Ändra sökning
Avgränsa sökresultatet
1 - 28 av 28
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Butler, Orpheus M.
    et al.
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Warren, Charles R.
    Community composition and physiological plasticity control microbial carbon storage across natural and experimental soil fertility gradients2023Ingår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 17, nr 12, s. 2259-2269Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 2.
    Chakrawal, Arjun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Novel approaches in modeling of soil carbon: Upscaling theories and energetics2021Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    Novel approaches in modeling of soil carbon
    Ladda ner (jpg)
    presentationsbild
  • 3.
    Enfors, Elin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen. Stockholms universitet, Stockholm Resilience Centre.
    Barron, Jennie
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Makurira, Hodson
    University of Zimbabwe.
    Rockström, Johan
    Stockholms universitet, Stockholm Resilience Centre, Stockholm Environment Institute.
    Tumbo, Siza
    Sokoine University of Agriuclture.
    Yield and soil system changes from conservation tillage in dryland farming: A case study from North Eastern Tanzania2011Ingår i: Agricultural Water Management, ISSN 0378-3774, E-ISSN 1873-2283, Vol. 98, nr 11, s. 1687-1695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Yield levels in smallholder farming systems in semi-arid sub-Saharan Africa are generally low. Water shortage in the root zone during critical crop development stages is a fundamental constraining factor. While there is ample evidence to show that conservation tillage can promote soil health, it has recently been suggested that the main benefit in semi-arid farming systems may in fact be an in situ water harvesting effect. In this paper we present the result from an on-farm conservation tillage experiment (combining ripping with mulch and manure application) that was carried out in northeastern Tanzania from 2005 to 2008, testing this hypothesis. Special attention was given to the effects on the water retention properties of the soil. The tested conservation treatment only had a clear yield increasing effect during one of the six experimental seasons (maize grain yields increased by 41%, and biomass by 65%), and this was a season that received exceptional amounts of rainfall (549 mm). While the other seasons provided mixed results, there seemed to be an increasing yield gap between the conservation tillage treatment and the control towards the end of the experiment. Regarding soil system changes, small but significant effects on chemical and microbiological properties, but not on physical properties, were observed. This raises questions about the suggested water harvesting effect and its potential to contribute to stabilized yield levels under semi-arid conditions. We conclude that, at least in a shorter time perspective, the tested type of conservation tillage seems to boost productivity during already good seasons, rather than stabilize harvests during poor rainfall seasons. Highlighting the challenges involved in upgrading these farming systems, we discuss the potential contribution of conservation tillage towards improved water availability in the crop root zone in a longer-term perspective.

  • 4. Fuchslueger, Lucia
    et al.
    Wild, Birgit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi. University of Vienna, Austria.
    Mooshammer, Maria
    Takriti, Mounir
    Kienzl, Sandra
    Knoltsch, Anna
    Hofhansl, Florian
    Bahn, Michael
    Richter, Andreas
    Microbial carbon and nitrogen cycling responses to drought and temperature in differently managed mountain grasslands2019Ingår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 135, s. 144-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Grassland management can modify soil microbial carbon (C) and nitrogen (N) cycling, affecting the resistance to extreme weather events, which are predicted to increase in frequency and magnitude in the near future. However, effects of grassland management on microbial C and N cycling and their responses to extreme weather events, such as droughts and heatwaves, have rarely been tested in a combined approach. We therefore investigated whether grassland management affects microbial C and N cycling responses to drought and temperature manipulation. We collected soils from in situ drought experiments conducted in an extensively managed and an abandoned mountain grassland and incubated them at two temperature levels. We measured microbial respiration and substrate incorporation, as well as gross rates of organic and inorganic N cycling to estimate microbial C and N use efficiencies (CUE and NUE). The managed grassland was characterized by lower microbial biomass, lower fungi to bacteria ratio, and higher microbial CUE, but only slightly different microbial NUE. At both sites drought induced a shift in microbial community composition driven by an increase in Gram-positive bacterial abundance. Drought significantly reduced C substrate respiration and incorporation by microbes at both sites, while microbial CUE remained constant. In contrast, drought increased gross rates of N mineralization at both sites, whereas gross amino acid uptake rates only marginally changed. We observed a significant direct, as well as interactive effect between land management and drought on microbial NUE. Increased temperatures significantly stimulated microbial respiration and reduced microbial CUE independent of drought or land management. Although microbial N processing rates showed no clear response, microbial NUE significantly decreased at higher temperatures. In summary in our study, microbial CUE, in particular respiration, is more responsive to temperature changes. Although N processing rates were stronger responding to drought than to temperature microbial NUE was affected by both drought and temperature increase. We conclude that direct effects of drought and heatwaves can induce different responses in soil microbial C and N cycling similarly in the studied land management systems.

  • 5. Gharasoo, Mehdi
    et al.
    Centler, Florian
    Fetzer, Ingo
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. UFZ Helmholtz Center for Environmental Research, Germany.
    Thullner, Martin
    How the chemotactic characteristics of bacteria can determine their population patterns2014Ingår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 69, s. 346-358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spatial distribution of soil microorganisms is relevant for the functioning and performance of many ecosystem processes such as nutrient cycling or biodegradation of organic matters and contaminants. Beside the multitude of abiotic environmental factors controlling the distribution of microorganisms in soil systems, many microbial species exhibit chemotactic behavior by directing their movement along concentration gradients of nutrients or of chemoattractants produced by cells of their own kind. This chemotactic ability has been shown to promote the formation of complex distribution patterns even in the absence of environmental heterogeneities. Microbial population patterns in heterogeneous soil systems might be, hence, the result of the interplay between the heterogeneous environmental conditions and the microorganisms' intrinsic pattern formation capabilities. In this modeling study, we combined an individual-based modeling approach with a reactive pore-network model to investigate the formation of bacterial patterns in homogeneous and heterogeneous porous media. We investigated the influence of different bacterial chemotactic sensitivities (toward both substrate and bacteria) on bacterial distribution patterns. The emerging population patterns were classified with the support of a geostatistical approach, and the required conditions for the formation of any specific pattern were analyzed. Results showed that the chemotactic behavior of the bacteria leads to non-trivial population patterns even in the absence of environmental heterogeneities. The presence of structural pore scale heterogeneities had also an impact on bacterial distributions. For a range of chemotactic sensitivities, microorganisms tend to migrate preferably from larger pores toward smaller pores and the resulting distribution patterns thus resembled the heterogeneity of the pore space. The results clearly indicated that in a porous medium like soil the distribution of bacteria may not only be related to the external constraints but also to the chemotactic behavior of the bacterial cells.

