{"title":"Issue Information","authors":"","doi":"10.1002/ppp.2120","DOIUrl":"https://doi.org/10.1002/ppp.2120","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46313248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
General geomorphometry is concerned with the geometric form of the continuous land surface and can be useful for identifying topographic “signatures.” Hypsometry has found numerous applications in several subfields of geomorphology, but has not been used extensively in published periglacial work. Hypsometric analysis was applied in this study to several unglaciated and glaciated locales in Alaska's Yukon‐Tanana Upland and Indian River Upland physiographic sections, extensive areas of eastern Beringia in which cryoplanation landforms are ubiquitous. Never‐glaciated terrain in this region has a hypsometric signature distinctly different from that of glaciated areas within sample areas ranging in size from 0.25 to 100 km2. Cryoplanated terrain exhibits a distinctive convex‐upward hypsometric signature, a reflection of a greater proportion of the reference solid (land mass) remaining intact than in typical mature fluvial or glaciated terrain. Because the elevational position of cryoplanation terraces is slightly below and parallel with snowline position it is, in effect, climatically determined from above, and localized planar surfaces develop near that level. Comparison with terrain in the southwestern USA demonstrates that substantial differences also exist between the hypsometry of upland periglacial terrain in eastern Beringia and that of inselbergs and pediments in warm‐desert geomorphic landscapes, casting doubt on a suggestion that cryoplanation terraces and cryopediments in high‐latitude mountains could be inherited from past intervals of subtropical desert conditions We conclude that characteristic periglacial erosional topography exists in unglaciated areas of Beringia and can be detected and described quantitatively through objective methods.
{"title":"Characteristic periglacial topography: Multi‐scale hypsometric analysis of cryoplanated uplands in eastern Beringia","authors":"C. Queen, F. Nelson","doi":"10.1002/ppp.2148","DOIUrl":"https://doi.org/10.1002/ppp.2148","url":null,"abstract":"General geomorphometry is concerned with the geometric form of the continuous land surface and can be useful for identifying topographic “signatures.” Hypsometry has found numerous applications in several subfields of geomorphology, but has not been used extensively in published periglacial work. Hypsometric analysis was applied in this study to several unglaciated and glaciated locales in Alaska's Yukon‐Tanana Upland and Indian River Upland physiographic sections, extensive areas of eastern Beringia in which cryoplanation landforms are ubiquitous. Never‐glaciated terrain in this region has a hypsometric signature distinctly different from that of glaciated areas within sample areas ranging in size from 0.25 to 100 km2. Cryoplanated terrain exhibits a distinctive convex‐upward hypsometric signature, a reflection of a greater proportion of the reference solid (land mass) remaining intact than in typical mature fluvial or glaciated terrain. Because the elevational position of cryoplanation terraces is slightly below and parallel with snowline position it is, in effect, climatically determined from above, and localized planar surfaces develop near that level. Comparison with terrain in the southwestern USA demonstrates that substantial differences also exist between the hypsometry of upland periglacial terrain in eastern Beringia and that of inselbergs and pediments in warm‐desert geomorphic landscapes, casting doubt on a suggestion that cryoplanation terraces and cryopediments in high‐latitude mountains could be inherited from past intervals of subtropical desert conditions We conclude that characteristic periglacial erosional topography exists in unglaciated areas of Beringia and can be detected and described quantitatively through objective methods.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"241 - 263"},"PeriodicalIF":5.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43212740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The longest time series of surface velocities recorded on a rock glacier in the French Alps, covering more than three decades, has been recorded since 1983 on the Laurichard rock glacier (Ecrins range). The time signal of velocity changes is extracted from variance analyses separating time and space variabilities on the rock glacier surface to provide an average‐wide time signal. We show that changes in velocity from year to year are virtually uniform at all locations with homogeneous accelerations or decelerations on the scale of the rock glacier as a whole. The spatial structure of velocity was found to be nearly at steady state over 35 years. Nonlinear effects are located in low‐velocity areas such as the rock glacier margins where accelerations/decelerations tend to be proportional to the local velocity. Over the period of record, a long‐term trend in rock glacier acceleration was detected with a rate of +0.2 m/yr per decade. Two main phases of acceleration were identified from the mid‐1980s to 1999 and from 2010 to 2015. In between, those two periods were interrupted by a 10‐year period of almost steady‐state velocities with an abrupt deceleration from 2006 to 2009 of −0.35 m/yr. The process of internal increases in ice temperatures alone (and associated changes in creep rates) would seem insufficient to explain the long‐term rise of surface velocities and their annual variations. Changes in the liquid water are a possible contributing factor, due to the injection of seasonal water caused by melting snow cover or internal melt due to heat generated by enhanced ice creep and friction in the ice/debris mixture.
