The breeding system and floral development were compared in mid-range (West Greenland) and marginal (North Iceland) populations of Campanula uniflora, a widespread high arctic species which is rare in large parts of its range. Seed set and germination were compared among outcrossed, passively and actively selfed, and control flowers. There were no significant differences in seed set or seed quality among treatments or populations. Seed viability was high and germination rapid following GA³ pretreatment in both populations, but germination was delayed by a week in the Icelandic seeds. The populations showed similar flowering phenology with a short and synchronized flowering period. While the population in Greenland had a floral development typical of the genus Campanula, the Icelandic flowers can be classified as pre-anthesis cleistogamous. Both populations appeared to be predominantly inbreeding, despite being protandrous with pollen released before the flower opened. This method of pollen deposition is interpreted as a secondary mechanism of reproductive assurance, securing seed production. This indicates that an evolutionary switch has occurred, from selection for outbreeding in the ancestral group toward inbreeding in the only truly high arctic species in the genus.

A 35 year chronology from 1965 to 2000 of the deposition of wind-blown sediment is constructed from snowpits for coastal southern Victoria Land, Antarctica. Analysis of local meteorology, contemporary eolian sedimentation, and mineralogy confirm a Victoria Valley provenance, while the presence of volcanic tephra is ascribed to an Erebus volcanic province source. Winter foehn winds associated with anticyclonic circulation are considered responsible for transporting fine-grained sediment from the snow- and ice-free Victoria Valley east toward the coast, while cyclonic storms transport tephra north along the Scott Coast. No trend could be identified in the occurrence of either tephra or wind-blown sediments sourced from the Victoria Valley and retrieved from the snowpits excavated on the Victoria Lower and Wilson Piedmont Glaciers. We infer this to indicate that the region has not undergone a significant change in weather patterns for at least the last 35 years. Our results also confirm the McMurdo Dry Valleys as a regionally significant source of wind-blown sediment.

Severe road-making disturbance of a New Zealand high-alpine cushionfield initiated a secondary succession which has been assessed against the adjacent undisturbed community with permanent transects over 24 yrs. The succession has recently (yrs 11–24) accelerated as areas of bare soil-stone pavement continue to be colonized. Total plant cover has increased on the disturbed sites over this period (from 36 to 48%) and is now within the range of that in the intact cushionfield (48–59%), while the early dominant graminoids, particularly Poa colensoi, are now declining as other species establish. Floristic richness in the recovering system (33 species) now exceeds that of the intact cushionfield (21–27 species) with establishment of nine apparently seral species plus several mainly cushion species characteristic of the undisturbed cushionfield. Transition probabilities among seven recognized cover states for the most recent period (1986–1999) further clarify the succession by showing the “other species” category increasing in importance at the expense of the other six states. This contrasts with the relative stability of the intact cushionfield where autotransitions predominate over the same period. The severe high-alpine environment rather than physical differences between the disturbed and undisturbed sites appears to be limiting the rate of succession toward the undisturbed state. Despite establishment of several characteristic cushionfield species, the still minor role of its dominant, Dracophyllum muscoides (1% vs. 26–32% cover), indicates that the succession remains far from complete. Among the various succession models, autosuccession is untenable given the establishment of nine apparently seral species; only the inhibition and intermediate disturbance hypotheses could be entertained with the results to date.

The colonization of the underside of rocks normally requires that the material is sufficiently translucent to allow the penetration of photosynthetically active radiation. We examined the underside of 950 opaque rocks in sixteen locations in the Arctic for hypolithic colonization by photosynthetic microorganisms. Greater than 90% of rocks were colonized. The mean width of the bands of colonization was 3.1 ± 1.9 cm on Devon Island, and 3.0 ± 1.6 cm on Cornwallis Island. The width of the bands of colonization was less in the interior of frost-sorted polygons compared to their edges (in the arctic location, 0.7 ± 0.8 and 3.6 ± 1.4 cm in the interior and at the edges, respectively), suggesting the importance of frost sorting in enhancing the penetration of light around the edges of rocks to their undersides, and thus allowing colonization by photosynthetic organisms. We observed a similar pattern of colonization in antarctic polygons. The hypolithic habitat provides protection from environmental extremes. We show that within the hypolithic habitat organisms are protected from UV radiation. From radiolabeled carbon uptake measurements we estimate the productivity of the arctic communities to be approximately 0.8 g m⁻² a⁻¹, potentially as high as above-ground productivity. We discuss the potential implications of climate change for these communities.