  • 6.
    Guasconi, Daniela
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Roth, Nina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Hugelius, Gustaf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Spatial and temporal variability in soil and vegetation carbon dynamics under experimental drought and soil amendments2023Ingår i: Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Soils are the largest carbon (C) pool on the planet, and grassland soils have a particularly large C sequestration potential. Appropriate land management strategies, such as organic matter additions, can improve soil health, increase soil C stocks, and increase grassland resilience to drought by improving soil moisture retention. However, soil C dynamics are deeply linked to vegetation response to changes in both management and climate, which may also be manifested differently in roots and shoots. This study presents findings from a three-year experiment that assessed the impact of a compost amendment and of reduced precipitation on soil and vegetation C pools. Compost addition increased aboveground biomass and soil C content (%C), but because bulk density decreased, there was no significant effect on soil C stocks. Drought decreased aboveground biomass, but did not significantly affect root biomass. Overall, the soil amendment shifted C allocation to aboveground plant organs, and drought to belowground organs. We also observed significant spatial and temporal variability in vegetation biomass and soil C over the study period. These results highlight the need to consider multiple biotic and abiotic factors driving ecosystem C dynamics across spatial scales when upscaling results from field trials.

  • 7. Han, Yi
    et al.
    Zhao, Wenwu
    Ding, Jingyi
    Ferreira, Carla Sofia Santos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Polytechnic Institute of Coimbra, Portugal.
    Soil erodibility for water and wind erosion and its relationship to vegetation and soil properties in China's drylands2023Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 903, artikel-id 166639Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Drylands with fragile socio-ecological systems are vulnerable to soil erosion. China's drylands face the dual threat of water (WAE) and wind erosion (WIE). To mitigate soil erosion in drylands, China has implemented numerous ecological restoration measures. However, whether vegetation and soil have different effects on soil erodibility for water erosion (soil erodibility, K) and wind erosion (soil erodible fraction, EF) in drylands is unclear, hindering decision makers to develop suitable ecological restoration strategies. Here, we conducted a large-scale belt transect survey to explore the spatial variation of K and EF in China's drylands, and examined the linear and nolinear effects of aridity (aridity index), vegetation (fractional vegetation cover and below-ground biomass), and soil properties (bulk density, total nitrogen, and total phosphorus) on K and EF. The results showed in China's drylands that the K ranges from 0.02 to 0.07, with high values recorded in the northern Loess Plateau and the eastern Inner Mongolia Plateau. The EF ranges from 0.26 to 0.98, and shows longitudinal zonation with higher values in the east and lower values in the west. Aridity has a negative linear effect on K and an inverse U-shaped nonlinear effect on EF. Aridity can affect K and EF by suppressing vegetation growth and disrupting soil properties. However, K and EF had different responses to some vegetation and soil variables. K and EF had opposite relationships with soil bulk density, and EF was significantly affected by fractional vegetation cover, while K was not. Overall, the effects of aridity and soil properties on soil erodibility were more pronounced than those from vegetation, whose effect on soil erodibility was limited. This study provides relevant information to support reducing soil water and wind erosion by highlighting the hotspot areas of soil erodibility, relevant for implementing vegetation restoration and soil conservation measures in drylands.

  • 8.
    Hjulström, Björn
    et al.
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur. Arkeologiska Forskningslaboratoriet.
    Isaksson, Sven
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur. Arkeologiska Forskningslaboratoriet.
    Dolda spår av forntida verksamhet2007Ingår i: Hus och bebyggelse i Uppland: Delar av förhistoriska sammanhang, 2007Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 9.
    Ihse, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). ekologisk geografi.
    Från våtmark till våtmark: - ett akademiföretal2008Ingår i: Svensk Mosskultur: odling, torvanvändning, och landskapets förändring, Svenska Skogs- och Lantbruksakademien, Stockholm , 2008Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [sv]

    Framför dig har du intressant bok om en alldeles speciell epok i Sveriges odlingshistoria, uppodlingen av myrarna för drygt hundra år sedan och framväxten av en hel agrar kultur, mossekulturen. Som akademiledamot och naturgeograf med intresse för landskapets ekologiska historia finner jag denna bok högst angelägen. Boken ger inte bara en solid kunskap om mossodlingen och torvanvändningen. Den ger också en utmärkt förståelse för tidigare agrarers arbete med att säkra matförsörjningen, i en tid när befolkningen snabbt ökade och man hade stort sett utnyttjat alla kända tillgängliga marker för livsmedelsproduktion. Boken är av ett stort allmänt intresse, inte bara för de akademiledamöter som har agrar bakgrund utan också för forskare och handläggare och för en intresserad allmänhet. Den ger framförallt genom sitt breda innehåll en beskrivning av ett historiskt landskapsutnyttjande och landskapsförändring på ett tema som skulle kunna beskrivas med ett modernare begrepp ”från våtmark till våtmark”. Här visas hur ändrad kunskap och ändrade behov gett upphov till förändrat nyttjande av torvmarkernas olika ekosystemtjänster, från livsmedelsproducent till koldioxidfångare, vattenreglerare och biodiversitetsbevarare.

