Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2024
Abstract
Old plant communities are of utmost importance for nature conservation, carbon sequestration, as well as gene pool maintenance. Shrub populations occurring in extreme environments beyond abiotic tree-lines provide diverse ecosystem services and have potential as proxy archives because they often inhabit areas with scarce and short instrumental records. We provide dendrochronological insight into one such population made up of prostrate Juniperus communis shrubs in the northern Scandinavian tundra (Norway), growing on a competition-free boulder field. We dated and provided a growth chronology of the oldest living shrub population (190 ± 148 years) from Scandinavia with the oldest individual being 683 years old. This is a conservative estimate, as shrubs in extreme environments do not form even a single row of cells in some years. The cross-dating issues of poorly growing shrubs do not fully allow to rely on climate sensitivity of the juniper population studied, although the species' potential for dendroclimatological reconstructions is generally considered high, also because the common juniper is an abundant woody species distributed globally. Old populations present an important gene source in plant recruitment, particularly in the context of the present environmental change.
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Authors
Michal SposobAbstract
This study aimed to evaluate and optimize trickle bed reactor (TBR) performance for biological biogas upgrading at different gas loading rates (10-35 m3/m3d) by adjusting H2 flow (H2/CO2 ratio 4-3.7) and utilizing various packing materials. The three TBR reactors operated at thermophilic conditions (50○C) with different packing materials under same gas loading rate. Obtained results indicated that optimal performance was achieved at a gas loading rate of 14.3 m3/m3d and H2/CO2 ratio of 3.7, with average CH4 concentrations in the effluent gas from 90.8 % to 91.5 %, regardless of the packing material employed. Increasing the gas loading rate resulted in decreased CH4 content (<90 %), indicating limited treatment capacity at higher loading rates. The studied packing materials had a slight impact on reactor performance indicating that the shape of the making material has a greater influence of the reactor performance. Microbial communities analyses revealed dominance of hydrogenotrophic methanogens (Methanobacterium, Methanothermobacter, and Methanoculleus). This study highlights the importance of optimizing the H2/CO2 and considering packing materials for TBR performance.
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Authors
Qiang Liu Haoyu Zhang Shou Chen Yeqing Li Mahmoud Mazarji Lu Feng Junting Pan Hongjun Zhou Chunming XuAbstract
Humic acids (HAs), whether naturally present in anaerobic digestion (AD) substrates or HAs newly formed during fermentation, can become inhibitory to methanogenesis as their concentrations reach certain levels. This study delved extensively into the mechanism underlying the alleviation of HAs inhibition in photo-AD by N-doped carbon quantum dots (NCQDs). These NCQDs were efficiently synthesized from straw using an environmentally friendly pretreatment method. Our proposed method harnessed the combined effect of light exposure and NCQDs, resulting in synergistic enhancement of the cumulative CH4 yield within the HA-inhibited AD system, achieving a remarkable yield of 293.7 ± 17.7 mL/g VS. In-depth analyses were conducted on the remaining dissolved organic matter (DOM) within digesters using 3D-EEM and ESI FT-ICR MS. Simultaneously, the remaining HAs were extracted and subjected to FT-IR analysis. The findings revealed that NCQDs effectively degraded humic acid-like components in DOM into smaller, more manageable micromolecules characterized by lower carbon numbers and reduced double bond equivalent. Additionally, under the influence of light, NCQDs promoted the degradation of aromatic components within HAs. These resulting micromolecules were made readily available for utilization by microorganisms, further contributing to methanogenesis. Furthermore, photoelectrochemical analysis and specific gene qPCR analysis revealed that the photoelectrons from NCQDs and HAs were received and transferred by Ech (electron acceptors) for methanogenesis. Remarkably, this methanogenesis pathway, akin to photosynthesis, played a pivotal and transformative role in the photo-AD system. This work comprehensively revealed the remarkable potential mechanism of semiconductors within the photo-AD system, offering profound insights that can catalyze the development of innovative AD reactors and semiconductor accelerators.
Authors
Annette Folkedal SchjøllAbstract
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Authors
Carl-Fredrik Johannesson Jenni Nordén Holger Lange Hanna Marika Silvennoinen Klaus Steenberg LarsenAbstract
Non-steady-state chambers are often used for greenhouse gas flux measurements, and while there are recommendations on how long to keep the chamber closed, it is less investigated to what extent the length of the chamber closure period affects the estimated flux rates and which closure periods may provide the most accurate linear and non-linear flux estimates. Previous studies have shown that the closure of non-steady-state chambers induces a non-linear concentration development inside the chamber, even across short chamber closure periods, and that both linear and non-linear flux estimates are impacted by the chamber closure period itself. Based on 3,159 individual soil CO2 and CH4 flux measurements, we analyzed how linear regression and Hutchinson and Mosier (1981) modeled flux estimates are affected by the length of the chamber closure period by increasing it in increments of 30 sec, with a minimum and maximum chamber closure period of 60 and 300 sec, respectively. Across all detected flux measurements, the effect of chamber closure period length varied between 1.4–8.0 % for linear regression estimates and between 0.4–17.8 % for Hutchinson–Mosier estimates, and the largest effect sizes were observed in high flux regions. While both linear regression and Hutchinson–Mosier based estimates decreased as the chamber closure period increased, we observed a clear convergence of flux estimates as shorter and longer chamber closure periods were used for linear regression and Hutchinson–Mosier based estimation, respectively. This suggests using closure periods as short as possible for linear regression flux estimation or ensuring long-enough closure periods to observe a stabilization of Hutchinson–Mosier flux estimates over time. This analysis was based on soil flux measurements, but because the perturbation of the concentration gradient is related to the non-steady-state chamber technique rather than the measured ecosystem component, our results have implications for all flux measurements conducted with non-steady-state chambers.
Abstract
• For more than 20 years, methyl jasmonate (MeJA) has been used to study inducible defenses in conifers and to increase tree resistance to pests and pathogens. Despite the numerous studies on the subject, no attempts have been made to summarize or quantify how MeJA affects resistance and growth in conifers. Here we present a quantitative meta-analysis of the effects of MeJA treatment on the conifer genera Pinus and Picea, two of the most economically and ecologically important tree genera in boreal, temperate, and alpine forests. • A literature search yielded 120 relevant papers. We summarized the key experimental methods used in these papers and performed a meta-analysis of how MeJA affects tree growth and resistance to pests and pathogens. • The results show that MeJA negatively affects tree growth, with an overall effect size of −0.63. The overall effect size of MeJA for tree resistance was −0.76, indicating that MeJA treatment significantly reduces tree damage caused by biotic stressors. • Although our meta-analysis shows that MeJA is effective in enhancing conifer defenses, there are still gaps in our understanding of the durability and ecological consequences of MeJA treatment. We provide suggestions for how future research should be conducted to address these gaps.