{"title":"Changes in surface velocities over four decades on the Laurichard rock glacier (French Alps)","authors":"E. Thibert, Xavier Bodin","doi":"10.1002/ppp.2159","DOIUrl":"https://doi.org/10.1002/ppp.2159","url":null,"abstract":"The longest time series of surface velocities recorded on a rock glacier in the French Alps, covering more than three decades, has been recorded since 1983 on the Laurichard rock glacier (Ecrins range). The time signal of velocity changes is extracted from variance analyses separating time and space variabilities on the rock glacier surface to provide an average‐wide time signal. We show that changes in velocity from year to year are virtually uniform at all locations with homogeneous accelerations or decelerations on the scale of the rock glacier as a whole. The spatial structure of velocity was found to be nearly at steady state over 35 years. Nonlinear effects are located in low‐velocity areas such as the rock glacier margins where accelerations/decelerations tend to be proportional to the local velocity. Over the period of record, a long‐term trend in rock glacier acceleration was detected with a rate of +0.2 m/yr per decade. Two main phases of acceleration were identified from the mid‐1980s to 1999 and from 2010 to 2015. In between, those two periods were interrupted by a 10‐year period of almost steady‐state velocities with an abrupt deceleration from 2006 to 2009 of −0.35 m/yr. The process of internal increases in ice temperatures alone (and associated changes in creep rates) would seem insufficient to explain the long‐term rise of surface velocities and their annual variations. Changes in the liquid water are a possible contributing factor, due to the injection of seasonal water caused by melting snow cover or internal melt due to heat generated by enhanced ice creep and friction in the ice/debris mixture.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"323 - 335"},"PeriodicalIF":5.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44202398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Jiang, Siru Gao, A. Lewkowicz, Hongting Zhao, Shou-ji Pang, Qingbai Wu
An active layer detachment slide (ALDS) in the interior portion of the Qinghai–Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8° to 9°) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2–2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai–Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.
{"title":"Development of a rapid active layer detachment slide in the Fenghuoshan Mountains, Qinghai–Tibet Plateau","authors":"G. Jiang, Siru Gao, A. Lewkowicz, Hongting Zhao, Shou-ji Pang, Qingbai Wu","doi":"10.1002/ppp.2151","DOIUrl":"https://doi.org/10.1002/ppp.2151","url":null,"abstract":"An active layer detachment slide (ALDS) in the interior portion of the Qinghai–Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8° to 9°) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2–2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai–Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"298 - 309"},"PeriodicalIF":5.0,"publicationDate":"2022-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48600790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Forte, H. French, R. Raffi, I. Santin, M. Guglielmin
The results of a combined geophysical and geomorphological investigation of thermal‐contraction‐crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6–7 m above current sea level on Holocene‐age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present‐day shoreline.
{"title":"Investigations of polygonal patterned ground in continuous Antarctic permafrost by means of ground penetrating radar and electrical resistivity tomography: Some unexpected correlations","authors":"E. Forte, H. French, R. Raffi, I. Santin, M. Guglielmin","doi":"10.1002/ppp.2156","DOIUrl":"https://doi.org/10.1002/ppp.2156","url":null,"abstract":"The results of a combined geophysical and geomorphological investigation of thermal‐contraction‐crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6–7 m above current sea level on Holocene‐age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present‐day shoreline.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"226 - 240"},"PeriodicalIF":5.0,"publicationDate":"2022-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43776368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000‐km2 region of northern Québec that spans the northward transition from discontinuous to continuous permafrost. A population of 4,567 TCCP sites was sampled and analyzed from 80,737 georeferenced high‐resolution aerial photographs and 264,504 km2 of ESRI satellite basemaps. For each site, six parameters were inventoried and compiled into a database: (a) network geometric arrangement; (b) intersection angles; (c) number of subdivisions and nested polygons (referred to as generations of development); (d) dominant polygon morphology; (e) surficial geology; and (f) vegetation cover. Statistical analyses of the tabulated data revealed a strong association between Holocene glacial, glacio‐fluvial, fluvial, marine, and organic landforms and the different intersections angles in the networks, providing insight into how the processes of thermal contraction cracking function and manifest geomorphically across varied permafrost landscapes. Orthogonal polygons (intersection angle of 90°) dominate on flat terrains where the thermo‐mechanical stresses are probably spatially homogeneous. Hexagonal (angles of 120°) and poorly structured polygons tend to form where topography variability probably generates heterogeneous heat flow patterns and thermo‐mechanical stresses in the ground, resulting in irregular cracking patterns.
