Rock glaciers and the geomorphological evolution of deglacierizing mountains

Knight, Jasper; Harrison, Stephan; Jones, Darren

doi:10.1016/j.geomorph.2018.09.020

Cited by 103 publications

(73 citation statements)

References 106 publications

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“…Indeed, warmer temperatures will increase chemical weathering of bedrock minerals (e.g., calcite and apatite) which will subsequently alter water chemistry, particularly via increased N and P (Heath and Baron, 2014;Price et al, 2017). Rock glaciers, which are likely to be less affected by atmospheric warming and will therefore persist on the landscape longer than their surface counterparts (Knight et al, 2019), release solute-rich outflows into headwaters and labile C that can fuel heterotrophic production (Fegel et al, 2016(Fegel et al, , 2019. Thus, the ratio of surface:rock glacier meltwater in headwaters is likely to decline with solute concentrations in available water shifting toward levels typical of rock glaciers occurring simultaneously.…”

Section: Nutrientsmentioning

confidence: 99%

Ecological Stoichiometry of the Mountain Cryosphere

et al. 2019

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Roughly 10% of the Earth's surface is permanently covered by glaciers and ice sheets and in mountain ecosystems, this proportion of ice cover is often even higher. From an ecological perspective, ice-dominated ecosystems place harsh controls on life including cold temperature, limited nutrient availability, and often prolonged darkness due to snow cover for much of the year. Despite these limitations, glaciers, and perennial snowfields support diverse, primarily microbial communities, though macroinvertebrates and vertebrates are also present. The availability and mass balance of key elements [(carbon (C), nitrogen (N), phosphorous (P)] are known to influence the population dynamics of organisms, and ultimately shape the structure and function of ecosystems worldwide. While considerable attention has been devoted to patterns of biodiversity in mountain cryosphere-influenced ecosystems, the ecological stoichiometry of these habitats has received much less attention. Understanding this emerging research arena is particularly pressing in light of the rapid recession of glaciers and perennial snowfields worldwide. In this review, we synthesize existing knowledge of ecological stoichiometry, nutrient availability, and food webs in the mountain cryosphere (specifically glaciers and perennial snowfields). We use this synthesis to develop more general understanding of nutrient origins, distributions, and trophic interactions in these imperiled ecosystems. We focus our efforts on three major habitats: glacier surfaces (supraglacial), the area beneath glaciers (subglacial), and adjacent downstream habitats (i.e., glacierfed streams and lakes). We compare nutrient availability in these habitats to comparable habitats on continental ice sheets (e.g., Greenland and Antarctica) and show that, in general, nutrient levels are substantially different between the two. We also discuss how ongoing climate warming will alter nutrient and trophic dynamics in mountain glacier-influenced ecosystems. We conclude by highlighting the pressing need for studies to understand spatial and temporal stoichiometric variation in the mountain cryosphere, ideally with direct comparisons to continental ice sheets, before these imperiled habitats vanish completely.

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Section: Nutrientsmentioning

confidence: 99%

Ecological Stoichiometry of the Mountain Cryosphere

et al. 2019

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“…Among these, glacier-fed streams are typically the coldest and least physically stable, groundwater-fed springs the warmest and most stable, and snowmelt-fed streams intermediate between the two. Given their inorganic debris cover and/or subterranean nature, rock glaciers and other icy seep sources may be more buffered against warming atmospheric conditions than glaciers and perennial snowfields, making them less susceptible to climate change (Anderson, Anderson, Armstrong, Rossi, & Crump, 2018;Clark, Clark, & Gillespie, 1994;Knight, Harrison, & Jones, 2019). These "icy seeps" generally occur at geological transition zones, are cold like glacier-fed streams, but seasonally stable like groundwater-fed springs, and are most commonly fed by rock glaciers, masses of subterranean ice insulated by thick layers of inorganic debris (Janke, 2007(Janke, , 2013Millar, Westfall, & Delany, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…These "icy seeps" generally occur at geological transition zones, are cold like glacier-fed streams, but seasonally stable like groundwater-fed springs, and are most commonly fed by rock glaciers, masses of subterranean ice insulated by thick layers of inorganic debris (Janke, 2007(Janke, , 2013Millar, Westfall, & Delany, 2013). Given their inorganic debris cover and/or subterranean nature, rock glaciers and other icy seep sources may be more buffered against warming atmospheric conditions than glaciers and perennial snowfields, making them less susceptible to climate change (Anderson, Anderson, Armstrong, Rossi, & Crump, 2018;Clark, Clark, & Gillespie, 1994;Knight, Harrison, & Jones, 2019). In the contiguous United States alone, there may be more than 10,000 rock glacier features (Johnson, 2018) versus ~5,000 surface glaciers and perennial snowfields (Fountain, Glenn, & Basagic Iv, 2017).…”

