A 1977 tundra fire burned a hillslope where prefire soils and vegetation ranged from poorly drained moist tussock-shrub tundra on the lower slopes to well-drained dwarf shrub tundra on the back slope and very poorly drained wet sedge meadow on the flat crest. We sampled the vegetation on this slope before the fire and at 8 sites following the fire at irregular intervals from 1 yr to 25 yr. During the first decade after the fire, short-term recovery was dominated by bryophytes, sedges, and grasses from both regrowing sedge tussocks and seedlings. However, during the second and third decade, and by 24 yr after the fire, evergreen (Ledum palustre) and deciduous shrubs (mainly Salix pulchra willow) expanded dramatically so that shrub cover was generally higher than before the fire. Labrador tea has increased by vegetative means on the poorly drained lowest 3 tussock-shrub tundra sites. Upslope on the better-drained and more severely burned tussock-shrub and dwarf shrub tundra sites, willows became established from seed mainly during the first 10 yr after the fire and, based on their relatively large size (0.5–1 m tall) and cover, have grown rapidly during the past 15 to 20 yr. There has been very little or no recovery of Sphagnum moss and fruticose lichens after 24 yr at any site, except for Sphagnum moss in the wet meadow site. The permafrost active layer thickness has diminished to prefire levels at the lower slope tussock-shrub tundra sites but is much greater or degraded completely on the steeper slope, corresponding with the distribution of willow shrub colonization. These changes in tundra vegetation and permafrost following fire suggest that such fires could accelerate the predicted effects of climate warming on ecosystems in the Arctic.

Our study examined carbon dioxide exchange and nitrogen cycling over two consecutive years (winter and summer) in a grazed alpine grassland and in an embedded long-term grazing exclosure to ascertain whether grazing history had resulted in divergent soil carbon attributes, CO₂ exchange rates, and different vegetation C and N and soil N processes. Soil C and N concentrations and masses were significantly higher in the grazed than in the ungrazed area, though grass leaf N was higher in the ungrazed area, as was vegetation biomass. Detectable amounts of CO₂ were lost from the grazed and ungrazed areas of this grassland during the winters of 1998, 1999, and 2000, and at 6 of 15 winter flux sample dates, CO₂ efflux was greater in the grazed area than in the ungrazed area. The ungrazed area consistently gained more C during the summer months than the grazed area, with net CO₂ exchange peaking in mid-July 1998 at nearly 5 μmol m⁻² s⁻¹ in the ungrazed area compared to <2 μmol m⁻² s⁻¹ in the grazed area. During the 2-yr study period, the grazed area was a carbon source of 170 g C m⁻², while the ungrazed area was a carbon sink of 83 g C m⁻². Lower N mineralization rates early and late in the summer (1999) in the grazed site at Libby Flats corresponded to reductions in net CO₂ exchange and lower plant N content compared to the ungrazed exclosure. Based on these results, we suggest that: (1) long-term grazing in high-altitude rangelands can alter annual CO₂ exchange and N dynamics; (2) temporal synchrony in C and N processes occur during the summer; that is, increased C exchange rates accompany increased N mineralization rates; and (3) integrative (total soil C and N) and instantaneous (CO₂ exchange and vegetation N) measures of C and N dynamics may not necessarily lead to the same interpretation regarding C sequestration and N cycling in alpine grasslands.

Kärkevagge, an alpine ecosystem in the subarctic, has been the subject of scientific study for half a century. We investigated the relationship of its vegetation to soil properties. At the lowest elevations, on stable portions of the landscape dominated by Betula and Empetrum, are found Spodosols developed in glacio-fluvial sediments. Cryosaprists occur in scattered bedrock depressions with bog-type vegetation. Cryofluvents are found in flood-prone areas covered by dwarf-willow thickets. Intermediate elevations have meadow-type vegetation with Cryofluvents on floodplains and on lower colluvial slopes, Cryaquents in wetter areas, and Cryorthents on steeper soliflucted slopes. Above that, on steep, west-facing Dryas-covered colluvial slopes, soils are Ca-rich Eutrocryepts and Haplocryolls. The highest-elevation soils are infertile with poor horizonation, despite their possible antiquity, and vegetation that is largely cryptogams. Dystrocryepts occur on more stable alpine locations; Cryorthents on soliflucted areas; and Haploturbels, with shallow permafrost, above 1400 m. Measured annual soil temperatures range from 2.4°C at a Dryas site to −3.4°C at 1585 m at an alpine cryptogam site. Vegetation distribution in Kärkevagge is related to climatic factors, which are controlled by elevation and landscape position, and edaphic factors, which control soil moisture and nutrient availability.

