| 385651. |
- Palmtag, Juri, 1980-
(författare)
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Grain size controls on cryoturbation and soil organic carbon density in permafrost-affected soils
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This meta-analysis aims to describe the relationship between grain size distributions and soil organic carbon (SOC) storage in mineral subsoil and carbon (C)-enriched cryoturbated pockets in five areas of continuous permafrost that differ in glaciation history and soil parent materials. Our results show a positive relationship between fine-grained (colloid to medium silt) fractions and SOC storage. Finer textured soils had a significantly higher SOC storage in mineral subsoil samples (not C-enriched through cryoturbation) than coarser textured soils. However, the process of C-enrichment through cryoturbation was most pronounced in soils with coarser grain sizes in the range of coarse silt and very fine sand. Even though fine-grained textures provide a better physical and biochemical protection for soil organic matter, their strong cohesion reduces the mixing of soil horizons and the effectiveness of cryoturbation. A higher % coarse silt to % clay ratio in samples was a good predictor of C-enrichment through cryoturbation across soil samples, soil profiles and study areas.
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| 385652. |
- Palmtag, Juri, 1980-
(författare)
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Improved landscape partitioning and estimates of deep storage of soil organic carbon in the Zackenberg area (NE Greenland) using geomorphological landforms
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This study aims to improve the previous soil organic carbon (SOC) storage estimates for the Zackenberg area (NE Greenland) that were based on a land cover classification (LCC) approach, by using geomorphological upscaling. In addition, novel SOC estimates for deeper deposits (to 300 cm depth) are presented. We hypothesize that landforms will better represent the long-term slope and depositional processes that result in deep SOC burial in this type of mountain permafrost environments. The updated mean SOC storage for the 0–100 cm soil depth is 4.8 kg C m−2, which is 42% lower than the previous estimate of 8.3 kg C m−2 based on land cover upscaling. We ascribe the difference to a previous areal overestimate of SOC-rich vegetated land cover classes. The landform-based approach more correctly constrains the depositional areas in alluvial fans and deltas with high SOC storage. These are also areas of deep carbon storage with an additional 2.4 kg C m−2 in the 100–300 cm depth interval. This research emphasizes the need to consider geomorphology when assessing SOC pools in mountain permafrost landscapes.
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| 385653. |
- Palmtag, Juri, 1980-
(författare)
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Landscape partitioning and burial processes of soil organic carbon in contrasting areas of continuous permafrost
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies have shown that permafrost soils in the northern circumpolar region store almost twice as much carbon as the atmosphere. Since soil organic carbon (SOC) pools have large regional and landscape-level variability, detailed SOC inventories from across the northern permafrost region are needed to assess potential remobilization of SOC with permafrost degradation and to quantify the permafrost carbon-climate feedback on global warming.This thesis provides high-resolution data on SOC storage in five study areas located in undersampled regions of the continuous permafrost zone (Zackenberg in NE Greenland; Shalaurovo and Cherskiy in NE Siberia; Ary-Mas and Logata in Taymyr Peninsula). The emphasis throughout the five different study areas is put on SOC partitioning within the landscape and soil horizon levels as well as on soil forming processes under periglacial conditions. Our results indicate large differences in mean SOC 0–100 cm storage among study areas, ranging from 4.8 to 30.0 kg C m-2, highlighting the need to consider numerous factors as topography, geomorphology, land cover, soil texture, soil moisture, etc. in the assessment of landscape-level and regional SOC stock estimates.In the high arctic mountainous area of Zackenberg, the mean SOC storage is low due to the high proportion of bare grounds. The geomorphology based upscaling resulted in a c. 40% lower estimate compared to a land cover based upscaling (4.8 vs 8.3 kg C m-2, respectively). A landform approach provides a better tool for identifying hotspots of SOC burial in the landscape, which in this area corresponds to alluvial fan deposits in the foothills of the mountains. SOC burial by cryoturbation was much more limited and largely restricted to soils in the lower central valley. In the lowland permafrost study areas of Russia the mean SOC 0–100 cm storage ranged from 14.8 to 30.0 kg C m-2. Cryoturbation is the main burial process of SOC, storing on average c. 30% of the total landscape SOC 0–100 cm in deeper C-enriched pockets in all study areas. In Taymyr Peninsula, the mean SOC storage between the Ary-Mas and Logata study areas differed by c. 40% (14.8 vs 20.8 kg C m-2, respectively). We ascribe this mainly to the finer soil texture in the latter study area. Grain size analyses show that cryoturbation is most prominent in silt loam soils with high coarse silt to very fine sand fractions. However, in profiles and samples not affected by C-enrichment, C concentrations and densities were higher in silt loam soils with higher clay to medium silt fractions.
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| 385654. |
- Palmtag, Juri, et al.
(författare)
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Soil organic carbon storage in continuous permafrost terrain; two case studies from NE Greenlandand NE Siberia
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The northern circumpolar permafrost region occupies about 16% of the global soil areaand holds approximately 50% of the global belowground soil organic carbon (SOC). We describe thequantity and quality of soil organic matter (SOM) in two areas of continuous permafrost in NE Greenland andNE Siberia. The main emphasis lies on the role of cryoturbation and Pleistocene loess-like deposits(yedoma) for SOC storage. This study is based on field work in three different study sites: Zackenberg(Greenland) and Shalaurovo and Chersky (Siberia), as well as laboratory analysis and radiocarbon dating.The estimated mean SOC storage in the upper meter of soil for Zackenberg is 10.5 kg C m-2 with 16% incryoturbated soil pockets. In Shalaurovo, the mean SOC storage is 29.0 kg C m-2 and in Chersky 21.7 kg Cm-2 with more than 30% stored in cryoturbated soil pockets. The study also presents new analyses for deepyedoma deposits(down to 5 m depth). Data from these sites show that the dry bulk densities are muchlower (due to excess ground ice) than those previously reported in the literature, leading to lower estimatesof SOC storage in these deposits.
