geometry is discussed. Vast depressions on the glacier surface favor concentration of meltwater and development of moulin systems.
We assessed culturable soil microfungal diversity in various habitats around Hornsund, Spitsbergen in the High Arctic, using potato dextrose agar ( PDA) medium. Thermal growth classification of the fungi obtained was determined by incubating them in 4 ° Cand 25 ° C, permitting separation of those with psychrophilic, psychrotolerant and mesophilic characteristics. In total, 68 fungal isolates were obtained from 12 soil samples, and grouped into 38 mycelial morphotypes. Intergenic spacer regions of these morphotypes were sequenced, and they represented 25 distinct taxonomic units, of which 21 showed sufficient similarity with available sequence data in NCBI to be identified to species level. Soil under ornithogenic influence showed the highest species diversity, including sequences assigned to Mortierella macrocystis, M. elongata, Mortierella sp., Cudoniella sp., Varicosporium elodeae , Beauveria bassiana , Geomyces pannorum , Penicillium sp. and Atradidymella muscivora . Fourteen taxa were classified as psychrophilic, seven mesophilic, and four psychrotolerant.
This paper presents distribution and properties of soils within the Fuglebekken catchment in neighbourhood of the Polish Polar Station in Hornsund, SW Spitsbergen (Svalbard Archipelago). The present study describes 8 representative soil profiles out of 34 profiles studied for the whole catchment. Soils of the Fuglebekken catchment show initial stage of their formation because of very slow rate of chemical and biological weathering in Arctic climate conditions . Uplifted marine terraces of the Fuglebekken catchment are characterized by domination of Haplic Cryosols which ar e related to stony and gravelly parent material (reworked marine sediments). Such soils constitute of 17% of the studied area. Turbic Cryosols forming characteristic micro−relief occur on flat surfaces and gentle slopes. Such soils (covering 7% of the catchment) are formed from loamy parent material. Along streams Hyperskeletic Cryosols (Reduc taquic) and Turbic Histic Cryosols occur. The last two soil units (constituting 11% of the catchment) are mantled by continuous and dense vegetation cover (especially mosses) due to high content of water rich in nutrients flowing from colonies of sea birds located on slopes of Ariekammen and Fugleberget. The studied soils are generally characterized by shallow occurrence of permafrost ( i.e. at 30–50 cm), high content of pebbles, sandy or sandy loam texture, and neutral or s lightly alkaline reaction. Soils occurring along streams and near colonies of sea birds show higher content of nutrients (N and P) in comparison with other soils and are covered by more dense vegetation. This indicates important impact of bird guano on chemical composition of soil solution and fertility of such soils.
The diversity of cyanobacterial assemblages from various microhabitats in the Arctic area of Petuniabukta, Billefjorden, central Svalbard, was described. The present article contains the introductory common review of the cyanobacterial diversity and ecological data concerning main habitats, while the characteristics of individual taxonomic groups will be presented in following specific studies. Eight distinct main habitats were recognized, which differed in their species composition and especially the dominant species. More than 80 morphospecies were registered during our investigation, but only about 1/3 of them could be assigned to known and described taxa. The others require additional analyses based on modern taxonomic methods (the polyphasic approach ). The composition of cyanobacterial micro flora was comparable with assemblages in coastal Antarctica. The diversity of unicellular and colonial morphotypes (36 taxa) was higher tha n other groups. The number of filamentous species without heterocytes and akinetes, with 30 species, and heterocytous types, with only 20 species, were similar in both of these ecosystems. These numbers will be surely changed in the future, but the overall proportion of different groups will likely stay the same. In contrast to the limited species diversity, simple filamentous aheterocytous species were dominant and formed massive populations. Fewheterocy tous taxa, mostly grouped within the genus Nostoc ( N. commune –complex), were dominant in tundra soils.
