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  • 1.
    Ablieieva, Iryna
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center. Sumy State University, Ukraine.
    Chernysh, Yelizaveta
    Sumy State University, Ukraine; Czech University of Life Sciences Prague, Czech Republic.
    Chubur, Viktoriia
    Sumy State University, Ukraine; Czech University of Life Sciences Prague, Czech Republic.
    Skvortsova, Polina
    Sumy State University, Ukraine.
    Roubik, Hynek
    Czech University of Life Sciences Prague, Czech Republic.
    Biopotential of Agricultural Waste: Production of Biofertilizers and Biofuels2022In: 22nd International Multidisciplinary Scientific Geoconference: Energy and Clean Technologies, SGEM 2022, Vienna, 6 December 2022 - 8 December 2022 / [ed] Trofymchuk O., Rivza B., Vienna, 2022, Vol. 22, 4.2, p. 39-47Conference paper (Refereed)
    Abstract [en]

    This article is focused on performing a SWOT analysis of agricultural waste management methods. This approach can be applied in the biogas technology strategic planning process in Ukraine, which can solve the issue of implementation of environmental guidelines for the development of biofuels and biofertilizers. The main factors that determine how digestate is used are its quality, local conditions, regulations, and documents. Fertilizing fields with digestate provides many advantages, for example: reduced demand for plant protection products, reduction of unpleasant odor, and destruction of possible pathogens. The strengths and weaknesses of the implementation of biogas plants in Ukraine have been identified, and opportunities and threats have been considered. In general, the introduction of biogas technology is a very promising solution for the agricultural sector. Taking into account that a biogas plant is considered a potentially hazardous object for workers, it is necessary to constantly monitor the parameters of reactor operation in order to ensure the technological and environmental safety of the engineering facilities. For Ukraine, there is a shortage of specialists to set up an effective operation of biogas equipment and bring it to the industrial scale. It is necessary to consult with medium and small farms interested in the feasibility study and implementation of biogas technologies. 

  • 2. Abramoff, Rose Z.
    et al.
    Georgiou, Katerina
    Guenet, Bertrand
    Torn, Margaret S.
    Huang, Yuanyuan
    Zhang, Haicheng
    Feng, Wenting
    Jagadamma, Sindhu
    Kaiser, Klaus
    Kothawala, Dolly
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Mayes, Melanie A.
    Ciais, Philippe
    How much carbon can be added to soil by sorption?2021In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 152, no 2-3, p. 127-142Article in journal (Refereed)
    Abstract [en]

    Quantifying the upper limit of stable soil carbon storage is essential for guiding policies to increase soil carbon storage. One pool of carbon considered particularly stable across climate zones and soil types is formed when dissolved organic carbon sorbs to minerals. We quantified, for the first time, the potential of mineral soils to sorb additional dissolved organic carbon (DOC) for six soil orders. We compiled 402 laboratory sorption experiments to estimate the additional DOC sorption potential, that is the potential of excess DOC sorption in addition to the existing background level already sorbed in each soil sample. We estimated this potential using gridded climate and soil geochemical variables within a machine learning model. We find that mid- and low-latitude soils and subsoils have a greater capacity to store DOC by sorption compared to high-latitude soils and topsoils. The global additional DOC sorption potential for six soil orders is estimated to be 107 ± 13 Pg C to 1 m depth. If this potential was realized, it would represent a 7% increase in the existing total carbon stock.

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  • 3.
    Adediran, Gbotemi A.
    et al.
    Department of Soil and Environment Swedish University of Agricultural Sciences Uppsala Sweden;UK Centre for Ecology and Hydrology Wallingford United Kingdom.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology. Department of Geosciences Swedish Museum of Natural History Stockholm Sweden.
    Gustafsson, Jon‐Petter
    Department of Soil and Environment Swedish University of Agricultural Sciences Uppsala Sweden.
    Significance of phosphorus inclusions and discrete micron‐sized grains of apatite in postglacial forest soils2022In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 73, no 5, article id e13310Article in journal (Refereed)
  • 4.
    Ahlgren, Serina
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Behaderovic, Danira
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Woodhouse, Anna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Att räkna med markkol i livscykelanalys av nötkött2020Report (Other academic)
    Abstract [sv]

    Markanvändning och förändringar i markkol kan ha en stor påverkan på klimatpåverkan från livsmedelsproduktion. En vanlig metod för att beräkna klimatpåverkan av livsmedel är livscykelanalys (LCA). Här räknar man ihop alla utsläpp från produktionskedjan till ett tal.

    Det finns idag dock ingen konsensus kring hur vi bör räkna med markkol i LCA vilket innebär att många studier helt enkelt inte tar med markkol eller gör väldigt olika val vilket försvårar tolkning av resultaten. Det finns också en begreppsförvirring som gör det svårt att kommunicera kring markkol och dess effekter.

    I denna rapport ger vi en bakgrund till problemen, varför det är så svårt att räkna med markkol. Vi gör ett försök att reda ut begreppen, och att ge några råd för hur markkol kan inkluderas i LCA. Rapporten vänder sig till utförare av LCA men även till dig som vill veta mer om markkol i LCA på ett generellt plan och för att kunna tolka resultat.

    I rapporten delar vi upp markkolsförändringar som kan ske på fyra principiellt olika nivåer:1. Ändring mellan olika kategorier av markanvändning, till exempel från skog till jordbruksmark.2. Odling av en mark som inte är i jämvikt, till exempel att bruka en torvmark eller mark som bytt kategori för länge sen men som fortfarande inte kommit i jämnvikt.3. Ändring i marknyttjande, till exempel byte av gröda från ettåriga till fleråriga grödor.4. Att ändra eller införa skötselåtgärder, till exempel tillförsel av organiskt material.

    För att inkludera markkolsförändringar i LCA, behövs tre steg (1) uppskatta ändringen i markkol (2) fördela påverkan över tid och (3) beräkna klimatpåverkan. I rapporten går vi systematiskt igenom dessa tre steg och pekar ut vilka svårigheter som finns.Det är svårt att ge specifika råd kring markkol, då alla val är tätt kopplade till syftet med studien som ska utföras. Vi tycker att det viktigaste är, att LCA-utövaren är medveten om de olika alternativen i varje steg och tydligt beskriver och motiverar sina val, så att det för slutanvändaren av resultaten är tydligt vad som ligger grund för resultaten.

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    RISE Rapport 2020:67
  • 5. Ahmed, Engy
    et al.
    Hugerth, Luisa W.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Logue, Jürg Brendan
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Bruchert, Volker
    Andersson, Anders F.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Holmström, Sara J. M.
    Mineral Type Structures Soil Microbial Communities2017In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 34, no 6, p. 538-545Article in journal (Refereed)
    Abstract [en]

    Soil microorganisms living in close contact with minerals play key roles in the biogeochemical cycling of elements, soil formation, and plant nutrition. Yet, the composition of microbial communities inhabiting the mineralosphere (i.e., the soil surrounding minerals) is poorly understood. Here, we explored the composition of soil microbial communities associated with different types of minerals in various soil horizons. To this effect, a field experiment was set up in which mineral specimens of apatite, biotite, and oligoclase were buried in the organic, eluvial, and upper illuvial horizons of a podzol soil. After an incubation period of two years, the soil attached to the mineral surfaces was collected, and microbial communities were analyzed by means of Illumina MiSeq sequencing of the 16S (prokaryotic) and 18S (eukaryotic) ribosomal RNA genes. We found that both composition and diversity of bacterial, archaeal, and fungal communities varied across the different mineral surfaces, and that mineral type had a greater influence on structuring microbial assemblages than soil horizon. Thus, our findings emphasize the importance of mineral surfaces as ecological niches in soils.

  • 6.
    Alakukku, Laura
    University of Helsinki, Finland.
    28 Soil Compaction2012In: Sustainable Agriculture / [ed] Christine Jakobsson, Uppsala: Baltic University Press , 2012, 1500, p. 217-221Chapter in book (Other (popular science, discussion, etc.))
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    ehsa 1-28
  • 7.
    Alfredsson, Hilda
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Soil Organic Carbon in Boreal Agricultural Soil: Tillage interruption and its effect on Soil Organic Carbon2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Farmers have been disrupting the carbon cycle ever since humans started converting forests to agricultural lands. But are there farming practices that can be applied to increase the carbon storage in the soil and subsequently counteract increasing carbon dioxide levels in the atmosphere? In this study I investigate if soil organic matter (SOM) and soil organic carbon (SOC) change with longer interruption between tillage events. The study was conducted by studying SOM concentrations and SOC pools in eight fields with different time since tillage (1 to 14 years). I found that SOM concentrations increased in the O horizon of the studied soil in response to increased time since tillage. Here, SOM concentrations were on average around 13 % one year after tillage, while fourteen-year-old farmland had a concentration around 15 %. In similar, SOC pool increased from around 0.1 kg C m-2 in the O horizon of 1 year old soil to 0.33 kg C m-2 14 years after tillage. While both SOM concentrations and SOC pools increased in the O horizon over time since tillage, the SOM concentration and SOC pools decreased in the subsoil. I found no net sequestering of SOC in response to less frequent tillage in comparison to more frequency tillage. My conclusion is that limiting tillage to 14-year cycles is not enough to increase carbon sequestration. 

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  • 8.
    Alsterhag, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Förslag till modell av kemikaliespridning i mark anpassad för användning vid räddningsinsats - Kemspill Mark 4.02005Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    After emergencies involving chemical spills it is of great importance that correct measures are taken with short notice, both for the security of people and in order to minimize future environmental consequences. The RIB-unit at the Swedish Rescue Services Agency initiated this study, the aim of which is to propose changes to the existing chemical transport calculation tool: Chemical Spill 3.4, included in RIB - Integrated Decision Support for Civil Protection, so that it can be used for decision support as well as in preventive work. A rough estimation of chemical transport in the subsurface is considered being of great importance when making decisions during emergency response operations.

    The proposition presented in this report is a non site specific chemical transport model which is designed to give a rough estimation of NAPL flow in homogenous isotropic soil shortly after an instantaneous release. The model can be used at two levels; both in situations without access to information on subsurface properties, and with more accuracy in situations with knowledge of the included parameters. For that reason the user can choose among predefined alternatives or assign the parameters a numeric value to increase the quality of the model output. The predefined alternatives are represented by default values for different parameters in the model.

    Suggested model output are vertical and horizontal transport of NAPL phase, horizontal transport of dissolved chemical in the aqueous phase, as well as the amounts of spill that are evaporated and entrapped in the soil, all at the time specified by the user. Moreover the maximum transport of the chemical phase and time to groundwater pollution are given. To make the uncertainty of the model clear for the user the results are given as the most likely value together with the smallest and largest values that can be expected.

    Equations presented in this report describe a selection of subsurface processes which occur after a release of chemicals. The selection is made with the aim to reach satisfying result when the model is used within its domain without making the model complicated for the user. Therefore simplifying assumptions have been made in the descriptions of some processes while some other processes are neglected. Simplifications have been based on recognized references or on theoretical arguments, but the overall performance of the model as well as some of the default input parameters need to be further tested and validated before the new version of the model can be included in RIB. However, compared with the existing version Chemical Spill 3.4 several changes have been suggested; including additional processes, development of default values and making model uncertainty clear to the user. These changes are thought to significantly improve the existing model.