{"title":"Thermal contraction crack polygons in Nunavik (northern Quebec): Distribution and development of polygonal patterned ground","authors":"Alexandre Chiasson, M. Allard","doi":"10.1002/ppp.2150","DOIUrl":"https://doi.org/10.1002/ppp.2150","url":null,"abstract":"We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000‐km2 region of northern Québec that spans the northward transition from discontinuous to continuous permafrost. A population of 4,567 TCCP sites was sampled and analyzed from 80,737 georeferenced high‐resolution aerial photographs and 264,504 km2 of ESRI satellite basemaps. For each site, six parameters were inventoried and compiled into a database: (a) network geometric arrangement; (b) intersection angles; (c) number of subdivisions and nested polygons (referred to as generations of development); (d) dominant polygon morphology; (e) surficial geology; and (f) vegetation cover. Statistical analyses of the tabulated data revealed a strong association between Holocene glacial, glacio‐fluvial, fluvial, marine, and organic landforms and the different intersections angles in the networks, providing insight into how the processes of thermal contraction cracking function and manifest geomorphically across varied permafrost landscapes. Orthogonal polygons (intersection angle of 90°) dominate on flat terrains where the thermo‐mechanical stresses are probably spatially homogeneous. Hexagonal (angles of 120°) and poorly structured polygons tend to form where topography variability probably generates heterogeneous heat flow patterns and thermo‐mechanical stresses in the ground, resulting in irregular cracking patterns.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"195 - 213"},"PeriodicalIF":5.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41342463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With ongoing climate change water availability in the source regions of alpine streams are at stake. In particular, dry mountain regions which currently rely on glacial meltwater will need to adapt. Since rock glaciers are more resilient to climate change and occur in nearly all high‐mountain catchments around the globe with some form of glacierization, it is of interest to investigate their contribution to runoff under different climate scenarios. Three well‐monitored rock glacier sites in the Swiss Alps (Murtèl, Ritigraben, and Schafberg) have been investigated under the climate change scenarios corresponding to low, medium and high greenhouse gas emissions to determine how their runoff contribution is affected. By the end of the 21st century, runoff from permafrost melting could account for 5–12% (12.0% for Murtèl, 7.0% for Ritigraben, and 5.0% for Schafberg) of monthly catchment runoff at maximum in an average year, and up to 50% in extreme years. For the low‐emission scenario, little change in the runoff contribution from rock glaciers is found, while the medium‐emission scenario shows increased variability and a shift in the seasonal runoff peak to earlier in the year. The high‐emission scenario indicates a further increase in the variability of the permafrost runoff contribution and also the development of a secondary seasonal peak in autumn, most prominently in the late century.