  • 10.
    Johansson, Anna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Livsey, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Swedish University of Agricultural Sciences, Sweden.
    Guasconi, Daniela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Hugelius, Gustaf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Long-term soil organic carbon changes after cropland conversion to grazed grassland in Southern Sweden2024Ingår i: Soil use and management, ISSN 0266-0032, E-ISSN 1475-2743, Vol. 40, nr 1, artikel-id e13004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is growing awareness of the potential value of agricultural land for climate change mitigation. In Sweden, cropland areas have decreased by approximately 30% over recent decades, creating opportunities for these former croplands to be managed for climate change mitigation by increasing soil organic carbon (SOC) stocks. One potential land-use change is conversion of cropland to grazed grasslands, but the long-term effect of such change in management is not well understood and likely varies with soil type and site-specific conditions. Through sampling of mineral and peatland soils within a 75-year chronosequence of land converted from crop production to grazed grassland, we assessed how time since conversion, catenary position, and soil depth affected SOC storage. The SOC stocks calculated at an equivalent soil or ash mass increased through time since conversion in mineral soils at all topographic positions, at a rate of ~0.65% year−1. Soils at low topographic positions gained the most carbon. Peat SOC stock gains after conversion were large, but only marginally significant and only when calculated at an equivalent ash mass. We conclude that the conversion of mineral soil to grazed grassland promotes SOC accumulation at our sites, but climate change mitigation potential would need to be evaluated through a full greenhouse gas balance.

  • 11.
    Kumblad, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Aronsson, Helena
    Hammer, Monica
    Policy brief: Inkludera näringsläckaget från hästgårdar i övergödningsarbetet2024Övrigt (Övrigt vetenskapligt)
    Abstract [sv]

    Hästhållning kan leda till betydande läckage av kväve och fosfor och därmed orsaka övergödning. Dessa utsläpp bör inkluderas bättre i nationella beräkningar och arbetet mot övergödning, så att åtgärder kan sättas in för att minska näringsläckaget.

    Ladda ner fulltext (pdf)
    fulltext
  • 12. Li, Meijun
    et al.
    Su, Ye
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Charles University, Czech Republic.
    Song, Qinghai
    Zhang, Yiping
    Gao, Hongkai
    Dong, Jianzhi
    Shao, Wei
    Identified temporal variation of soil hydraulic parameters under seasonal ecosystem change using the particle batch smoother2024Ingår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 442, artikel-id 116782Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil hydraulic parameters are influenced by various inherent soil properties, such as pore structure and organic matter content, which can vary with changes in the ecosystem. However, identifying the temporal variations of soil hydraulic parameters in a co-evolving soil-vegetation system remains a challenge. This study focused on a tropical forest with significant seasonal variations in vegetation attributes, evaporation, and carbon fluxes over a five-year monitoring period. The particle batch smoother algorithm was integrated with an unsaturated flow model to identify the seasonally varied soil hydraulic parameters through assimilation of in-situ measured soil moisture. As a benchmark, the Generalized Likelihood Uncertainty Estimation method was applied to optimize soil hydraulic parameters without considering temporal variation. The results indicated that the temporally varying soil hydraulic parameters exhibited regular seasonal patterns and outperformed the unvaried soil hydraulic parameters in terms of reducing the errors in modeling of soil moisture and evaporation. Moreover, the seasonal variations in soil hydraulic parameters were closely linked to changes in the litterfall and terrestrial carbon fluxes over time. Specifically, due to the hysteresis of the transformation from litterfall to soil organic matter, the accumulated litterfall in Hot-dry season can replenish the soil organic matter, resulting in an increase in field capacity and saturated hydraulic conductivity in the Hot-rainy season. However, the intense decomposition of soil organic matter under high temperature in Hot-dry season led to a decrease in field capacity and saturated hydraulic conductivity. This study emphasizes the value of the particle batch smoother algorithm in detecting temporal variations in soil hydraulic parameters within a coevolving soil-vegetation system, thereby contributing to a more comprehensive understanding of the intricate dynamics within the ecohydrological system under a changing environment.

  • 13.
    Li, Xiankun
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Leizeaga, Ainara
    Rousk, Johannes
    Hugelius, Gustaf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Drying intensity and acidity slow down microbial growth recovery after rewetting dry soils2023Ingår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 184, artikel-id 109115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil microbes perceive drying and rewetting (DRW) events as more or less harsh depending on the previous soil moisture history. If a DRW event is not perceived as harsh, microbial growth recovers rapidly after rewetting (referred to as ‘type 1’ response), while a harsh DRW will be followed by a delayed growth recovery (‘type 2’ response). Predicting these responses based on pedoclimatic factors is important because they can determine how carbon is partitioned between growth (soil C stabilization) and respiration (C loss to the atmosphere). To characterize the microbially perceived harshness between the two extreme types 1 and 2, and its pedoclimatic drivers, we described microbial growth with a single logistic function and respiration with a rescaled gamma distribution using ∼100 growth and respiration datasets. These functions captured microbial growth and respiration rates well during the recovery phase after rewetting. Therefore, the fitted parameters from these functions could help us to capture the continuum of microbial recovery between type 1 and 2 and characterize harshness levels. The product of growth parameters τ (delay time) and b (the slope of the growth curve at time τ) was an effective index that could capture and quantify perceived harshness because it allowed separating type 1 and 2 responses better than τ or b alone or than any other parameter describing the growth or respiration response. The drier the soil before rewetting and the lower the pH, the higher was the perceived harshness (τ×b), the longer the delay of growth recovery, and the larger the CO2 loss at rewetting. Overall, this study places soil microbial responses to DRW along a continuous gradient from fast to slow recovery, where the faster the recovery, the better adapted the microbial community is to the DRW event.

