Genesis of Turbic Cryosols on north-facing slopes in a dissected, unglaciated landscape, west-central Yukon Territory

2009 ◽  
Vol 89 (5) ◽  
pp. 611-622 ◽  
Author(s):  
C A.S. Smith ◽  
P T Sanborn ◽  
J D Bond ◽  
G Frank
Keyword(s):  
Organic Matter ◽  
Active Layer ◽  
Forest Fires ◽  
Mass Movement ◽  
Clay Mineralogy ◽  
Yukon Territory ◽  
Element Geochemistry ◽  
Radiocarbon Dates ◽  
Carbon Mass ◽  
Dawson City

The characteristics and landscape distribution of Histic Dystric Turbic Cryosols were examined on a steep (>30%) northerly slope in the unglaciated Klondike Plateau, near Dawson City, Yukon Territory. Based on texture, major element geochemistry, and clay mineralogy, the mineral parent materials were crudely stratified, with a silty material of likely aeolian origin overlying sandy gravelly colluvium. Discontinuous organic matter-enriched horizons occurred 50 cm or more below the active layer, and contained abundant partially decomposed plant detritus. Eight accelerator radiocarbon dates, ranging from 350 ± 40 to 3680 ± 40 14C years BP, suggested that incorporation of organic materials within and below the active layer was geologically recent, and had likely occurred by a combination of cryoturbation and slope processes. The widespread and rapid initiation of mass movements on slopes containing permafrost that followed forest fires in 2004 on the Klondike Plateau may be an analogue for the processes that contributed to organic matter burial in these Cryosols. These soils may represent a significant reservoir of C, as similar sites occupy at least 15% of a representative portion of the Plateau. This reservoir may be vulnerable to mobilization if future climatic warming increases the frequency of forest fires and resulting slope instability.Key words: Tyrbic Cryosol, Yukon Territory, cryoturbation, soil organic carbon, mass movement

On the nature and origin of "muck" deposits in the Klondike area, Yukon Territory

1997 ◽  
Vol 34 (10) ◽  
pp. 1333-1344 ◽  
Author(s):  
T. A. Fraser ◽  
C. R. Burn
Keyword(s):  
Organic Matter ◽  
Fine Sand ◽  
Yukon Territory ◽  
Low Flow ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Yukon River ◽  
Laboratory Investigations ◽  
Late Wisconsinan ◽  
Kluane Lake

Organic-rich "muck" deposits, which blanket auriferous gravels in the Klondike area, Yukon Territory, comprise two principal stratigraphic units: (i) a silty Late Pleistocene deposit, and (ii) Holocene organics lying unconformably on the silt. The deposits are found predominantly in valley bottoms and, if undisturbed, are normally perennially frozen. Field and laboratory investigations of particle size, mineralogy, and morphology, as well as organic matter and sedimentary structures, indicate that the silt is both primary (massive) and redeposited (bedded) loess (by weight 87% medium and coarse silt and fine sand). Radiocarbon dates indicate that the loess was deposited during Late Wisconsinan McConnell glaciation, beginning after 27 000 14C years BP. The loess was likely derived from the floodplain of the Yukon River during periods of low flow. Turf in growth position and organic matter in the silt similar to that of loessal grasslands near Kluane Lake suggest a grassland environment for the area during McConnell glaciation. A mummified carcass in the silts indicates that some of these sediments have been frozen since shortly after deposition. Ice wedges are commonly found in the upper portion of the silt, but these wedges rarely extend into the overlying organic material. Separate, smaller ice wedges are found in the Holocene unit. Radiocarbon dates indicate that peat growth began at the start of the Holocene, as in other unglaciated portions of Yukon, when the climate became abruptly wetter.

scholarly journals Soils in Karst Sinkholes Record the Holocene History of Local Forest Fires at the North of European Russia

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1268
Author(s):  
Nikita Mergelov ◽  
Dmitry Petrov ◽  
Elya Zazovskaya ◽  
Andrey Dolgikh ◽  
Alexandra Golyeva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Fires ◽  
Soil Formation ◽  
Soil Morphology ◽  
Deep Soil ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
The North ◽  
Peat Deposits

