Plant Formations in the Kerguelenian BioProvince Peter Martin Rhind Kerguelenian Crassula maritime cliff formation Restricted to areas strongly influenced by salt-spray this vegetation is mainly characterized by the presence of the two succulent species Crassula moschata and Cotula plumosa. In the most saline areas just above high tide few other species apart from Ranunculus biternatus are found, but where groundwater permeates surface soil providing some freshwater influence species such as Callitriche antarctica and the mosses Clasmatocolea vermicularis and Eriopus apiculatus make their appearance. Areas strongly exposed to wind are typified by an increased frequency of the cushion plants Azorella selago and the endemic Colobanthus kerguelensis (Caryophyllaceae). Other species found scattered within the Crassula zone are Agrostis magellanica and various endemic bryophytes like Distichophyllum imbricatum, Lophocolea randii and Philonotis angustifolia, while On Iles Kerguelen the endemic Ranunculus pseudotrullifolius (Ranunculaceae) may be encountered growing in close association with Crassula moschata and Cotula plumosa. Kerguelenian Poa cookii Grassland Characterized by the endemic tussock grass Poa cookii (Poaceae), this vegetation is one of the southern hemisphere’s so-called ornithocoprophilus or bird guano loving communities found around seabird colonies and, in this case, penguin rookeries. It has a similar structure and ecology to the Poa foliosa and Poa flabellata communities found on other sub Antarctic islands like Macquarie, South Georga, Gough and Tristan da Cunha. There are no large herbivores so grazing is not an important factor, but trampling, especially by herds of elephant seals, can have a major impact. Consequently there are areas, often between tussocks of Poa cookii, where the vegetation has a pioneer character consisting largely of therophytes, particularly Callitriche antarctica and Montia fontana. Where there is less guano and trampling, other species may be found, notable mosses such as Brachythecium rutabulum, Leptodontium proliferum, Mielichoferia campylocarpa and liverworts like Marchantia berteroana and the endemic Lophozia cylindriformis. Other endemic liverworts associated with these grasslands are Andrewsianthus carinatus, A. lancistipus, Cephalozia randii and Metzgeria grollei. Kerguelenian Acaena magellanica wetlands Wetland vegetation characterized by Acaena magellanica typically forms along riverbanks and in springs and flushes. The few other vascular plants found here include Agrostis magellanica and the endemic Pringlea antiscorbutica (Brassicaceae), and these are often outnumbered by bryophytes. Typical species are Brachythecium subplicatum, Breutelia integrifolia, Drepanocladus uncinatus, Philonotis angustifolia, and several have bi-polar or cosmopolitan distrubutions, although the latter is endemic. Communities dominated by Acaena magellanica are recorded from most sub Antarctic islands, and in fact, on Kerguelen and Crozet, it forms the dominant vegetation over large parts of the lowlands. Kerguelenian Juncus scheuchzerioides oligotrophic mire Wherever drainage is impeded, the cool hyper-oceanic climate of these islands favours the formation of peat and extensive areas have developed on some islands. However, Sphagnum species, which form the foundation of important bog communities throughout much of World, are absent, and do not play a significant role in the mire vegetation of any of sub Antarctic islands. Juncus scheuchzerioides is the most conspicuous species of these mires, but despite this, bryophytes are still the most important peat-forming plants, and the role of Sphagnum has been largely replaced by species such as Copyright © 2010 Peter Martin Rhind Blepharidophyllum densifolium, Breutelia integrifolium, Drepanocladus uncinatus, Jamesoniella colorata and Racomitrium lanuginosum. Few other vascular plants are found in these mires although Lycopodium magellanicum is more or less confined to them. They do, however, provide habitat for a large number of other bryophytes including several endemic species such as Andrewsianthus marionensis, Jungermannia coniflora, Metzgeria marionensis, Plagiochila