{"title":"Temperature evolution and runoff contribution of three rock glaciers in Switzerland under future climate forcing","authors":"L. Pruessner, M. Huss, D. Farinotti","doi":"10.1002/ppp.2149","DOIUrl":"https://doi.org/10.1002/ppp.2149","url":null,"abstract":"With ongoing climate change water availability in the source regions of alpine streams are at stake. In particular, dry mountain regions which currently rely on glacial meltwater will need to adapt. Since rock glaciers are more resilient to climate change and occur in nearly all high‐mountain catchments around the globe with some form of glacierization, it is of interest to investigate their contribution to runoff under different climate scenarios. Three well‐monitored rock glacier sites in the Swiss Alps (Murtèl, Ritigraben, and Schafberg) have been investigated under the climate change scenarios corresponding to low, medium and high greenhouse gas emissions to determine how their runoff contribution is affected. By the end of the 21st century, runoff from permafrost melting could account for 5–12% (12.0% for Murtèl, 7.0% for Ritigraben, and 5.0% for Schafberg) of monthly catchment runoff at maximum in an average year, and up to 50% in extreme years. For the low‐emission scenario, little change in the runoff contribution from rock glaciers is found, while the medium‐emission scenario shows increased variability and a shift in the seasonal runoff peak to earlier in the year. The high‐emission scenario indicates a further increase in the variability of the permafrost runoff contribution and also the development of a secondary seasonal peak in autumn, most prominently in the late century.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"310 - 322"},"PeriodicalIF":5.0,"publicationDate":"2022-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44624786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qingfeng Wang, H. Jin, Qingbai Wu, Ting-jun Zhang, Ziqiang Yuan, Xiaoying Li, Jiao Ming, Chengsong Yang, R. Serban, Yadong Huang
Currently, we know little about accumulation of soil carbon and nitrogen in permafrost‐affected wetlands on the Qinghai–Tibet Plateau (QTP). In this study, we analyze the vertical distribution of concentrations, stocks, and apparent accumulation rates of soil organic carbon (SOC) and total nitrogen (TN) in a wetland underlain by ice‐rich permafrost in the Headwater Area of the Yellow River (HAYR) on the northeastern QTP in the context of Holocene environmental change. SOC and TN stocks at depths of 0–216 cm were 80.0 kg C m−2 and 6.7 kg N m−2, respectively. During the past 7.3 kyr, the general regional climate trend in the HAYR was cooling and drying, as indicated by the decline in chemical weathering in the soil profile. Overall, SOC and TN concentrations increased during this period. Meanwhile, an intense period of SOC and TN accumulation occurred at 1,110–720 yr BP, in contrast to much lower apparent accumulation rates of SOC and TN for the other periods during the past 7.3 kyr. This suggests that the accumulation of SOC and TN in permafrost‐affected wetlands was also affected by local environmental factors, such as soil material deposition rate, in addition to climatic controls as exerted mainly by temperature and precipitation. This study may help integrate relevant studies on plateau wetlands into global models and estimates to better simulate and predict interactions between the carbon cycle and climate changes on a global scale.
目前，我们对青藏高原多年冻土影响湿地的土壤碳氮积累知之甚少。在本研究中，我们分析了全新世环境变化背景下黄河源头富冰多年冻土湿地土壤有机碳（SOC）和总氮（TN）的浓度、储量和表观积累率的垂直分布。0–216深处的SOC和TN储量 cm分别为80.0 kg C m−2和6.7 kg N m−2。在过去的7.3 kyr期间，HAYR的总体区域气候趋势是冷却和干燥，这表明土壤剖面中化学风化的减少。总的来说，SOC和TN浓度在这一时期有所增加。同时，在1110–720时出现了SOC和TN的强烈积累期 yr BP，相比之下，在过去7.3 kyr的其他时期，SOC和TN的表观积累率要低得多。这表明，受永久冻土影响的湿地中SOC和TN的积累也受到当地环境因素的影响，如土壤物质沉积速率，以及主要由温度和降水施加的气候控制。这项研究可能有助于将高原湿地的相关研究纳入全球模型和估计，以更好地模拟和预测全球范围内碳循环与气候变化之间的相互作用。
{"title":"The vertical distribution of soil organic carbon and nitrogen in a permafrost‐affected wetland on the Qinghai–Tibet Plateau: Implications for Holocene development and environmental change","authors":"Qingfeng Wang, H. Jin, Qingbai Wu, Ting-jun Zhang, Ziqiang Yuan, Xiaoying Li, Jiao Ming, Chengsong Yang, R. Serban, Yadong Huang","doi":"10.1002/ppp.2146","DOIUrl":"https://doi.org/10.1002/ppp.2146","url":null,"abstract":"Currently, we know little about accumulation of soil carbon and nitrogen in permafrost‐affected wetlands on the Qinghai–Tibet Plateau (QTP). In this study, we analyze the vertical distribution of concentrations, stocks, and apparent accumulation rates of soil organic carbon (SOC) and total nitrogen (TN) in a wetland underlain by ice‐rich permafrost in the Headwater Area of the Yellow River (HAYR) on the northeastern QTP in the context of Holocene environmental change. SOC and TN stocks at depths of 0–216 cm were 80.0 kg C m−2 and 6.7 kg N m−2, respectively. During the past 7.3 kyr, the general