Specimens of the Arctic sympagic amphipod Gammarus wilkitzkii, which were collected in the ice-covered areas near Spitsbergen, Norway, were infested with protozoan epibionts in densities of 499 to 3346 individuals per amphipod. The epibionts belong to the five ciliate genera: Ephelota, Cryptacineta, Acineta and Podophrya (suctorian ciliates), and Epistylis (peritrich ciliate). In this study we present the first observations of epibionts on ice-associated crustaceans and provide a detailed description of morphological and taxonomical aspects of the different ciliate genera. Cryptacineta has not been found earlier in the marine environment. This ciliate showed the highest density values (215–2571 individuals per amphipod), followed by Ephelota (2–1302 ind./amphipod). The number of individuals of Acineta, Podophrya, and Epistylis did not surpass 240 ind./amphipod. Epibionts colonized all appendages and the entire body surface, but were most numerous on the anterior body part of G. wilkitzkii. The body length of the gammarid and the number of epibionts of Ephelota, Podophrya, and Epistylis were positively correlated. The highest density of epibionts was found on the anterior body parts with the antennae bearing up to 613 individuals. In contrast, the posterior body showed only little burden. The number of epibionts along the caput-telson axis of the amphipod body shows a decrease towards the posterior end of the amphipod. The highest degree of infestation was found on females, followed by juveniles and eventually, males. When grouping the 37 anatomical units (including left and right appendages) to 8 body “regions,” the pereiopods, as a whole, showed the highest density (39.25%), followed by the gnathopods (22.29%), and antennulae and antennae. Basibiont got infested with the sessile ciliates in the benthic and pelagic environment during the ice-free season and carried them along back to the sympagic ecosystem when colonizing the newly formed ice. Epibionts are therefore considered as indicators for bentho-sympagic coupling processes.

The 154-year (1850–2004) chronosequence of the Forni Glacier foreland has been studied by sampling ant, centipede, ground beetle, and spider species assemblages. Species numbers increase with terrain age along the chronosequence from 2 to 26 on the oldest soils. Thirty-nine species were collected; species richness and diversity (Shannon's Index) of communities are correlated to the year of soil deglaciation. Shannon Index values increase with sites deglaciated between 1 and 61 years ago; sites deglaciated between 61 and 78 years ago produce similar values, and those deglaciated 78 to 154 years ago show a further increase in diversity. Ground beetles and spiders are found at all sites, while ants and centipedes were associated with mature forest soils. On the glacier surface, pioneer species such as the wolf-spider Pardosa saturatior and the ground beetle Oreonebria castanea permanently inhabit the supraglacial detritus surviving on trophic resources. Wingless ground beetle species are associated with mature soils, especially those with high hydric stability. Open land species typical of primary succession are found in the pioneer and intermediate stages, while community assemblages found on older terrain are linked to forest vegetation structure and dynamics.