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    FULLTEXT01
  • 9.
    Arnebrant, Kriatina
    et al.
    Department of Microbial Ecology, University of Lund, Lund, Sweden.
    Schnürer, Johan
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Changes in atp content during and after chloroform fumigation1990In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 22, no 6, p. 875-877Article in journal (Refereed)
  • 10. Arp, Hans Peter H.
    et al.
    Lundstedt, Staffan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Josefsson, Sarah
    Cornelissen, Gerard
    Enell, Anja
    Allard, Ann-Sofie
    Kleja, Dan Berggren
    Native Oxy-PAHs, N-PACs, and PAHs in historically contaminated soils from Sweden, Belgium, and France: their soil-porewater partitioning behavior, bioaccumulation in Enchytraeus crypticus, and bioavailability2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 19, p. 11187-11195Article in journal (Refereed)
    Abstract [en]

    Soil quality standards are based on partitioning and toxicity data for laboratory-spiked reference soils, instead of real world, historically contaminated soils, which would be more representative. Here 21 diverse historically contaminated soils from Sweden, Belgium, and France were obtained, and the soil-porewater partitioning along with the bioaccumulation in exposed worms (Enchytraeus crypticus) of native polycyclic aromatic compounds (PACs) were quantified. The native PACs investigated were polycyclic aromatic hydrocarbons (PAHs) and, for the first time to be included in such a study, oxygenated-PAHs (oxy-PAHs) and nitrogen containing heterocyclic PACs (N-PACs). The passive sampler polyoxymethylene (POM) was used to measure the equilibrium freely dissolved porewater concentration, C-pw, of all PACs. The obtained organic carbon normalized partitioning coefficients, K-TOC, show that sorption of these native PACs is much stronger than observed in laboratory-spiked soils (typically by factors 10 to 100), which has been reported previously for PAHs but here for the first time for oxy-PAHs and N-PACs. A recently developed K-TOC model for historically contaminated sediments predicted the 597 unique, native K-TOC values in this study within a factor 30 for 100% of the data and a factor 3 for 58% of the data, without calibration. This model assumes that TOC in pyrogenic-impacted areas sorbs similarly to coal tar, rather than octanol as typically assumed. Black carbon (BC) inclusive partitioning models exhibited substantially poorer performance. Regarding bioaccumulation, C-pw combined with liposome-water partition coefficients corresponded better with measured worm lipid concentrations, C-lipid (within a factor 10 for 85% of all PACs and soils), than C-pw combined with octanol-water partition coefficients (within a factor 10 for 76% of all PACs and soils). E. crypticus mortality and reproducibility were also quantified. No enhanced mortality was observed in the 21 historically contaminated soils despite expectations from PAH spiked reference soils. Worm reproducibility weakly correlated to C-lipid of PACs, though the contributing influence of metal concentrations and soil texture could not be taken into account. The good agreement of POM-derived C-pw with independent soil and lipid partitioning models further supports that soil risk assessments would improve by accounting for bioavailability. Strategies for including bioavailability in soil risk assessment are presented.

  • 11.
    Arvidsson, Johan
    et al.
    Swedish University of Agricultural Sciences.
    Etana, Ararso
    Swedish University of Agricultural Sciences.
    Myrbeck, Åsa
    Swedish University of Agricultural Sciences.
    Rydberg, Tomas
    Swedish University of Agricultural Sciences.
    29 Ploughless Tillage  in Long- and Short-term  Experiments2012In: Sustainable Agriculture / [ed] Christine Jakobsson, Uppsala: Baltic University Press , 2012, 1500, p. 222-228Chapter in book (Other (popular science, discussion, etc.))
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    ehsa 1-29
  • 12.
    Azizi, Soghra
    et al.
    Tarbiat Modares Univ, Iran.
    Tabari, Masoud
    Tarbiat Modares Univ, Iran.
    Abad, Ali Reza Fallah Nosrat
    Agr Res Educ & Extens Org AREEO, Iran.
    Ammer, Christian
    Georg August Univ Göttingen, Germany.
    Guidi, Lucia
    Univ Pisa, Italy.
    Bader, Martin K.-F.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Linnaeus University, Linnaeus Knowledge Environments, Green Sustainable Development.
    Soil Inoculation With Beneficial Microbes Buffers Negative Drought Effects on Biomass, Nutrients, and Water Relations of Common Myrtle2022In: Frontiers in Plant Science, E-ISSN 1664-462X, Vol. 13, article id 892826Article in journal (Refereed)
    Abstract [en]

    Common myrtle (Myrtus communis L.) occurs in (semi-)arid areas of the Palearctic region where climate change, over-exploitation, and habitat destruction imperil its existence. The evergreen shrub is of great economic and ecological importance due to its pharmaceutical value, ornamental use, and its role in urban greening and habitat restoration initiatives. Under greenhouse conditions, we investigated the effect of soil inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on biomass allocation, water relations, and nutritional status of drought-stressed myrtle seedlings. Single and dual AMF (Funneliformis mosseae and Rhizophagus irregularis) and PGPR (Pseudomonas fluorescens and P. putida) soil inoculations were applied to myrtle seedlings growing under different soil water regimes (100, 60, and 30% of field capacity) for 6 months using a full factorial, completely randomized design. AMF and PGPR treatments, especially dual inoculations, alleviated negative drought effects on biomass and morpho-physiological traits, except for water-use efficiency, which peaked under severe drought conditions. Under the greatest soil water deficit, dual inoculations promoted leaf biomass (104%-108%), root biomass (56%-73%), mesophyll conductance (58%), and relative water content (1.4-fold) compared to non-inoculated controls. Particularly, dual AMF and PGPR inoculations stimulated nutrient dynamics in roots (N: 138%-151%, P: 176%-181%, K: 112%-114%, Ca: 124%-136%, and Mg: 130%-140%) and leaves (N: 101%-107%, P: 143%-149%, K: 83%-84%, Ca: 98%-107%, and Mg: 102%-106%). Our findings highlight soil inoculations with beneficial microbes as a cost-effective way to produce highly drought resistant seedling stock which is vital for restoring natural myrtle habitats and for future-proofing myrtle crop systems.

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  • 13. Baken, S.
    et al.
    Larsson, M. A.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Cubadda, F.
    Smolders, E.
    Ageing of vanadium in soils and consequences for bioavailability2012In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 63, no 6, p. 839-847Article in journal (Refereed)
    Abstract [en]

    Total vanadium (V) concentrations in soils commonly range from 20 to 120 mg kg-1. Vanadium added directly to soils is more soluble than geogenic V and can be phytotoxic at doses within this range of background concentrations. However, it is unknown how slow sorption reactions change the fate and effect of added V in soils. This study addresses the changes in V solubility, toxicity and bioavailability in soils over time. Four soils were amended with pentavalent V in the form of a soluble vanadate salt, and extractable V concentrations were monitored over 100 days. The toxicity to barley and tomato plants was evaluated in freshly spiked soils and in the corresponding aged soils that were equilibrated for up to 330 days after spiking. The V concentrations in 0.01 m CaCl2 soil extracts decreased approximately two-fold between 14 and 100 days after soil spiking, and the reaction kinetics were similar for all soils. The phytotoxicity of added V decreased on average two-fold between freshly spiked and aged soils. The reduced toxicity was associated with a corresponding decrease in V concentrations in the isolated soil solutions and in the shoots. The V speciation in the soil solution of the aged soils was dominated by V(V); less than 8% was present as V(IV). Oxalate extractions suggest that the V(V) added to soils is predominantly sorbed onto poorly crystalline oxyhydroxides. It is concluded that the toxicity of V measured in freshly spiked soils may not be representative of soils subject to a long-term V contamination in the field.

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  • 14.
    Bandau, Franziska
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Importance of tannins for responses of aspen to anthropogenic nitrogen enrichment2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Boreal forests are often strongly nitrogen (N) limited. However, human activities are leading to increased N inputs into these ecosystems, through atmospheric N deposition and forest fertilization. N input into boreal forests can promote net primary productivity, increase herbivore and pathogen damage, and shift plant species composition and community structure. Genetic diversity has been suggested as a key mechanism to promote a plant species’ stability within communities in response to environmental change. Within any plant population, specific traits (e.g. growth and defense traits) can vary substantially among individuals, and a greater variation in traits may increase chances for the persistence of at least some individuals of a population, when environmental conditions change. One aspect of plant chemistry that can greatly vary among different genotypes (GTs) are condensed tannin (CTs). These secondary metabolites have been suggested to affect plant performance in many ways, e.g. through influencing plant growth, the interactions of plants with herbivores and pathogens, and through affecting litter decomposition, and hence the return of nutrients to plants. To investigate how genotypic variation in foliar CT production may mediate the effects that anthropogenic N enrichment can have on plant performance and litter decomposition, I performed a series of experiments. For these experiments, aspen (Populus tremula) GTs with contrasting abilities to produce foliar CTs (i.e. low- vs. high-tannin producers) were grown under 3 N conditions, representing ambient N (+0 kg ha-1), upper level atmospheric N deposition (+15 kg ha-1), and forest fertilization rates (+150 kg ha-1). This general experimental set-up was once established in a field-like environment, from which natural enemies were excluded, and once in a field, in which enemies were present. In my first two studies, I investigated tissue chemistry and plant performance in both environments. I observed that foliar CT levels decreased in response to N in the enemy‑free environment (study I), but increased with added N when enemies were present (study II). These opposing responses to N may be explained by differences in soil N availability in the two environments, or by induction of CTs after enemy attack. Enemy damage generally increased in response to N, and was higher in low-tannin than in high-tannin plants across all N levels. Plant growth of high‑tannin plants was restricted under ambient and low N conditions, probably due to a trade-off between growth and defense. This growth constraint for high‑tannin plants was weakened, when high amounts of N were added (study I and II), and when enemy levels were sufficiently high, so that benefits gained through defense could outweigh the costs of defense production (study II). Despite those general responses of low- and high‑tannin producers to added N, I also observed a number of individual responses of GTs to N addition, which in some case were not connected to the intrinsic ability of the GTs to produce foliar CTs. In study III, gene expression levels in young leaves and phenolic pools of the plants that were grown in the enemy‑free environment were studied. This study revealed that gene control over the regulation of the phenylpropanoid pathway (PPP) was distributed across the entire pathway. Moreover, PPP gene expression was higher in high-tannin GTs than in low‑tannin GTs, particularly under ambient N. At the low N level, gene expressions declined for both low- and high-tannin producers, whereas at the high N level expression at the beginning and the end of the PPP was upregulated and difference between tannin groups disappeared. Furthermore, this study showed that phenolic pools were frequently uncorrelated, and that phenolic pools were only to some extent related to tannin production and gene expression. In study IV, I investigated the decomposability of litter from the field plants. I found that N enrichment generally decreased mass loss, but there was substantial genetic variation in decomposition rates, and GTs were differentially responsive to added N. Study IV further showed that CTs only had a weak effect on decomposition, and other traits, such as specific leaf area and the lignin:N ratio, could better explain genotypic difference in mass loss. Furthermore, N addition caused a shift in which traits most strongly influenced decomposition rates. Collectively, the result of these studies highlight the importance of genetic diversity to promote the stability of species in environments that experience anthropogenic change.

