Saxifraga Cespitosa Research Articles

ONCE AGAIN ON THE RELATIONSHIP BETWEEN SPECIES DIVERSITY AND BEDROCK COMPOSITION: A CASE STUDY OF THE UNIQUE MRAMORNY ISLAND, VON’GA BAY, WHITE SEA

Сarbonate rocks of unique Mramorny (Marble) Island (65.420921 N, 34.631167 E) constitute a ca. 5-40 m thick lens-shaped body thrown into isoclinal folds. They are associated, interbedded and deformed jointly with amphibolites and are cut by granite-aplites. Their major minerals are dolomite (ca. 70-90%), calcite, biotite and hornblende. Isotopic data show that Mramorny Island carbonate rocks are endogenously igneous carbonatites. Geochronology data date the magmatic stage of carbonatite formation to 2420±20 Ma and metamorphic alterations of this rock to 1845±15 Ma. During the survey in 2018, 82 species of vascular plants, 25 mosses and 44 lichens were recorded from the island. The vascular plant flora was not very specific, but richer in species compared to other White Sea islands of similar size. High frequencies and abundances were noted also for such calciphilous species as Botrychium lunaria , Draba incana and Saxifraga cespitosa . The moss flora was not rich, but the proportion of calciphilous species was quite high – there occurred Brachythecium glareosum , Brachythecium turgidum , Distichium inclinatum and Ditrichum flexicaule . For Brachythecium glareosum Mramorny Island is the only location among White Sea islands where the species has been found. The calciphilous lichens encountered were Bilimbia sabuletorum , Caloplaca stillicidiorum , Candelariella aurella , Cladonia pocillum , Fuscopannaria praetermissa , and Xanthoria elegans . Five species ( Rhodiola rosea, Brachythecium glareosum, Brachythecium turgidum, Distichium inclinatum and Ramalina subfarinacea ) are listed in the regional Red Data Book. The unique geological structure of the island has had the most pronounced effect on the bryoflora, less so on the lichen flora, and the weakest effect on the flora of vascular plants. The latter can be attributed to the small size of the island and the peculiarities of its relief, which leads to an almost unhindered transport of carbonatite weathering products into the sea by rainfall and seawater.

Additions to the Vascular Flora of the Pasvik Strict Nature Reserve, Murmansk Region

Information about 24 vascular plant species found for the first time in the Pasvik strict nature reserve in 2008–2014 is reported. Seventeen of the species: Woodsia glabella , Botrychium multifidum , Equisetum × litorale , Equisetum × trachyodon , Arctagrostis latifolia , Poa lapponica , Carex lapponica , Carex serotina , Eriophorum latifolium , Eriophorum gracile, Dactylorhiza incarnata , Nuphar lutea , Salix reticulata , Saxifraga cespitosa , Ribes nigrum , Ribes spicatum and Alchemilla kolaensis are native; three species: Anthoxanthum odoratum , Alchemilla propinqua and Trifolium hybridum are adventitious; four species: Juncus minutulus , Coccyganthe flos-cuculi , Myosotis nemorosa and Lactuca sibirica are presumably adventitious. Five of these species are rare and listed in the Red Data Book of the Murmansk Region (2014). The patterns of distribution of each species in the Murmansk Region and the area adjacent to the nature reserve, as well as the reasons for classifying some species native in the region as adventitious in the nature reserve are discussed. For many of both native and adventitious species the newly detected habitats are the northernmost in the Murmansk Region.

Monitoring Populations of Saxifraga cespitosa in Scotland

Saxifraga cespitosa is listed as Endangered on the UK Red List, compiled using IUCN criteria (Cheffings & Farrell, 2005). It is also one of the species listed for conservation priority at the Royal Botanic Garden Edinburgh (RBGE) under Target 8 of the Global Strategy for Plant Conservation (GSPC). The species has been monitored extensively in the past, but there have been limited surveys in recent years. RBGE and the National Botanic Garden of Wales plan to survey all the UK locations of this species to increase information on existing populations and the threats to its survival. The field work and surveys carried out in 2013 are described in this paper and they have proved to be a useful learning experience for developing both staff skills and survey methods. Information on cultivation of the species from seed is also given. A field data sheet is provided as an appendix.

