There have been only a few truly integrated quantitative studies on sediment budgets and relief development in cold environments. For a combined quantitative investigation of the relevant denudative slope processes and stream work in the 7 km² catchment Hrafndalur, situated in a rhyolite area in the northern part of the Icelandic Eastern Fjords region (Austfirðir), information was collected on the absolute and relative importance of the different denudative processes. Integration of the six-year monitoring program with the analysis of Holocene storage elements using geophysical techniques allows estimates on Holocene process intensities in addition to the measured present-day sedimentary transfers. With respect to mass transfers, fluvial suspended sediment plus bed-load transport is most relevant and is followed by fluvial solute transport, rock and boulder falls, chemical slope denudation, mechanical fluvial slope denudation (slope wash), creep processes, avalanches, debris flows, translational slides, and deflation. Due to comparably high mechanical weathering and sedimentary transfer rates, postglacial modification of the Pleistocene glacially formed landscape is clearly more advanced than in the extended basalt areas of Austfirðir. Postglacial relief development is characterized by a valley widening due to the active retreat of rock walls and the formation of extended talus cones coupled with channel systems.

Proglacial outwash plains, or “sandar,” can be recognized to be a part of a geomorphic, sedimentary, and hydrological system. At a global scale, glacial meltwater regimes and hence proglacial fluvial systems are strongly determined by glacier basal water conditions and glacier behavior. At a catchment scale it is necessary to consider that proglacial fluvial sedimentation can have a range of frequency and magnitude regimes. This paper presents geomorphological and sedimentological data from Franz Josef Glacier and Fox Glacier sandar, which have adjacent catchments. We determine that glaciofluvial facies are the most abundant sediment-landform association at both sites. However, we also observe considerable intra-catchment variability with respect to the magnitude-frequency regime of fluvial deposition and the relative importance of fluvial processes for sandur character. Franz Josef Glacier sandur is relatively high relief and superficially composed of boulder bedforms that are laterally and longitudinally extensive. It has a sedimentology dominated by massive, poorly sorted sediments containing outsized clasts. Franz Josef Glacier sandur thus has a character consistent with formation by episodic high-magnitude fluvial flows, i.e. jökulhlaups. In contrast, Fox Glacier sandur is of low cross-section relief and comprises two distinct components: an aggrading braided river and paraglacial debris fan deposits. With the exception of the contemporary ice margin, Fox Glacier sandur is of significantly finer-grained material than that at Franz Josef Glacier. We suggest that the contemporary Fox Glacier sandur contains widespread evidence that refutes a hypothesis of high-magnitude episodic events. Additionally, contemporary paraglacial inputs from recently deglaciated valley walls at Fox Glacier are far more important to sandur sedimentation than water or sediment from Fox Glacier. These results present a conceptual model of the predominant contemporary land-forming processes within a glaciated tectonically active region with exceptionally high denudation rates. Intra-catchment variability has important implications for predicting sediment fluxes in response to hydro-climatic forcing.

Active denudation processes occurring on slopes in north and northwestern Iceland have contributed to the buildup of large colluvial cones. These processes have been active since around 10,000 ¹⁴C yr BP when the ice sheet retreated during the last deglaciation. Stratigraphic records provide information of the kind of sedimentary transfer processes that have been active on slopes through time. Vertical sections in colluvial cones in north and northwestern Iceland exhibit a characteristic stratigraphy with successions of material from mass-movements interbedded with soil horizons occurring throughout the Holocene, under periglacial conditions of varying intensity. The alternating organic and minerogenic units are indicators of phases of slope activity and stability.

The dating of the deposits is possible with tephrochronology and ¹⁴C dating. The quantitative analysis of sediment on colluvial cones shows the relative importance of aggradation due to slope processes vs. soil formation during the Holocene. Increasing accumulation rates have been observed over historical time since at least a.d. 1104. The clastic deposits observed in north and northwestern Iceland are thought to provide information on extreme events during the Holocene, as the occurrence of mass-wasting release cannot be clearly related to Holocene climatic trends.