  • 14.
    Livsey, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Sustainable agriculture: From global challenges to local land management2021Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Despite the success of agriculture management practices in increasing the availability of food needed to meet the requirements of the expanding global population, there are increasing demands placed on the resources on which the sector depends. Opportunities for the development of agricultural systems are constrained by increasing competition, from other sectors, for shared resources. In tackling this constraint, agricultural management solutions are often narrowly focused on problems related to single resources. But this single focus may lead to unintended trade-offs. To make sound management decisions, there is a need to better understand trade-offs which may occur from resource use efficiency solutions implemented in the agricultural sector. With a particular focus on soil and water resources, the aim of this thesis was to investigate trade-offs that occur, when meeting demands placed on agriculture systems, if management solutions are narrowly focused. Broadly, we hypothesize that approaches to land management that take a more holistic view of agricultural systems being part of an ecosystem mosaic should be adopted to ensure sustainability. A global assessment of potential land requirements shows that national level production of sufficiently nutritious food may be constrained by land availability, such that allocation of land to nutritious crop production might come at the cost of lost land for other crops or uses. This constraint will be the most prevalent in African states. In further studies, we focused on the management of water resources, which are becoming particularly limiting for crops that have high water demands, such as rice. Through a meta-analysis of paired plot experiments, which assessed the effect of water saving irrigation in rice production, and soil sampling within An Giang, a major rice producing province of Vietnam, we examined the effect of water management practices on soil properties. The meta-analysis finds that significant reductions in soil organic carbon, and potentially organic matter bound nutrients, have been observed when water efficient practices replace continual flood irrigation. This suggests that, although yield reductions may not be seen in the short term, water saving irrigation may, over time, lead to reductions in soil fertility and yields. Within An Giang province, there are concerns regarding the loss of flood-borne, nutrient rich, sediments in fields where the annual flood waters have been completely regulated. However, we find that this complete regulation does not result in reduced soil nutrient properties when compared to areas where floods are only partially regulated. The effect of different land management practices on soil properties were further explored within the Kilombero Valley, Tanzania. Comparing farming practices along a gradient of intensity, we found contrasting effects of irrigation and fertilization, with irrigation increasing soil organic carbon and fertilization reducing soil organic carbon. Overall, the results of this thesis highlight the importance of looking beyond meeting short term needs, which can have negative long term consequences. The success of land management practices implemented now do not, necessarily, equate to their continued success in the future. As demands placed on agriculture are going to increase, the long term trade-offs which may occur from present practices must be at the forefront of agricultural management.

    Ladda ner fulltext (pdf)
    Sustainable agriculture: From global challenges to local land management
    Ladda ner (jpg)
    presentationsbild
  • 15.
    Manzoni, Stefano
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Ahmed, Mohammad Hafez
    Amilcare, Porporato
    Ecohydrological and Stoichiometric Controls on Soil Carbon and Nitrogen Dynamics in Drylands2019Ingår i: Dryland Ecohydrology / [ed] Paolo D'Odorico; Amilcare Porporato; Christiane Wilkinson Runyan, Springer, 2019, 2nd, s. 279-307Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The cycling of soil carbon (C) and nitrogen (N) is mediated by microbial organisms, the activity of which depends on soil-water availability. In this chapter, we review how water availability affects C and N cycling, starting from fine-scale microbial responses to changes in soil moisture, and moving up in scale to the dynamics of soil C and N compartments at the plot scale and finally to the climatic and stoichiometric controls on decomposition along broad climatic gradients. In arid and semiarid ecosystems, water is available only intermittently and often in limited amount, forcing microorganisms to adopt a range of physiological drought response strategies to cope with these conditions (e.g., osmoregulation). These strategies, however, do not always allow microorganisms to remain active in dry conditions because physical limits to substrate movement in dry soils reduce the supply of C to sustain their metabolism. Thus, both biological and physical constraints are at play and determine how C and N fluxes in dryland soils vary during drying and wetting cycles. A coupled soil C–N cycling model, which integrates these aspects, is then described and applied to an African savanna. The model results show a multitude of response time scales of the various organic matter compartments (faster responses of microbial biomass, slower for stabilized organic matter), and decoupled dynamics of mineral N production by microorganisms and consumption by plants under prolonged dry periods. We conclude by outlining areas of future research, including the complexities of C and N dynamics at rewetting, the propagation of extreme hydrologic events on C and N cycles, and the challenges in scaling up microbial processes from soil pore- to plot-scales. 

    Ladda ner fulltext (pdf)
    Manzoni et al. Ecohydrological and stoichiometric controls
  • 16. Morini, Leonardo
    et al.
    Ferrari, Claudio
    Bartoli, Marco
    Zilius, Mindaugas
    Broman, Elias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholms universitets Östersjöcentrum.
    Visioli, Giovanna
    Vallisneria spiralis L. adaptive capacity improves pore water chemistry and increases potential nitrification in organic polluted sediments2024Ingår i: Ecological Processes, EISSN 2192-1709, ISSN 2192-1709, Vol. 13, nr 1, artikel-id 26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Macrophytes may modify benthic biodiversity and biogeochemistry via radial oxygen loss from roots. This condition contrasts sediments anoxia, allows roots respiration, and facilitates aerobic microbial communities and processes in the rhizosphere. Simultaneously, the rhizosphere can stimulate anaerobic microorganisms and processes via exudates or by favoring the build-up of electron acceptors as nitrate. As eutrophication often results in organic enrichment in sediments and large internal nutrients recycling, an interesting research question is to investigate whether plants maintain the capacity to stimulate aerobic or anaerobic microbial communities and processes also under elevated organic pollution. Methods: A manipulative experiment was carried out under laboratory-controlled conditions. Microcosms containing bare sediments and sediments transplanted with the macrophyte Vallisneria spiralis L. were created. The effect of the plant was investigated on sediments with moderate (8%) and elevated (21%) organic matter content, after an acclimatization period of 30 days. Chemical and physical parameters, microbial community composition and the potential rates of nitrification, denitrification and nitrate ammonification were measured at two different depths (0–1 and 1–5 cm) after the acclimatization period to evaluate the role of roots. Results: Vallisneria spiralis grew and assimilated pore water nutrients at the two organic matter levels and vegetated sediments had always nutrient-depleted porewaters as compared to bare sediments. Nitrifying microbes had a lower relative abundance and diversity compared to denitrifying bacteria. However, regardless of the organic content, in vegetated sediments nitrifiers were detected in deeper horizons as compared to bare sediments, where nitrification was confined near the surface. In contrast, potential denitrification rates were not affected by the presence of roots, but probably regulated by the presence of nitrate and by root-dependent nitrification. Potential nitrate ammonification rates were always much lower (< 3%) than potential denitrification rates. Conclusions: Vallisneria spiralis affects N-related microbial diversity and biogeochemistry at moderate and elevated organic matter content, smoothing bottom water–pore water chemical gradients and stimulating nitrification and nitrogen loss via denitrification. These results suggest the possibility to deploy V. spiralis as a nature-based solution to counteract eutrophication in freshwater systems impacted by high loads of organic matter, for example, downstream of wastewater treatment plants.