Meziadin Lake (34 km², 133 m maximum depth) is located on the east side of the Coast Mountains in northern British Columbia. Inflow from Strohn Creek is dominated by the nival flood, despite a glacier cover of 50.5 km² in the drainage basin. The nival flood generates turbid underflows in the lake that distribute sandy mud within 2 km of the point of inflow. During our study in 1999, turbidity currents and interflows along the thermocline continued intermittently through the summer, although the inflow of water and the suspended sediment loads decreased substantially. Sediment collected in traps throughout the lake indicate mass accumulation rates in the proximal region in excess of 200 g m⁻² d⁻¹ (11 mm) averaged over 69 d of observation during summer 1999, decreasing downlake to 1 g m⁻² d⁻¹ (0.06 mm) in the most distal region of the lake. The sediment trapped near the point of inflow has a strong mode of fine sand and is strongly negatively skewed, reflecting the competence of the turbidity currents. Texture of the sediments deposited on the lake floor decreases distally from material dominated by coarse silt and fine sand to clay sized material. Sub-bottom acoustic data document more than 180 m of accumulation in the proximal region, decreasing to <20 m distally, making the mean rates of accumulation since deglaciation (16 and 1.8 mm yr⁻¹, respectively) somewhat greater than those at present. This decrease is associated with changing environmental conditions and diversion of a significant portion of the drainage basin associated with the retreat of Strohn Glacier in the 20th century.

In the Aigue Agnelle Valley (Queyras, southern French Alps), between 2200 and 2300 m a.s.l., several travertine deposits are present. Some, containing leaf imprints and pine cones, have been dated back to the early Holocene. Others containing charcoal fragments and dating back to the middle Holocene have also been found. The study of the plant imprints and charcoal within these travertines allowed us to reconstruct the vegetation dynamics of this valley. During the early Holocene (9800 B.P.), Pinus uncinata (mountain pine) was the most common tree. It was gradually replaced by Pinus cembra (arrola pine) in association with Betula (birch) and Vaccinium sp. (berry), probably as a result of climatic warming (ca. 7600 B.P.). Since ca. 5600 B.P., Pinus cembra seems to have regressed in correlation with the development of Larix decidua/Picea abies (larch/spruce) as a consequence of fire events related to climatic and/or anthropogenic factors.

Despite the international reputation of Lesotho's severely eroded landscape, there have been no previous quantitative accounts of soil erosion processes and associated consequences from the alpine belt. This paper examines sedimentological, geomorphological, and geoecological controls and processes following gully development within alpine mires in eastern Lesotho. Contemporary gully extension is controlled by exposure to various sedimentary sequences, by gully sidewall crack development, and by topographic aspect. Significant vertical gully denudation rates of 8 cm (mineral sediment) to 13 cm (peat) were recorded over an 18-mo period. During a 5-d field experiment in July 1999, the continuously frozen south-facing gully walls recorded considerable horizontal movement of peat blocks (avg. = 19.8 mm/5 d), whereas needle ice–induced horizontal particle movement rates on north-facing walls averaged 10.2 mm/5 d. Soil moisture transect data show a pronounced reduction in surface soil moisture toward and between the gullied areas of a mire. The percentage of moisture loss toward midwinter was found to be greater between the gullies (47.4%) than in the adjoining zones, where moisture loss averaged 33.6%. Similarly, vegetation transects indicate a reduction in vegetation cover at the drier and more intensely burrowed (by Otomys, or “ice rats”) zones close to the gullies. Invasive dwarf Karroid shrubs (e.g., Chrysocoma ciliata) are now establishing themselves alongside gullies, burrowed sites, and fringe areas of mires. We found that dryland plant invasions around grazing posts and heavily grazed areas on the slopes subsequently spread along alpine hydrological systems, particularly where gully erosion has created a suitable habitat.

Glacial deposits are identified from within and near Sinks Canyon, southwest of Lander, Wyoming, representing 6 first-order Pleistocene glaciations. Relative-age analyses of the deposits (including moraine morphology and soil development characteristics) indicate that they correspond to 4 glaciations previously identified from the Wind River Range (Pinedale, Early Wisconsin, Bull Lake, and Sacagawea Ridge) and to 2 older glacial events (Younger and Older Pre–Sacagawea Ridge). ¹⁰Be and ²⁶Al exposure ages associated with recessional Pinedale deposits are similar to those associated with recessional Pinedale deposits elsewhere in the range. ¹⁰Be and ²⁶Al exposure ages also support the identification of Early Wisconsin deposits here. The Early Wisconsin deposits represent the second locality where O-isotope stage 4 glacial deposits are described from the Wind River Range. Preliminary analysis of ¹⁰Be exposure data from the Older Pre–Sacagawea Ridge deposit suggests that a glacial advance occurred here before O-isotope stage 18 (>800 ka). If true, then Sinks Canyon contains the most complete record to date of glaciation in the Wind River Range and the only reported record of Pleistocene glaciation prior to O-isotope stage 18 in the Rocky Mountains.