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  • 15.
    Bar-Am, Maya
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Akademiska sjukhuset: Befintliga geotekniska och hydrogeologiska förhållanden och dess markförutsättningar för framtida byggnationer2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Uppsala University Hospital is a large institution of vital societal function and many new buildings have been constructed and others rebuild during the past ten years. The hospital area is located on Uppsalaåsen and within a primary protection zone, i.e. there is a complex geology and requirements for the protection of the groundwater used for Uppsala’s water supply. The ground contains large sections of clay and has drastic changes in soil types. This has resulted in a subsidence problem within the hospital area. Region Uppsala has several plans regarding upcoming constructions at Uppsala University Hospital and due to the complicated soil situation is an investigation of the geotechnics and hydrogeology within the area sought for. The focus of this master thesis is on subsidence capacity and the ground water’s pressure levels. Four zones within the hospital area have been pointed out by Region Uppsala for potential future construction projects. The zones are at the parking garage T3, production kitchen, NOP-complex and new cyclotron building.

    The master thesis was divided into three parts; locating the soil layer sequence, calculation of subsidence based on CRS tests and study of the ground water’s pressure level. The soil layer sequence was construed in GeoSuite based on 474 probes conducted by the consultant company Bjerking. The probs respective soil layer was interpolated and illustrated as level curves using Topocad. Eight cross-sections were made within the zones of extra interest and the sections were made from a 3D-model created in Civil 3D. The soil layers examined throughout the master thesis were filling material, clay, granular soil, rock and ground surface. The subsidence capacity and its time were calculated based on two CRS trials and max-, min- and average values of the ground water’s pressure levels under the hospital area was computed based on 20 years of daily data retrieved from a measuring well in Stadsträdgården facilitated by Uppsala Vatten.

    The results confirm the ridge complex geology consisting of varying depths of clay under the hospital area. Several buildings will probably require deep foundations, e.g. the parking garage T3. The results also show areas of shallow layers of clay indicating lower risk of subsidence and hence will require a shallow foundation. The conducted subsidence calculations indicate that the parking garage T3 will sink 20 to 70 cm after 158 to 213 years if no foundation is implemented, which is in line with the current subsidence occurring at the building. The ground water’s pressure level has had an average value of + 2.3 m (RH2000) during the last 20 years and will probably not fluctuate in the future due to the existing decision on water management. Hence, some buildings within certain parts of the hospital area will require permission prior to construction within the primary zone. 

    The results establish a valuable overview of the hydrogeology at Uppsala University Hospital and give indications regarding how the foundations in the zones of extra interest should be dimensioned sustainable and economically. However, more data is needed, e.g. additional probes and CRS trials, to gain an increased complexity of the hospital area in respect to soil layer sequences and subsidence tendency. 

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  • 16. Baskaran, Preetisri
    et al.
    Ekblad, Alf
    Soucémarianadin, Laure N.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. CNRS, Laboratoire de Géologie de l’ENS, Ecole Normale Supérieure, Paris, France.
    Hyvönen, Riitta
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lindahl, Björn D.
    Nitrogen dynamics of decomposing Scots pine needle litter depends on colonizing fungal species2019In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 95, no 6, article id fiz059Article in journal (Refereed)
    Abstract [en]

    In boreal ecosystems plant production is often limited by low availability of nitrogen. Nitrogen retention in below-ground organic pools plays an important role in restricting recirculation to plants and thereby hampers forest production. Saprotrophic fungi are commonly assigned to different decomposer strategies, but how these relate to nitrogen cycling remains to be understood. Decomposition of Scots pine needle litter was studied in axenic microcosms with the ligninolytic litter decomposing basidiomycete Gymnopus androsaceus or the stress tolerant ascomycete Chalara longipes. Changes in chemical composition were followed by C-13 CP/MAS NMR spectroscopy and nitrogen dynamics was assessed by the addition of a N-15 tracer. Decomposition by C. longipes resulted in nitrogen retention in non-hydrolysable organic matter, enriched in aromatic and alkylic compounds, whereas the ligninolytic G. androsaceus was able to access this pool, counteracting nitrogen retention. Our observations suggest that differences in decomposing strategies between fungal species play an important role in regulating nitrogen retention and release during litter decomposition, implying that fungal community composition may impact nitrogen cycling at the ecosystem level.

  • 17.
    Beckman, Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kvävestatus och risk för nitrifikation i två avverkade skogsområden i Halland2005Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nitrogen deposition leads to environmental damage in areas where the nitrogen deposition is high. Southwest Sweden receives an annual nitrogen deposition of up to 20 kg N/ha. Nitrogen that is not assimilated by the vegetation is accumulated in the soil, which may lead to nitrogen saturation and an elevated risk of nitrogen leaching. Nitrogen leaching from forest areas in southern Sweden has proven to be higher than from agricultural areas, which have been thought to be the main contributors to elevated nitrogen levels in rivers and lakes. The amount of nitrogen that leaches depends on the fraction of the total nitrogen in the soil that consists of nitrate, since nitrate is easily transported through the soil. Nitrogen leaching increases after clear-cutting since the uptake by vegetation is greatly reduced.

    In this study the soil chemistry of two clear-cut spruce stands in Halland, in southwest Sweden, has been analyzed. A previous study in these areas has indicated higher nitrate concentrations in the groundwater in one of the areas and thus a greater nitrogen leaching. Nitrogen deposition in the two areas is estimated to be the same and therefore the soil chemistry has been analyzed to evaluate if differences in the soil can have resulted in differences in the nitrate concentration in the groundwater. The hypothesis is that the area with higher nitrate concentrations in the groundwater has properties more favorable for nitrification, which would be especially apparent in a lower carbon to nitrogen ratio. The pH and storage of nitrate, ammonium, total carbon, total nitrogen and exchangeable cations was analyzed in soil samples from both areas. In addition, a study of stand properties and previous use of the areas was made.

    The analyses performed in this study indicate that the soil properties could not explain the differences in nitrate concentration in the groundwater. The differences found between the areas were that the area with lower nitrate concentrations in the groundwater had higher nitrate and ammonium concentrations and higher pH in the soil. The reason for this might be that the soil in this area has larger capacity to bind elements. The fact that the soil samples were sampled during different seasons probably had a major effect on these results. The history and stand properties of the two areas were similar. According to site index one area was more fertile, which benefits nitrification. This fact was not confirmed by the analyses, but it probably caused the nitrification rate to be higher in this area.

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  • 18.
    Berg, Björn
    et al.
    Dipartimento biologia strutturale e funzionale, Complesso universitario di Monte S. Angelo, Napoli, Italy; Department of forest ecology, University of Helsinki, Helsinki, Finland.
    Davey, M. P.
    Department of plant sciences, University of Cambridge, Cambridge, United Kingdom.
    De Marco, A.
    Dipartimento biologia strutturale e funzionale, Complesso universitario di Monte S. Angelo, Napoli, Italy.
    Emmett, B
    Centre for ecology and hydrology, Bangor.
    Faituri, M.
    Department of soils and water, Omar AlMukhtar university, Elbeida, Libyan Arab Jamahiriya.
    Hobbie, S. E.
    Department of ecology, evolution and behavior, University of Minnesota, St. Paul, USA.
    Johansson, Maj-Britt
    University of Gävle.
    Liu, C.
    Department of landscape science and engineering, College of agriculture and biology, Shanghai, ChinaShanghai Jiao Tong university,.
    McClaugherty, C.
    Department of biology, Mount Union college, Alliance, USA.
    Norell, L.
    Unit of applied statistics and mathematics, SLU, Uppsala, Sweden.
    Rutigliano, F. A.
    Dipartimento di scienze ambientali, Seconda Università degli studi di Napoli, Caserta, Italy.
    Vesterdal, L.
    Forest & landscape Denmark, University of Copenhagen, Hørsholm, Denmark.
    Virzo De Santo, A.
    Dipartimento biologia strutturale e funzionale, Complesso universitario de Monte S. Angelo, Napoli, Italy.
    Factors influencing limit values for pine needle litter decomposition: A synthesis for boreal and temperate pine forest systems2010In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 100, no 1, p. 57-73Article in journal (Refereed)
    Abstract [en]

    We synthesized available data for decomposition of pine (Pinus) needle litter in pine forests to determine the litter chemical characteristics and climate factors that explained variation in the limit value, i. e. the level of accumulated mass loss at which the decomposition process either continues at a very low rate or possibly stops. Our data base included 56 separate studies on decomposition of pine needle litter, spanning Scots pine, lodgepole pine, Aleppo pine, stone pine and white pine, mainly incubated at the site of collection. Studies had 5 to 19 samplings, on average 10, and the decomposition was followed to a mass loss ranging from 47 to 83%, on average 67%. The periods from 3.0 to 5.4 years, on average 3.9 years, were of sufficient duration to allow estimates of limit values of decomposition. We used a linear mixed model with regression effects to relate limit values to potential explanatory variables, namely the sites' long-term mean annual temperature (MAT) and mean annual precipitation (MAP) and to substrate-chemistry factors. Regarding the latter, we explored two models; one that included initial concentrations of water solubles, lignin, N, P, K, Ca, Mg, and Mn and one that included only lignin, N, Ca, and Mn to focus on those nutrients known to influence lignin degradation. Using backward elimination significant explanatory variables were determined. For litter decomposed in its site of origin we found the limit value to depend mainly on the initial concentration of Mn, with higher Mn concentrations resulting in higher accumulated mass loss. Thus, litter with higher Mn reached a higher limit value and left a smaller stable fraction. This is likely due to the fact that Mn is an essential component of ligninolytic enzymes important for degrading litter in the later stages of decomposition. Manganese has received little attention in decomposition studies to date. Given its significance in this synthesis, the role of Mn in influencing variation in the late stages of decomposition among ecosystems and among litters of other genera besides Pinus deserves further attention.