Section: Introductionmentioning

confidence: 99%

Microbial assemblages reflect environmental heterogeneity in alpine streams

Hotaling

Foley

Zeglin

et al. 2019

Global Change Biology

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Alpine streams are dynamic habitats harboring substantial biodiversity across small spatial extents. The diversity of alpine stream biota is largely reflective of environmental heterogeneity stemming from varying hydrological sources. Globally, alpine stream diversity is under threat as meltwater sources recede and stream conditions become increasingly homogeneous. Much attention has been devoted to macroinvertebrate diversity in alpine headwaters, yet to fully understand the breadth of climate change threats, a more thorough accounting of microbial diversity is needed. We characterized microbial diversity (specifically Bacteria and Archaea) of 13 streams in two disjunct Rocky Mountain subranges through 16S rRNA gene sequencing. Our study encompassed the spectrum of alpine stream sources (glaciers, snowfields, subterranean ice, and groundwater) and three microhabitats (ice, biofilms, and streamwater). We observed no difference in regional (γ) diversity between subranges but substantial differences in diversity among (β) stream types and microhabitats. Within‐stream (α) diversity was highest in groundwater‐fed springs, lowest in glacier‐fed streams, and positively correlated with water temperature for both streamwater and biofilm assemblages. We identified an underappreciated alpine stream type—the icy seep—that are fed by subterranean ice, exhibit cold temperatures (summer mean <2°C), moderate bed stability, and relatively high conductivity. Icy seeps will likely be important for combatting biodiversity losses as they contain similar microbial assemblages to streams fed by surface ice yet may be buffered against climate change by insulating debris cover. Our results show that the patterns of microbial diversity support an ominous trend for alpine stream biodiversity; as meltwater sources decline, stream communities will become more diverse locally, but regional diversity will be lost. Icy seeps, however, represent a source of optimism for the future of biodiversity in these imperiled ecosystems.

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“…The terminal or lateral moraines are important clues to the past glacier extents and dimensions [13]. In the Himalayan glaciated regions, moraines are of greater significance in establishing the paleogeography [18,22] and paleo-climate [16,23,36]. In the glaciated Machoi Glacier valley, there are prominent and well-preserved lateral moraines that go downhill terminate in the River Drass.…”

Section: Morainesmentioning

confidence: 99%

Applying integrated remote sensing and field-based approach to map glacial landform features of the Machoi Glacier valley, NW Himalaya

2019

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Glacial landforms are important precursors of landscape's glaciological history. Such evidences are vital to understand the role of climate in shaping the earth's surface. The work presented in this paper is about the detailed geomorphological mapping of the Machoi Glacier valley in NW Himalaya in Drass, Jammu and Kashmir. The geomorphological map of the area at 1:6000 scale was generated by integrating detailed field data, collected using Global Positioning System and electronic total station, and the satellite remote sensing information. Most of the area was mapped on field; however, some inaccessible areas were mapped using high-resolution DigitalGlobe QuickBird imagery. Various landform features mapped in the study area include lateral and terminal moraines, serrate, basin ridge, crevasses, glacier accumulation and ablation, debris cones, drumlins, horn and outwash plain. The spatial information on the glacial landform features in the area is aimed to guide the reconstruction of paleo-glaciological setup using dating techniques and will ultimately improve the knowledge gaps about the glaciation in the NW Himalaya during the Pleistocene.

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Rock glaciers and the geomorphological evolution of deglacierizing mountains

Cited by 103 publications

References 106 publications

Ecological Stoichiometry of the Mountain Cryosphere

Ecological Stoichiometry of the Mountain Cryosphere

Microbial assemblages reflect environmental heterogeneity in alpine streams

Applying integrated remote sensing and field-based approach to map glacial landform features of the Machoi Glacier valley, NW Himalaya

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