Vegetation responses to rapid climatic changes during the last deglaciation 13,500–8,000 years ago on southwest Andøya, arctic Norway

The late-glacial vegetation development in northern Norway in response to climate changes during the Allerod, Younger Dryas (YD), and the transition to the Holocene is poorly known. Here we present a high-resolution record of floral and vegetation changes at lake Lusvatnet, south-west Andoya, between 13500 and 8000 cal b.p. Plant macrofossil and pollen analyses were done on the same sediment core and the proxy records follow each other very closely. The core has also been analyzed using an ITRAX XRF scanner in order to check the sediment sequence for disturbances or hiatuses. The core has a good radiocarbon-based chronology. The Saksunarvatn tephra fits very well chronostratigraphically. During both the Allerod and the Younger Dryas time-periods arctic vegetation prevailed, dominated by Salix polaris associated with many typically arctic herbs such as Saxifraga cespitosa, Saxifraga rivularis and Oxyria digyna. Both periods were cold and dry. Between 12450 and 12250 cal b.p. during the Younger Dryas chronozone, the assemblage changed, particularly in the increased abundance of Papaver sect. Scapiflora and other high-Arctic herbs, suggesting the development of polar desert vegetation mainly as a response to increased aridity. After 11520 cal b.p. a gradually warmer and more oceanic climate initiated a succession to dwarf-shrub vegetation and the establishment of Betula woodland after 1,000 years at c. 10520 cal b.p. The overall late-glacial aridity contrasts with oceanic conditions in southern Norway and is probably related to sea-ice extent.

Greater nitrogen and/or phosphorus availability increase plant species’ cover and diversity at a High Arctic polar semidesert

Enhanced nitrogen (N) deposition at high latitudes is a circumpolar phenomenon. Low soil phosphorus (P), however, may limit vegetation responses to increased N inputs. From 2000 to 2002, the effects of N at 0, 0.5 (a rate occurring in Greenland and Iceland) and 5 (equivalent to deposition in areas of Europe) g N m−2 a−1 and P (0.1 g m−2 a−1) treatments on plant species’ cover and diversity were determined at a polar semidesert site (ambient deposition c 0.1 g N m−2 a−1) in Svalbard (79°N). The largest response was to combined 5 g N plus 1 g P m−2 a−1, where cover of Saxifraga oppositifolia increased c fourfold, density of Salix polaris leaves c ninefold, seedlings of several ‘new’ species (Draba oxycarpa, Saxifraga caespitosa, Sagina nivalis) were established and ‘immigration’ of Bryum arcticum and ‘extinction’ of Schistidium apocarpum were observed. There were fewer, less pronounced, effects on the plant community at 0.5 g N m−2 a−1. Low P availability did indeed appear to restrict vegetation response to N. There was a trend for plant species’ richness and diversity to increase with 1 g P m−2 a−1 at 0 and 0.5 g N m−2 a−1, but not at 5 g N m−2. Plant species showed individualistic responses so that generalisation by functional type was not possible. Such increased colonisation by moss species of bare soil, and greater densities of previously unrecorded angiosperm seedlings, are not usually observed in more closed (subarctic) tundra as a response to N and P additions. These changes are likely to influence significantly nutrient cycles, whole system carbon budgets and surface energy and water balances.

The influence of temperature and nitrogen source on growth and nitrogen uptake of two polar-desert species, Saxifraga caespitosa and Cerastium alpinum.