There are few data on the effect of long-term manipulations on soil protozoa, and almost nothing is known about soil protozoa in Alaska. I studied the response of testate amoebae to nitrogen and phosphorus addition in an Arctic fen, at Toolik Lake Long-Term Experimental Research (LTER) Station, Alaska. Testate amoebae were extracted from Sphagnum mosses in control and fertilized plots. Of the 35 testate amoebae taxa recorded, 7 are first observations for the Arctic (excluding Russia) and 14 for Alaska. The total density and biomass of testate amoebae were significantly reduced, by 77% and 84%, in the fertilized plots. The structure of testate amoebae communities was also modified in those plots, although for most taxa the changes were not significant. Four taxa (Amphitrema flavum, Assulina muscorum, Placocista spinosa ssp. hyalina, and Hyalosphenia papilio) accounted for over half of the population in the control plots but only for 11% in the N and P plots. The densities of A. muscorum and Difflugia oviformis were significantly lower in the N and P–treated plots. The relative abundance and contribution to biomass of Centropyxis aerophila, Phryganella acropodia, and Tracheleuglypha dentata increased in the fertilized plots, while that of D. oviformis decreased. These effects suggest that testate amoebae respond to nutrient manipulations in the Arctic.

Once thought of as inert, ice has been increasingly recognized as a habitat suitable for life. The landscape of the MCMurdo Dry Valleys (MCM) of Antarctica is dominated by glaciers, and glacier melt is the primary water source for life in soils, streams, and lakes. The glaciers, despite their cold and lifeless appearance, offer functioning habitats for life. The major objective of this study was to examine biogeochemical characteristics of miniecosystems present in cryoconite holes and to determine links to other components (soils, streams, and lakes) of the dry valley landscape. We examined cryoconite holes from 5 glaciers spanning the length of Taylor Valley, one of many valleys in the MCM. Cryoconite biotic communities were composed of the same species observed in streams and lakes, namely, cyanobacteria (Chlorococcus, Chroococcus, Crinalium, Oscillatoria, Nostoc, and Sprirulina), rotifers (Philodina gregaria and Cephalodella catellina), tardigrades (Acutuncus antarcticus and Hypsibius spp.), and ciliates. Biotic communities did not reflect the composition of the immediately surrounding environments, suggesting the effects of eolian mixing and transport of sediments and biota across the valley. Gradients of chemistry and biotic abundance in cryoconite holes reflected the position of each glacier in the valley. Nitrogen and organic carbon concentration patterns across glaciers potentially resulted from biological activities in cryoconite holes. Properties of holes were stable from one to the next sampling season, suggesting that changes of cryoconite hole properties develop on longer than yearly time scales.

We quantitatively investigated a snow algal community on Tyndall Glacier of the Southern Patagonia Icefield, Chile, at an elevation from 300 to 1500 m a.s.l. We observed 7 species of snow and ice algae (Chlorophyta and cyanobacteria) on the glacier. These species were Mesotaenium (M.) berggrenii, Cylindrocystis (Cyl.) brébissonii, Ancylonema sp., Closterium sp., Chloromonas sp., Oscillatoriaceae cyanobacterium, and an unknown alga. The spatial distribution of these algae differed among the species. M. berggrenii, Cyl. brébissonii, Ancylonema sp., and Closterium sp. appeared mainly in the lower-elevation area (370–770 m a.s.l.), the unknown alga in the higher-elevation area (900–1500 m a.s.l.), and Chloromonas sp. and Oscillatoriaceae cyanobacterium in the middle part of the glacier. The mean cell concentration and total cell volume biomass ranged from 0 to 9.2 × 10⁴ (mean: 1.8 × 10⁴) cells mL⁻¹, from 0 to 327 (mean: 63) μL m⁻², respectively. The cell volume biomass generally decreased with altitude. The community structure showed that M. berggrenii was dominant in the ice area (65–100% of total cell volume) and lower snow area (50–70%) and that the unknown alga was dominant in the higher snow area (100%). The Simpson's species diversity index was significantly different among the study sites but was generally low (less than 1.9) at all sites. The cell volume biomass and diversity index are relatively smaller on the Patagonian glacier than those in algal communities on Alaskan and Himalayan glaciers. Lower nutrient levels in precipitation are likely to cause the smaller algal biomass on the glacier.