Atmospheric nitrogen (N) fixation is a key N input to arctic ecosystems, but relatively few estimates of annual N-fixation rates are available. We measured N-fixation of plant-soil cores by the acetylene reduction technique at different topographic positions in an upland tundra watershed, Imnavait Creek, through two growing seasons in order to evaluate spatial and temporal variation in N-fixation. We also examined the effects of light and temperature on N-fixation to estimate annual N-fixation rates of surface soil in this watershed using field meteorological data. Surface soil at Imnavait Creek had significant acetylene reduction potential throughout the watershed (generally 6 to 10 μmol C₂H₄ m⁻² h⁻¹), indicating that N-fixing organisms were present everywhere. Although acetylene reduction potential was roughly constant through the growing season, moisture, temperature and light intensity strongly affected the measured acetylene reduction rates in laboratory incubations. In addition, the relatively few samples that included the lichen, Peltigera apthosa, had significantly greater acetylene reduction potential, although the overall influence of Peltigera on N-fixation in this watershed seems to be small. The N input via N-fixation at Imnavait Creek was estimated at 80 to 131 mg N m⁻² yr⁻¹, indicating that N-fixation contributed 85 to 90% of total watershed N inputs.

We provide an index of successional status for arctic macrolichen communities based on a synthesis of literature reports. We amassed research from the past 50 years that studied lichen communities following disturbance, such as fire or grazing. Species scores were derived from these reports depending on when a particular macrolichen species appeared following disturbance. Weighted averaging of these data with a community matrix can create a successional score for each sample unit of interest. These scores can be used as a surrogate for community age estimates that are otherwise difficult to obtain from tundra environments above treeline. We test this approach using an example data set of macrolichen communities collected from the Bering Land Bridge National Preserve, Alaska. We found that our successional scores represented roughly 17 and 19% of the community variation, depending on whether the community data set was binary or quantitative. Abundance data tended to yield successional scores that were slightly higher (older) than those derived from a presence-absence data set. We recommend use of our successional metric for lichen communities throughout the arctic tundra to infer successional status of an area.

Changes in the amount of soil organic carbon (SOC) stored in arctic soils may influence the global carbon cycle and be an important feedback mechanism to global climate changes. In order to estimate the carbon stock and accumulation rates at Flakkerhuk on Disko Island in West Greenland, an 1800-ha study area was divided into land cover types using a satellite image. Total SOC was estimated to be on average 67.3 ton C ha⁻¹ (6.7 kg m⁻²) and the fen area contributing 42% of the total SOC. Soil profiles investigated at different terraces revealed that the SOC stock was significantly age-related, increasing six fold from a terrace dated to 7000 (BP) to one dated to 10,000 (BP). This equals an average soil C accumulation rate of 0.5 kg C m⁻² 100 yr⁻¹. This rate was compared to vegetation-specific accumulation rates in the last 7000 yr which were in the order of 0.05 kg C m⁻² 100 yr⁻¹ in heath and sparse vegetation, 0.4 in fen areas and between 2 and 5 kg C m⁻² the last 100 yr in the present salt marsh. The study shows the importance of landscape history and age when sampling and evaluating SOC stocks and provides estimates of arctic soil C accumulation rates during Holocene versus present rates.

This paper describes the results of a revegetation experiment involving partial removal of gravel fill followed by various revegetation treatments on five sites in the Prudhoe Bay Oilfield on Alaska's Arctic Coastal Plain. Gravel fill was removed to a residual thickness of approximately 25 cm. Revegetation treatments were transplanted tundra plugs and fertilizer; seeding with indigenous graminoids and fertilizer; seeding with native-grass cultivars and fertilizer; fertilizer only; and no treatment. We monitored surface stability, soil characteristics, and vegetation response from 1990 to 2003. Thaw settlement of 17–40 cm occurred over most areas (with >1 m over areas with ice wedges) between 1990 and 1997; sites had mostly stabilized by 2003. Soil properties important for plant growth generally were poor. The establishment of vegetation dominated by indigenous species was similar when adding only fertilizer as compared to also adding plant materials. Although total live vascular cover was similar among fertilized, tundra-plug transplant, and indigenous graminoid seed treatments (26.1–38.3%), species richness was highest for the indigenous graminoid seed and tundra-plug transplant treatments. The results from this study will drive decisions about planting and fertilization schemes for future North Slope rehabilitation projects.