regional climate trend in the HAYR was cooling and drying, as indicated by the decline in chemical weathering in the soil profile. Overall, SOC and TN concentrations increased during this period. Meanwhile, an intense period of SOC and TN accumulation occurred at 1,110–720 yr BP, in contrast to much lower apparent accumulation rates of SOC and TN for the other periods during the past 7.3 kyr. This suggests that the accumulation of SOC and TN in permafrost‐affected wetlands was also affected by local environmental factors, such as soil material deposition rate, in addition to climatic controls as exerted mainly by temperature and precipitation. This study may help integrate relevant studies on plateau wetlands into global models and estimates to better simulate and predict interactions between the carbon cycle and climate changes on a global scale.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"286 - 297"},"PeriodicalIF":5.0,"publicationDate":"2022-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46217112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rapidly increasing air temperatures will alter permafrost conditions across the Arctic, but variation in soils, vegetation, snow conditions, and their effects on ground thermal regime complicate prediction across spatial and temporal scales. Processes that result in the emergence of new surfaces (lake drainage, channel migration, isostatic uplift, etc.) provide an opportunity to assess the factors influencing permafrost aggradation and terrain evolution under a warming climate. In this study we describe ground temperatures, vegetation, and snow and soil conditions at six drained lake basins (DLBs) that have exposed new terrain in the Tuktoyaktuk Coastlands in the last 20–100 years. We also use one‐dimensional thermal modeling to assess the impact of ecological succession and future climate scenarios on permafrost conditions in historical and future DLBs. Our field observations show that deep snow pack and shallow organic layers at shrub‐dominated DLBs promote increased thaw depth and ground temperatures compared to a sedge‐dominated DLB and two ancient DLB reference sites. Modeling of past and future drainages shows that climate warming projected under RCP 8.5 will reduce rates of permafrost aggradation and thickness, and drive top‐down thaw that could degrade permafrost in shrub‐dominated DLBs by the end of the century. Permafrost at sedge‐dominated sites was more resilient to warming under RCP 8.5, with the onset of top‐down thaw delayed until about 2080. Together, this indicates that the effects of ecological succession on organic soil development and snow drifting will strongly influence the aggradation and resilience of permafrost in DLBs. Our analysis suggests that DLBs and other emergent landscapes will be the first permafrost‐free environments to develop under a warming climate in the continuous permafrost zone.
{"title":"Impacts of ecological succession and climate warming on permafrost aggradation in drained lake basins of the Tuktoyaktuk Coastlands, Northwest Territories, Canada","authors":"T. Lantz, Yu Zhang, S. Kokelj","doi":"10.1002/ppp.2143","DOIUrl":"https://doi.org/10.1002/ppp.2143","url":null,"abstract":"Rapidly increasing air temperatures will alter permafrost conditions across the Arctic, but variation in soils, vegetation, snow conditions, and their effects on ground thermal regime complicate prediction across spatial and temporal scales. Processes that result in the emergence of new surfaces (lake drainage, channel migration, isostatic uplift, etc.) provide an opportunity to assess the factors influencing permafrost aggradation and terrain evolution under a warming climate. In this study we describe ground temperatures, vegetation, and snow and soil conditions at six drained lake basins (DLBs) that have exposed new terrain in the Tuktoyaktuk Coastlands in the last 20–100 years. We also use one‐dimensional thermal modeling to assess the impact of ecological succession and future climate scenarios on permafrost conditions in historical and future DLBs. Our field observations show that deep snow pack and shallow organic layers at shrub‐dominated DLBs promote increased thaw depth and ground temperatures compared to a sedge‐dominated DLB and two ancient DLB reference sites. Modeling of past and future drainages shows that climate warming projected under RCP 8.5 will reduce rates of permafrost aggradation and thickness, and drive top‐down thaw that could degrade permafrost in shrub‐dominated DLBs by the end of the century. Permafrost at sedge‐dominated sites was more resilient to warming under RCP 8.5, with the onset of top‐down thaw delayed until about 2080. Together, this indicates that the effects of ecological succession on organic soil development and snow drifting will strongly influence the aggradation and resilience of permafrost in DLBs. Our analysis suggests that DLBs and other emergent landscapes will be the first permafrost‐free environments to develop under a warming climate in the continuous permafrost zone.