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| 385655. |
- Palmtag, Juri, 1980-
(författare)
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Storage, landscape partitioning and lability of soil organic matter in permafrost terrain
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent estimates indicate that soils in the northern circumpolar permafrost region store substantial amounts of soil organic carbon (SOC). This reservoir has accumulated over 10-100.000 years and is often preserved in a relatively undecomposed state because frozen and often water-logged conditions prevented microbial degradation. Under a projected future climate change caused by rising greenhouse gases, permafrost thaw and rapid decomposition of vulnerable soil organic matter (SOM) could provide a positive feedback on global warming by releasing large amounts of carbon dioxide and/or methane into the atmosphere.SOC pools have large regional and landscape-level variability depending on topographic, ecoclimatic and edaphic factors. As a consequence, large scale maps and even regional data sets describing SOC storage should be taken with caution since they are highly simplified. The purpose of this thesis is to improve our knowledge on quantity and quality of SOM in different areas of continuous permafrost and provide regional high quality data from hitherto under-sampled regions for future assessment of the potential remobilization of SOC under global warming. A special focus is put on SOC partitioning within the landscape and soil horizon levels as well as on soil forming processes under periglacial conditions. Throughout the five different study areas presented in this thesis the landscape mean SOC storage ranges between 8 and 30 kg C m-2, while site differences are in the order of 0 to 80 kg C m-2. Paper I presents new SOC data from contrasting areas in continuous permafrost: a mountainous High Arctic site in Zackenberg (NE Greenland) and lowland sites in Shalaurovo and Cherskiy lower Kolyma (NE Siberia). The main difference is that about 60% of the Zackenberg area is higher elevation terrain with mostly barren ground and very low SOC content, resulting in a much lower landscape-level mean SOC storage compared to the Siberian sites. In addition, Paper II shows that even when comparing two lowland sites located only 150 km apart in Taymyr Peninsula (N Siberia) the mean SOC storage differs with 40% between the areas. This emphasizes that even in lowlands on a regional scale not only different landforms and land cover but also microrelief, soil moisture and especially parent material play a very important role for obtaining more accurate SOC storage estimates.Throughout this thesis a special emphasis is put on understanding the role of cryoturbation for SOC storage. Signs of cryoturbation were observed at all sites and 14C dates show that this process is occurring since at least the early Holocene. On average, 30% of all SOC in the top meter of soil is located in buried C-enriched pockets. The only exception is Zackenberg, with only 12%, where slope processes were the dominant mechanism for burying C-enriched material into deeper layers.We use the weight ratio of Carbon/Nitrogen (C/N) to gain information about SOM decomposability. Generally, all sites show the same trend that the C/N ratio decreases with soil depth. Top organic soil and peat samples have always the highest C/N ratios, suggesting little decomposed SOM. Except for the Zackenberg site, the buried C-enriched pockets have significantly higher C/N ratios than the adjacent mineral subsoil samples. We assume that this C-enriched material was exposed over longer time periods to aerobic decomposition and was therefore relatively well decomposed before it was buried by reactivated slope processes.
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| 385656. |
- Palmu, Erkki
(författare)
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Ground beetle dynamics in intensively managed agricultural landscapes
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis I have focused on studying dynamics of ground beetle assemblages in intensively managed agricultural landscapes. By definition, the land cover of these landscapes is dominated by annually tilled farmland, comprising a range of different crop types, in the context of the southern Swedish province of Scania mostly winter wheat, spring barley, winter rapeseed, and sugar beets. This background begs the question: can the presence of ground beetles in intensively managed agricultural landscapes be facilitated without sacrificing land dedicated to crop production? Crop diversification has been mentioned as a possible greening measure to mitigate agricultural intensity. Our results show that semi-natural grasslands and leys may not function as source habitats at a landscape-scale if they comprise a low proportion of the total land-use, while increasing crop diversity is correlated to ground beetle richness and diversity in agricultural landscapes dominated by arable land. Autumn breeding ground beetles were indicative of low crop diversity landscape. This is likely a result of high proportions of winter sown cereals that increase dominance of the species Pterostichus melanarius Illiger. Larger species were absent from assemblages emerging ground beetle assemblages in intensively managed crops such as sugar beet. Further, our results suggest that winter wheat fields are less adverse habitats for overwintering larger ground beetles as compared to sugar beet fields. Sugar beet management reduces emergence of larger ground beetle species that dominate actively moving assemblages, indicating that especially larger species are drivers of local ground beetle dynamics. Differences in isotopic composition between emerging and colonizing individuals of Trechus quadristriatus Schrank suggests that a significant proportion of individuals of this species came from remote locations, perhaps crossing the Baltic Sea with easterly winds.
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| 385657. |
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| 385658. |
- Palmås, Karl, 1976
(författare)
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About "Too Late for History to End"
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Screening and discussion of the film Too Late for History to End (Palmås & Sanner, 2020) within the AAG Shorts Film Festival.
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| 385659. |
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| 385660. |
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