Water bears (Tardigrada) are known as one of the most extremophile animals in the world. They inhabit environments from the deepest parts of the oceans up to the highest mountains. One of the most extreme and still poorly studied habitats which tardigrades inhabit are cryoconite holes. We analysed the relation between area, depth, elevation and tardigrades densities in cryoconite holes on four glaciers on Spitsbergen. The mean (±SD) of cryoconite area was 1287.21±2400.8 cm2, while the depth was on average 10.8±11.2 cm, the elevation 172.6±109.66 m a.s.l., and tardigrade density 24.9±33.0 individuals per gram of wet material (n = 38). The densities of tardigrades on Hans Glacier reached values of up to 168 ind. cm3, 104 ind. g-1 wet weight, and 275 ind. g-1 dry weight. The densities of tardigrades of the three glaciers in Billefjorden were up to 82 ind. cm2, 326 ind. g-1 wet weight and 624 ind. g-1 dry weight. Surprisingly, although the model included area, depth and elevation as independent variables, it cannot explain Tardigrada density in cryoconite holes. We propose that due to the rapid melting of the glacier surface in the Arctic, the constant flushing of cryoconite sediments, and inter-hole water-sediment mixing, the functioning of these ecosystems is disrupted. We conclude that cryoconite holes are dynamic ecosystems for microinvertebrates in the Arctic.
This article presents the results of observations of selected fluxes of the radiation balance in north-western Spitsbergen in the years from 2010 to 2014. Measurements were taken in Ny-Ålesund and in the area of Kaffiøyra, on different surface types occurring in the Polar zone: moraine, tundra, snow and ice. Substantial differences in the radiation balance among the various types of surface were observed. The observations carried out in the summer seasons of 2010-2014 in the area of Kaffiøyra demonstrated that the considerable reflection of solar radiation on the Waldemar Glacier (albedo 55%) resulted in a smaller solar energy net income. During the polar day, a diurnal course of the components of the radiation balance was apparently related to the solar elevation angle. When the sun was low over the horizon, the radiation balance became negative, especially on the glacier. Diurnal, annual and multi-annual variations in the radiation balance have a significant influence on the functioning of the environment in polar conditions.
This paper presents the first results of measurements of global solar radiation, albedo, ground surface and 2−m air temperature, relative humidity, and wind speed and direction carried out in the central part of Spitsbergen Island in the period 2008–2010. The study site was located on the coastal ice−free zone of Petuniabukta (north−western branch of Billefjorden), which was strongly affected by local topography, character of the ground surface, and sea ice extent. Temporal analysis of the selected meteorological parameters shows both strong seasonal and inter−diurnal variation affected by synoptic−scale weather systems, channelling and drainage effects of the fjords and surrounding glaciers. The prevailing pattern of atmospheric circulation primarily determined the variation in global solar radiation, wind speed, ground surface and 2−m air temperatures. Furthermore, it was found that thermal differences between Petuniabukta and the nearest meteorological station (Svalbard Lufthavn) differ significantly due to differences in sea ice concentrations and ice types in the fjords during the winter and spring months.
The eight most abundant species (mean density >20 ind. m −2 ), which occurred at high frequencies (mean >30%) were selected from grab samples in the three Svalbard fjords: Hornsund, van Mijenfjord, and Kongsfjord, in the summer seasons between 1997 and 2007. Six polychaete and two bivalve species comprised more than 47% of the individuals and the biomass in all the samples examined. Four species are cosmopolitan, while the others are widely distributed Arctic−boreal species, and none has Arctic origin. Their density, frequency of occurrence, and biology are very similar across the wide geographical range from boreal to Arctic conditions. As the diversity of benthic fauna in the fjords studied increases (from 172 to 238 species), the dominance of the eight species in the soft bottom community diminishes from 76% to 47%. In times of hydrological regime shift, i.e. , the warming of the European Arctic, it is unlikely that the abundancy of these species in the soft bottom fjordic ecosystems will change. The most common soft bottom species are not good indicators of environmental change in the Arctic, and rare, specialized species are better option for indicative purposes.