  • 19.
    Berg, Björn
    et al.
    Department of Forest Sciences, University of Helsinki, Helsinki, Finland .
    Erhagen, Björn
    Department of Ecology and Environmental Sciences, University of Umeå, Umeå, Sweden .
    Johansson, Maj-Britt
    University of Gävle.
    Nilsson, Mats
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå.
    Stendahl, Johan
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala.
    Trum, Florence
    Earth and Life Institute, Universite' catolique de Louvain, Louvain-la-Neuve, Belgium .
    Vesterdal, Lars
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Fredriksberg C, Denmark .
    Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems: a review2015In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 358, p. 248-260, article id 15021Article, review/survey (Refereed)
    Abstract [en]

    We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same litter species and for the genus Pinus we found a range from 0.03 to 3.7mgg-1. Concentrations were related negatively to site mean annual temperature (MAT) and annual actual evapotranspiration (AET) for pine species litter but not for that of Norway spruce (Picea abies) as a single species. Combined data for several species showed a highly significant relationship to MAT.Manganese peroxidase is an Mn-dependent enzyme, found in white-rot fungi, essential for the degradation of lignin and ligninlike compounds. The decomposition rates of lignified litter tissue (late phase) is positively related to the litter’s Mn concentration. Further, the Mn concentration is positively related to the limit value for decomposition - the higher the Mn concentration the smaller the stable litter fraction. Manganese release from decomposing litter appears at least in part to be species related. Thus was release from pine needle litter significantly faster (p<. 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in Norway spruce mor increase more with decreasing MAT than in a gradient with Scots pine. Higher Mn concentrations in humus appear to decrease its stability and result in a higher release of carbon dioxide (CO<inf>2</inf>) and dissolved organic carbon (DOC). We conclude that this may explain (i) the lower amount of carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases - empirical - with negative interaction between Mn and N; (i) in pine foliar litter fall concentrations of Mn decrease with site MAT whereas those of N increase, (ii) in decomposing late-stage litter with N retarding and Mn stimulating decomposition, (iii) for the stable phase, limit values are related negatively to N and positively to Mn, and (iv) Mn concentrations in humus decrease with MAT whereas those of N increase.

  • 20.
    Berg, Björn
    et al.
    Department of Forest Ecology, University of Helsinki, Helsinki, Finlan; Dipartimento Biologia Strutturale e Funzionale, Complesso Universitario, Napoli, Italy.
    Johansson, Maj-Britt
    University of Gävle.
    Nilsson, Åke
    Department of Forest Soils, Swedish University of Agriculture, Uppsala, Sweden.
    Gundersen, Per
    Forest and Landscape Denmark, University of Copenhagen, HØrsholm, Denmark.
    Norell, Lennart
    Unit of Applied Statistics and Mathematics, Swedish University of Agrictulture, Uppsala, Sweden.
    Sequestration of carbon in the humus layer of Swedish forests - direct measurements2009In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 39, no 5, p. 962-975Article in journal (Refereed)
    Abstract [en]

    To determine sequestration rates of carbon dioxide (CO2) we calculated the carbon (C) storage rate in humus layers of Swedish forests with Podsolic soils, which account for 14.2 x 106 ha of the 22.7 x 106 ha of forested land in Sweden. Our data set covered 41 years of humus inventories and mean humus layer thickness in 82513 plots. We analysed three forest types: (i) all combinations of tree species, (ii) forests dominated (>70%) by Norway spruce (Picea abies (L.) Karst.), and (Ui) forests dominated (>70%) by Scots pine (Pinus sylvestris L.). To relate changes in humus layer thickness to land area we used the intersections in 25 km x 25 km grids and used kriging interpolation, permitting calculations for each forest type. For each intersection mean humus thickness for each year was calculated and regressed against time to obtain the rate of change. This rate, humus bulk density, and humus C concentration were used, to calculate sequestration rates. The mean sequestration rate was 251 kg C-ha-1'year1, which is higher than theoretical values. The sequestration rate was positively related to temperature sum, albeit including effects of forest management. The pine-dominated forest type had a mean rate of 283 kgCha⁁year-1, and. the spruce-dominated had a mean rate of 239 kg Cha-1-year1. Under similar site conditions, pine sequestered more C than spruce (difference of 71 kg Cha-1'year-1; p < 0.0001), showing the importance of this type of ecosystem for C sequestration.

  • 21.
    Blad, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Torkat bioavfall som jordförbättringsmedel2007Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main project Dry preservation of source-separated organic household wastes involves a new technique for treatment of biowaste through drying. Investigations are going on to determine how the dried biowaste best can be used to close the natural circular flow of nutrients. The objective of this degree project is to determine if the dried biowaste can be used as a soil conditioner. By restoring the nutrients in the material to the ground, the natural circular flow is closed. A declaration of contents, including the nutrient levels, C/N ratio, pH and the electrical conductivity of the dried biowaste, was constructed and a germination test was done to make sure that the material did not inhibit sprouting. Further on a method was developed to study the decomposition process, and in particular the nitrogen mineralization of the dried biowaste. This method was then used practically.

    The results of this degree project indicate that the decomposition capacity of the dried biowaste is very good. The germination test showed that the material in a diluted form (up to 50 % dried biowaste) did not inhibit sprouting. The examination of the nitrogen mineralization showed a fast liberalisation of nutrients available to plants, with only a shorter period of nitrogen immobilization. Together these results imply that the dried material could function well as a soil conditioner.

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  • 22.
    Blanck, Ylva-Li
    et al.
    Lund University, Sweden.
    Gowda, Juan
    CONICET-INIBIOMA-CRUB, Argentina.
    Mårtensson, Linda-Maria
    Lund University, Sweden.
    Sandberg, Jakob
    Lund University, Sweden.
    Fransson, Ann-Mari
    Swedish University of Agriculture, Sweden.
    Plant species richness in a natural Argentinian matorral shrub-land correlates negatively with levels of plant phosphorus2010In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 345, no 1-2, p. 11-21Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to ascertain whether there is a relationship between plant species richness and plant-available N, P and water in an environment subject to little anthropogenic disturbance. To accomplish this we studied the vegetation in matorral shrub-lands in northern Patagonia, Argentina. Due to the variation in slope, precipitation and aspect between the sites water status was determined using the 12C/13C fraction, δ13C, to investigate whether this was a confounding factor. The numbers of herb, shrub, liana and tree species were determined at 20 sites along an estimated precipitation gradient. Leaf P and N content and the δ13C of Berberis buxifolia were determined, as well as the soil P and N content at the different sites. A negative correlation was found between species richness and Berberis buxifolia foliar P concentration (52% of the species richness variation was accounted for), and a positive correlation was found between plant species richness and Berberis buxifolia foliar N: P ratios (54% of the species richness variation was accounted for). The relationship between species richness and foliar P was seen when all layers of vegetation were included (trees, lianas, shrubs and herbs). Foliar N showed no correlation with species richness, while soil extractable NH4 showed a weak positive correlation with the number of shrub layer species (lianas, shrubs and trees). The species richness of the shrub layer increased with decreasing values of δ13C. Low soil P availability thus affects local species richness in the matorral shrub-lands of Patagonia in Argentina although the growth of vegetation in the area has been shown to be limited by N. We suggest that low P levels increase plant species richness because low soil P concentration is associated with a high P partitioning and high potential for niche separation.

  • 23.
    Blombäck, Karin
    et al.
    Swedish Univ Agr Sci, Dept Soil & Environm, POB 7014, SE-75007 Uppsala, Sweden.
    Bolster, Carl H.
    USDA ARS, Food Anim Environm Syst Res Unit, 2413 Nashville Rd B-5, Bowling Green, KY 42101 USA.
    Lindsjö, Anders
    Swedish Univ Agr Sci, Dept Soil & Environm, POB 7014, SE-75007 Uppsala, Sweden.
    Hesse, Kathrin
    Swedish Univ Agr Sci, Dept Soil & Environm, POB 7014, SE-75007 Uppsala, Sweden.
    Linefur, Helena
    Swedish Univ Agr Sci, Dept Soil & Environm, POB 7014, SE-75007 Uppsala, Sweden.
    Parvage, Mohammed Masud
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Swedish Univ Agr Sci, Dept Soil & Environm, POB 7014, SE-75007 Uppsala, Sweden.
    Comparing measures for determination of phosphorus saturation as a method to estimate dissolved P in soil solution2021In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 383, article id 114708Article in journal (Refereed)
    Abstract [en]

    In response to concerns over the translocation of P from soils to P-sensitive water bodies, there is high demand for developing simple indicators for evaluating a soil’s risk of releasing P into solution. Many studies have shown that the degree of soil phosphorus saturation (DPS), calculated as the ratio of soil P concentration to soil P sorption capacity (PSC), is good predictor of a soil’s risk of releasing P in solution. In this study we compared four different DPS indices in how well they predicted dissolved P following extraction with either a 0.01 M CaCl2 (PCaCl2) solution or deionized water (PW). The first two indices were calculated from the ratio of extractable P to extractable Al and Fe using either acid ammonium oxalate (AlOX + FeOX) or ammonium lactate solutions (AlAL + FeAL). The second two DPS indices were calculated from the ratio of either Olsen-extractable P or AL-extractable P with sorption capacity estimated from the single point P sorption index (PSI). On a subset of 11 soils, we compared the different methods for estimating PSC with fitted Langmuir sorption maximum (Smax) using data from complete sorption isotherms. Both (AlOX + FeOX) and PSI were well correlated with Smax and hence regarded as good estimates for P sorption capacity. Conversely, (AlAL + FeAL) was not significantly correlated with Smax. P saturation calculated from PSI together with PAL or POls predicted PCaCl2 and PW best, whereas P saturation calculated from ammonium oxalate predicted PCaCl2 and PW the least. We did not find notable improvements in the regression models when we added a second explanatory variable (clay content, pH or total carbon) to the models. Our results show that multiple measures of P saturation provide similar predictions of a soiĺs potential for releasing dissolved P into soil solution. This provides flexibility in how P saturation indices are calculated to identify leaching prone hotspots.

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  • 24.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Biodiversity and Natural Environment, Research Institute for Nature and Forest INBO, Kliniekstraat 25,1070 Brussels, Belgium.
    Root phenology unresponsive to earlier snowmelt despite advanced above-ground phenology in two subarctic plant communities2017In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 31, no 7, p. 1493-1502Article in journal (Refereed)
    Abstract [en]

    1. Earlier snowmelt at high latitudes advances above-ground plant phenology, thereby affecting water, nutrient and carbon cycles. Despite the key role of fine roots in these ecosystem processes, phenological responses to earlier snowmelt have never been assessed below-ground. 2. We experimentally advanced snowmelt in two contrasting plant community types (heath and meadow) in northern Sweden and measured above- and below-ground phenology (leaf-out, flowering and fine root growth). We expected earlier snowmelt to advance both above- and below-ground phenology, and shrub-dominated heath to be more responsive than meadow. 3. Snow melted on average 9 days earlier in the manipulated plots than in controls, and soil temperatures were on average 0.9 degrees C higher during the snowmelt period of 3 weeks. This resulted in small advances in above-ground phenology, but contrary to our expectations, root phenology was unresponsive, with root growth generally starting before leaf-out. These responses to the snowmelt treatment were similar in both plant community types, despite strong differences in dominating plant functional types and root properties, such as root length and turnover. 4. The lack of a response in root phenology, despite warmer soil temperatures and above-ground phenological advances, adds evidence that above-ground plant responses might not be directly translated to below-ground plant responses, and that our understanding of factors driving below-ground phenology is still limited, although of major importance for water, nutrient and carbon cycling.