Polar-desert plants experience low average air temperatures during their short growing season (4–8 °C mean July temperature). In addition, low availability of inorganic nitrogen in the soil may also limit plant growth. Our goals were to elucidate which N sources can be acquired by polar-desert plants, and how growth and N-uptake are affected by low growth temperatures. We compared rates of N-uptake and increases in mass and leaf area of two polar-desert species (Cerastium alpinum L. and Saxifraga caespitosa L.) over a period of 3 weeks when grown at two temperatures (6 °C vs. 15 °C) and supplied with either glycine, NH4+ or NO3−. At 15 °C, plants at least doubled their leaf area, whereas there was no change in leaf area at 6 °C. Measured mean N-uptake rates varied between 0.5 nmol g−1 root DM s−1 on glycine at 15 °C and 7.5 nmol g−1 root DM s−1 on NH4+ at 15 °C. Uptake rates based upon increases in mass and tissue N concentrations showed that plants had a lower N-uptake rate at 6 °C, regardless of N source or species. We conclude that these polar-desert plants can use all three N sources to increase their leaf area and support flowering when grown at 15 °C. Based upon short-term (8 h) uptake experiments, we also conclude that the short-term capacity to take up inorganic or organic N is not reduced by low temperature (6 °C). However, net N-uptake integrated over a three-week period is severely reduced at 6 °C.

Vascular plant reproduction, establishment, and growth and the effects of cryptogamic crusts within a polar desert ecosystem, Devon Island, N.W.T., Canada

Most of the ice-free lands within the Canadian High Arctic are classified as polar desert (44%) or semidesert (49%). Much of this desert landscape supports no more than 6-10 vascular species that provide 1-3% cover and cryptogamic organisms that occupy 0-5% cover on the soil surface. The barrenness of these lands results from a short growing season and low summer temperatures that limit plant growth and the production of viable seeds. Limited areas have a 50-80% cover of cryptogamic crust and an 8-12% cover of vascular plants. These are areas in which surfaces remain moist for considerable periods in summer from snowflush waters. Where such cryptogamic soil crusts develop, they play a central role in soil development and nitrogen fixation. The two major components of this study were (i) an examination of fundamental reproductive, establishment, and growth characteristics of polar desert plants in the field and (ii) the relationship of these characteristics to environmental conditions in areas with and without cryptogamic crusts. Summer conditions during the study ranged from unusually warm (1991; 252 degree-days) to unusually cool (1992; 123 degree-days) with two average years (1994 and 1995; 172 and 166 degree-days, respectively). Differences in reproduction and establishment among these summers included (i) higher germination ability of seeds produced in the warm summer (1991) compared with more average summers (1994 and 1995) and (ii) significant seedling occurrence only in the average summers of 1994 and 1995. Seedling densities were much higher at crusted (206 seedlings/m2) than noncrusted sites (26 seedlings/m2). In both sites, root elongation of seedlings and older plants were significantly greater than shoot elongation, yet in established plants, shoot biomass was much greater than root biomass (root/shoot ratios from 0.1 to 0.3). Reproductive attributes varied among the species examined. Saxifraga caespitosa L. produced much smaller seeds then Draba corymbosa R. Br. ex DC. and Papaver radicatum Rottb., but the largest seeds of S. caespitosa (produced in the warm summer of 1991) had much higher germination rates than any seeds of the other species. Based on an analysis of population age structures, seedling survivorship was low for all species but was especially low for S. caespitosa, despite its higher germination rates. All species were slow to germinate, with isolated seeds under ideal controlled conditions requiring a minimum of 20-30 days at a 20°C day and 15°C night. Seed germination in excised soil blocks under comparable conditions averaged 36-48 days. We believe these polar desert plant species lack special attributes to uniquely exploit the environment of these very stressful locations. Rather, they are simply adept at surviving the rigors experienced there. The same species grow much larger, flower and fruit more abundantly, and produce more viable seeds in high arctic environments more favorable than polar deserts, such as lowland polar oases (e.g., Truelove Lowland, Devon Island, Canada). Within the harsh polar desert landscape of the High Arctic, the presence of a cryptogamic crust that retains surface moisture, prevents soil churning, and includes nitrogen-fixing organisms provides a more favorable habitat for plant reproduction, establishment, and growth.Key words: High Arctic, plant reproduction, plant establishment, plant growth, cryptogamic crust, polar desert, Devon Island.