crozetensis, Ptychomnium ringianum and Symphyogyna marionensis. Kerguelenian Blechnum penna-marina swards On well drained relatively dry lowland slopes dense swards of the fern Blechnum penna- marina may occur. Stands of this species, many of which are almost monospecific, cover the largest part of the lowland slopes of Kerguelen, Marion and Prince Edward Islands. The few other associated vascular plants include Uncinia compactum. Bryophytes are also thin on the ground, but characteristic species include Campylopus polytrichoides, Isopterygium pulchellum var. antarcticum, Metzgeria decipiens and Plagiophyllum platyphyllum. Blechnum penna-marina is widespread in sub Antarctic and southern temperate regions and occurs on many of the sub Antarctic islands. Kerguelenian Azorella Fjaeldmark Fjaeldmark is an open vegetation of sporadic, stunted, often cushion forming flowering plants and bryophytes usually accompanied by lichens. They develop wherever the climate is sufficiently harsh to prevent the formation of closed vegetation, and typically occur in cold, windy upland areas sometimes described as ‘wind-deserts’ On Marion and Prince Edward Islands they cover large areas between 100-500m above sea level. However, despite the severe conditions, these are some of the most species-rich parts of this BioProvince. The most conspicuous plants are the cushion forming flowering plant Azorella selago and the mosses Andreaea acutifolia and Racomitrium crispulum. The cushion forming moss Ditrichum strictum is also distinctive. Among the other characteristic taxa are several endemic or near endemic bryophytes including Grimmia kerguelensis, Psilopilum cf. tristaniense and Verrucidens microcarpus. An interesting feature of the vegetation is the occurrence of completely spherical colonies of moss, which are free to blow around in the wind. Species such as Andreaea regularis, Ditrichum strictum and Holodontium pumilum have all been recorded as ‘moss balls’. It is not completely clear how these form but because they seem to be confined to cold climates it has been suggested that the instability of the substratum as a result of cryoturbatic processes is one of the causative factors. Azorella selago fjaeldmark occur on a number of sub Antarctic islands. Kerguelen also has a form fjaeldmark dominated by the endemic species Lyallia kerguelensis (Caryophyllaceae) and Poa kerguelensis (Poaceae). Further information required. References Bergstrom, D. M. & Chown, S. L. 1999. Life at the front: history, ecology and change on southern ocean islands. Tree, 14: 472-477. Chapuis, J. L., Frenot, Y. & Lebouvier, M. 2004. Recovery of native plant communities after eradication of rabbits from the sub Antarctic Kerguelen Islands, and the influence of climate change. Biological Conservation, 117: 167-179. Copyright © 2010 Peter Martin Rhind Frenot, Y., Gloaguen, J. C., Cannavacciuolo, M. & Bellido, A. 1998. Primary succession on the glacier forelands in the sub Antarctic Kerguelen Islands. Journal of Vegetation Science, 9: 75-84. Gremmen, N. J. M. 1982. The vegetation of the sub Antarctic islands Marion and Prince Edward. Dr W. Junk Publishers. Grolle, R. 2002. The Hepaticae and Anthocerotae of the sub Antarctic and temperate islands in the eastern Southern Hemisphere - an annotated list. Journal of Bryology, 24: 57-80. Kidder, J. H. 1876. Contributions to the natural history of Kerguelen Island made in connection with the United States transit-of-Venus Expedition, 1874-75. Bulletin of United States National Museum, No. 3. Scott, J. J. 1990. Changes in the vegetation on Heard Island 1947-1987. In: Antarctic Ecosystems. Ecological Change and Conservation. Eds. K. R. Kerry and G. Hempel. Springer-Verlag. Smith, H. G. et al. 1974. A biological survey of St Paul’s Rocks in the equatorial Atlantic Ocean. Biological Journal of the Linnaean Society, 6: 89-96. Wace, N. M. 1960. The botany of southern oceanic islands. The Royal Society Expedition to Southern Chile. Proceedings of the Royal Society, 152: 475-490. Wace, N. M. 1965. Vascular Plants. In: Biogeography and Ecology in Antarctica. Eds. Mieghem, J. Van, Oye, P. Van and Schell, J. Dr Junk Publishers. The Hague. Copyright © 2010 Peter Martin Rhind .