  • 17. Rahmati, Omid
    et al.
    Soleimanpour, Seyed Masoud
    Arabkhedri, Mahmood
    Mehrjo, Sardar
    Kalantari, Zahra
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). KTH Royal Institute of Technology, Sweden.
    Cavalli, Marco
    Crema, Stefano
    Bahmani, Aref
    Towards quantification of soil conservation performance using sediment connectivity concept at hillslope scale: proposing a new framework for data-scarce regions2023Ingår i: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 23, nr 5, s. 2298-2309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose Although contour trenching is one of the widely used nature-based solutions for soil conservation around the world, its efficiency has not been quantitatively investigated. This study aimed to scrutinize the performance of the contour trenching program, a nature-based solution and common soil erosion prevention measure in hillslopes of a data-scarce region based on the sediment connectivity approach.

    Materials and methods Six different hillslopes (A–F) were selected in the Khamsan watershed in Iran, a representative area where contour trenching has been implemented. The sediment connectivity map of each hillslope was generated using the index of connectivity (IC) based on two real scenarios: with (scenario I) and without (scenario II) contour trenching. Two different field-based validation methods were applied on the base of (i) in situ measurements of the sediment depth in contour trenches and Pearson’s correlation analysis, and (ii) field index of connectivity (FIC). The validity of the sediment connectivity results was verified using both validation approaches. The sediment connectivity in two scenarios was compared and the impact of the contour trenching was analyzed. The performance of the contour trenching program was quantitatively determined for each hillslope.

    Results and discussion The results revealed that contour trenching significantly affected sediment routing and reduced the IC values of all selected hillslopes. The differences in IC value between the two scenarios (∆IC) for hillslopes A, B, C, D, E, and F were found to be 22.6%, 11.27%, 14.69%, 5.83%, 15%, and 7.27%, respectively. Therefore, the spatial pattern of sediment connectivity also differed significantly after implementing contour trenching. Furthermore, Pearson’s correlation coefficients revealed that the sediment connectivity and the sediment depth in contours in all hillslopes had a significant negative relationship, resulting in confirming the validity of the sediment connectivity results for all six hillslopes in the current study.

    Conclusion Contour trenching significantly reduced the sediment connectivity on all six hillslopes studied. Furthermore, in situ measurements of the sediment depth in contour trenches should be conducted to verify the simulation of sediment connectivity. The proposed methodology can be applied in other data-scarce regions to evaluate the performance of the contour trenching program.

  • 18.
    Schwarz, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Johansson, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Lerda, Cristina
    Livsey, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Swedish University of Agricultural Science, Sweden.
    Scaini, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Said-Pullicino, Daniel
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Organic carbon stabilization in temperate paddy fields and adjacent semi-natural forests along a soil age gradient2024Ingår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 443, artikel-id 116825Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rice paddy soils have high organic carbon (OC) storage potential, but predicting OC stocks in these soils is difficult due to the complex OC stabilization mechanisms under fluctuating redox conditions. Especially in temperate climates, these mechanisms remain understudied and comparisons to OC stocks under natural vegetation are scarce. Semi-natural forests could have similar or higher OC inputs than rice paddies, but in the latter mineralization under anoxic conditions and interactions between OC and redox-sensitive minerals (in particular Fe oxyhydroxides, hereafter referred to as Fe oxides) could promote OC stabilization. Moreover, management-induced soil redox cycling in rice paddies can interact with pre-existing pedogenetic differences of soils having different degrees of evolution. To disentangle these drivers of soil OC stocks, we focused on a soil age gradient in Northern Italy with a long (30 + years) history of rice cultivation and remnant semi-natural forests. Irrespective of soil age, soils under semi-natural forest and paddy land-use showed comparable OC stocks. While, in topsoil, stocks of crystalline Fe and short-ranged Fe and Al oxides did not differ between land-uses, under paddy management more OC was found in the mineral-associated fraction. This hints to a stronger redox-driven OC stabilization in the paddy topsoil compared to semi-natural forest soils that might compensate for the presumed lower OC inputs under rice cropping. Despite the higher clay contents over the whole profile and more crystalline pedogenetic Fe stocks in the topsoil in older soils, OC stocks were higher in the younger soils, in particular in the 50–70 cm layer, where short-range ordered pedogenetic oxides were also more abundant. These patterns might be explained by differences in hydrological flows responsible for the translocation of Fe and dissolved OC to the subsoil, preferentially in the younger, coarse-textured soils. Taken together, these results indicate the importance of the complex interplay between redox-cycling affected by paddy-management and soil-age related hydrological properties.