Glacial survival does not matter – II: RAPD phylogeography of Nordic Saxifraga cespitosa

It has been suggested that many arctic‐alpine plant species have limited dispersal ability and cannot have arrived in Scandinavia and the arctic archipelago of Svalbard by long‐distance dispersal after a total glaciation. It has therefore been proposed that such species must have survived the entire glaciation(s) in ice‐free refugia in southern Norway, northern Norway and Svalbard. We investigated random amplified polymorphic DNA (RAPD) variation among 28 populations from Norway and Svalbard of one of these arctic‐alpine ‘short‐distance dispersers’, the selfing polyploid Saxifraga cespitosa. In an analysis of molecular variance (AMOVA), more variation was found among populations within the three postulated refugia regions (45%) than among these regions (25%). Spatial autocorrelation (Mantel) analyses showed that the genetic distance monotonously increased with increasing geographical distance. In UPGMA and PCO analyses, the populations from Norway and Svalbard formed a south–north cline that continued across the Barents Sea barrier. The results suggest that there has been recent dispersal among the three postulated refugia regions and thus that postglacial dispersal into these refugia regions from other distant areas also must represent a possibility. The observed geographical pattern of the genetic variation may have been established after expansion from different source areas outside the North European ice sheet and/or from different refugia areas ‘within’ the ice sheet, but it is probably not possible to distinguish among these alternatives. The results for S. cespitosa are consistent with a dynamic late‐ and postglacial scenario with extensive plant dispersal, and support the conclusion from our previous study of the outbreeding Saxifraga oppositifolia; the hypothesis of glacial survival in Norway and/or Svalbard is superfluous.

The Influence of Cryptogamic Crusts on the Thermal Environment and Temperature Relations of Plants in a High Arctic Polar Desert, Devon Island, N.W.T., Canada

The thermal microenvironment and leaf temperatures of two plants (Saxifraga caespitosa and S. oppositifolia) were studied in a high arctic polar desert over four summers. Surface and plant temperatures exceeded air temperatures by 5 to 150C during sunny periods, with smaller effects on soil temperature in plant rooting zones. Midday plant temperatures of 20 to 300C measured during good weather are favorable for physiological activity, but the number of such days is restricted by a short snow-free period (16-45 d). Surfaces in polar deserts are dominated by sorted stones and bare mineral soil with sparse vascular plant cover (usually <5%). Infrequent snowflush sites are scattered within this landscape, containing greater plant cover and a cryptogamic crust on the mineral soil surfaces. The potential role of this black crust in facilitating greater plant cover by enhancing the thermal relations of plants was investigated in this cold environment. Reduced albedo of crusted surfaces led to higher surface (8-12'C) and soil (4-50C) temperatures than in noncrusted areas. However, adult plants did not differ in tissue temperature on cryptogamic and bare surfaces. Root growth and survival of seedlings, which were thermally coupled to the surface by their small mass, are more likely to be highly influenced by the presence of crusted surfaces in this high arctic polar desert ecosystem.

The Influence of Cryptogamic Crusts on the Thermal Environment and Temperature Relations of Plants in a High Arctic Polar Desert, Devon Island, N.W.T., Canada

The thermal microenvironment and leaf temperatures of two plants (Saxifraga caespitosa and S. oppositifolia) were studied in a high arctic polar desert over four summers. Surface and plant temperatures exceeded air temperatures by 5 to 15°C during sunny periods, with smaller effects on soil temperature in plant rooting zones. Midday plant temperatures of 20 to 30°C measured during good weather are favorable for physiological activity, but the number of such days is restricted by a short snow-free period (16-45 d).Surfaces in polar deserts are dominated by sorted stones and bare mineral soil with sparse vascular plant cover (usually <5%). Infrequent snowflush sites are scattered within this landscape, containing greater plant cover and a cryptogamic crust on the mineral soil surfaces. The potential role of this black crust in facilitating greater plant cover by enhancing the thermal relations of plants was investigated in this cold environment. Reduced albedo of crusted surfaces led to higher surface (8-12°C) and soil (4-5°C) temperatures than in noncrusted areas. However, adult plants did not differ in tissue temperature on cryptogamic and bare surfaces. Root growth and survival of seedlings, which were thermally coupled to the surface by their small mass, are more likely to be highly influenced by the presence of crusted surfaces in this high arctic polar desert ecosystem.