The distribution of mountain permafrost in the northern hemisphere depends on topographic and climatic factors, ranging from the maritime conditions of Iceland over transitional conditions in southern Norway to continental conditions in Mongolia, and from alpine mountains to paleic mountains. This study discusses the different environmental factors that govern permafrost distribution based on personal studies and a literature review. It is hypothesized that the thermal state of the ground is an important parameter to understand the time and spatial scale of sediment transfer and landscape development in cold mountainous regions. This is exemplified for the cases of rock walls, glacier forefields, rock glaciers, and the case of sediment remobilization due to glacier advance. The authors propose that thorough knowledge of the ground thermal regime is an important basis for addressing sediment budgets in space and time.

Exceptional and persistent warm temperatures recorded during July 2007 at Cape Bounty, Melville Island, Canada (74°54′N, 109°35′W), resulted in rapid and deep active layer formation. The thickened active layer, together with up to 10.8 mm of rainfall in late July, resulted in widespread active layer detachments across the West watershed during 23–31 July. Mapping indicates that approximately 1.9% of the watershed was directly impacted by disturbances. By contrast, only two small detachments occurred in the adjacent East watershed.

The immediate fluvial impact of the detachments was primarily in the form of abrupt, short-lived rises in river turbidity, along with a more gradual increase in discharge and overall turbidity. Sediment transport pulses resulted from the hydrological connection of major detachment slides, most of which were upslope from the main channel. The largest detachment dammed the river over a length of 200 m, and resulted in an upstream pond and prolonged increased sediment transport. In total, the increased sediment transport during the last week of July amounted to an estimated 44.3 Mg, or 18% of the seasonal yield. While the detachments had an immediate and substantial impact on river conditions, erosion of unstable material is likely to have a sustained impact on watershed fluxes in future years.

Fieldwork within the framework of SEDAG (SEDiment cascades in Alpine Geosystems) has focused on hydrology, fluvial sediment transport dynamics, and hydrogeomorphological characteristics of the alpine river Partnach (Reintal Valley, Bavarian Alps, Germany). In August 2005 a dambreak flood occurred in the Reintal Valley. The contributing catchment area supplying material for bed load transport at the outlet of the catchment has been enlarged by more than 33% (4.3 km² 1.6 km²) due to lake infilling, and thus, reconnecting formerly disconnected parts of the catchment. Post-dambreak downstream variation of total and specific stream power, bed shear stress, and particle characteristics (size and shape) were determined and compared with pre-dambreak findings. As to our knowledge, results of pre- and post-dambreak fluvial-geomorphic investigations have not been published so far for an individual river. Results show high values for total and specific stream power in the post-dambreak regime. In addition, general trends for downstream decreasing in particle size, stream power, and bed shear stress show a degree of regularity after disturbance. Nevertheless, further adjustments of the Partnach channel system in response to the dambreak event are expected in the near future.

We have estimated the erosion of sediment and organic carbon input from the Kara Sea coast based on extensive mapping, geologic and cryolithologic investigations of coastal zone and seafloor sediments, and revision of previously published data. The amount of coastal sediment eroded into the Kara Sea was determined to be approximately 35 million tons. Twenty-seven million tons are attributed to solid material, 7.6 million to thawed ground ice, 0.4 million to organic carbon, and 0.3 million to soluble salts. The estimate of organic carbon input presented herein is 2.5-fold less than previously published elsewhere. The majority of organic carbon in marine clayey deposits was found to be present in an adsorbed form. Its quantity corresponds to the content of clay particles in Pleistocene sediments. Organic carbon content in clay marine sediments remains unchanged during freeze-thaw processes, indicating that this form of carbon is stable unless thermoerosion is taking place.

We investigated dietary variation during three winters in female Svalbard reindeer (Rangifer tarandus platyrhynchus) on the basis of rumen samples from animals culled in early and late winter during 2000–2002. The winter diet was compared to a late summer diet on the basis of samples from 1999, with variations in dietary composition in early and late winter among years also investigated. We conducted our assessment by identifying plant fragments in rumen samples using a point identification method. The effects of season and year on dietary composition of females were tested using non-parametric multifactorial MANOVA. During early winter, the diet seemed to be a function of both plant availability and plant quality, with the latter also highly important for the summer diet. During late winter, restricted forage availability due to snow cover seemed to have influenced dietary composition. We also found dietary variation among years both in early and late winter. We hypothesize that climatic effects previously found on the growth rate of Svalbard reindeer populations may be mediated through interannual variation in their diet where increased summer precipitation and winter rain may affect the dietary composition through decreased availability of forage biomass.

