One century of vegetation change on Isla Persa, a nunatak in the Bernina massif in the Swiss Alps

Abstract Question: How did the vascular plant species composition of a nunatak in the alpine vegetation belt change over a time span of 100 years? Location: A 5.6-ha nunatak, Isla Persa in the Swiss Alps, that remained ice-free during the last maximum glacier advance in the 1850s and is today partly covered with climactic alpine grassland and dwarf heath shrubs. Methods: Floristic inventories in 1906, 1927, 1972, 1995, 2003 and 2004 and a comparative analysis of the species composition over the period 1906–2004. Results: 31 species that were not recorded in the first inventory were found in the following surveys. However, among them only six were common by 2004. Generally, the new species prefer warmer conditions than those previously present and most newcomers are associated with montane or sub-alpine grasslands and woodlands. In particular, the observed increase of Vaccinium myrtillus and the arrival of shrub and tree species further substantiate a trend towards vegetation composition of the lower altitudinal belt. Ferns represented 26% of the newcomers, probably due to the high dispersal ability of their lightweight spores. The observed species enrichment was globally small compared to previously inventoried summits. Conclusion: Floristic change strongly suggests warmer climatic conditions as the main factor contributing to species compositional change. The relative stability of species richness may be explained by several factors: the isolation of the nunatak and the difficulties for plants to reach the site, the colder local climate, a limited available species pool and interactions of established alpine plants with newly immigrating taxa. Supplementary data collected at a similar altitude would be necessary to better understand the influence of climate change on alpine grasslands. Nomenclature: Aeschimann et al. (2004).

[1]  Michael Gottfried,et al.  Prediction of Vegetation Patterns at the Limits of Plant Life: A New View of the Alpine-Nival Ecotone , 1998 .

[2]  Antoine Guisan,et al.  How reliable is the monitoring of permanent vegetation plots? A test with multiple observers , 2007 .

[3]  E. Maarel,et al.  Pattern and process in the plant community: Fifty years after A.S. Watt , 1996 .

[4]  P. Choler,et al.  Increasing species richness on mountain summits: Upward migration due to anthropogenic climate change or re-colonisation? , 2007 .

[5]  Josep Peñuelas,et al.  A global change‐induced biome shift in the Montseny mountains (NE Spain) , 2003 .

[6]  C. Burga.  Vegetation development on the glacier forefield Morteratsch (Switzerland) , 1999 .

[7]  P. Vittoz,et al.  Flore alpine et réchauffement climatique: observation de trois sommets valaisans à travers le XXe siècle , 2006 .

[8]  G. Walther,et al.  Trends in the upward shift of alpine plants , 2005 .

[9]  J. Braun-Blanquet.  Ein Jahrhundert Florenwandel am Piz Linard (3414 m) , 1957 .

[10]  R. Harrison,et al.  Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. VII. Overview and discussion , 2001 .

[11]  Jan Lepš,et al.  How reliable are our vegetation analyses , 1992 .

[12]  R. D. Harrison,et al.  Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. V. Colonization by figs (Ficus spp.), their dispersers and pollinators , 2001 .

[13]  L. Kullman,et al.  Late Holocene reproductional patterns of Pinus sylvestris and Picea abies at the forest limit in central Sweden , 1986 .

[14]  R. Chevalier,et al.  Effects of sampling time, species richness and observer on the exhaustiveness of plant censuses , 2006 .

[15]  J. Camarero,et al.  Pace and Pattern of Recent Treeline Dynamics: Response of Ecotones to Climatic Variability in the Spanish Pyrenees , 2004 .

[16]  P. D. Körner.  Alpine Plant Life , 2003, Springer Berlin Heidelberg.

[17]  J. Ninot,et al.  Patterns of plant traits in Pyrenean alpine vegetation , 2006 .

[18]  Martin Zobel,et al.  Pattern and process in the plant community: fifty years after AS Watt. , 1995 .

[19]  A. Guisan,et al.  Assessing alpine plant vulnerability to climate change: a modeling perspective , 2000 .

[20]  Frédéric Médail,et al.  Species attributes and invasion success by alien plants on Mediterranean islands , 2005 .

[21]  H. Birks,et al.  Recent increases in species richness and shifts in altitudinal distributions of Norwegian mountain plants , 2003 .

[22]  Thomas Wohlgemuth,et al.  The upward shift in altitude of pine mistletoe (Viscum album ssp. austriacum) in Switzerland—the result of climate warming? , 2005, International journal of biometeorology.

[23]  Jean-Paul Theurillat,et al.  Flora alpina: Ein Atlas sämtlicher 4500 Gefässpflanzen der Alpen , 2004 .