Hørbyebreen surged in the 19th or early 20th century, as suggested by geomorphological evidences and looped medial moraines. In this study, we investigate its wide−spread geometry changes and geodetic mass balance with 1960 contour lines, 1990 and 2009 digital elevation models, in order to define the present−day state of the glacier. We also study its thermal structure from ground−penetrating radar data. Little is known about the glacier behaviour in the first part of the 20th century, but from its surge maximum until 1960 it has been retreating and losing its area. In the period 1960–1990, fast frontal thinning (2–3 m a −1 ) and a slow mass build−up in the higher zones (~0.15 m a −1 ) have been noted, resulting in generally negative mass balance (−0.40 ± 0.07 m w. eq. a −1 ). In the last studied period 1990–2009, the glacier showed an acceleration of mass loss (−0.64 m ± 0.07 w. eq. a −1 ) and no build−up was observed anymore. We conclude that Hørbyebreen system under present climate will not surge anymore and relate this behaviour to a considerable increase in summer temperature on Svalbard after 1990. Radar soundings indicate that the studied glacial system is polythermal, with temperate ice below 100–130 m depth. It has therefore not (or not yet) switched to cold−bedded, as has been suggested in previous works for some small Svalbard surge−type glaciers in a negative mass balance mode.
The archipelago of Svalbard in the European High Arctic lies on the convergence of the Palaearctic and Nearctic flora and fauna and contains elements of both regions. The island of Hopen is located in the south east of the archipelago within the path of the cold south−westerly flowing East Svalbard Current originating in the Arctic ocean and flowing along the north Russian coast. This current is postulated as a colonization route of the invertebrate fauna of Svalbard. Few reports of the terrestrial invertebrates of Hopen exist and none of the mite suborders Oribatida or Mesostigmata. With the taxonomic confusion existing in the inventories of this important region of the Arctic, new sampling campaigns with species identified by modern taxonomic principles and with material deposited in accessible museums and collections are essential. Identified mites included six species of oribatid mites with Diapterobates notatus dominating, and five species of Mesostigmata with Zercon forsslundi forming the dominant species. None of the species collected was a new record for Svalbard and all have wide circumpolar, Palaearctic or Holarctic distributions. Dispersal to Svalbard from northern Russia is hence neither supported nor rejected. The expected oribatid and mesostigmatid diversity of the island is greater than observed from the limited sampling described here.
In order to simulate the warming effects on Arctic wetlands, three passive open−top chambers (OTCs) and three control cage−like structures (CCSs) equipped with soil temperature and soil volumetric water content (VWC) probes for continuous micro− climatic measurements were installed in a wet hummock meadow, Petuniabukta, Billefjorden, central Spitsbergen, in 2009. The warming effects on primary productivity were investigated during summer seasons 2009 and 2010 in cyanobacterial colonies of Nostoc commune s.l., which plays an important role in the local carbon and nitrogen cycles. The microclimatic data indicated that the effect of OTCs was dependent on microtopography. During winter, two short−term snow−thaw episodes occurred, so that liquid water was available for the Nostoc communities. Because of the warming, the OTC hummock bases remained unfrozen three weeks longer in comparison to the CCSs and, in spring, the OTC hummock tops and bases exceeded 0 ° C several days earlier than CCS ones. Mean summer temperature differences were 1.6 ° C in OTC and CCS hummock tops, and 0.3 ° Cinthe OTC and CCS hummock bases. The hummock tops were drier than their bases; however the VWC difference between the OTCs and CCSs was small. Due to the only minor differences in the microclimate of OTC and CCS hummock bases, where the Nostoc colonies were located, no differences in ecophysiological characteristics of Nostoc colonies expressed as photochemistry parameters and nitrogenase activities were detected after two years exposition. Long−term monitoring of Nostoc ecophysiology in a manipulated environment is necessary for understanding their development under climate warming.