In this study, we created a database of 633 species collected from alpine meadows on the eastern Qinghai-Tibet Plateau, and considered the correlation of interspecific seed germinability variation with ecological, life-history, and phylogenetic background. We found that taxonomic membership accounted for the majority of the weighted germination index (WGI) variation (71%). The strong taxonomic effect suggests that WGI variation within taxonomic membership is constrained, and a large proportion of WGI variation is explained by life-history traits also correlated with taxonomic membership. The overlap does not negate the adaptive significance of the relationship between these life-history traits and germinability. In addition, the altitudes and habitats when considered first had no significant effect on seed germinability variation, but we found that there were significant interactions between altitudes (or habitats) and some phylogenetic groups. Although their interactions were all less than the main effects of phylogenetic groups, they could explain that the effect of phylogenetic constraint on seed germination was also impacted by environmental factors. Thus, we could not exclude the effect of longtime selection by environmental factors on seed germination, and we think interspecific seed germinability variation was affected by phylogenetic, life-history, and ecological factors together.

Pollen limitation (PL) is thought to be an important factor driving the evolution of floral traits in alpine plants. However, results of pollen supplementation experiments in alpine plants do not always show high levels of PL, and a general review of the importance of PL on alpine-plant reproduction is needed. We assessed to what extent alpine plants are pollen limited, and whether the intensity of PL differs between alpine and lowland species. Moreover, we assessed whether or not PL of alpine species depends on their reproductive system and, finally, whether the outcome of PL studies depends on whether supplemental-pollination was done at the whole-plant level or within a subset of available flowers. We performed both classical and phylogenetic meta-analysis. Our results show that alpine plants are pollen limited. However, PL did not differ significantly between alpine and lowland species. In the alpine, self-incompatible and self-compatible species show similar levels of PL. We did not find differences in PL between different manipulation levels. These results will help understand the real importance of PL of seed production in the alpine. We identify gaps in our knowledge of PL in the alpine that could serve to guide future directions of research in this field.

Seedling establishment is an important factor dictating the altitudinal limits of treeline species. Factors which affect seedling mortality and survival, however, have yet to be fully characterized, especially for deciduous treeline species. Here we describe microsite characteristics of successfully established Betula litwinowii seedlings at the alpine-treeline ecotone. Possible harmful effects of sky exposure on seedling physiology (i.e. photoinhibition of photosynthesis) were also examined, as well as possible facilitative effects of co-occurring Rhododendron caucasicum shrubs on northern slopes and microtopographical depressions (mainly watercourses) in ridgetop meadows. On northern slopes, seedling density was highest in newly exposed soils, with 90% of the youngest seedlings (<2 cm) occurring in patches of rocky, bare, or moss-covered soils within the Rhododendron thicket. R. caucasicum was not a significant source of shade for B. litwinowii, as most seedlings were established 0.25–0.5 m away from the nearest shrub, and shade cover generated by R. caucasicum was observed in only 1% of seedlings at midday. On ridgetops, density of B. litwinowii was sixfold higher inside microtopographical depressions compared to outside. Sky exposure of seedlings within depressions was similar to northern slopes, ranging from 50% to 87%. Across all microsites, seedlings were most abundant under 70–87% sky exposure. This preference for open microsites, combined with the observation that sustained photoinhibition of photosynthesis (F_v/F_m < 0.65) was observed only in the most open microsites (i.e. >80% sky exposure), suggests that sky exposure is likely not a significant factor affecting seedling mortality in B. litwinowii, in contrast to results reported for conifer and broadleaf evergreen species at treeline. A higher photosynthetic capacity and a deciduous life history may provide both tolerance and avoidance to the physiological stresses associated with high sky exposure for B. litwinowii seedlings, and other factors, such as soil moisture, more likely account for successful establishment within microtopographical depressions and R. caucasicum thickets.