Reproductive System and Population Structure in Three Arctic Saxifraga Species

Saxifraga cespitosa, S. tenuis and S. cernua were examined in the Abisko area, N Sweden. Populations of S. cespitosa were gynodioecious. Hermaphrodite individuals showed a high selfing efficiency and low pollen:ovule ratios, consistent with a lower outbreeding rate. Saxifraa tenuis was hermaphrodite with some indication of sexual asymmetry. Pollen:ovule ratios were low, but the ability to set seed by autodeposition was lower in S. tenuis than in S. cespitosa. Saxifraga cernua was androdioecious, with some populations that contained only female-sterile individuals and other populations with both female-sterile and hermaphrodite individuals. The higher production of bulbils by female-sterile individuals, coupled with self-incompatibility in hermaphrodites, suggests a means by which androdioecy may be maintained in S. cernua, in the absence of differences in male reproductive success between gender classes. Although all three species showed significant inter-population differentiation, the morphometric distances between populations were not related to the geographic distances between populations. Most of the total diversity in leaf shape was accounted for by inter-population differentiation in all three species, with <1% of the diversity due to variation within individuals. The mosaic pattern of variation in the three saxifrages is consistent with a scenario of localized founder effect and may still reflect patterns of recruitment after the deglaciation of the study area c8200BP. -from Authors (Less)

Growth Forms, Carbon Allocation, and Reproductive Patterns of High Arctic Saxifrages

Components of reproductive strategy are described for seven species of Saxifraga representing three important forb growth forms (dwarf erect, cushion, and rosette) in the High Arctic. Reproductive effort, flowering frequency, dispersal patterns, and carbon allocation (dry weight, caloric) to roots, leaves, and inflorescences were determined for each species. Although reproductive strategies could not be generalized for each growth form, three trends in carbon allocation and reproduction were apparent. Saxifraga cernua (dwarf erect forb), S. foliolosa (rosette), and S. flagellaris (rosette) had high carbon allocation to vegetative versus flowering tissue, and reproduced by vegetative means (bulbils, basal budding, stoloniferous bulbils). Saxifraga rivularis (dwarf erect forb) and S. nivalis (rosette) had a high carbon allocation to flowering versus vegetative tissue, reproduced by seed, and had a high ratio of immature to mature plants. Saxifraga caespitosa (cushion) and S. tenuis (rosette) had a high carbon allocation to flowering versus vegetative tissue, reproduced by seeds, and had a high ratio of mature to immature plants. These three reproductive patterns roughly follow those outlined in 1979 by other workers.

Flavonoid variation in some North Americna Saxifraga species

Eight species of Saxifraga representing sections Micranthes, Hirculus, Dactyloides and Xanthizoon were studied for their flavonoids ( S. california, S. integrifolia, S. michauxii, S. ferruginea, S. eschscholtzii, S. hirculus, S. caespitosa and S. aizoides). The major compounds present in most species were kaempferol and quercetin monogluocosides and galactosides. Glucosides of kaempferol and quercetin predominate in the first four species listed, while galactosides of quercetin and myricetin are dominant in the lastthree. 3- O-Methyl- and 3,3′-di- O-methylquercetin were identified from S. californica and S. integrifolia. Saxifraga caespitosa synthesizes a complex mixture of O-methylated flavonols as well as a novel O-methylated dihydrokaempferol.Species pairs S. michauxii/S. ferruginea and S. californica/S.integrifolia exhibit close flavonoid similarity which may reflect their morphological similarities.