The ability to grow clonally is generally considered important for plants in Arctic regions but analyses of clonal characteristics are lacking for entire plant communities. To fill this gap, we assessed the clonal growth of 78 plant species in the Petuniabukta region, central Spitsbergen (Svalbard), and analyzed the clonal and other life−history traits in the regional flora and plant communities with respect to environmental gradients. We distinguished five categories of clonal growth organs: perennial main roots produced by non− clonal plants, epigeogenous rhizomes, hypogeogenous rhizomes, bulbils, and stolons. Clonal growth differed among communities of the Petuniabukta region: non−clonal plants prevailed in open, early−successional communities, but clonal plants prevailed in wetlands. While the occurrence of plants with epigeogenous rhizomes was unrelated to stoniness or slope, the occurrence of plants with hypogeogenous rhizomes diminished with increasing stoniness of the substratum. Although the overall proportion of clonal plants in the flora of the Petuniabukta region was comparable to that of central Europe, the flora of the Petuniabukta region had fewer types of clonal growth organs, a slower rate of lateral spread, and a different proportion of the two types of rhizomes.
The aim of this study was to provide an estimation of climate variability in the Hornsund area in Southern Spitsbergen in the period 1976-2100. The climatic variables were obtained from the Polar-CORDEX initiative in the form of time series of daily air temperature and precipitation derived from four global circulation models (GCMs) following representative concentration pathways (RCP) RCP 4.5 and RCP 8.5 emission scenarios. In the first stage of the analysis, simulations for the reference period from 1979 to 2005 were compared with observations at the Polish Polar Station Hornsund from the same period of time. In the second step, climatic projections were derived and monthly and annual means/sums were analysed as climatic indices. Following the standard methods of trend analysis, the changes of these indices over three time periods - the reference period 1976-2005, the near-future period 2021-2050, and far-future period 2071-2100 - were examined. The projections of air temperature were consistent. All analysed climate models simulated an increase of air temperature with time. Analyses of changes at a monthly scale indicated that the largest increases were estimated for winter months (more than 11°C for the far future using the RCP 8.5 scenario). The analyses of monthly and annual sums of precipitation also indicated increasing tendencies for changes with time, with the differences between mean monthly sums of precipitation for the near future and the reference period similar for each months. In the case of changes between far future and reference periods, the highest increases were projected for the winter months.
Determination of High Arctic regions bathymetry is strictly dependent from weather and ice mass quantity. Due to safety, it is often necessary to use a small boat to study fjords area, especially close to glaciers with unknown bathymetry. This precludes the use of modern multi−beam echosounders, and so traditional single−beam echosounders have been used for bathymetry profiling. Adequate interpolation techniques were determined for the most probable morphological formations in−between bathymetric profiles. Choosing the most accurate interpolation method allows for the determination of geographical regionalisation of submarine elevations of the Brepollen area (inner part of Hornsund, Spitsbergen). It has also been found that bathymetric interpolations should be performed on averaged grid values, rather than individual records. The Ordinary Kriging Method was identified as the most adequate for interpolations and was compared with multi beam scanning, which was possible to make due to a previously modelled single beam interpolation map. In total, eight geographical units were separated in Brepollen, based on the bathymetry, slope and aspect maps. Presented results provide a truly new image of the area, which allow for further understanding of past and present processes in the High Arctic.
In the southern Spitsbergen area, thermal and mineral waters are primarily associated with subpermafrost deep circulation, being mixed with shallow circulation and glacial waters. Four thermal springs, located in the region of Stormbukta (Sørkappland), were studied and analyzed. In the thermal waters, the main cation is sodium, while the main anions are chloride and bicarbonate. The temperatures of the mineral and thermal waters range from 3.4 to 15.1°C. The pH values are between 7.43 and 8.41. The total dissolved solids (TDS) content of the geothermal waters is in the range of 346–4031 mg/l and the Olsok thermal spring has the highest TDS values. Based on the variation in physicochemical characteristics, two thermal water types were distinguished in the study area. The first type is associated with thermal waters originating from deep circulation waters. The second type is associated with the thermal and mineral waters originating from the mixture of subpermfrost hot brines with glacial waters.