Nitrogen availability is considered to be a key limiting factor for plant growth in arctic tundra. Freeze-thaw cycles, which can produce patterned-ground features, may also limit the establishment and growth of arctic plants. In this experiment, we fertilized nonsorted circles, a type of patterned-ground feature, and the surrounding more stable vegetation in moist nonacidic tundra of northern Alaska to determine if nitrogen availability limited plant communities on these disturbance-dominated features. Similar to other studies in moist nonacidic tundra, the fertilized stable vegetation showed an increase in graminoid biomass and a decrease in moss biomass, but no total biomass response. The plant communities on nonsorted circles were less responsive to the addition of nitrogen as compared to the well-vegetated rims. The nonsorted circle vegetation may be limited by additional factors, such as frost heave disturbance, availability of buried seeds, and/or other nutrients. This difference in fertilization response shows that the presence of these features creates spatial heterogeneity in tundra plant community dynamics that should be taken into account when studying tundra responses to environmental change.

Glacial erosion patterns on northwest Iceland are quantified using a Geographic Information System (GIS) in order to interpret subglacial characteristics of part of northwest Iceland affected by ice sheet glaciation. Ice scour lake density is used as a proxy for glacial erosion. Erosion classes are interpreted from variations in the density of lake basins. Lake density was calculated using two different methods: the first is sensitive to the total number of lakes in a specific area, and the second is sensitive to total lake area in a specific area. Both of these methods result in a value for lake density, and the results for lake density calculated using the two methods are similar. Areas with the highest density of lakes are interpreted as areas with the most intense erosion with the exception of alpine regions. The highest density of lakes in the study area exceeds 8% and is located on upland plateaus where mean elevations range from 400 to 800 m a.s.l. Low lake density (0–2%) is observed in steep alpine areas where steep topography does not favor lake development. The GIS analysis is combined with geomorphic mapping to provide ground truth for the GIS interpretations and to locate paleo-ice flow indicators and landforms. The patterns identified in this study illustrate distinct regions of glacial erosion and flow paths that are best explained by two independent ice sheets covering northwest Iceland during the Last Glacial Maximum (LGM). Areas of alpine glacial landforms and the presence of nunataks within the glaciated region support interpretations that ice-free regions or cold-based ice cover existed on parts of northwest Iceland during the LGM. The methods developed in this study are easily transferable to other formerly glaciated regions and provide tools to evaluate subglacial properties of former ice sheets. The data generated yield important subglacial boundary conditions for ice sheet models of Iceland.

We mapped Little Ice Age (LIA) moraines in the Brooks Range to estimate former equilibrium-line altitudes (ELAs), and combined this information with available proxy temperature estimates to infer precipitation trends because little is known about precipitation changes associated with centennial-scale climate variability in the Arctic during the late Holocene. The Brooks Range, northern Alaska (68°N), hosts hundreds of extant glaciers that exhibit geomorphic evidence for multiple fluctuations in ice extent during the past millennium. Our lichenometric age estimates for LIA moraines in the forefields of five cirque glaciers in the Sagavinerktok River valley and Oolah Valley suggest two intervals of LIA moraine formation centered around a.d. 1250 and 1650. The outermost LIA moraine was mapped on aerial photographs for 114 relatively large (1.2 ± 0.5 km) and geographically simple glaciers along a 700-km-long transect following the range crest. At their maximum extent during the LIA, these glaciers were an average of 0.2 ± 0.1 km longer than the ice margins shown on most recent U.S. Geological Survey topographic maps (1956 and 1972). The ELA was estimated using an accumulation-area-ratio method and GIS analysis. The reconstructed ELAs needed to maintain an equilibrium length for the LIA glaciers were an average of 51 ± 29 m lower than for the smaller glacier sizes of the mid 20th century. This small ELA lowering during the LIA is less than would be expected from available proxy temperature estimates from elsewhere in Alaska that indicate warm-season temperature reductions of about 1 °C. To explain this discrepancy, we suggest that precipitation decreased during the LIA. A prolonged southern displacement of the Arctic front might explain the drier conditions in the Brooks Range during the LIA.