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We report on a revisit in 2009 to sites where vegetation was recorded in 1967 and 1970 on Disko Island, West Greenland. Re-sampling
of the same clones of the grass Phleum alpinum after 39 years showed complete stability in biometrics but dramatic earlier onset of various phenological stages that were
not related to changes in population density. In a fell-field community, there was a net species loss, but in a herb-slope
community, species losses balanced those that were gained. The type of species establishing and increasing in frequency and/or
cover abundance at the fell-field site, particularly prostrate dwarf shrubs, indicates a possible start of a shift towards
a heath, rather than a fell-field community. At the herb-slope site, those species that established or increased markedly
in frequency and/or cover abundance indicate a change to drier conditions. This is confirmed both by the decrease in abundance
of Alchemilla glomerulans and Epilobium hornemanii, and the drying of a nearby pond. The causes of these changes are unknown, although mean annual temperature has risen since
1984. 相似文献
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Callaghan TV Tweedie CE Akerman J Andrews C Bergstedt J Butler MG Christensen TR Cooley D Dahlberg U Danby RK Daniëls FJ de Molenaar JG Dick J Mortensen CE Ebert-May D Emanuelsson U Eriksson H Hedenås H Henry H R G Hik DS Hobbie JE Jantze EJ Jaspers C Johansson C Johansson M Johnson DR Johnstone JF Jonasson C Kennedy C Kenney AJ Keuper F Koh S Krebs CJ Lantuit H Lara MJ Lin D Lougheed VL Madsen J Matveyeva N Mcewen DC Myers-Smith IH Narozhniy YK Olsson H Pohjola VA Price LW Rigét F Rundqvist S 《Ambio》2011,40(6):705-716
Understanding the responses of tundra systems to global change has global implications. Most tundra regions lack sustained environmental monitoring and one of the only ways to document multi-decadal change is to resample historic research sites. The International Polar Year (IPY) provided a unique opportunity for such research through the Back to the Future (BTF) project (IPY project #512). This article synthesizes the results from 13 papers within this Ambio Special Issue. Abiotic changes include glacial recession in the Altai Mountains, Russia; increased snow depth and hardness, permafrost warming, and increased growing season length in sub-arctic Sweden; drying of ponds in Greenland; increased nutrient availability in Alaskan tundra ponds, and warming at most locations studied. Biotic changes ranged from relatively minor plant community change at two sites in Greenland to moderate change in the Yukon, and to dramatic increases in shrub and tree density on Herschel Island, and in subarctic Sweden. The population of geese tripled at one site in northeast Greenland where biomass in non-grazed plots doubled. A model parameterized using results from a BTF study forecasts substantial declines in all snowbeds and increases in shrub tundra on Niwot Ridge, Colorado over the next century. In general, results support and provide improved capacities for validating experimental manipulation, remote sensing, and modeling studies. 相似文献
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