Neoproterozoic ( c. 640 Ma) amphibolite facies metamorphism and deformation have been shown recently to have affected the Isbj ø rnhamna and Eimfjellet Complex of Wedel Jarlsberg Land in southwestern Spitsbergen. New SHRIMP zircon U−Pb and in situ electron microprobe monazite and uraninite U−Th−total Pb ages are presented here on a pegmatite occurring within the Isbj ø rnhamna metasedimentary rocks. Although the dated zircons are full of inclusions, have high−U contents and are metamict and hence have experienced notable Pb−loss, the new Cryogenian ages are consistent with the age of regional metamorphism of the host metasediments, providing additional evidence for a clear distinction of the Southwestern Province from the other parts of the Svalbard Caledonides.
A significant limit to current understanding of cold coast evolution is the paucity of field observations regarding development of rocky coastlines and, in particular, lack of precise recognition of mechanisms controlling rock coast geomorphology in polar climates. Results are presented from a pilot survey of rock resistance using Schmidt Hammer Rock Tests (SHRT) across the recently deglacierized Nordenskioldbreen forefield and coastal zone, in central Spitsbergen, Svalbard. The aim is to improve understanding of the effects of rock weathering on high latitude coasts. SHRT across a field of roches moutonnées of metamorphic rocks, uncovered from ice over the last century and exposed to the operation of littoral processes, demonstrated significant relationships between rock surface resistance and distance from present shoreline, distance from the ice cliff as well as thickness of the snow cover. Sites closest to the present−day shoreline were characterized by lower resistance in comparison with more inland locations. The result support models that advocate intensification of weathering processes in cold region coastal settings.
In this study, weather conditions causing warm waves in north−western Spits − bergen, exemplified by Ny− Å lesund station, were analyzed. Between 1981 and 2010, 536 days with the maximum temperature exceeding 8.3 ° C (the value of 95 percentile) were selected. 37 warm waves, which altogether lasted 268 days, were identified. A typical feature of pressure pattern causing warm waves was the appearance of positive anomalies of both the sea level pressure and the height of isobaric surface 500 hPa in the Euro−Atlantic sector of the Arctic. This indicates a presence of high−pressure systems in this region. Extremely warm days appeared more often with the circulation from the eastern than the western sector. Longer and warmer heat waves occurring in the last decade of the analyzed period may be considered as a sign of climate warming, which has a significant impact on environment, i.e. reduction in area and thickness of glaciers, reduction of permafrost and snow cover, changes in biodiversity, etc . The increase in the air temperature and more frequent occurrence of heat waves may encourage development of tourism in polar areas, potentially causing further changes in the environment.
The Ebbabreen ice−cored moraine area is covered with a sediment layer of up to 2.5 m thick, which mostly consists of massive diamicton. Due to undercutting by lateral streams, debris flow processes have been induced in marginal parts of this moraine. It was recognized that the sedimentology of deposits within the deposition area of debris flows is the effect of: (1) the origin of the sediments, (2) the nature of the debris flow, and (3) post−debris flow reworking. Analysis of debris flow deposits in microscale (thin sections) suggests a common mixing during flow, even though a small amount of parent material kept its original structure. The mixing of sediments during flow leads to them having similar sedimentary characteristics across the deposition area regardless of local conditions ( i.e. slope angle, water content, parent material lithology). After the deposition of sediments that were transported by the debris flow, they were then reworked by a further redeposition process, primarily related to meltwater stream action.
A 2.5−metre−long marine core from Isvika bay in Nordaustlandet (80 ° N, 18 ° E) was AMS 14 C dated and analysed for its sedimentological and magnetic parameters. The studied record was found to cover the entire Holocene and indicates major turnovers in the palaeohydrography and sedimentary depositional history. The area was deglaciated at around 11,300 BP. The early Holocene has indications of rapid melting of glaciers and frequent deposition of ice−rafted debris (IRD). The climatic optimum terminated with a probable glacier re−advance event occurring ca. 5800 cal BP. This event caused the deposition of a diamicton unit in Isvika bay, followed by a shift towards a colder and a more stratified hydrographic set − ting. The reduction in IRD indicates gradual cooling, which led to the stratification of the bay and eventually to more persistent fast sea−ice conditions by 2500 cal BP. For the last 500 years, Isvika has again been seasonally open.
