Holocene Development and Permafrost History of the Usinsk Mire, Northeast European Russia

This study discusses Holocene vegetation succession, permafrost dynamics and peat accumulation in the Usinsk mire, located in the Pechora lowlands of Northeast European Russia. At present, the area is situated in the extreme northern taiga subzone near the southern limit of permafrost. Reconstructions are based on plant macrofossil analysis, physico-chemical analysis and AMS (accelerator mass spectrometry) radiocarbon dating of two peat profiles investigated in detail. Additional information is available from seven other sites. Organic accumulation started at ca. 11 350 BP (14C yrs). Terrestrialization of ponds was the most common pathway for mire initiation. During a large part of their history, the sites have been Cyperaceae-dominated fens. A change into Sphagnum-dominated ecosystems is recorded at 3700-3000 BP. Permafrost became established around 2300 BP, although first signs of embryonic palsa formation can be tentatively traced back to about 2900 BP. Palsas and peat plateaus have experienced several periods of freezing and entire or partial thawing. The extant permafrost stages are young. The long-term carbon accumulation rate in the investigated sites is 19 g/m2/yr. The average rate of carbon accumulation in the dynamic permafrost stage is 23 g/m2/yr.Cette étude discute de la succession de la végétation, de la dynamique du pergélisol et de l'accumulation de la tourbe à l'Holocène dans la tourbière d'Usinsk, située dans les basses terres de Pechora, au nord-est de la Russie d’Europe. La région se trouve dans l'extrême nord de la taïga actuelle, près de la limite méridionale du pergélisol. Les reconstitutions sont fondées sur l'analyse macrofossile des plantes, l'analyse physico-chimique et les dates au radiocarbone déterminées par spectrométrie de masse à l’aide d’un accélérateur de particules (SMA) de deux profils de tourbe étudiés en détail. De l'information additionnelle provient de sept autres sites. L'accumulation de matière organique a commencé vers 11 350 BP (années 14C). L’accumulation de tourbe dans les étangs était alors le point de départ le plus habituel des tourbières. Pendant une grande partie de leur formation, ces sites ont été des marais dominés par les Cyperaceae. La transition vers des écosystèmes dominés par les Sphagnum est enregistrée entre 3700 et 3000 BP. Le pergélisol s'est établi vers 2300 BP, bien que des signes de formation embryonnaire de palses soient déjà observables vers 2900 BP. Les palses ont connu plusieurs épisodes de gel et de dégel complet ou partiel. Les couches de pergélisol actuellement observables sont d'origine récente. Le taux d'accumulation du carbone à long terme dans les sites étudiés est de 19 g/m2/an. Le taux moyen d'accumulation du pergélisol en phase active est de 23 g/m2/an.Изучены развитие растительности в голоцене, динамика вечной мерзлоты и аккумуляция торфа на Усинском болоте, которое находится на Печорской равнине Северо-Востока европейской Россий. В настоящее время район расположен в крайнесеверной тайге вближи южной границы вечной мерзлоты. Реконструкция основана на анализе растительных остатков, физико-химического анализа и радиоуглеродной датировки (AMS) двух подробно изученных профилей торфа. Также получена информация из семи других точек. Органическая аккумуляция началась примерно в 11 350 BP (14C годы). заболачивание как правило пройсходило путем зарастания озер. На протяжении большей части их развития в растительности изученных болотных участков преобладало семейство Cyperaceae. Изменение в преобладании Sphagnum отмечено в 3700-3000 BP. Вечная мерзлота сформировалась в 2300 BP, хотя первые признаки формации эмбрионального мерзлотного бугра можно проследить в 2900 BP. Мерзлотные бугры проходили многие периоды замерзания и полного или частичного таяния. Существующие в настоящее время мерзлотные фазы молодые. Долгосрочная скорость аккумуляции угля на изученных участках 19 гр/м2/г. Средняя скорость аккумуляции в динамичной фазе вечной мерзлоты 23 гр/м2/г

Subfossil oribatid mite communities indicate Holocene permafrost dynamics in Canadian mires

Permafrost thaw in peatlands is one of the most widespread and worrying consequences of climate warming in the sub-Arctic area. To predict future climate feedbacks, it is important to study the history of permafrost aggradation and thaw. Plant macrofossil analysis with radiocarbon dating has been widely used in detecting past permafrost dynamics in peatlands, however, due to a lack of permafrost-specific plant indicator species, determining the exact timing of permafrost aggradation remains a challenge. In this study, we investigated if oribatid mites can be used to determine Holocene permafrost aggradation and degradation in Canadian mires. Based on analyses of subfossil oribatid mite assemblages of Holocene peat profiles from two mires in the Hudson Bay Lowlands area, our results suggest that two species, Carabodes labyrinthicus and Neoribates aurantiacus, are useful bioindicators, which can be used in palaeoecological studies determining permafrost histories. Moreover, our results show that subfossil oribatid mite remains can reveal periods of permafrost, which cannot be determined with certainty based on plant macrofossils alone

Soil organic carbon stocks in mountain periglacial areas of northern Patagonia (Argentina)