  • 25.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Krab, Eveline J
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Onteux, Sylvain
    Department of Environmental Science, Stockholm University, Stockholm, Sweden; Bolin Center for Climate Research, Stockholm University, Stockholm, Sweden.
    Ideas and perspectives: Alleviation of functional limitations by soil organisms is key to climate feedbacks from arctic soils2023In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 20, no 10, p. 1979-1990Article in journal (Refereed)
    Abstract [en]

    Arctic soils play an important role in Earth's climate system, as they store large amounts of carbon that, if released, could strongly increase greenhouse gas levels in our atmosphere. Most research to date has focused on how the turnover of organic matter in these soils is regulated by abiotic factors, and few studies have considered the potential role of biotic regulation. However, arctic soils are currently missing important groups of soil organisms, and here, we highlight recent empirical evidence that soil organisms' presence or absence is key to understanding and predicting future climate feedbacks from arctic soils. We propose that the arrival of soil organisms into arctic soils may introduce "novel functions", resulting in increased rates of, for example, nitrification, methanogenesis, litter fragmentation, or bioturbation, and thereby alleviate functional limitations of the current community. This alleviation can greatly enhance decomposition rates, in parity with effects predicted due to increasing temperatures. We base this argument on a series of emerging experimental evidence suggesting that the dispersal of until-then absent micro-, meso-, and macroorganisms (i.e. from bacteria to earthworms) into new regions and newly thawed soil layers can drastically affect soil functioning. These new observations make us question the current view that neglects organism-driven "alleviation effects"when predicting future feedbacks between arctic ecosystems and our planet's climate. We therefore advocate for an updated framework in which soil biota and the functions by which they influence ecosystem processes become essential when predicting the fate of soil functions in warming arctic ecosystems.

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  • 26. Bokhorst, Stef
    et al.
    Veen, G. F. (Ciska)
    Sundqvist, Maja K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE901-83 Umeå, Sweden; Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, DK-1307 Copenhagen K, Denmark.
    De Long, Jonathan R.
    Kardol, Paul
    Wardlea, David A.
    Contrasting responses of springtails and mites to elevation and vegetation type in the sub-Arctic2018In: Pedobiologia, ISSN 0031-4056, E-ISSN 1873-1511, Vol. 67, p. 57-64Article in journal (Refereed)
    Abstract [en]

    Climate change is affecting the species composition and functioning of Arctic and sub-Arctic plant and soil communities. Here we studied patterns in soil microarthropod (springtails and mites) communities across a gradient of increasing elevation that spanned 450 m, across which mean temperature declined by approximately 2.5 degrees C, in sub-Arctic Sweden. Across this gradient we characterized microarthropod communities in each of two types of vegetation, i.e., heath and meadow, to determine whether their responses to declining temperature differed with vegetation type. Mite abundance declined with increasing elevation, while springtail abundance showed the opposite response. Springtail communities were dominated by larger species at higher elevation. Mite abundance was unaffected by vegetation type, while springtail abundance was 53% higher in the heath than meadow vegetation across the gradient. Springtails but not mites responded differently to elevation in heath and meadow vegetation; hemi-edaphic species dominated in the heath at higher elevation while epiedaphic species dominated in the meadow. Our results suggest that sub-Arctic mite and springtail communities will likely respond in contrasting ways to changes in vegetation and soil properties resulting from climate warming.

  • 27.
    Bonde, Torben A.
    et al.
    Department of Water in Environment and Society, University of Linköping, Linköping, Sweden.
    Schnürer, Johan
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Rosswall, Thomas
    Department of Water in Environment and Society, University of Linköping, Linköping, Sweden.
    Microbial biomass as a fraction of potentially mineralizable nitrogen in soils from long-term field experiments1988In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 20, no 4, p. 447-452Article in journal (Refereed)
    Abstract [en]

    Aerobic long-term incubations (40-wk) were employed to measure the potentially mineralizable nitrogen (N0) in five 30-yr old cropping systems. The cropping systems consisted of: (1) bare fallow; (2) cropping with no additions; (3) cropping with 80 kg N ha-1 y-1 as Ca(NO3)2; (4) cropping with 80 kg N ha-1 yr-1 as Ca(NO3)2 plus 1800kg C ha-1 yr-1 as straw; and (5) cropping with 80 kg N ha-1 yr-1 plus 1800 kg C ha-1 yr-1 as farmyard manure. The amounts of N mineralized during the 40-wk incubations were between 93 and 168 μg g-1 (302-543 kg N ha-1 down to 25cm depth) with the lowest value for the fallow and the highest for the farmyard manure treatment. Microbial biomass-C and -N were measured on four occasions during the incubations. The biomass-C showed a rapid decrease to week 4 (to 36% of the initial mass), a slower decrease to week 9 (to 23% of initial mass) and a very slow decline to the final determination at the end of the incubation (to 8% of initial mass). The biomass-N displayed a similar pattern. Two related models were employed to describe the kinetics of N-mineralization during incubation: (1) a two-component first-order; and (2) a simplified special case of the two-component model. In all cases except the straw-amended soil, the simplified two-component model offered the best description of the curves of accumulated mineral-N. The available fraction, Na, of soil organic-N had mineralization rate constants similar to those for mineralization of microbial biomass.

  • 28. Bonner, Mark T. L.
    et al.
    Castro, David
    Schneider, Andreas N.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sundstrom, Gorel
    Hurry, Vaughan
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Nasholm, Torgny
    Why does nitrogen addition to forest soils inhibit decomposition?2019In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 137, article id 107570Article in journal (Refereed)
    Abstract [en]

    Enrichment of forest soils with inorganic nitrogen (N) tends to inhibit oxidative enzyme expression by microbes and reduces plant litter and soil organic matter decomposition rates. Without further explanation than is currently presented in the scientific literature, we argue that upregulation of oxidative enzymes seems a more competitive response to prolonged N enrichment at high rates than the observed downregulation. Thus, as it stands, observed responses are inconsistent with predicted responses. In this article, we present a hypothesis that resolves this conflict. We suggest that high rates of N addition alter the competitive balance between enzymatic lignin mineralisation and non-enzymatic lignin oxidation. Using metatransciptomics and chemical assays to examine boreal forest soils, we found that N addition suppressed peroxidase activity, but not iron reduction activity (involved in non-enzymatic lignin oxidation). Our hypothesis seems positioned as a parsimonious and empirically consistent working model that warrants further testing.

  • 29.
    Bonner, Mark TL.
    et al.
    School of Biology and Environmental Science, Queensland University of Technology (QUT), Brisbane, Australia; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Franklin, Oskar
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden; International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Hasegawa, Shun
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Näsholm, Torgny
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Those who can don't want to, and those who want to can't: An eco-evolutionary mechanism of soil carbon persistence2022In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 174, article id 108813Article in journal (Refereed)
    Abstract [en]

    Reliable manipulation of soil organic matter (SOM) – a necessity for optimal land management – is constrained by our limited mechanistic understanding of SOM formation. Here we propose a novel mechanistic element that may contribute to SOM dynamics, supplementing existing frameworks, based on evolutionary-ecological rather than chemical or physical limitations to decomposition. We argue that decomposition of some substrates may be constrained by spatial competition from opportunists. We describe and test a mathematical model based on our framework, providing a proof-of-concept that substrate can, in principle, be spared decomposition and accumulate even when it is physically and chemically accessible. Our framework can help explain a variety of SOM dynamics, including priming and the suppression of decomposition by nitrogen addition, as well as the typical composition of SOM. An augmented mechanistic framework for understanding SOM dynamics can help guide targeted empirical study, which in turn can contribute to more optimised land management.

  • 30.
    Boström, Björn
    et al.
    Örebro University, Department of Natural Sciences.
    Comstedt, Daniel
    Örebro University, Department of Natural Sciences.
    Ekblad, Alf
    Örebro University, Department of Natural Sciences.
    Can isotopic fractionation during respiration explain the 13C-enriched sporocarps of ectomycorrhizal and saprotrophic fungi?2008In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 177, no 4, p. 1012-1019Article in journal (Refereed)
    Abstract [en]

    • The mechanism behind the 13C enrichment of fungi relative to plant materials is unclear and constrains the use of stable isotopes in studies of the carbon cycle in soils.

    • Here, we examined whether isotopic fractionation during respiration contributes to this pattern by comparing δ13C signatures of respired CO2, sporocarps and their associated plant materials, from 16 species of ectomycorrhizal or saprotrophic fungi collected in a Norway spruce forest.

    • The isotopic composition of respired CO2 and sporocarps was positively correlated. The differences in δ13C between CO2 and sporocarps were generally small, < ±1‰ in nine out of 16 species, and the average shift for all investigated species was 0.04‰. However, when fungal groups were analysed separately, three out of six species of ectomycorrhizal basidiomycetes respired 13C-enriched CO2 (up to 1.6‰), whereas three out of five species of polypores respired 13C-depleted CO2 (up to 1.7‰; P < 0.05). The CO2 and sporocarps were always 13C-enriched compared with wood, litter or roots.

    • Loss of 13C-depleted CO2 may have enriched some species in 13C. However, that the CO2 was consistently 13C-enriched compared with plant materials implies that other processes must be found to explain the consistent 13C-enrichment of fungal biomass compared with plant materials.

  • 31.
    Bringmark, Ewa
    et al.
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden.
    Bringmark, Lage
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden.
    Sonesten, Lars
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden .
    Mjöfors, Kristina
    Department of Soil and Environment, SLU, Uppsala, Sweden.
    Johansson, Maj-Britt
    University of Gävle.
    Long-term monitoring of scots pine litter decomposition rates throughout sweden indicates formation of a more recalcitrant litter in the south2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 8, p. 878-890Article in journal (Refereed)
    Abstract [en]

    Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987-1989 and repeated in 2007-2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20-10%) over 3-5 years for all northern (> 60A degrees N) sites but decreased sharply from 30 to 10% in the third year in southern (< 60A degrees N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.

  • 32.
    Buckland, Philip I
    et al.
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    Johan, Olofsson
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    Engelmark, Roger
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    SEAD: Strategic Environmental Archaeology Database, planning report2006Report (Other academic)
    Abstract [en]

    This document lays out a strategy for the development of SEAD – A Strategic Environmental Archaeology Database, which will facilitate the digitisation and accessibility augmentation of MAL’s existing data from nearly thirty years of work in the fields of archaeology and environmental science. SEAD will also provide a framework for the entry of data from all future research and consultancy work at MAL, and allow guest researchers and external partners to contribute to, and work with the same data. The planned system will be implemented at both local and internet levels, and be designed with an aim towards broadening its scope with external partners in the future. SEAD will be made available online in order to increase the ease of access to environmental archaeology data and encourage an expansion of both the discipline and Sweden’s role in it. This is inline with current EU strategies on enhancing research infrastructure, and providing a greater insight into human-environment interactions for long term planning.