    Ladda ner fulltext (pdf)
    fulltext
  • 19.
    Seibert, Jan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi.
    Stendahl, Johan
    Sørensen, Rasmus
    Topographical influences on soil properties in boreal forests2007Ingår i: Geoderma, Vol. 141, nr 1-2, s. 139-148Artikel i tidskrift (Refereegranskat)
  • 20. Shao, Wei
    et al.
    Chen, Sijie
    Li, Meijun
    Su, Ye
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Charles University, Czech Republic.
    Ni, Junjun
    Dong, Jianzhi
    Zhang, Yonggen
    Yang, Zongji
    Reducing uncertainties in hydromechanical modeling with a recently developed Rosetta 3 podeotransfer function2023Ingår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 324, artikel-id 107250Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stability analysis of unsaturated landslide deposits requires reliable estimates of soil moisture and pore water pressure. However, modeled soil moisture and pore water pressure contain substantial uncertainties due to imperfect information on soil hydraulic properties. Due to the relatively high dimensionality, commonly used parameter optimization strategies can be significantly affected by equifinality problems. This study investigates the effectiveness of reducing parameter estimation dimensionality using soil pedo-transfer functions. Specifically, we first estimated soil hydraulic parameters using the traditional Generalized Likelihood Uncertainty Estimation (GLUE) method, with parameters randomly drawn from the entire space (refer to as GLUE-random). In a second strategy, we use the Rosetta 3 pedotransfer function to constrain soil hydraulic parameters (refer to as GLUE-Rosetta). The two methods were tested in a typical landslide deposit with in-situ measured soil moisture dynamics for inverse modeling. The GLUE-random estimated soil hydraulic parameters contained substantial uncertainties –resulting in poorly constrained soil water retention curves (SWCC) and hydraulic conductivity functions (HCF). As a result, the uncertainty bands of pore water pressure and slope stability can cross values with several orders of magnitudes. In contrast, GLUE-Rosetta provided well-constrained SWCC and HCF, which significantly reduce the uncertainties in pore water pressure and slope stability estimates. These results suggest that the Rosetta 3 pedotransfer function can significantly improve the reliability of soil hydraulic parameters by reducing the dimensionality of the optimization problem and high-quality prior information of soil hydraulic properties. In conclusion, Rosetta 3 can enhance the reliability of soil parameters estimates and the reliability of subsurface hydrology, which may benefit the development of landslide early-warning systems.

  • 21. Shao, Wei
    et al.
    Chen, Sijie
    Su, Ye
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Charles University, Czech Republic.
    Dong, Jianzhi
    Ni, Junjun
    Yang, Zongji
    Zhang, Yonggen
    Reduce uncertainty in soil hydrological modeling: A comparison of soil hydraulic parameters generated by random sampling and pedotransfer function2023Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 623, artikel-id 129740Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerical simulation of unsaturated soil hydrology relies on calibrated soil hydraulic parameters, which are subject to uncertainty due to imperfect information during the inverse modelling. This study investigates the effectiveness of reducing parameter uncertainty using the recently developed Rosetta 3 pedotransfer function. The GLUE method was employed for numerical modeling using the Darcy-Richards equation under two strategies for sampling Mualem-van Genuchten (MvG) parameters: the first uses conventional random generation of MvG parameters (GLUE-random), while the second adopts Rosetta 3 to transfer soil particle composition to MvG parameter (GLUE-Rosetta). Both approaches were used for inverse modeling of 9 typical soils, each with a recommended parameter set defined as true values and associated soil moisture dynamics as observations. The posterior parameters selected with both GLUE-random and GLUE-Rosetta show an equifinality phenomenon. GLUE-random fails to provide well-constrained posterior parameters to recover the pre-defined true values, and its posterior results of soil water characteristic curve (SWCC) and soil hydraulic conductivity function (HCF) are poorly constrained. In contrast, GLUE-Rosetta significantly improves the accuracy of the inversely-estimated soil hydraulic parameters, and the ensemble of posterior SWCC and HCF also encompasses the predefined true curves. The results demonstrate the effectiveness of using Rosetta 3 to reduce the dimensionality of the optimization problem, which results in reliable estimation of soil hydraulic parameters and soil particle compositions. Moreover, GLUE-Rosetta outperforms GLUE-random in predicting soil moisture dynamics under different rainfall intensities. Overall, it is recommended to integrate Rosetta 3 with existing optimization tools to reduce the uncertainty of soil parameters and support more reliable modeling of unsaturated soil hydrology.

  • 22. Soares, Pedro R.
    et al.
    Harrison, Matthew T.
    Kalantari, Zahra
    Zhao, Wenwu
    Ferreira, Carla S. S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Polytechnic Institute of Coimbra, Portugal.
    Drought effects on soil organic carbon under different agricultural systems2023Ingår i: Environmental Research Communications (ERC), E-ISSN 2515-7620, Vol. 5, nr 11, artikel-id 112001Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Drought is a natural hazard occurring with increasing frequency due to climate change. Drought events reduce soil water content and also soil organic carbon (SOC) content, with negative impacts on crop development and food security. This study investigates the impact of drought on SOC dynamics in agricultural systems and the influence of water availability and farm management practices in these impacts. The manuscript is a systematic review, based on Scopus database for scoping the literature on the topic. A total of 283 records were retrieved, but only 16 papers were relevant for the review. The main findings are: (1) water plays a key role in regulating SOC mineralization due to its impact on dynamics of soil microbial communities, necessitating further research on water management to mitigate carbon losses during drought; (2) different agricultural systems can have differing impacts on SOC under drought conditions depending on crop type (e.g. pastures are more resilient than arable systems) and farm management practices; and (3) SOC loss generally occurs after a drought event, regardless of farm management regime, but the contribution of drought to this loss requires further research. Best management practices, such as cover cropping and soil amendment, can minimize SOC losses, but further research is required to optimize these practices in counteracting the effect of drought. A better understanding of the effects of drought on SOC dynamics, and of short-term and long-term ways to mitigate these effects, is important to ensure soil health and crop productivity.