Despite the abundance of charcoal material entrapped in soils, they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g., lacustrine and peat deposits), and that is especially the case in most of Russia’s territory. We report here on the deep soil archives of the Holocene forest fires from the Pinega District of the Arkhangelsk region (64.747° N, 43.387° E). Series of buried soil profiles separated by charcoal layers and clusters were revealed in specific geomorphological traps represented by the active and paleokarst subsidence sinkholes on sulfate rocks overlaid by glacial and fluvial deposits. We combine the study of soil morphology and stratigraphy with a set of radiocarbon data on charcoal and soil organic matter, as well as the anthracomass analysis, to extract a set of paleoenvironmental data. A total of 45 radiocarbon dates were obtained for the macrocharcoal material and the soil organic matter. The maximum temporal “depth” of archives estimated from the radiocarbon dating of macrocharcoal reached 10,260 ± 35 cal yr BP. Soil formation with Podzols established at the inter-pyrogenic stages repeatedly reproduced within the period of ten thousand years, while the dominant tree species was Pinus sp. According to the macrocharcoal data, the intervals between fires have shortened in the last thousand years. Dendrochronological estimates suggest the occurrence of fires in almost every decade of the 20th and early 21st centuries. This is the first study of the millennia-scale soil record of forest fires in this particular region of Russia.

The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory

1998 ◽  
Vol 35 (2) ◽  
pp. 184-199 ◽  
Author(s):  
C R Burn
Keyword(s):  
Active Layer ◽  
Forest Fires ◽  
Ground Surface ◽  
Yukon Territory ◽  
River Valley ◽  
Permafrost Degradation ◽  
Near Surface ◽  
Surface Conditions ◽  
Mean Temperature ◽  
Discontinuous Permafrost

Forest fires in permafrost areas often modify ground surface conditions, causing deepening of the active layer and thawing of near-surface permafrost. Takhini River valley lies in the discontinuous permafrost zone of southern Yukon Territory. The valley floor is covered by glaciolacustrine deposits, which are locally ice rich. In 1958 extensive forest fires burned most of the vegetation and the soil organic horizon in the valley, but, 50 km west of Whitehorse, 1 km2 of spruce forest adjacent to the Alaska Highway escaped burning. Permafrost beneath this stand of trees is in equilibrium with surface conditions: the active layer is 1.4 m thick, the base of permafrost is at 18.5 m, the annual mean temperature at the top of permafrost (1.5 m) is -0.8°C, and the temperature gradient in permafrost is constant with depth. At burned sites nearby there has been little regeneration of forest vegetation since the fire, and long-term permafrost degradation has occurred. At one burned site, the permafrost table is more than 3.75 m below the ground surface, the mean annual ground temperature is -0.2°C or warmer throughout the profile, the annual mean temperature at 1.5 m is 0.1°C, and permafrost is thawing from top and bottom. A simplified analytical model for thawing of permafrost indicates that over a millennium will be required to degrade permafrost completely at this site, if thawing proceeds from the top down. The result demonstrates the persistence of ice-rich permafrost a few metres below the ground surface, even at sites near the southern margin of permafrost in Canada.

The long-term impact of low-intensity surface fires on litter decomposition and enzyme activities in boreal coniferous forests

2016 ◽  
Vol 25 (2) ◽  
pp. 213 ◽  
Author(s):  
Kajar Köster ◽  
Frank Berninger ◽  
Jussi Heinonsalo ◽  
Aki Lindén ◽  
Egle Köster ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Enzymatic Activity ◽  
Litter Decomposition ◽  
Forest Fires ◽  
Biological Activities ◽  
Coniferous Forest ◽  
Fire Disturbance ◽  
Coniferous Forests ◽  
Long Term Impact

In boreal forest ecosystems fire, fungi and bacteria, and their interactions, have a pronounced effect on soil carbon dynamics. In this study we measured enzymatic activities, litter decomposition rates, carbon stocks and fungal and microbial biomasses in a boreal subarctic coniferous forest on a four age classes of non-stand replacing fire chronosequence (2, 42, 60 and 152 years after the fire). The results show that microbial activity recovered slowly after fire and the decomposition of new litter was affected by the disturbance. The percent mass loss of Scots pine litter increased with time from the last fire. Slow litter decomposition during the first post-fire years accelerates soil organic matter accumulation that is essential for the recovery of soil biological activities. Fire reduced the enzymatic activity across all the enzyme types measured. Carbon-degrading, chitin-degrading and phosphorus-dissolving enzymes showed different responses with the time elapsed since the fire disturbance. Microbial and enzymatic activity took decades before recovering to the levels observed in old forest stands. Our study demonstrates that slower post-fire litter decomposition has a pronounced impact on the recovery of soil organic matter following forest fires in northern boreal coniferous forests.