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  • 33. Butler, Orpheus M.
    et al.
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Warren, Charles R.
    Community composition and physiological plasticity control microbial carbon storage across natural and experimental soil fertility gradients2023In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 17, no 12, p. 2259-2269Article in journal (Refereed)
    Abstract [en]

    Many microorganisms synthesise carbon (C)-rich compounds under resource deprivation. Such compounds likely serve as intracellular C-storage pools that sustain the activities of microorganisms growing on stoichiometrically imbalanced substrates, making them potentially vital to the function of ecosystems on infertile soils. We examined the dynamics and drivers of three putative C-storage compounds (neutral lipid fatty acids [NLFAs], polyhydroxybutyrate [PHB], and trehalose) across a natural gradient of soil fertility in eastern Australia. Together, NLFAs, PHB, and trehalose corresponded to 8.5–40% of microbial C and 0.06–0.6% of soil organic C. When scaled to “structural” microbial biomass (indexed by polar lipid fatty acids; PLFAs), NLFA and PHB allocation was 2–3-times greater in infertile soils derived from ironstone and sandstone than in comparatively fertile basalt- and shale-derived soils. PHB allocation was positively correlated with belowground biological phosphorus (P)-demand, while NLFA allocation was positively correlated with fungal PLFA : bacterial PLFA ratios. A complementary incubation revealed positive responses of respiration, storage, and fungal PLFAs to glucose, while bacterial PLFAs responded positively to PO43-. By comparing these results to a model of microbial C-allocation, we reason that NLFA primarily served the “reserve” storage mode for C-limited taxa (i.e., fungi), while the variable portion of PHB likely served as “surplus” C-storage for P-limited bacteria. Thus, our findings reveal a convergence of community-level processes (i.e., changes in taxonomic composition that underpin reserve-mode storage dynamics) and intracellular mechanisms (e.g., physiological plasticity of surplus-mode storage) that drives strong, predictable community-level microbial C-storage dynamics across gradients of soil fertility and substrate stoichiometry.

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  • 34.
    Calogiuri, Tullia
    et al.
    Wageningen Univ & Res, Soil Biol Grp, Wageningen, Netherlands.;Wageningen Univ & Res, Soil Chem & Chem Soil Qual, Wageningen, Netherlands..
    Hagens, Mathilde
    Wageningen Univ & Res, Soil Chem & Chem Soil Qual, Wageningen, Netherlands..
    Van Groenigen, Jan Willem
    Wageningen Univ & Res, Soil Biol Grp, Wageningen, Netherlands..
    Corbett, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Hartmann, Jens
    Univ Hamburg, Inst Geol, Ctr Earth Syst Res & Sustainabil, Hamburg, Germany..
    Hendriksen, Rick
    Wageningen Univ & Res, Tupola, Wageningen, Netherlands..
    Janssens, Iris
    Univ Antwerp, IMEC, Dept Comp Sci, IDLab, Antwerp, Belgium..
    Janssens, Ivan A.
    Univ Antwerp, Biol Dept, Plants & Ecosyst PLECO, Antwerp, Belgium..
    Dominguez, Guillermo Ledesma
    Univ Antwerp, Biol Dept, Plants & Ecosyst PLECO, Antwerp, Belgium..
    Loescher, Grant
    Univ Hamburg, Inst Geol, Ctr Earth Syst Res & Sustainabil, Hamburg, Germany..
    Mortier, Steven
    Univ Antwerp, IMEC, Dept Comp Sci, IDLab, Antwerp, Belgium..
    Neubeck, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Niron, Harun
    Univ Antwerp, Biol Dept, Plants & Ecosyst PLECO, Antwerp, Belgium..
    Poetra, Reinaldy P.
    Univ Hamburg, Inst Geol, Ctr Earth Syst Res & Sustainabil, Hamburg, Germany..
    Rieder, Lukas
    Univ Hamburg, Inst Geol, Ctr Earth Syst Res & Sustainabil, Hamburg, Germany..
    Struyf, Eric
    Univ Antwerp, Biol Dept, Plants & Ecosyst PLECO, Antwerp, Belgium..
    Van Tendeloo, Michiel
    Univ Antwerp, Res Grp Sustainable Energy Air & Water Technol, Antwerp, Belgium..
    De Schepper, Tom
    Univ Antwerp, IMEC, Dept Comp Sci, IDLab, Antwerp, Belgium..
    Verdonck, Tim
    Univ Antwerp, IMEC, Dept Math, Antwerp, Belgium..
    Vlaeminck, Siegfried E.
    Univ Antwerp, Res Grp Sustainable Energy Air & Water Technol, Antwerp, Belgium..
    Vicca, Sara
    Univ Antwerp, Biol Dept, Plants & Ecosyst PLECO, Antwerp, Belgium..
    Vidal, Alix
    Wageningen Univ & Res, Soil Biol Grp, Wageningen, Netherlands..
    Design and Construction of an Experimental Setup to Enhance Mineral Weathering through the Activity of Soil Organisms2023In: Journal of Visualized Experiments, E-ISSN 1940-087X, no 201, article id e65563Article in journal (Refereed)
    Abstract [en]

    Enhanced weathering (EW) is an emerging carbon dioxide (CO2) removal technology that can contribute to climate change mitigation. This technology relies on accelerating the natural process of mineral weathering in soils by manipulating the abiotic variables that govern this process, in particular mineral grain size and exposure to acids dissolved in water. EW mainly aims at reducing atmospheric CO2 concentrations by enhancing inorganic carbon sequestration. Until now, knowledge of EW has been mainly gained through experiments that focused on the abiotic variables known for stimulating mineral weathering, thereby neglecting the potential influence of biotic components. While bacteria, fungi, and earthworms are known to increase mineral weathering rates, the use of soil organisms in the context of EW remains underexplored. This protocol describes the design and construction of an experimental setup developed to enhance mineral weathering rates through soil organisms while concurrently controlling abiotic conditions. The setup is designed to maximize weathering rates while maintaining soil organisms' activity. It consists of a large number of columns filled with rock powder and organic material, located in a climate chamber and with water applied via a downflow irrigation system. Columns are placed above a fridge containing jerrycans to collect the leachate. Representative results demonstrate that this setup is suitable to ensure the activity of soil organisms and quantify their effect on inorganic carbon sequestration. Challenges remain in minimizing leachate losses, ensuring homogeneous ventilation through the climate chamber, and avoiding flooding of the columns. With this setup, an innovative and promising approach is proposed to enhance mineral weathering rates through the activity of soil biota and disentangle the effect of biotic and abiotic factors as drivers of EW.

  • 35. Campos Pereira, H.
    et al.
    Ullberg, M.
    Kleja, D. B.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Swedish University of Agricultural Sciences, Sweden.
    Ahrens, L.
    Sorption of perfluoroalkyl substances (PFASs) to an organic soil horizon – Effect of cation composition and pH2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 207, p. 183-191Article in journal (Refereed)
    Abstract [en]

    Accurate prediction of the sorption of perfluoroalkyl substances (PFASs) in soils is essential for environmental risk assessment. We investigated the effect of solution pH and calculated soil organic matter (SOM) net charge on the sorption of 14 PFASs onto an organic soil as a function of pH and added concentrations of Al3+, Ca2+ and Na+. Often, the organic C-normalized partitioning coefficients (KOC) showed a negative relationship to both pH (Δlog KOC/ΔpH = −0.32 ± 0.11 log units) and the SOM bulk net negative charge (Δlog KOC = −1.41 ± 0.40 per log unit molc g−1). Moreover, perfluorosulfonic acids (PFSAs) sorbed more strongly than perfluorocarboxylic acids (PFCAs) and the PFAS sorption increased with increasing perfluorocarbon chain length with 0.60 and 0.83 log KOC units per CF2 moiety for C3–C10 PFCAs and C4, C6, and C8 PFSAs, respectively. The effects of cation treatment and SOM bulk net charge were evident for many PFASs with low to moderate sorption (C5–C8 PFCAs and C6 PFSA). However for the most strongly sorbing and most long-chained PFASs (C9–C11 and C13 PFCAs, C8 PFSA and perfluorooctane sulfonamide (FOSA)), smaller effects of cations were seen, and instead sorption was more strongly related to the pH value. This suggests that the most long-chained PFASs, similar to other hydrophobic organic compounds, are preferentially sorbed to the highly condensed domains of the humin fraction, while shorter-chained PFASs are bound to a larger extent to humic and fulvic acid, where cation effects are significant.

  • 36.
    Castaño, Carles
    et al.
    Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Hallin, Sara
    Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Egelkraut, Dagmar
    Department of Biological Sciences, University of Bergen, Bergen, Norway.
    Lindahl, Björn D.
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Clemmensen, Karina Engelbrecht
    Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Contrasting plant–soil–microbial feedbacks stabilize vegetation types and uncouple topsoil C and N stocks across a subarctic–alpine landscape2023In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 238, no 6, p. 2621-2633Article in journal (Refereed)
    Abstract [en]

    Global vegetation regimes vary in belowground carbon (C) and nitrogen (N) dynamics. However, disentangling large-scale climatic controls from the effects of intrinsic plant–soil–microbial feedbacks on belowground processes is challenging. In local gradients with similar pedo-climatic conditions, effects of plant–microbial feedbacks may be isolated from large-scale drivers. Across a subarctic–alpine mosaic of historic grazing fields and surrounding heath and birch forest, we evaluated whether vegetation-specific plant–microbial feedbacks involved contrasting N cycling characteristics and C and N stocks in the organic topsoil. We sequenced soil fungi, quantified functional genes within the inorganic N cycle, and measured 15N natural abundance. In grassland soils, large N stocks and low C : N ratios associated with fungal saprotrophs, archaeal ammonia oxidizers, and bacteria capable of respiratory ammonification, indicating maintained inorganic N cycling a century after abandoned reindeer grazing. Toward forest and heath, increasing abundance of mycorrhizal fungi co-occurred with transition to organic N cycling. However, ectomycorrhizal fungal decomposers correlated with small soil N and C stocks in forest, while root-associated ascomycetes associated with small N but large C stocks in heath, uncoupling C and N storage across vegetation types. We propose that contrasting, positive plant–microbial feedbacks stabilize vegetation trajectories, resulting in diverging soil C : N ratios at the landscape scale.

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  • 37.
    Chakrawal, Arjun
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Novel approaches in modeling of soil carbon: Upscaling theories and energetics2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Soils contain more carbon (C) than terrestrial (above ground) and atmospheric carbon combined. Mismanagement of soil C could lead to increased greenhouse gas emissions, whereas practices leading to increased C storage would help mitigate climate change while improving soil fertility and ecological functions. At the center of these complex feedbacks, soil microorganisms play a pivotal role in the cycling of C and nutrients, and thus in soil-climate interactions. However, this role is not fully understood; therefore, developing new methods for studying their dynamics is essential for an understanding of bio-physicochemical processes leading to mineralization or stabilization of soil organic matter (SOM).

    Current soil C cycling models lack a robust upscaling approach that links SOM decomposition from process (μm) to observation scale (cm to km). Moreover, these models often neglect energy fluxes from microbial metabolism, which may provide additional constraints in model parameterization and alternative observable quantities such as heat dissipation rate to study decomposition processes. In this doctoral work, I investigated two aspects of microbial processes and their consequences for SOM dynamics: 1) use of energetics to constrain SOM dynamics by explicitly accounting for thermodynamics of microbial growth, and 2) spatial constraints at microscale resulting from the non-uniform distribution of microorganisms and substrates.