The value of glacier fluctuations as indicators of climate change detection has been increasingly recognized in recent years. Tropical glaciers are of particular interest. The Cordillera Blanca in Perú (77°30′W, 9°S) is the largest glaciated area within the tropics. Its 20th-century fluctuations have been analyzed. The total ice coverage around 1990 was obtained using optical satellite data SPOT XS. Based on the 1990 results, inventories and estimates of the glaciation during the 20th century had to be corrected. The data in this paper illustrate the general ice retreat in the tropical Cordillera Blanca: 620 km² in 1990, 660–680 km² in 1970, and 800–850 km² in 1930. The 1930 value documents the extent of glaciation shortly after an intense advance in the 1920s. The Little Ice Age extent is estimated as 850–900 km². The ice recession during the 20th century was not constant but was concentrated in two periods. Strong ice retreat occurred in the 1930s and 1940s and intermediate retreat from the mid-1970s until the end of the century. The ice coverage at the end of the 20th century is considered to be slightly below 600 km².

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.

Analysis of mass balance data from arctic mountain and subpolar glaciers with an aggregate area of more than 300*10³ km² reveals that these glaciers were the main source of increased freshwater inflow to the Arctic Ocean over the 1961–1998 period. The sum of net water inflow from glaciers was larger than net water inflow from rivers in the panarctic region, and the combined contribution from both glacier and land components had accelerated. Compared to the 1961–1990 averaged values, the largest combined contribution was observed at the end of the 1970s, declined in the 1980s, and began increasing again in the mid-1990s. Net glacier inflow supposedly increased due to Northern Hemisphere temperature warming. We attribute the increase in net river inflow to an increase in annual precipitation over the 50–70°N latitude belt in North America and Eurasia.

Subantarctic Marion island (46°S) is a shield volcano of basal “gray” lavas and younger “black” lava outflows. Rock weathering rates, as determined by annual mass loss from small clasts (<400 g), was measured over a 3-yr period at 4 sites on the island on an altitudinal transect from the coast toward the interior. Mass loss from gray lava clasts was found to be 0.02% near sea level, increasing to 0.10% yr⁻¹ at 730 m a.s.l. Black lava clasts yielded mean losses of up to 0.72% at the sites, although no altitudinal trend in mass loss was evident. In the sea-spray zone, gray and black lava clasts monitored over 1 yr had mean losses of 0.30% and 0.41%, respectively. Weathering rates are marginally inflated by the annual weighing procedure, which has been determined to contribute approximately 0.01% to the measured gray lava clast mass losses, and 0.07% to the black lavas. Since none of the clasts showed visual signs of fracturing or flaking, mass loss appears to be on a granular scale at most, and material removal is probably assisted by rainwash. Extrapolated values suggest that black lava clasts can weather completely within 200 yr and gray lava clasts within approximately 1000 yr at high altitudes. These data have implications for the lifespan of periglacial landforms constituting small clasts, particularly those formed in the early Holocene.

Snowmelt infiltration into alpine soils can be severely reduced and even impeded by soil frost. In order to learn more about the true nature of infiltration pathways into alpine soils, dye tracer experiments were set up at 2 locations in southern Switzerland: at Hannigalp (2100 m) and at Gd St Bernard. Over the course of two winters (2000–2001 and 2001–2002) we excavated vertical soil profiles during snowmelt to examine the distribution of a dye tracer (Brilliant Blue FCF) that had been applied on the surface of a 7-m² plot at the beginning of the winter. Soil conditions varied between the winters, with the soils remaining unfrozen during the first and a significant frozen layer forming during the second. With this method the dominant infiltration processes at these 2 sites were identified. During the first winter the water infiltration at Hannigalp showed a pronounced preferential behavior, whereas at Gd St Bernard we found a more homogeneous front-like infiltration. During the second winter the impeding impact of the frozen soil was clearly seen at the Hannigalp site—however, only in the first stage of the snowmelt. More decisive for the formation of lateral surface runoff was the buildup of an ice layer on the soil surface due to melting and refreezing. Cold-chamber experiments, in which intact soil columns were irrigated with a dye tracer and a fluorescent tracer solution, confirmed our in situ observations with regard to heterogeneity and soil frost effect on the infiltration pattern. Our study showed that both tracers can be applied to frozen soil in the laboratory, whereas at the remote alpine locations only the dye tracer method was applicable.