This article describes the morphological characteristics of the populations of green alga, Tetraspora gelatinosa , growing in the stressful Arctic conditions (77 ° 00’22” N, 015 ° 32’54.33” E). We present the first detailed morphological characteristics of this species from such a high latitude. Populations from both stagnant and flowing waters were studied. Depending on the type of habitat, their mucilaginous colonies (thalli) have different shapes, but the structure, size and the placement of the vegetative cells, akinetes and ameboid forms, as well as the pseudocilia morphology of both populations, were very similar. Literature data on the distribution of T. gelatinosa indicate that it is a cosmopolitan species. Our data are compared with some characteristic features of this species growing in different geographical and climatic zones. No significant differences were found in the morphology of the colonies compared, nor in the location and the inner structure of cells. How − ever, there were slight differences in cell size between the populations from warm and cold zones.
Filamentous types from the order Oscillatoriales, particularly the species Phormidium autumnale , have widely diverse morphotypes, which dominate in Arctic aquatic microbial mats and wet soils. We cultivated 25 strains of Ph . autumnale from Svalbard and compared them with available strains from surrounding regions. The comparison of strains, based on 16S rDNA and 16S−23S rDNA intergenic spacer sequences, revealed the similarity of strains from Ellesmere Island, the Canadian Arctic and Abisko, Sweden with strains from Svalbard. The rate of colonization of Ph. atumnale from aquatic habitats is relatively high and we suggest geese as a main transmission vector from surrounding lands. Strains of Ph. autumnale were positioned in the phylogenetic tree according to their occurrence in similar habitats. An apparent clustering factor is the duration of availability of water in lakes and long−lasting streams in contrast to rapid and repeated desiccation in soil and on wetted rock in the spray zone of waterfalls. Strains that grow in very cold waters just above the melting point of snow or ice form a distinct genetic group. The strains investigated in this study show morphological similarity in the shape of the trichomes of the studied specimens. Overall, the cell diameter, except for terminal cells, of our strains varied between 3 and 10 μm. Comparison of 16S rDNA sequences of the genus Ph. autumnale with the previously published definition of the species Microcoleus vaginatus revealed the identity of these two species.
Diurnal measurements of photosynthetic pr ocesses, effective quantum yield of photosystem II ( F PSII ), photosynthetic electron transport rate (ETR) were done in three domi− nant species of Arctic tundra ( Silene acaulis , Dryas octopetala , Salix polaris ) in Petunia− bukta, Spitsbergen. Daily courses of net photosynthesis (P N ) were calculated from chloro− phyll fluorescence data and daily photosynthesi s evaluated. The short−term field measure− ments were carried out in summer 2009, and 2010. Fluorometric parameters ( F PSII and ETR) were measured each 5 minutes as well as microc limate characteristics of the site for 10 (2009) and 8 days (2010), respectively. In all species photosynthetic ETR was well related to incident photosynthetically active radiation a nd leaf temperature. In general, D. octopetala exhibited slightly lower ETR than the other two speci es. Estimated maximu m photosynthetic rate (P Nmax ) reached 17.6, 21.4, and 22.9 μmol CO 2 m −2 s −1 for S. polaris , S. acaulis ,and D. octopetala , respectively. Daily photosynthesis reach ed comparable values in all species, D. otopetala , however, exhibited slightly lower values than the other two species both for overcast and fully sunny days (3.9 and 13.4 mmol CO 2 m −2 d −1 , respectively). The range of daily photosynthesis for S. polaris and S. acaulis studied, reached the ranges of 4.6–6.9 and 14.6–15.2 mmol CO 2 m −2 d −1 for overcast and fully sunny day, respectively.