    In the first part of the thesis, I developed a general mass and energy balance framework for the uptake of added substrates and native SOM. This framework provided the theoretical underpinnings for understanding variations in the calorespirometric ratios—the ratio of rates of heat dissipation to CO2 production—a useful metric used as a proxy for microbial carbon-use efficiency (CUE). Moreover, in a follow-up work, I extended this mass-energy framework to describe dynamic (time-varying) conditions, which was used to interpret rates of heat and CO2 evolution from different soils amended with glucose. The dynamic mass-energy framework was also used as a tool for data-model integration and estimation of microbial functional traits, such as their CUE and maximum substrate uptake rates. In the second part of the thesis, I linked the micro and macroscale dynamics of decomposition using scale transition theory. The findings of this study were further validated from laboratory experiments, in which spatial heterogeneity in the added substrate was manipulated.

    Results from the first part show that the calorespirometric ratios can be used to identify active metabolic pathways and to estimate CUE. Further, the heat dissipation rate can be used as a reliable complement or alternative to mass fluxes such as respiration rates for estimating microbial traits and constraining model parameters. In the second part, I show that the co-location of microorganisms and substrates increased, and separation decreased the microbial activity measured as heat dissipation from the incubation experiment. These results were in line with the expectation from the scale transition theory. In summary, this work provides novel approaches for studying soil C cycling and explicitly highlights a way forward to address two fundamental issues in microbial decomposition—the role of spatial heterogeneities and of energetic constraints on microbial metabolisms.

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  • 38.
    Cheeke, Tanya E.
    et al.
    Washington State Univ, Sch Biol Sci, 2710 Crimson Way, Richland, WA 99354 USA; Swedish Univ Agr Sci, Uppsala Bio Ctr, Dept Forest Mycol & Plant Pathol, Uppsala, Sweden.
    Phillips, Richard P.
    Indiana Univ, Dept Biol, 1001 E Third St, Bloomington, IN 47405 USA.
    Kuhn, Alexander
    Univ Calif Irvine, Dept Ecol & Evolutionary Biol, 321 Steinhaus Hall, Irvine, CA 92697 USA.
    Rosling, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Fransson, Petra
    Swedish Univ Agr Sci, Uppsala Bio Ctr, Dept Forest Mycol & Plant Pathol, Uppsala, Sweden.
    Variation in hyphal production rather than turnover regulates standing fungal biomass in temperate hardwood forests2021In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 102, no 3, article id 03260Article in journal (Refereed)
    Abstract [en]

    Soil fungi link above- and belowground carbon (C) fluxes through their interactions with plants and contribute to C and nutrient dynamics through the production, turnover, and activity of fungal hyphae. Despite their importance to ecosystem processes, estimates of hyphal production and turnover rates are relatively uncommon, especially in temperate hardwood forests. We sequentially harvested hyphal ingrowth bags to quantify the rates of Dikarya (Ascomycota and Basidiomycota) hyphal production and turnover in three hardwood forests in the Midwestern United States, where plots differed in their abundance of arbuscular (AM)-vs. ectomycorrhizal (ECM)-associated trees. Hyphal production rates increased linearly with the percentage of ECM trees and annual production rates were 66% higher in ECM- than AM-dominated plots. Hyphal turnover rates did not differ across the mycorrhizal gradient (plots varying in their abundance of AM vs. ECM trees), suggesting that the greater fungal biomass in ECM-dominated plots relates to greater fungal production rather than slower fungal turnover. Differences in hyphal production across the gradient aligned with distinctly different fungal communities and activities. As ECM trees increased in dominance, fungi inside ingrowth bags produced more extracellular enzymes involved in degrading nitrogen (N)-bearing relative to C-bearing compounds, suggesting greater fungal (and possibly plant) N demand in ECM-dominated soils. Collectively, our results demonstrate that shifts in temperate tree species composition that result in changes in the dominant type of mycorrhizal association may have strong impacts on Dikarya hyphal production, fungal community composition and extracellular enzyme activity, with important consequences for soil C and N cycling.

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  • 39.
    Chen, Peng
    et al.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Peoples R China.;Hohai Univ, Sch Earth Sci & Engn, Nanjing 210098, Peoples R China.;Joint Int Res Lab Global Change & Water Cycle, Nanjing 210098, Peoples R China..
    Yi, Peng
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Peoples R China.;Joint Int Res Lab Global Change & Water Cycle, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Czymzik, Markus
    Leibniz Inst Baltic Sea Res Warnemunde IOW, Marine Geol, D-18119 Rostock, Germany..
    Aldahan, Ala
    United Arab Emirates Univ, Dept Geol, Al Ain 17551, U Arab Emirates..
    Ljung, Karl
    Lund Univ, Dept Geol Quaternary Sci, S-22362 Lund, Sweden..
    Yu, Zhongbo
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Peoples R China.;Joint Int Res Lab Global Change & Water Cycle, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Hou, Xiaolin
    Chinese Acad Sci, Xian AMS Ctr, Inst Earth Environm, State Key Lab Loess & Quaternary Geol, Xian 710061, Peoples R China.;Tech Univ Denmark, Ctr Nucl Technol, Riso Campus, DK-4000 Roskilde, Denmark..
    Zheng, Minjie
    Lund Univ, Dept Geol Quaternary Sci, S-22362 Lund, Sweden..
    Chen, Xuegao
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Peoples R China.;Joint Int Res Lab Global Change & Water Cycle, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Relationship between precipitation and Be-10 and impacts on soil dynamics2020In: Catena (Cremlingen. Print), ISSN 0341-8162, E-ISSN 1872-6887, Vol. 195, article id 104748Article in journal (Refereed)
    Abstract [en]

    Meteoric beryllium-10 (Be-10) is commonly used as a proxy of landscape dynamics (erosion and sedimentation rates) and soil development. Soil represents the first-stage reservoir of meteoric Be-10, and variability in the concentration of the isotope in soils may be affected by soil properties and atmospheric deposition. Although many investigations have targeted this issue, there are still problems in estimating the atmospheric input of the isotope in different soil environments. Here, we used Be-10 data measured in soils distributed across China to explore the potential influence of meteorological and pedological conditions on the isotope concentration and related applications. In addition, to determine the mechanisms controlling Be-10 concentrations in topsoil on a regional scale, the soil samples were sub-divided into 18 different catchments according to fluvial systems. The results indicated that there were significant negative correlations between precipitation and the soil Be-10 concentration in high-precipitation regions (> 1200 mm.y(-1)) and significant positive correlations for soils in low precipitation regions (< 1200 mm.y(-1)). The data also revealed that precipitation is the most important variable controlling the Be-10 concentration in soils of China when compared with the effects of soil properties such as grain size, mineralogy, pH, and cation exchange capacity. Land use and soil erosion may have limited impacts on the distribution of Be-10 in soils.

  • 40.
    Collado, Eduardo
    et al.
    Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain; Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain .
    Castaño, Carles
    Swedish Univ Agr Sci, Dept Forest Mycol & Plant Pathol, SE-75007 Uppsala, Sweden..
    Antonio Bonet, Jose
    Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain; Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain .
    Hagenbo, Andreas
    Örebro University, School of Science and Technology. Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain; Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain; Norwegian Institute of Bioeconomy Research (NIBIO), Ås, Norway .
    Martínez de Aragón, Juan
    Forest Science and Technology Centre of Catalonia (CTFC), Ctra de Sant Llorenç de Morunys, Solsona, Lleida, Spain .
    de-Miguel, Sergio
    Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain; Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain .
    Divergent above- and below-ground responses of fungal functional groups to forest thinning2020In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 150, article id 108010Article in journal (Refereed)
    Abstract [en]

    Forest disturbances have a strong effect on soil fungal communities and associated ecosystem processes. However, little is known about the response of mycelial biomass to disturbances, and how fungi reallocate carbon into different fungal structures under environmental stressors. We investigated above- and below-ground fungal biomass shifts in response to different intensities of forest management in Mediterranean Pinus pinaster forests. Soil fungal biomass was estimated by ergosterol quantification and production of sporocarps was estimated from repeated field samplings during 5 years in 26 experimental plots. Abundance of mycorrhizal and saprotrophic fungi belowground was determined using Pacific Biosciences sequencing of fungal ITS2 amplicons. Thinning had a prolonged negative effect belowground, inter- and intra-annually, on total fungal biomass and on the biomass of ectomycorrhizal fungi, but not on saprotrophic fungi. Total and ectomycorrhizal mushroom yields were negatively correlated with the total and the ectomycorrhizal mycelial biomass, respectively. Thinning also correlated positively with the aboveground/belowground ratio of both total and ectomycorrhizal fungal biomass. We show potential short-term shifts in resource allocation of fungi from below-to above-ground structures under disturbances such as forest thinning. Ectomycorrhizal fungi may respond to disturbances by increasing reproduction rather than colonizing the surrounding soil.

  • 41. Coucheney, E.
    et al.
    Eckersten, H.
    Hoffmann, H.
    Jansson, Per Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gaiser, T.
    Ewert, F.
    Lewan, E.
    Key functional soil types explain data aggregation effects on simulated yield, soil carbon, drainage and nitrogen leaching at a regional scale2018In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 318, p. 167-181Article in journal (Refereed)
    Abstract [en]

    The effects of aggregating soil data (DAE) by areal majority of soil mapping units was explored for regional simulations with the soil-vegetation model CoupModel for a region in Germany (North Rhine-Westphalia). DAE were analysed for wheat yield, drainage, soil carbon mineralisation and nitrogen leaching below the root zone. DAE were higher for soil C mineralization and N leaching than for yield and drainage and were strongly related to the presence of specific soils within the study region. These soil types were associated to extreme simulated output variables compared to the mean variable in the region. The spatial aggregation of these key functional soils within sub-regions additionally influenced the DAE. A spatial analysis of their spatial pattern (i.e. their presence/absence, coverage and aggregation) can help in defining the appropriate grid resolution that would minimize the error caused by aggregating soil input data in regional simulations.

  • 42.
    Cucarella Cabañas, Victor
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Recycling Filter Substrates used for Phosphorus Removal from Wastewater as Soil Amendments2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis studied the viability of recycling filter substrates as soil amendments after being used in on-site systems for phosphorus (P) removal from wastewater. Focus was put on the materials Filtra P and Polonite, which are commercial products used in compact filters in Sweden. A prerequisite for this choice was to review filter materials and P sorption capacity. The filter substrates (Filtra P, Polonite and wollastonite tailings) were recycled from laboratory infiltration columns as soil amendments to a neutral agricultural soil and to an acid meadow soil to study their impacts on soil properties and yield of barley and ryegrass. The amendments tended to improve the yield and showed a liming effect, significantly increasing soil pH and the availability of P. In another experiment, samples of Filtra P and Polonite were equilibrated in batch experiments with the two soils in order to study the P dynamics in the soil-substrate system.  Batch equilibrations confirmed the liming potential of Filtra P and Polonite and showed that improved P availability in soils was strongly dependent on substrate P concentration, phase of sorbed P, and soil type. Finally, samples of Polonite used for household wastewater treatment were recycled as soil amendments to a mountain meadow and to an agricultural field for wheat cropping. The liming effect of Polonite was confirmed under field conditions and the results were similar to those of lime for the mountain meadow soil. However, the results were quite different for the agricultural field, where Polonite did not affect soil pH or any other chemical and physical soil properties investigated and had no impact on wheat yield and quality. The results from field experiments suggested that Polonite can be safely recycled to meadows and cropping fields at rates of 5-10 ton ha-1 but long-term studies are needed to forecast the effects of accumulation.