Large populations of the threadleaf water-crowfoot, Ranunculus trichophyllus, were discovered in several high-altitude lakes in the Himalayas of Nepal in which the species did not occur as recently as 1987. One of the study lakes, at 4760 m, is the highest altitude from which an aquatic angiosperm has been reported. A canonical discriminant analysis suggests that the key environmental factors differing between vegetated and non-vegetated lakes among a chain of five interconnected water bodies are length of the ice-free season, conductivity, non-volatile suspended solids, and bicarbonate. We believe, however, that an increased length of the ice-free season is likely the controlling factor in the recent invasion by Ranunculus trichophyllus. Its range expansion is likely a signal of a warming alpine climate in our study area.

Terminus fluctuations of five glaciers and the correspondence of these fluctuations to temperature and precipitation patterns were assessed at Oregon's Mount Hood over the period 1901–2001. Historical photographs, descriptions, and climate data, combined with contemporary GPS measurements and GIS analysis, revealed that each glacier experienced overall retreat, ranging from −62 m at the Newton Clark Glacier to −1102 m at the Ladd Glacier. Within this overall trend, Mount Hood's glaciers experienced two periods each of retreat and advance. Glaciers retreated between 1901 and 1946 in response to rising temperatures and declining precipitation. A mid-century cool, wet period led to glacier advances. Glaciers retreated from the late 1970s to the mid-1990s as a result of rising temperatures and generally declining precipitation. High precipitation in the late 1990s caused slight advances in 2000 and 2001. The general correspondence of Mount Hood's glacier terminus fluctuations with glaciers in Washington and Oregon suggests that regional, decadal-scale weather and climate events, driven by the Pacific Decadal Oscillation, play a key role in shaping atmosphere-cryosphere interactions in Pacific Northwest mountains. Deviations from the general glacier fluctuation pattern may arise from local differences in glacier aspect, altitude, size, and steepness as well as volcanic and geothermal activity, topography, and debris cover.

Reindeer, Rangifer tarandus, live in subarctic and alpine environments with spatially and temporally heterogeneous resource distribution. In this study, we used a hierarchical approach to test whether reindeer responded to spatial heterogeneity during the plant growing season (divided into three distinct periods) in a mountainous subarctic environment in northern Sweden. A reindeer herd in northern Sweden was surveyed using radio-telemetry (8 female reindeer) and the selection of feeding habitats by observing individuals/groups (135 observations) using laser range-finding binoculars. Reindeer selected feeding areas (evaluated at 5-km grid size), as well as feeding habitats (evaluated at 0.5- and 1-km grid size) during spring, in response to high terrain ruggedness and habitat heterogeneity. Reindeer switched during summer to select against terrain ruggedness and habitat heterogeneity at the level of feeding habitats, while preferring southward facing habitats. During autumn, a broader spectrum of feeding habitats was used. We conclude that reindeer seem to adopt a hierarchical strategy in agreement with general foraging theory, and are capable of responding to seasonal changes in resource distribution occurring across spatial scales. Furthermore, our results support the idea that spatial heterogeneity is an important factor to large-sized herbivores at high and intermediate levels of habitat selection. Conservation of large continuous and undeveloped landscapes is an important management goal, as they provide a wide range of habitats necessary for animals such as reindeer that use large territories.

The aim of this study was to assess the influence of comparable unequal environmental conditions on primary vegetation succession in an alpine glacier valley by the means of transects. Two longitudinal transects were established along the glacier foreland of the Rotmoosferner, Tyrol, Austria, and two transverse transects were established across the valley on the 1923 and 1858 moraines. The progressions of alpha- and beta-diversity were compared, and vegetation data within the glacier foreland were analyzed. Moraine age emerged as the primary factor within a canonical correspondence analysis (CCA), while the second axis separated the two valley sides. A clearly differentiated development of plant communities became obvious especially within the early development stages. Early development of vegetation cover and alpha diversity was further developed on the shaded valley side, and progression of beta diversity differed significantly among the valley sides. The results indicate two different successional pathways, on both the qualitative and the quantitative level. These can be attributed to differences in the extent of solar irradiation (sunny vs. shaded side), lithology, geomorphic processes, and a multitude of other factors, reinforcing the dissimilarity between the valley sides. Our approach highlights the necessity of a deliberate sampling design within different glacier forelands sensitive to environmental conditions created by the topography that may impact comparisons among the forelands.