Comparison of the mineralogical effects of an experimental forest fire on a goethite/ferrihydrite soil with a topsoil that contains hematite, maghemite and goethite

Clay Minerals ◽  
2009 ◽  
Vol 44 (2) ◽  
pp. 239-247 ◽  
Author(s):  
P. Nørnberg ◽  
A. L. Vendelboe ◽  
H. P. Gunnlaugsson ◽  
J. P. Merrison ◽  
K. Finster ◽  
...  
Keyword(s):  
Organic Matter ◽  
High Temperature ◽  
Forest Fire ◽  
Forest Fires ◽  
Organic Matter Content ◽  
Matter Content ◽  
Humid Climate ◽  
Fe Mineralogy ◽  
Reducing Environment

AbstractA long-standing unresolved puzzle related to the Danish temperate humid climate is the presence of extended areas with large Fe contents, where goethite and ferrihydrite are present in the topsoil along with hematite and maghemite. Hematite and, particularly, maghemite would normally be interpreted as the result of high temperature as found after forest fires. However, a body of evidence argues against these sites having been exposed to fire. In an attempt to get closer to an explanation of this Fe mineralogy, an experimental forest fire was produced. The results showed a clear mineralogical zonation down to 10 cm depth. This was not observed at the natural sites, which contained a mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. The experimental forest fire left charcoal and ashes at the topsoil, produced high pH and decreased organic matter content, all of which is in contrast to the natural sites. The conclusion from this work is that the mineralogy of these sites is not consistent with exposure to forest fire, but may instead result from long-term transformation in a reducing environment, possibly involving microbiology.

Soil water repellency persistence after recurrent forest fires on Mount Carmel, Israel

2013 ◽  
Vol 22 (4) ◽  
pp. 515 ◽  
Author(s):  
Naama Tessler ◽  
Lea Wittenberg ◽  
Noam Greenbaum
Keyword(s):  
Organic Matter ◽  
Soil Water ◽  
Forest Fires ◽  
Water Drop ◽  
Chemical Properties ◽  
Water Repellency ◽  
Mediterranean Ecosystem ◽  
Long Term Effects ◽  
Soil Water Repellency ◽  
Chemical Properties Of Soils

Variations in forest fires regime affect: (1) the natural patterns of community structure and vegetation; (2) the physico-chemical properties of soils and consequently (3) runoff, erosion and sediment yield. In recent decades the Mediterranean ecosystem of Mount Carmel, north-western Israel, is subjected to an increasing number of forest fires, thus, the objectives of the study were to evaluate the long-term effects of single and recurrent fires on soil water repellency (WR) and organic matter (OM) content. Water repellency was studied by applying water drop penetration time (WDPT) tests at sites burnt by single-fire, two fires, three fires and unburnt control sites. Water repellency in the burnt sites was significantly lower than in the unburnt control sites, and the soil maintained its wettability for more than 2 decades, whereas after recurrent fires, the rehabilitation was more complicated and protracted. The OM content was significantly lower after recurrent than after a single fire, causing a clear proportional decrease in WR. The rehabilitation of WR to natural values is highly dependent on restoration of organic matter and revegetation. Recurrent fires may cause a delay in recovery and reduced productivity of the soil for a long period.

Arctic Permafrost Active Layer Detachments Stimulate Microbial Activity and Degradation of Soil Organic Matter

2010 ◽  
Vol 44 (11) ◽  
pp. 4076-4082 ◽  
Author(s):  
Brent G. Pautler ◽  
André J. Simpson ◽  
David J. Mcnally ◽  
Scott F. Lamoureux ◽  
Myrna J. Simpson
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Activity ◽  
Active Layer

Pleistocene Mammals from Gold Run Creek, Yukon Territory

1973 ◽  
Vol 10 (5) ◽  
pp. 697-759 ◽  
Author(s):  
C. R. Harington ◽  
F. V. Clulow
Keyword(s):  
Yukon Territory ◽  
Radiocarbon Date ◽  
Common Elements ◽  
Radiocarbon Dates ◽  
Equus Asinus ◽  
Wild Ass ◽  
Pleistocene Mammals ◽  
First Time