[24]  J. Stöcklin.  Umwelt, Morphologie und Wachstumsmuster klonaler Pflanzen : eine Übersicht , 1992 .

[25]  Robin Engler,et al.  Seed dispersal distances: a typology based on dispersal modes and plant traits , 2007, Botanica Helvetica.

[26]  G. Walther,et al.  "Fingerprints" of climate change : adapted behaviour and shifting species ranges , 2001 .

[27]  C. Burga,et al.  Biomonitoring: General and Applied Aspects on Regional and Global Scales , 2001, Tasks for vegetation science.

[28]  H. Godwin,et al.  Verbreitungsbiologie der Blutenpflanzen. , 1956 .

[29]  G. Greer.  The influence of soil topography and spore-rain density on gender expression in gametophyte populations of the homosporous fern Aspidotis densa , 1993 .

[30]  Andreas Kääb,et al.  Rapid disintegration of Alpine glaciers observed with satellite data , 2004 .

[31]  Daniel Moser,et al.  Liste rouge des espèces menacées de Suisse : fougères et plantes à fleurs , 2002 .

[32]  T. Kučera,et al.  Scale‐dependent biases in species counts in a grassland , 2001 .

[33]  Text Och Foto,et al.  Förändringar i fjällens växtvärld - effekter av ett varmare klimat , 2003 .

[34]  Ruprecht Düll,et al.  Zeigerwerte von Pflanzen in Mitteleuropa , 1992 .

[35]  Gabriele Broll,et al.  Sensitivity and response of northern hemisphere altitudinal and polar treelines to environmental change at landscape and local scales , 2005 .

[36]  M. Sturm,et al.  Climate change: Increasing shrub abundance in the Arctic , 2001, Nature.

[37]  Gian-Reto Walther,et al.  An ecological ‘footprint’ of climate change , 2005, Proceedings of the Royal Society B: Biological Sciences.

[38]  M. Rebetez,et al.  Monthly air temperature trends in Switzerland 1901–2000 and 1975–2004 , 2008 .

[39]  G. Grabherr,et al.  Patterns and Current Changes in Alpine Plant Diversity , 1995 .

[40]  Stefan Dullinger,et al.  A regional impact assessment of climate and land‐use change on alpine vegetation , 2003 .

[41]  A. Tolvanen,et al.  Plant traits: Their role in the regeneration of alpine plant communities in sub-arctic Finland , 2005 .

[42]  A. Taylor.  Forest expansion and climate change in the mountain hemlock (Tsuga mertensiana) zone , 1995 .

[43]  S. Shiyatov,et al.  Vegetation Dynamics at the Treeline Ecotone in the Ural Highlands, Russia , 2003 .

[44]  G. Grabherr,et al.  Signals of range expansions and contractions of vascular plants in the high Alps: observations (1994–2004) at the GLORIA * master site Schrankogel, Tyrol, Austria , 2007 .

[45]  M. Ret,et al.  Vegetation responses in Alaskan arctic tundra after 8 years of a summer warming and winter snow manipulation experiment , 2005 .

[46]  G. Rossi,et al.  Upward migration of vascular plants following a climate warming trend in the Alps , 2008 .

[47]  G. Grabherr,et al.  Long-Term Monitoring of Mountain Peaks in The Alps , 2001 .

[48]  Gian-Reto Walther,et al.  Plants in a warmer world , 2003 .

[49]  J. Schaminée,et al.  Dispersal potential in plant communities depends on environmental conditions , 2004 .

[50]  M. Westoby,et al.  Seed dispersal spectra: a comparison of temperate plant communities , 1990 .

[51]  J. Stöcklin,et al.  Seed rain, seedling establishment and clonal growth strategies on a glacier foreland , 1996 .

[52]  Pascal Vittoz,et al.  Effects of Climate and Land-Use Change on the Establishment and Growth of Cembran Pine (Pinus cembra L.) over the Altitudinal Treeline Ecotone in the Central Swiss Alps , 2008 .

[53]  G. Grabherr,et al.  High summits of the Alps in a changing climate , 2001 .

[54]  Joy B. Zedler,et al.  Effects of sampling teams and estimation methods on the assessment of plant cover , 2003 .

[55]  R. Macarthur,et al.  The Theory of Island Biogeography , 1969 .

[56]  H. Hofer.  Veränderungen in der Vegetation von 14 Gipfeln des Berninagebietes zwischen 1905 und 1985 , 1992 .

[57]  G. Grabherr,et al.  Climate effects on mountain plants , 1994, Nature.