This study presents a detailed soil organic carbon (SOC) inventory for two areas in the mountain periglacial zone of northern Patagonia (altitude range c. 1,400–2,100 m). We describe plant cover and soil profiles at twenty-seven sites representing the main land cover classes and landform types at and above the treeline. The mean SOC 0–100 cm storage is 2.31 kg C m−2 for the combined study areas, which includes 69 percent of bare ground surfaces with negligible SOC stocks. If we consider the vegetated alpine belt only, mean SOC 0–100 cm storage increases to 6.96 kg C m−2. Solifluction has resulted in areas with dense plant cover and deep soil profiles with mean SOC 0–100 cm of 17.1 to 18.3 kg C m−2 and a maximum total stock of 51.5 kg C m−2. Lowest SOC storages of 0.13 to 0.63 kg C m−2 are found in bare and sparsely vegetated high-elevation areas with shallow and stony soils developed in patterned ground (stripes and sorted circles). Projected future increases in ambient temperature will likely result in an upward shift of the alpine vegetation belt with soil development, creating new areas of ecosystem carbon storage.Fil: Fröjd, Christina. Stockholms Universitet; SueciaFil: Trombotto, Dario Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Scheer, Christopher. Stockholms Universitet; SueciaFil: Pecker Marcosig, Ivanna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Kuhry, Peter. Stockholms Universitet; Sueci

Soil organic carbon stocks in the high mountain permafrost zone of the semi-arid Central Andes (Cordillera Frontal, Argentina)

This study presents the first detailed soil organic carbon (SOC) inventory for a high mountain permafrost zone in the semi-arid Central Andes of South America. We describe plant cover and soil profiles at 31 sites representing the main land cover and landform types in the Veguitas catchment (Cordillera Frontal, Argentina), which ranges in elevation from c. 3000 to 5500 m. The vegetated area with soil development is largely confined to altitudes of < 3650 m and represents only 8.2% of the total catchment area. Mean SOC 0–100 cm storage for the vegetated portion of the catchment is 3.62 kg C m−2, which is reduced to 0.33 kg C m−2 if we consider negligible SOC stocks in the extensive bare ground and glaciated areas at higher elevations. Hotspots of SOC storage are wet meadow areas, with peat deposits up to 102 cm deep and a maximum observed total SOC storage of 53.07 kg C m−2. These wet meadow areas, however, occupy only 0.11% of the total catchment area and their contribution to mean SOC storage is limited. Among soils at well-drained sites, highest mean SOC 0–100 cm storage is found on backslope positions of moraines that predate the Last Glacial Maximum (6.87 kg C m−2). Only 2% of all SOC stocks in the catchment are found in permafrost terrain and none are located in the permafrost layer itself. The main ecoclimatic control on SOC storage is plant cover, with vegetation limits being sensitive to ambient temperature. Projected increases in temperatures will not remobilize any frozen SOC stocks but will likely result in an upward shift of the upper vegetation belt with soil development creating new areas of phytomass carbon and SOC storage. The area is expected to represent a net C sink and thus a negative feedback on future global warming.Fil: Kuhry, Peter. Stockholms Universitet; SueciaFil: Makopoulou, Eirini. Stockholms Universitet; SueciaFil: Pascual Descarrega, Didac. Stockholms Universitet; SueciaFil: Pecker Marcosig, Ivanna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Trombotto, Dario Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

The permafrost mineral reserve: identify potential mineral nutrient hotspots upon thawing

The thawing of permafrost exposes organic matter to decomposition but also mineral constituents to water. To evaluate the potential to create mineral nutrients hotspots upon thawing, an inventory of the mineral element content and its local variability in permafrost terrain is needed. Based on measurements from major Arctic regions (Alaska, Greenland, Svalbard and Siberia), it is suggested that the mineral reserve in permafrost is firstly controlled by the local lithology. More specifically, the data highlight the potential for mineral nutrient hotspots to be generated upon thawing in soils derived from deltaic deposits, but not in thermokarst deposits. Finally, we suggest that portable X-ray fluorescence (pXRF) may present a quick and low-cost alternative to total digestion and ICP-AES measurements to build a mineral element inventory in permafrost terrain at a large spatial scale

Circumpolar dataset of Soil Organic Carbon north of treeline derived from ENVISAT ASAR GM, link to GeoTIFF

A new approach for the estimation of soil organic carbon (SOC) pools north of the tree line has been developed based on synthetic aperture radar (SAR; ENVISAT Advanced SAR Global Monitoring mode) data. SOC values are directly determined from backscatter values instead of upscaling using land cover or soil classes. The multi-mode capability of SAR allows application across scales. It can be shown that measurements in C band under frozen conditions represent vegetation and surface structure properties which relate to soil properties, specifically SOC. It is estimated that at least 29 Pg C is stored in the upper 30 cm of soils north of the tree line. This is approximately 25 % less than stocks derived from the soil-map-based Northern Circumpolar Soil Carbon Database (NCSCD). The total stored carbon is underestimated since the established empirical relationship is not valid for peatlands or strongly cryoturbated soils. The approach does, however, provide the first spatially consistent account of soil organic carbon across the Arctic. Furthermore, it could be shown that values obtained from 1 km resolution SAR correspond to accounts based on a high spatial resolution (2 m) land cover map over a study area of about 7 × 7 km in NE Siberia. The approach can be also potentially transferred to medium-resolution C-band SAR data such as ENVISAT ASAR Wide Swath with ~120 m resolution but it is in general limited to regions without woody vegetation. Global Monitoring-mode-derived SOC increases with unfrozen period length. This indicates the importance of this parameter for modelling of the spatial distribution of soil organic carbon storage