Studies of past vegetation from the inner fjords of the Svalbard archipelago have not previously been reported. This study assesses the potential of sediments retrieved from two sites in Petuniabukta, Billefjorden to track vegetation response to Quaternary climate change. The first sediment profile was retrieved from periodic lake on a 4 m a.s.l. marine terrace with a basal radiocarbon dated to 5 080 ± 30 BP, the second was retrieved from a depression in wet tundra on a 24 m a.s.l. marine terrace, which upper part was dated to 9 470 ± 30 BP. The study is primarily focused on macro- and micro−fossils. Pollen grains are present in very low concentrations. Macro−fossils were represented mostly by leafs and buds of Salix species and Dryas octopetala as well as the hybrid Salix herbacea x polaris . Fossil moss remains represent an important part of arctic ecosystems. Tardigrada remains were found in the sediments in high abundance whilst eggs and exuviae of at least six species were identified. The sediments are definitely suitable for the reconstruction of past conditions. However, it is necessary to take care not to focus at single type of analysis, as pollen analysis appeared uninformative and more information was obtained from plant macro − fossils (mosses, vascular plants). Little attention has been given to Tardigrada in the past, as they were overlooked and the preservation in sediments is usually very low.
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.
Vegetation was described in various spatial scales in the area of 37.8 km 2 including distinguishing vegetation units, vegetation mapping, recording phytosociological relevés (53), and completing species lists of vascular plants (86), mosses (124) and lichens (40). Phytosociological relevés were elaborated using ordination methods DCA and CCA. The relevés formed clusters corresponding well to a priori assigned vegetation units. Slope and stoniness significantly influenced the vegetation pattern. Despite the high latitude (nearly 80 ° N), the vegetation is rather rich in species. Non−native species do not expand. The moss Bryum dichotomum is reported for the first time from Svalbard archipelago.
The present contribution to lichen−forming and lichenicolous biota of northern− most Billefjörden (Petuniabukta area, central Spitsbergen, Svalbard) contains 40 species of lichens. Four species: Arthonia ligniariella, Candelariella lutella, Ochrolechia upsaliensis, Polyblastia pernigrata are new for the Svalbard Archipelago.