Mauro Guglielmin

Unexpected impacts of climate change on alpine vegetation

The vegetation in a high alpine site of the European Alps experienced changes in area between 1953 and 2003 as a result of climate change. Shrubs showed rapid expansion rates of 5.6% per decade at altitudes between 2400 m and 2500 m. Above 2500 m, vegetation coverage exhibited unexpected patterns of regression associated with increased precipitation and permafrost degradation. As these changes follow a sharp increase in both summer and annual temperatures after 1980, we suggest that vegetation of the alpine (2400–2800 m) and nival (above 2800 m) belts respond in a fast and flexible way, contradicting previous hypotheses that alpine and nival species appear to have a natural inertia and are able to tolerate an increase of 1–2°C in mean air temperature.

Antarctic climate change and the environment: an update

We present an update of the ‘key points’ from the Antarctic Climate Change and the Environment (ACCE) report that was published by the Scientific Committee on Antarctic Research (SCAR) in 2009. We summarise subsequent advances in knowledge concerning how the climates of the Antarctic and Southern Ocean have changed in the past, how they might change in the future, and examine the associated impacts on the marine and terrestrial biota. We also incorporate relevant material presented by SCAR to the Antarctic Treaty Consultative Meetings, and make use of emerging results that will form part of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report

ACCELERATING CLIMATE CHANGE IMPACTS ON ALPINE GLACIER FOREFIELD ECOSYSTEMS IN THE EUROPEAN ALPS

In the European Alps the increase in air temperature was more than twice the increase in global mean temperature over the last 50 years. The abiotic (glacial) and the biotic components (plants and vegetation) of the mountain environment are showing ample evidence of climate change impacts. In the Alps most small glaciers (80% of total glacial coverage and an important contribution to water resources) could disappear in the next decades. Recently climate change was demonstrated to affect higher levels of ecological systems, with vegetation exhibiting surface area changes, indicating that alpine and nival vegetation may be able to respond in a fast and flexible way in response to 1-2 degrees C warming. We analyzed the glacier evolution (terminus fluctuations, mass balances, surface area variations), local climate, and vegetation succession on the forefield of Sforzellina Glacier (Upper Valtellina, central Italian Alps) over the past three decades. We aimed to quantify the impacts of climate change on coupled biotic and abiotic components of high alpine ecosystems, to verify if an acceleration was occurring on them during the last decade (i.e., 1996-2006) and to assess whether new specific strategies were adopted for plant colonization and development. All the glaciological data indicate that a glacial retreat and shrinkage occurred and was much stronger after 2002 than during the last 35 years. Vegetation started to colonize surfaces deglaciated for only one year, with a rate at least four times greater than that reported in the literature for the establishment of scattered individuals and about two times greater for the well-established discontinuous early-successional community. The colonization strategy changed: the first colonizers are early-successional, scree slopes, and perennial clonal species with high phenotypic plasticity rather than pioneer and snowbed species. This impressive acceleration coincided with only slight local summer warming (approximately -0.5 degree C) and a poorly documented local decrease in the snow cover depth and duration. Are we facing accelerated ecological responses to climatic changes and/or did we go beyond a threshold over which major ecosystem changes may occur in response to even minor climatic variations?

Relationships between vegetation patterns and periglacial landforms in northwestern Svalbard

We studied the small-scale vegetation pattern in the high Arctic at Ny Ålesund to assess if the plant distribution was related to periglacial landforms. The whole area has been deglaciated for millennia but only a modest part of the area was covered by mature vegetation. The plant cover varied considerably in relation to ground patterning originated by periglacial processes, especially frost heave, frost creep, gelifluction and ice segregation, giving rise to a mosaic of microhabitats sharply differing from each other as regards physical properties and microclimate. The distributional patterns of vascular plants, lichens and bryophytes were primarily affected by complex responses to substrate texture, soil moisture content and substrate disturbance. Since global warming will probably affect both periglacial processes and plant responses to altered habitat conditions, we concluded that long-term monitoring of relationships between landforms and vegetation represents a suitable tool for assessing the impact of global change on arctic regions.

Searching for eukaryotic life preserved in Antarctic permafrost

Fungi and yeasts isolated in pure culture from Antarctic permafrost collected at different depths in the McMurdo Dry Valleys were identified with cultural, physiological and molecular methods. Fungi belonged to the genera Penicillium, Eurotium, Cladosporium, Alternaria, Engyodonthium, Aureobasidium, Cordyceps, Rhizopus and yeasts to the genera Cryptococcus and Sporidiobolus. All the strains can be defined as mesophilic psychrotolerant. The molecular analyses revealed that these fungal genotypes do not deviate from the global gene pool of fungi commonly spreading worldwide at present, but possible ancestral strains have been found on the base of metabolic profiles.

Primary succession of lichen and bryophyte communities following glacial recession on Signy Island, South Orkney Islands, Maritime Antarctic

Abstract A directional primary succession with moderate species replacement was quantitatively characterized on Signy Island in zones of a glacial valley corresponding to their age since deglaciation. A continuous increase in diversity and abundance of lichens and bryophytes was observed between terrains deglaciated in the late 20th century, to areas where deglaciation followed the Little Ice Age, and others thought to be ice-free since soon after the Last Glacial Maximum. Classification (UPGMA) and ordination (principal co-ordinate analysis) of vegetation data identified three different stages of development: a) pioneer communities, which rapidly develop in a few decades, b) immature communities developing on three to four century old terrains, and c) a climax stage (Polytrichum strictum-Chorisodontium aciphyllum community) developing on the oldest terrains, but only where local-scale environmental features are more favourable. Multivariate analysis including environmental parameters (canonical correspondence analysis) indicated terrain age as being the dominant controlling factor, with other environmental factors also exhibiting significant conditional effects (duration of snow cover, surface stoniness). These findings not only quantitatively verify reports of the rapid colonization of Maritime Antarctic terrains following recent climate amelioration and associated decrease in glacial extent, but also show how local-scale environmental resistance may slow or even prevent vegetation succession from pioneer to more mature stages in future.

