Kieler terrestrisch-biologische Polarforschung

Vegetationskundler, Ökologen, Mikrobiologen und Bodenkundler aus Deutschland, die sich z.B. mit der Vegetation in der Antarktis beschäftigen wollten, haben sich bisher jeweils ausländischen Expeditionen, im Einzelfall auch einer deutschen geologisch-geophysikalischen Expedition der Bundesanstalt für Rohstoffe und Geowissenschaften, Hannover, (Ganovex II) angeschlossen. Dies erzeugte sehr bald gute Kooperationen mit Wissenschaftlern von Staaten, die eine terrestrische Antarktisstation unterhalten (bisher Argentinien, Australien, Chile, Neuseeland, Polen, Spanien, UK, USA). In dieser Saison 1997/98 startet ein von britischen Wissenschaftlern initiiertes Forschungsprogramm in Rothera (Adelaide Island, 68°S) mit Kieler Beteiligung. Es ist damit auch klar, daß immer nur einzelne deutsche Wissenschaftler mit kleinen Programmen Chancen fanden. Eine größere Initiative für ein koordiniertes terrestrisches Programm konnte so nicht entwickelt werden

Plant Activity under Snow and Ice, with Particular Reference to Lichens

In polar ecosystems primary producers have to cope with the very limited living conditions of the harsh climate. Vascular plants in the Northern Hemisphere extend to the northern-most edges of the continents, but only two taxa are present as far south as the Antarctic Peninsula region in the Southern Hemisphere. Lower plants, lichens in particular, become more important with increasing latitudes and form the dominant element of the Antarctic vegetation. Based on recent investigations and literature, this paper discusses to what extent lichens are better adapted to snow and ice than vascular plants. Vascular plants in high latitudes have high freezing tolerances but are photosynthetically inactive in winter (e.g., evergreen coniferous species), while lichens in a highly freezing-tolerant stage can be active and productive under winter conditions. Vascular plants can be active under snow but have no photosynthesis if the tissue is frozen. Recent in situ measurements indicate that lichens are able to photosynthesize at temperatures below -10C, apparently in the frozen state. It was recorded for coniferous trees at the arctic timberline. This uptake may reduce water stress in conifers but apparently has no relevance for metabolic activity. Water uptake from snow and metabolic activity at -10C are possible for lichens because they are able to photosynthesize at water potentials lower than -20 MPa. Although lichens are adapted to be active in snow at low temperatures, strong light on clear days may inhibit the photosynthetic apparatus.Key words: lichens, higher plants, water relations, life strategies, photosynthetic production, ice, snowDans les écosystèmes polaires, les producteurs primaires doivent s'accommoder des conditions de vie précaires dues à la rigueur du climat. L'habitat des plantes vasculaires de l'hémisphère boréal s'étend aux confins nordiques des continents, mais seuls 2 taxons sont présents à l'extrême sud de la région de la péninsule Antarctique de l'hémisphère austral. Plus la latitude augmente, plus les végétaux inférieurs, en particulier les lichens, prennent de l'importance et forment l'élément dominant de la végétation antarctique. S'appuyant sur des recherches et de la documentation récentes, cet article discute du degré auquel les lichens sont mieux adaptés à la neige et à la glace que les plantes vasculaires. Sous de hautes latitudes, ces dernières ont une tolérance élevée au gel mais sont inactives en hiver sur le plan de la photosynthèse (p. ex., les espèces conifériennes à feuilles persistantes), alors que les lichens, dans un état tolérant très bien le gel, peuvent être actifs et productifs en hiver. Les plantes vasculaires peuvent être actives sous la neige, mais elles ne font pas de photosynthèse si le tissu est gelé. Des mesures prises récemment in situ révèlent que les lichens peuvent faire la photosynthèse à des températures inférieures à -10 °C, apparemment dans un état gelé. On a aussi trouvé que l'échange photosynthétique de CO2 dans les thalles secs peut être activé par la neige durant le gel. On a aussi enregistré l'absorption d'eau durant l'hiver pour les conifères à la limite forestière arctique. Cette absorption peut réduire le niveau de stress hydrique dans les conifères, mais ne semble pas influer sur l'activité métabolique. À -10 °C, les lichens peuvent absorber l'eau à partir de la neige et avoir une activité métabolique en raison de leur capacité à réaliser la photosynthèse à des potentiels hydriques inférieurs à -20 MPa. Bien que les lichens soient adaptés pour être actifs dans la neige à de basses températures, une lumière excessive les jours dégagés peut empêcher l'appareil photosynthétique de fonctionner.Mots clés : lichens, végétaux supérieurs, rapports hydriques, stratégies de survie, production photosynthétique, glace, neig

Analysis of Unusual Sulfated Constituents and Anti-infective Properties of Two Indonesian Mangroves, Lumnitzera littorea and Lumnitzera racemosa (Combretaceae)

Lumnitzera littorea and Lumnitzera racemosa are mangrove species distributed widely along the Indonesian coasts. Besides their ecological importance, both are of interest owing to their wealth of natural products, some of which constitute potential sources for medicinal applications. We aimed to discover and characterize new anti-infective compounds, based on population-level sampling of both species from across the Indonesian Archipelago. Root metabolites were investigated by TLC, hyphenated LC-MS/MS and isolation, the internal transcribed spacer (ITS) region of rDNA was used for genetic characterization. Phytochemical characterization of both species revealed an unusual diversity in sulfated constituents with 3,3’,4’-tri-O-methyl-ellagic acid 4-sulfate representing the major compound in most samples. None of these compounds was previously reported for mangroves. Chemophenetic comparison of L. racemosa populations from different localities provided evolutionary information, as supported by molecular phylogenetic evidence. Samples of both species from particular locations exhibited anti-bacterial potential (Southern Nias Island and East Java against Gram-negative bacteria, Halmahera and Ternate Island against Gram-positive bacteria). In conclusion, Lumnitzera roots from natural mangrove stands represent a promising source for sulfated ellagic acid derivatives and further sulfur containing plant metabolites with potential human health benefits

ACTIVITY OF LICHENS UNDER THE INFLUENCE OF SNOW AND ICE (18th Symposium on Polar Biology)

A major aim of our investigations is to explain the adaptation of vegetation to the peculiar environmental conditions in polar regions. Our concept describes the main limiting and favorable factors influencing photosynthetic production of cryptogams, mainly lichens. Snow and ice-usually stress factors to the activity of plants-can be effectively used by lichens because of their poikilohydrous nature. Light, the basic driving force for photosynthetic activity, may be deleterious under certain circumstances of the cold environment. In moderate climates the summer season is most favorable to plant activity and production and is therefore called the growing season. In the continental Antarctic as well as in the high Arctic region the favorable light and temperature conditions during the summer period may not be as profitable to the productivity of lichens as expected because water is deficient. As in many arid regions, climatic conditions during transient seasons (early summer, fall) merit greater attention if lichen activity is considered and investigated. Our way of investigating this is to establish measuring systems that automatically record micro-environmental parameters and lichen activity over the whole annual period. Another is to investigate physiological responses of lichens to the environmental conditions with experiments mainly carried out in the field