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"176 - 192"},"PeriodicalIF":5.0,"publicationDate":"2022-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49216576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accuracy of electrical resistivity tomography (ERT) as a method for locating frozen‐to‐unfrozen interfaces in permafrost environments was investigated systematically for simplified scenarios using forward modeling. The impacts of varying the resistivity, thickness, and lateral continuity of the frozen region, altering the thickness of the surface thaw layer, and of differing array types were evaluated in relation to the detection and positioning of frozen–unfrozen interfaces. The results from these simple scenarios show that boundaries between frozen and unfrozen ground are more accurately indicated by maximum gradients rather than a fixed threshold value based on the resistivity at the base of the surface thawed layer. The resistivity of the frozen region plays a significant role in interpreted boundary locations, with high resistivity values causing a decrease in model sensitivity at depth and increased uncertainty in the interpreted base of the frozen zone, particularly in laterally continuous permafrost. Error in the interpreted base of the frozen zone also increases for thicker permafrost bodies, while thaw layer thickness plays a less significant role. In laterally discontinuous permafrost, wider frozen bodies cause the boundary at the base of the frozen region to become less distinct. Array type affected the appearance of the inverted resistivity models and the frozen–unfrozen boundaries located using the threshold method, but boundary locations were comparable among array types when the maximum gradient method was used. This synthetic modeling showed that the boundaries between unfrozen and frozen regions in ERT images should be interpreted with caution, particularly in ice‐rich, laterally continuous permafrost where sensitivity at depth is low. We conclude that forward modeling is a useful tool for permafrost investigations, both for assessing the likelihood of achieving ERT survey goals prior to fieldwork, and as an interpretive aid after field data have been acquired.
{"title":"A systematic evaluation of electrical resistivity tomography for permafrost interface detection using forward modeling","authors":"T. Herring, A. Lewkowicz","doi":"10.1002/ppp.2141","DOIUrl":"https://doi.org/10.1002/ppp.2141","url":null,"abstract":"The accuracy of electrical resistivity tomography (ERT) as a method for locating frozen‐to‐unfrozen interfaces in permafrost environments was investigated systematically for simplified scenarios using forward modeling. The impacts of varying the resistivity, thickness, and lateral continuity of the frozen region, altering the thickness of the surface thaw layer, and of differing array types were evaluated in relation to the detection and positioning of frozen–unfrozen interfaces. The results from these simple scenarios show that boundaries between frozen and unfrozen ground are more accurately indicated by maximum gradients rather than a fixed threshold value based on the resistivity at the base of the surface thawed layer. The resistivity of the frozen region plays a significant role in interpreted boundary locations, with high resistivity values causing a decrease in model sensitivity at depth and increased uncertainty in the interpreted base of the frozen zone, particularly in laterally continuous permafrost. Error in the interpreted base of the frozen zone also increases for thicker permafrost bodies, while thaw layer thickness plays a less significant role. In laterally discontinuous permafrost, wider frozen bodies cause the boundary at the base of the frozen region to become less distinct. Array type affected the appearance of the inverted resistivity models and the frozen–unfrozen boundaries located using the threshold method, but boundary locations were comparable among array types when the maximum gradient method was used. This synthetic modeling showed that the boundaries between unfrozen and frozen regions in ERT images should be interpreted with caution, particularly in ice‐rich, laterally continuous permafrost where sensitivity at depth is low. We conclude that forward modeling is a useful tool for permafrost investigations, both for assessing the likelihood of achieving ERT survey goals prior to fieldwork, and as an interpretive aid after field data have been acquired.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"134 - 146"},"PeriodicalIF":5.0,"publicationDate":"2022-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46337395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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