Diversity trends of bryophytes in continental Antarctica

Bryophytes exhibit a decline in species richness with latitude across the sub-Antarctic islands, Antarctic Peninsula and Antarctic continent, but not within the Antarctic continent itself. We analyzed diversity and biogeographic patterns of bryophytes at intra-regional scale across the Ross Sector of continental Antarctica, also comparing the “coast” and “slope” provinces within this region, and placed these patterns in the context of bryophyte biogeography across Antarctica. Our study area included 63 sites along a transect through Victoria Land and the Transantarctic Mountains. Distributions of bryophyte species were collated from recent field surveys, the Antarctic Plant Database and the literature. Data analyses included rarefaction, hierarchical classification, multivariate analyses and description of richness trends by latitude bands. Despite an almost linear climatic gradient, bryophyte diversity in the Ross Sector is not influenced by latitude, and patterns differ depending on the scale of analysis. At local scale, diversity “hot spots” appear to be related to favorable local microclimatic conditions. At intra-regional scale, site location in the coast or slope province is the most effective predictor of bryophyte diversity. The site clustering within each province is consistent with precipitation and biogeographic separation of two sub-regions due to important dispersal barriers, as also reported for the microarthropod fauna. At continental scale, bryophyte diversity patterns among sectors suggest a continent–Antarctic Peninsula separation, consistent with the Gressitt Line, suggesting a common feature in the evolutionary history of the vegetation and invertebrate fauna. The high similarities of the floras of adjacent continental sectors suggest a potential route for bryophyte dispersal along the coast of continental Antarctica.

Changes in lichen diversity and community structure with fur seal population increase on Signy Island, South Orkney Islands

Abstract Signy Island has experienced a dramatic increase in fur seal numbers over recent decades, which has led to the devastation of lowland terrestrial vegetation, with the eradication of moss turfs and carpets being the most prominent feature. Here we demonstrate that fur seals also affect the other major component of this region’s typical cryptogamic vegetation, the lichens, although with a lower decrease in variability and abundance than for bryophytes. Classification (UPGMA) and ordination (Principal Coordinate Analysis) of vegetation data highlight differences in composition and abundance of lichen communities between areas invaded by fur seals and contiguous areas protected from these animals. Multivariate analysis relating lichen communities to environmental parameters, including animal abundance and soil chemistry (Canonical Correspondence Analysis), suggests that fur seal trampling results in the destruction of muscicolous-terricolous lichens, including several cosmopolitan and bipolar fruticose species. In addition, animal excretion favours an increase in nitrophilous crustose species, a group which typically characterizes areas influenced by seabirds and includes several Antarctic endemics. The potential effect of such animal-driven changes in vegetation on the fragile terrestrial ecosystem (e.g. through modification of the ground surface temperature) confirms the importance of indirect environmental processes in Antarctica.

An Old Relict Glacier Body Preserved in Permafrost Environment: The Foscagno Rock Glacier Ice Core (Upper Valtellina, Italian Central Alps)

Abstract This paper shows the results of chemical and crystallographic analyses carried out on a core drilled within the frontal part of the Foscagno rock glacier in the Italian Alps. We use 58 vertical thin sections spaced along the massive ice core, found between depths of 2.5 and 7.65 m, to describe the ice fabric of the core. We also discuss the results of chemical analyses of more than 50 samples. The lower part of the massive ice core between 4 and 7.65 m shows a mean crystal size of 1.5 cm and a crystal shape predominantly elongated along the horizontal plane with c-axes. These characteristics are similar to those of firn ice. In contrast, the upper core between 2.5 and 4 m displays vertical elongation of large bubbles, indicating superimposed ice and the influence of melting and refreezing processes. The presence of a seasonal signal in sulfate distribution and the strong correlation between sodium and chloride in the lower part of the core confirm cold firnification without appreciable phase changes. This well-preserved glacier ice body is probably younger than 2200 ± 60 yr B.P., a minimum age for the rock glacier as indicated by the 14C age of a buried paleosoil, although the possibility that it may be older age cannot be excluded. The glacier ice body seems to be a relict of a former glacier preserved within a larger permafrost body that characterizes almost all of the rock glacier and also occurs beneath the massive ice. This finding points out that different types of ice can be preserved within a single rock glacier, reflecting a complex geological and paleoclimatic history.

Relationships between periglacial features and vegetation development in Victoria Land, continental Antarctica

Abstract The relationships between vegetation patterns and periglacial features and their underlying ecology are still poorly understood and lack specific investigations in Antarctica. Here we present the results of vegetation colonization of different types of sorted patterned ground and gelifluction features (lobes and terracettes) at four sites in northern Victoria Land. This paper aims to understand the relationships between vegetation and the most widespread periglacial features in Victoria Land, discuss the role of periglacial features and vegetation in determining the ground surface temperature, and assess whether periglacial features provide ecological niches for vegetation colonization and development. Vegetation patterns are influenced by the feature type, mainly relating to patterned ground and debris island versus gelifluction features. The relations between vegetation and the periglacial features investigated in continental Antarctic are similar to those described for the Arctic, although in this part of the Antarctic vegetation is exclusively composed of cryptogams. Frost heave, ground texture and relief associated with different types of periglacial features provide a range of ecological niches sustaining vegetation biodiversity. Our data confirm the importance of periglacial features in shaping flora and vegetation biodiversity, as previously assessed only for the soil fauna in continental Antarctic.