Remains of thirteen species of mammals are reported from Pleistocene deposits at Gold Run Creek near Dawson, Yukon Territory. Eight of the thirteen species are extinct and two are no longer living in the Yukon. The most common elements of the fauna are Equus (Asinus) lambei (Yukon wild ass), and Bison crassicornis (large-horned bison). Taxidea (badger) and Bison alaskensis (Alaskan bison) are reported for the first time from the Yukon Pleistocene. A kiang-like horse is also reported from deposits at Gold Run Creek.These mammals may have inhabited a cool grassland or open parkland during late Wisconsin time. Bison crassicornis and mammoth bone from deposits at Gold Run Creek have yielded radiocarbon dates of 22 200 ± 1400 yr B.P. and 32 250 ± 1750 yr B.P. respectively. Bison alaskensis is evidently older than the remainder of the fauna as bone from the specimen yielded a radiocarbon date of over 39 900 yr B.P.

scholarly journals Evaluating Bayesian radiocarbon-dated event-count [REC] models for the study of long-term human and environmental processes

2020 ◽  
Author(s):  
William Christopher Carleton
Keyword(s):  
Forest Fires ◽  
Simulated Data ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
New Class ◽  
Environmental Processes ◽  
Growth Decline ◽  
Marine Ingression ◽  
Event Times

Chronological uncertainty complicates attempts to use radiocarbon dates as proxies for processes like human population growth/decline, forest fires, and marine ingression. Established approaches involve turning databases of radiocarbon-date densities into single summary proxies that cannot fully account for chronological uncertainty. Here, I use simulated data to explore an alternate Bayesian approach that instead models the data as what they are, namely radiocarbon-dated event-counts. The approach involves assessing possible event-count sequences by sampling radiocarbon date densities and then applying MCMC to estimate the parameters of an appropriate count-based regression model. The regressions based on individual sampled sequences were placed in a multilevel framework, which allowed for the estimation of hyperparameters that account for chronological uncertainty in individual event times. Two processes were used to produce simulated data. One represented a simple monotonic change in event-counts and the other was based on a real palaeoclimate proxy record. In both cases, the method produced estimates that had the correct sign and were consistently biased toward zero. These results indicate that the approach is widely applicable and could form the basis of a new class of quantitative models for use in exploring long-term human and environmental processes.

scholarly journals Organic carbon and total nitrogen stocks in soils of the Lena River Delta

2012 ◽  
Vol 9 (12) ◽  
pp. 17263-17311 ◽  
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
G. Grosse ◽  
A. Desyatkin ◽  
E.-M. Pfeiffer
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Active Layer ◽  
River Delta ◽  
River Terrace ◽  
Total N ◽  
Lena River ◽  
Carbon Mass ◽  
Organic Carbon Pool ◽  
Lena River Delta

Abstract. The Lena River Delta, which is the largest delta in the Arctic, extends over an area of 32 000 km2 and likely holds more than half of the entire soil organic carbon mass stored in the seven major deltas in the northern permafrost regions. The geomorphic units of the Lena River Delta which were formed by true deltaic sedimentation processes are a Holocene river terrace and the active floodplains. Their mean soil organic carbon stocks for the upper 1 m of soils were estimated at 29 kg m−2 ± 10 kg m−2 and at 14 kg m−2 ± 7 kg m−2, respectively. For the depth of 1 m, the total soil organic carbon pool of the Holocene river terrace was estimated at 121 Tg ± 43 Tg, and the soil organic carbon pool of the active floodplains was estimated at 120 Tg ± 66 Tg. The mass of soil organic carbon stored within the observed seasonally thawed active layer was estimated at about 127 Tg assuming an average maximum active layer depth of 50 cm. The soil organic carbon mass which is stored in the perennially frozen ground below 50 cm soil depth, which is excluded from intense biogeochemical exchange with the atmosphere, was estimated at 113 Tg. The mean nitrogen (N) stocks for the upper 1 m of soils were estimated at 1.2 kg m−2 ± 0.4 kg m−2 for the Holocene river terrace and at 0.9 kg m−2 ± 0.4 kg m−2 for the active floodplain levels, respectively. For the depth of 1 m, the total N pool of the river terrace was estimated at 4.8 Tg ± 1.5 Tg, and the total N pool of the floodplains was estimated at 7.7 Tg ± 3.6 Tg. Considering the projections for deepening of the seasonally thawed active layer up to 120 cm in the Lena River Delta region within the 21st century, these large carbon and nitrogen stocks could become increasingly available for decomposition and mineralization processes.

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