  • 23. Tao, Feng
    et al.
    Huang, Yuanyuan
    Hungate, Bruce A.
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Frey, Serita D.
    Schmidt, Michael W. I.
    Reichstein, Markus
    Carvalhais, Nuno
    Ciais, Philippe
    Jiang, Lifen
    Lehmann, Johannes
    Wang, Ying-Ping
    Houlton, Benjamin Z.
    Ahrens, Bernhard
    Mishra, Umakant
    Hugelius, Gustaf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Hocking, Toby D.
    Lu, Xingjie
    Shi, Zheng
    Viatkin, Kostiantyn
    Vargas, Ronald
    Yigini, Yusuf
    Omuto, Christian
    Malik, Ashish A.
    Peralta, Guillermo
    Cuevas-Corona, Rosa
    Di Paolo, Luciano E.
    Luotto, Isabel
    Liao, Cuijuan
    Liang, Yi-Shuang
    Saynes, Vinisa S.
    Huang, Xiaomeng
    Luo, Yiqi
    Microbial carbon use efficiency promotes global soil carbon storage2023Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 618, nr 7967, s. 981-985Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soils store more carbon than other terrestrial ecosystems. How soil organic carbon (SOC) forms and persists remains uncertain, which makes it challenging to understand how it will respond to climatic change. It has been suggested that soil microorganisms play an important role in SOC formation, preservation and loss. Although microorganisms affect the accumulation and loss of soil organic matter through many pathways, microbial carbon use efficiency (CUE) is an integrative metric that can capture the balance of these processes. Although CUE has the potential to act as a predictor of variation in SOC storage, the role of CUE in SOC persistence remains unresolved. Here we examine the relationship between CUE and the preservation of SOC, and interactions with climate, vegetation and edaphic properties, using a combination of global-scale datasets, a microbial-process explicit model, data assimilation, deep learning and meta-analysis. We find that CUE is at least four times as important as other evaluated factors, such as carbon input, decomposition or vertical transport, in determining SOC storage and its spatial variation across the globe. In addition, CUE shows a positive correlation with SOC content. Our findings point to microbial CUE as a major determinant of global SOC storage. Understanding the microbial processes underlying CUE and their environmental dependence may help the prediction of SOC feedback to a changing climate.

    Ladda ner fulltext (pdf)
    fulltext
  • 24. Torppa, Kaisa A.
    et al.
    Castaño, Carles
    Glimskär, Anders
    Skånes, Helle
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Klinth, Mårten
    Roslin, Tomas
    Taylor, Astrid R.
    Viketoft, Maria
    Clemmensen, Karina E.
    Maaroufi, Nadia I.
    Soil moisture and fertility drive earthworm diversity in north temperate semi-natural grasslands2024Ingår i: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 362, artikel-id 108836Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intensive management of arable land reduces earthworm density and diversity. This may impair earthworm-mediated soil functions, such as nutrient mineralization and soil structure formation. To sustain earthworm source populations for re-colonization of cultivated soils, it is therefore important to preserve habitats with high earthworm diversity. Semi-natural grasslands, with a long continuity without soil disturbance, could serve as such earthworm diversity reservoirs. This is particularly important in mixed agricultural landscapes with elements of multiple land uses. Nonetheless, earthworm density and diversity vary greatly among grasslands. To preserve and optimally manage the most suitable grasslands, knowledge about which grassland characteristics best explain earthworm diversity is needed. Additionally, we have a limited picture of earthworm diversity in general, because previous studies have neglected juvenile earthworms and cryptic species. The juvenile fraction commonly comprises the main part of earthworm samples, whereas morphologically inseparable cryptic species account for an unknown fraction. This fraction is of particular importance, as juveniles reflect the local reproductive and regeneration potential of earthworm populations and communities. To determine the full species composition of earthworm communities, we sampled earthworms from 28 semi-natural grasslands in south-central Sweden and identified them to species by DNA barcoding. To test how grassland characteristics explain earthworm density, diversity, and community composition, we measured several characteristics of soils, vegetation, and management of the grasslands, and descriptors of the surrounding landscape. DNA barcoding revealed nearly twice as many species as were identified morphologically. Earthworm densities were higher in grasslands with higher Ellenberg moisture indicator values and lower soil C:N ratios. The diversity and occurrence of many earthworm species was also higher in grasslands with higher soil moisture indicator values and lower C:N ratios, and further increased with habitat heterogeneity. Certain species occurred more likely in grasslands with higher grazing intensity. Epigeic earthworms, which live in and feed on surface litter, were more common in grasslands with higher moisture indicator values and SOM content. Thus, dry and relatively unproductive semi-natural grasslands, which are common in Sweden, are unlikely to sustain high earthworm diversity – a pattern contrasting to previously reported plant diversity responses. Instead, earthworm diversity seems concentrated to more productive grazed grasslands, with large within-grassland heterogeneity. Therefore, we highlight the importance of considering soil animals in conservation policies for semi-natural grasslands.

  • 25. Wei, Liping
    et al.
    Liira, Jaan
    Ehrmann, Steffen
    Lenoir, Jonathan
    Decocq, Guillaume
    Brunet, Jörg
    Wulf, Monika
    Diekmann, Martin
    Naaf, Tobias
    Scherer-Lorenzen, Michael
    Hansen, Karin
    De Smedt, Pallieter
    Valdés, Alicia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Verheyen, Kris
    De Frenne, Pieter
    Impact of patch age and size on forest soil characteristics in European agricultural landscapes2023Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 898, artikel-id 165543Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many landscapes worldwide are characterized by the presence of a mosaic of forest patches with contrasting age and size embedded in a matrix of agricultural land. However, our understanding of the effects of these key forest patch features on the soil nutrient status (in terms of nitrogen, carbon, and phosphorus) and soil pH is still limited due to a lack of large-scale data. To address this research gap, we analyzed 830 soil samples from nearly 200 forest patches varying in age (recent versus ancient forests) and size (small versus larger patches) along a 2500-km latitudinal gradient across Europe. We also considered environmental covariates at multiple scales to increase the generality of our research, including variation in macroclimate, nitrogen deposition rates, forest cover in a buffer zone, basal area and soil type. Multiple linear mixed-effects models were performed to test the combined effects of patch features and environmental covariates on soil nutrients and pH. Recent patches had higher total soil phosphorus concentrations and stocks in the mineral soil layer, along with a lower nitrogen to phosphorus ratio within that layer. Small patches generally had a higher mineral soil pH. Mineral soil nitrogen stocks were lower in forest patches with older age and larger size, as a result of a significant interactive effect. Additionally, environmental covariates had significant effects on soil nutrients, including carbon, nitrogen, phosphorus, and their stoichiometry, depending on the specific covariates. In some cases, the effect of patch age on mineral soil phosphorus stocks was greater than that of environmental covariates. Our findings underpin the important roles of forest patch age and size for the forest soil nutrient status. Long-term studies assessing edge effects and soil development in post-agricultural forests are needed, especially in a context of changing land use and climate.