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  • 43.
    Cucarella, Victor
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Zaleski, T.
    Mazurek, R.
    Recycling of calcium-silicate material after wastewater filtration to agriculture -Soil condition impact2012In: Ecological Chemistry and Engineering S, ISSN 1898-6196, Vol. 19, no 3, p. 373-382Article in journal (Refereed)
    Abstract [en]

    Reactive filter materials aimed at phosphorus (P) recovery is a novel method for on-site wastewater treatment. Once the bed filter is no longer effective, the sorbent must be replaced and can then be recycled as a soil amendment to agriculture. This study investigated the short-term effects of such amendments in a field with a wheat crop in order to evaluate the risks and/or potential benefits of this disposal option. The developed product Polonite (manufactured from Opoka) was used as a model filter sorbent in the field trial. Rates corresponding to approximately 6 and 8 tons per hectare were applied. In the short-term, this amending did not affect soil physical and sorption properties. The rate of Polonite used here, as P source for wheat was irrelevant in this kind of soil. The usefulness of this disposal option of exhausted filter material is discussed.

  • 44. De Long, Jonathan R.
    et al.
    Laudon, Hjalmar
    Blume-Werry, Gesche
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kardol, Paul
    Nematode community resistant to deep soil frost in boreal forest soils2016In: Pedobiologia, ISSN 0031-4056, E-ISSN 1873-1511, Vol. 59, no 5-6, p. 243-251Article in journal (Refereed)
    Abstract [en]

    As global climate change advances, shifts in winter precipitation are becoming more common in high latitude ecosystems, resulting in less insulating snow cover and deeper soil frost. Long-term alterations to soil frost can impact on ecosystem processes such as decomposition, microbial activity and vegetation dynamics. In this study we utilized the longest running, well-characterized soil frost manipulation experiment in a boreal forest. We measured nematode family composition and feeding group abundances at four different soil layer depths from plots that had been subjected to deep soil frost for one and 11 years. The overall abundance of nematodes and the different feeding groups were unaffected by deep soil frost. However, a higher Maturity Index was weakly associated with deep soil frost (indicative of lower nutrient enrichment and more persister nematode (i.e., K-strategist) families), likely due to the loss of nutrients and reduced inputs from inhibited decomposition. Multivariate and regression analyses showed that most nematode families were weakly associated with dominant understory plant species and strongly associated with soil organic matter (SOM). This is probably the result of higher resource availability in the control plots, which is favorable to the nematode community. These results indicate that the nematode community was more strongly driven by the long-term indirect effects of deep soil frost on SOM as opposed to the direct effects. Our findings highlight that the indirect effects of altered winter precipitation and soil frost patterns may be more important than direct winter climate effects. Further, such indirect effects on SOM and the plant community that may affect the nematode community can only be seen in long-term experiments. Finally, given the critical role nematodes play in soil food webs and carbon and nutrient cycling, our results demonstrate the necessity of considering the response of nematodes to global climate change in boreal forest soils. 

  • 45.
    Djodjic, Faruk
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Bergström, Lars
    Swedish University of Agricultural Sciences, Sweden.
    Schmieder, Frank
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sandström, Corine
    Swedish University of Agricultural Sciences, Sweden.
    Agback, Peter
    Swedish University of Agricultural Sciences, Sweden.
    Hu, Yongfeng
    Univ Saskatchewan, Canada.
    Soils potentially vulnerable to phosphorus losses: speciation of inorganic and organic phosphorus and estimation of leaching losses2023In: Nutrient Cycling in Agroecosystems, ISSN 1385-1314, E-ISSN 1573-0867, Vol. 127, p. 225-245Article in journal (Refereed)
    Abstract [en]

    Eutrophication is an important threat to aquatic ecosystems world-wide, and reliable identification of areas vulnerable to phosphorus (P) losses from diffuse sources is essential for high efficiency of mitigation measures. In this three-step study we investigated (i) relationships between the agronomic (Olsen-P and P-AL) and environmental soil P tests (P-CaCl2) with molecular techniques (P-31 NMR and XANES) followed by (ii) rainfall simulation experiment on topsoil lysimeters and (iii) comparison to long-term field measurements of water quality. Soil samples were collected from seven sites indicated to be vulnerable to nutrient losses due to underlying geology. High P release correlated to standard agronomic P tests (Olsen P, r = 0.67; and P-AL, r = 0.74) and low P sorption capacity (r = - 0.5). High content of iron-bound P compounds indicated more labile P and higher release of dissolved P (r = 0.67). The leaching experiment showed that three out of four soils with high initial soil P status had both higher P leaching concentrations before fertilization (0.83-7.7 mg P l(-1)) compared to soil with low initial soil P status (0.007-0.23 mg P l(-1)), and higher increase in P concentrations after fertilization. Higher soil P sorption capacity reduced P leaching losses. Finally, long-term monitoring data show no significant trends in P losses in a field with low initial P content and moderate P fertilization rates whereas high and over time increasing P losses were recorded in a field with high initial soil P content and repetitively high P fertilization rates.

  • 46.
    Djukic, Ika
    et al.
    Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Zürich, Switzerland.
    Kepfer-Rojas, Sebastian
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark.
    Kappel Schmidt, Inger
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark.
    Steenberg Larsen, Klaus
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark.
    Beier, Claus
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark.
    Berg, Björn
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Biology. Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
    Verheyen, Kris
    Forest & Nature Lab, Department of Forest and Water Management, Ghent University, Gontrode, Belgium.
    Early stage litter decomposition across biomes2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 628, p. 1369-1394Article in journal (Refereed)
    Abstract [en]

    Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from −9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained <0.5% of the variation for Green tea and 5% for Rooibos tea, and was of significance only under unfavorable decomposition conditions (i.e. xeric versus mesic environments). When the data were aggregated at the biome scale, climate played a significant role on decomposition of both litter types (explaining 64% of the variation for Green tea and 72% for Rooibos tea). No significant effect of land-use on early stage litter decomposition was noted within the temperate biome. Our results indicate that multiple drivers are affecting early stage litter mass loss with litter quality being dominant. In order to be able to quantify the relative importance of the different drivers over time, long-term studies combined with experimental trials are needed.

  • 47.
    Dong, Lili
    et al.
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Sun, Tao
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
    Zhang, Lili
    National Engineering Laboratory for Soil Nutrient Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Zhang, Quanquan
    School of International Education, Beijing University of Chemical Technology, Beijing, China.
    Wang, Zhengwen
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Effects of different forms of N deposition on leaf litter decomposition and extracellular enzyme activities in a temperate grassland2019In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 134, p. 78-80Article in journal (Refereed)
    Abstract [en]

    Despite the importance of decomposition for biogeochemical cycles, it is still not clear how this process is affected by different forms of nitrogen (N). Equal amounts of N with different ratios of inorganic N: organic N (0 : 0, 10 : 0, 7 : 3, 5 : 5, 3 : 7, and 0 : 10) were added to the soil in a steppe. We studied the response of litter decomposition to different forms of N enrichment. The treatment with 30% organic N resulted in the fastest decomposition, which was higher than with inorganic N or organic N addition alone. Our results highlight the need for studies of N deposition on carbon cycles that consider different components in N deposition.

  • 48.
    Dong, Qian
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Studies of transport in some oxides by gas phase analysis2004Licentiate thesis, comprehensive summary (Other scientific)
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  • 49.
    Earon, Robert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Olofsson, Bo
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Initial Effects of a New Highway Section on Soil and Groundwater2012In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 223, no 8, p. 5413-5432Article in journal (Refereed)
    Abstract [en]

    The environmental impacts of 16 different contaminants originating from the E18 Highway (17,510 annual average daily traffic) were studied over the initial months of the highway's operational life. Investigative methods used included electrical resistivity surveying, water chemistry analyses, soil analyses, distribution modeling, and transportation modeling of contaminants. The study conclusively showed a year-round infiltration due to melting of the snowpack from road salt, and a strong preferential, anthropogenic pathway due to increased hydraulic conductivities of road construction materials relative to in situ soils. The resistivity surveys produced values well below the expected values for the highway materials, indicating increased ionic content within the unsaturated zone. Time lapse resistivity modeling showed a clear downwards spreading of contamination from the roadway to subsurface distances greater than 5 m. Elevated concentrations of nearly every studied contaminant relative to baseline values were observed, with many metal concentrations within the snow pack averaging values in excess of the Swedish Environmental Protection Agency's groundwater limitations. Distribution modeling demonstrated a potential offset of peak values from the road surface due to plowing and splash transport processes, and indicated different distribution behavior during winter months than during summer months. One-dimensional transport modeling demonstrated the importance of adsorption and other retentive factors to the migration of contaminants to groundwater and provided an estimate for potential long-term contaminant concentrations.

  • 50.
    Eckdahl, Johan A.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden.
    Rodriguez, Pere Casal
    Department of Geology, Lund University, Lund, Sweden.
    Kristensen, Jeppe A.
    Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, United Kingdom.
    Metcalfe, Daniel B.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ljung, Karl
    Department of Geology, Lund University, Lund, Sweden.
    Mineral soils are an important intermediate storage pool of black carbon in fennoscandian boreal forests2022In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 36, no 11, article id e2022GB007489Article in journal (Refereed)
    Abstract [en]

    Approximately 40% of earth's carbon (C) stored in land vegetation and soil is within the boreal region. This large C pool is subjected to substantial removals and transformations during periodic wildfire. Fire-altered C, commonly known as pyrogenic carbon (PyC), plays a significant role in forest ecosystem functioning and composes a considerable fraction of C transport to limnic and oceanic sediments. While PyC stores are beginning to be quantified globally, knowledge is lacking regarding the drivers of their production and transport across ecosystems. This study used the chemo-thermal oxidation at 375°C (CTO-375) method to isolate a particularly refractory subset of PyC compounds, here called black carbon (BC), finding an average increase of 11.6 g BC m−2 at 1 year postfire in 50 separate wildfires occurring in Sweden during 2018. These increases could not be linked to proposed drivers, however BC storage in 50 additional nearby unburnt soils related strongly to soil mass while its proportion of the larger C pool related negatively to soil C:N. Fire approximately doubled BC stocks in the mineral layer but had no significant effect on BC in the organic layer where it was likely produced. Suppressed decomposition rates and low heating during fire in mineral subsoil relative to upper layers suggests potential removals of the doubled mineral layer BC are more likely transported out of the soil system than degraded in situ. Therefore, mineral soils are suggested to be an important storage pool for BC that can buffer short-term (production in fire) and long-term (cross-ecosystem transport) BC cycling.

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