We provide a description of the structural and thermal characteristics of snow cover in the Snowy Mountains of southeast Australia. Using the snow classification system developed by Sturm et al. (1995), the snow cover in the Snowy Mountains is classified primarily as maritime in areas where there is sufficient accumulation, and as ephemeral at lower elevations and on ablating aspects. Maritime snow is generally deep (>100 cm), with a density >0.30 g cm⁻³. The snow-ground interface is maintained within 1°C of freezing and relatively high air temperatures promote equitemperature metamorphism throughout the winter. The formation of depth hoar (temperature gradient snow), which is considered to be important in facilitating the development of the subnivean space, does not occur under these conditions. Ephemeral snow is characterized by warm shallow snow that often melts before new snow is deposited. Basal melt is a common feature of snow cover in the Snowy Mountains throughout most of the winter. We reappraise the processes responsible for the formation of the subnivean space under Australian snow conditions and discuss the importance of these processes for understanding the ecology of fauna in the subnivean space. Our findings highlight the value of an explicit description of snow conditions to ecological research in snow-covered areas. As a minimum, researchers should provide a description of basic structural and thermal properties of the snow pack that would allow other researchers to view the work in an appropriate context.

Laminated sediments from Bolterskardet Lake on Svalbard provide a new 150-year record of heavy metals in the Arctic. Independent data of ¹³⁷Cs and ²¹⁰Pb indicate that these laminations are annually deposited varves. The high sedimentation rate and varved sediments make Lake Bolterskardet a good site for studying history of heavy metal pollution in the region. A suite of heavy metals (Pb, As, Cd , Cu, Cr, Co, Ni, and Sn) were studied. The variations of Cu, Cr, Co, and Ni concentrations show an inverse pattern with the median grain size. It suggests that the particle size has a significant role in the accumulation and enrichment of heavy metals in the sediments. In the concentration profiles of studied heavy metals, only Pb concentrations show a significant increase from the lower parts to the upper parts of the core. Profiles of “total,” “lithogenic,” and “anthropogenic” Pb flux also show an increasing pattern. Anthropogenic Pb flux varies between 0.1 μg cm⁻² yr⁻¹ and 12.3 μg cm⁻² yr⁻¹, with a mean value of 2.4 μg cm⁻² yr⁻¹. The anthropogenic Pb fluxes were relatively low at around 0.7 μg cm⁻² yr⁻¹ prior to 1945, slowly increased after 1945, and reached a sidestep (between 1940s and 1970s) with mean value of 1.8 μg cm⁻² yr⁻¹. Second high value period was between 1980s and 1990s with mean value of 5.9 μg cm⁻² yr⁻¹. The variation of anthropogenic Pb fluxes before 1970 in Bolterskardet Lake coincides with the sulfate record and Pb concentration data from Greenland snow and ice, and the acidity concentration in the Svalbard ice cores. However, the anthropogenic Pb fluxes during the last two decades show a rapidly increasing trend. This regional pattern may suggest that local source is an important factor for heavy metal contamination in Svalbard, and the complex of long-range transport contaminations for regional and global process.

Pollination ecology and habitat preference of Pedicularis species were studied in a transitional zone between subalpine coniferous forests and alpine meadows in northwestern Sichuan of China. Pedicularis species exhibited apparent preferences for different microhabitats. Species with long rostrate and contorted galea were nectarless and their mean corolla tube length ranged from 7 to 50 mm while species without long rostrate and contorted galea produced nectar and their corolla tube length averaged from 8 to 18 mm. Bumblebees were the sole pollinators of the studied species and five bee species pollinated seven Pedicularis species with one species pollinating all the Pedicularis species. Pollinators that visited nectariferous species had longer tongues than those that visited nectarless species and they spent longer time on nectariferous than on nectarless species. All Pedicularis species except for P. rex subsp. lipskyana were pollinated by worker bees. Pedicularis rex subsp. lipskyana was pollinated nototribically by worker, male and queen bumblebees through stigmatic contact with residual pollen on the left side of the bee's head. Morphology of pollinators, rather than pollinator species, may play the key role in diversification of Pedicularis. Microhabitats rather than pollination may be the separation barrier in propagation. Factors contributing to high diversity of Pedicularis need further study.

Meteorological records from about 30 British Navy ships that overwintered in the Canadian Arctic islands between 1818 and 1859 are the earliest detailed baseline of direct historical data in this region against which modern and future climate trends can be assessed. We describe the types of meteorological instruments and the observational methods employed aboard these ships. For measuring air temperatures, both mercurial and spirit thermometers were used. Observations of atmospheric pressure were made using marine and aneroid barometers. Wind direction and speed were also logged. The Royal Navy's ordered and disciplined daily regime was well-suited to regular scientific observations. Individual instruments on most Navy ships were calibrated against established Royal Observatory standards before and after expeditions. Many recording officers commented on the relative unreliability of spirit thermometers below the freezing point of mercury. Little contemporary written evidence exists regarding absolute accuracy or precision of meteorological instruments taken to the Arctic, but some calibration data are available to assess typical instrument errors between 32° and −38°F (0° and −39°C). Our comparison of minimum daily temperatures from four overwintering ships in 1853 and 1854 shows very high correlation coefficients. The mutual consistency of these records implies good instrumental precision. Although the absolute accuracy of temperatures recorded below the freezing point of mercury is in doubt, those above this point are relatively accurate. Guidance on the preferred methods of observing and recording were codified in, for example, the Admiralty's Manual of Scientific Enquiry (Herschel, 1851). Meteorological registers were regarded as official documents that were, as far as possible, required to be complete and no attempt was to be made to fill in missing data. The need to screen or cover instruments from both solar and terrestrial radiation was also recognized from the earliest expeditions. It was not until the 1850s that standardizing the exposure of thermometers was resolved through the introduction of louvered screens. This unique set of ships' meteorological registers presents opportunities to investigate a variety of meteorological parameters for the Canadian High Arctic in the 19th century, allowing quantitative assessment of change relative to contemporary climate.

Although arctic lakes rank among the most pristine ecosystems remaining on Earth, widespread paleoecological analyses have revealed rapid recent changes in lake ecology that largely surpass Holocene natural variability and that are generally attributed to climate warming since the end of the Little Ice Age. However, the possibility that climate is only one dimension of these unprecedented ecological shifts remains an untested possibility, especially given that current warming may not yet exceed maximum, naturally mediated, postglacial warmth. In this paper, we assess whether increased anthropogenic nitrogen (N) deposition from distant sources is contributing to directional changes in the biogeochemistry and ecology of two remote lakes on Baffin Island in the eastern Canadian Arctic. Paleolimnological analyses, including diatom assemblages and a suite of biogeochemical proxies (total organic matter, biogenic silica, organic N and C contents, and stable isotopic ratios) reveal a complex suite of progressive changes that are coherently expressed in both lakes. Diatom assemblages began to change as early as the mid-19th century, but major inflections in the biogeochemical proxies occurred significantly later, being most pronounced after 1950. Among these changes are increases in sediment organic matter, depletions of 2‰ in sediment δ¹⁵N, and decoupling of δ¹³C and δ¹⁵N signatures. It seems likely that climate warming, subsequently coupled to anthropogenic N deposition, is synergistically driving these ecosystems towards states for which no prior natural analogs exist.