  • 26.
    Wild, Birgit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Monteux, Sylvain
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Wendler, Bernd
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Hugelius, Gustaf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Keuper, Frida
    Circum-Arctic peat soils resist priming by plant-derived compounds2023Ingår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 180, artikel-id 109012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rapid Arctic warming increases permafrost thaw and CO2 production from soil organic matter decomposition, but also enhances CO2 uptake by plants. Conversely, plants can also stimulate soil organic matter decomposition near their roots, via rhizosphere priming. The recent PrimeSCale model suggests that this can accelerate Arctic soil carbon loss at a globally relevant rate, and points to large potential contributions from carbon-rich permafrost peatlands. At the same time, the high carbon content of peatlands might render them insusceptible to input of easily available organic compounds by plant roots, which is considered a key component of priming. We here investigated the sensitivity of permafrost peat soils to priming by plant compounds under aerobic conditions that resemble the dominant rooting zone, based on a 30-week laboratory incubation of peat soils from five circum-Arctic locations. No significant change in CO2 production from peat organic matter by organic carbon addition was observed, and an increase of 24% by organic nitrogen addition. Combining our data with a literature meta-analysis of priming studies showed similar, low priming sensitivity in organic layers of mineral soils, and significantly stronger priming in mineral horizons where organic carbon and nitrogen increased decomposition by 32% and 62%, respectively. Low sensitivity of permafrost peat to input of organic compounds was also supported under anaerobic conditions, by incubation of one soil type. In a new PrimeSCale sensitivity analysis, we show that excluding peatlands would reduce estimates of priming-induced carbon loss from the circum-Arctic by up to 40% (up to 18 Pg) until 2100, depending on peat priming sensitivity. While our study suggests a limited effect of plant-released organic compounds on peat decomposition, it does not preclude an effect of vegetation on decomposition under natural conditions, through other mechanisms. The large range of possible priming-induced peat carbon losses, and expected changes in vegetation and drainage, call for a sharpened focus on the combined effect of living plants on soil processes beyond carbon input, including changes in nutrient and water availability, aggregation, and microbial communities.

  • 27. Wolfgang, Adrian
    et al.
    Tack, Ayco J. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Berg, Gabriele
    Abdelfattah, Ahmed
    Reciprocal influence of soil, phyllosphere, and aphid microbiomes2023Ingår i: Environmental Microbiome, E-ISSN 2524-6372, Vol. 18, nr 1, artikel-id 63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    The effect of soil on the plant microbiome is well-studied. However, less is known about the impact of the soil microbiome in multitrophic systems. Here we examined the effect of soil on plant and aphid microbiomes, and the reciprocal effect of aphid herbivory on the plant and soil microbiomes. We designed microcosms, which separate below and aboveground compartments, to grow oak seedlings with and without aphid herbivory in soils with three different microbiomes. We used amplicon sequencing and qPCR to characterize the bacterial and fungal communities in soils, phyllospheres, and aphids.

    Results

    Soil microbiomes significantly affected the microbial communities of phyllospheres and, to a lesser extent, aphid microbiomes, indicating plant-mediated assembly processes from soil to aphids. While aphid herbivory significantly decreased microbial diversity in phyllospheres independent of soil microbiomes, the effect of aphid herbivory on the community composition in soil varied among the three soils.

    Conclusions

    This study provides experimental evidence for the reciprocal influence of soil, plant, and aphid microbiomes, with the potential for the development of new microbiome-based pest management strategies.

  • 28. Zumsteg, Anita
    et al.
    Luster, Joerg
    Göransson, Hans
    Smittenberg, Rienk H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Brunner, Ivano
    Bernasconi, Stefano M.
    Zeyer, Josef
    Frey, Beat
    Bacterial, archaeal and fungal succession in the forefield of a receding glacier2012Ingår i: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 63, nr 3, s. 552-564Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glacier forefield chronosequences, initially composed of barren substrate after glacier retreat, are ideal locations to study primary microbial colonization and succession in a natural environment. We characterized the structure and composition of bacterial, archaeal and fungal communities in exposed rock substrates along the Damma glacier forefield in central Switzerland. Soil samples were taken along the forefield from sites ranging from fine granite sand devoid of vegetation near the glacier terminus to well-developed soils covered with vegetation. The microbial communities were studied with genetic profiling (T-RFLP) and sequencing of clone libraries. According to the T-RFLP profiles, bacteria showed a high Shannon diversity index (H) (ranging from 2.3 to 3.4) with no trend along the forefield. The major bacterial lineages were Proteobacteria, Actinobacteria, Acidobacteria, Firmicutes and Cyanobacteria. An interesting finding was that Euryarchaeota were predominantly colonizing young soils and Crenarchaeota mainly mature soils. Fungi shifted from an Ascomycota-dominated community in young soils to a more Basidiomycota-dominated community in old soils. Redundancy analysis indicated that base saturation, pH, soil C and N contents and plant coverage, all related to soil age, correlated with the microbial succession along the forefield.

1 - 28 av 28
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf