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Palmqvist, Kristin
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Publications (10 of 35) Show all publications
Maaroufi, N. I., Nordin, A., Palmqvist, K., Hasselquist, N. J., Forsmark, B., Rosenstock, N. P., . . . Gundale, M. J. (2019). Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity. Global Change Biology, Article ID NBORG T, 1990, VEGETATIO, V90, P1 rg Bjorn, 1997, Environmental Reviews, V5, P1 ndahl Bjorn D., 2007, NEW PHYTOLOGIST, V173, P611 erer Noah, 2012, ISME JOURNAL, V6, P1007 sanen J., 2013, vegan: Community Ecology Package. R Package Version 2. 0-10, ndahl Bjorn D., 2010, ISME JOURNAL, V4, P872 ide Roger T., 2014, NEW PHYTOLOGIST, V201, P433.
Open this publication in new window or tab >>Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity
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2019 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, article id NBORG T, 1990, VEGETATIO, V90, P1 rg Bjorn, 1997, Environmental Reviews, V5, P1 ndahl Bjorn D., 2007, NEW PHYTOLOGIST, V173, P611 erer Noah, 2012, ISME JOURNAL, V6, P1007 sanen J., 2013, vegan: Community Ecology Package. R Package Version 2. 0-10, ndahl Bjorn D., 2010, ISME JOURNAL, V4, P872 ide Roger T., 2014, NEW PHYTOLOGIST, V201, P433Article in journal (Refereed) Epub ahead of print
Abstract [en]

There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal forest soils. However, it is unclear how free-living saprotrophs (bacteria and fungi, SAP) and ectomycorrhizal (EM) fungi responses to N addition impact soil C dynamics. Our aim was to investigate how SAP and EM communities are impacted by N enrichment and to estimate whether these changes influence decay of litter and humus. We conducted a long-term experiment in northern Sweden, maintained since 2004, consisting of ambient, low N additions (0, 3, 6, and 12 kg N ha(-1) year(-1)) simulating current N deposition rates in the boreal region, as well as a high N addition (50 kg N ha(-1) year(-1)). Our data showed that long-term N enrichment impeded mass loss of litter, but not of humus, and only in response to the highest N addition treatment. Furthermore, our data showed that EM fungi reduced the mass of N and P in both substrates during the incubation period compared to when only SAP organisms were present. Low N additions had no effect on microbial community structure, while the high N addition decreased fungal and bacterial biomasses and altered EM fungi and SAP community composition. Actinomycetes were the only bacterial SAP to show increased biomass in response to the highest N addition. These results provide a mechanistic understanding of how anthropogenic N enrichment can influence soil C accumulation rates and suggest that current N deposition rates in the boreal region (<= 12 kg N ha(-1) year(-1)) are likely to have a minor impact on the soil microbial community and the decomposition of humus and litter.

Place, publisher, year, edition, pages
WILEY, 2019
Keywords
carbon sequestration, ecological stoichiometry, Gadgil effect, high-throughput sequencing, ingrowth sh bags, ITS amplicons, litter decomposition, root exclosure, soil organic matter
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-162001 (URN)10.1111/gcb.14722 (DOI)000477200000001 ()31166650 (PubMedID)
Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13
Eriksson, A., Gauslaa, Y., Palmqvist, K., Ekström, M. & Esseen, P.-A. (2018). Morphology drives water storage traits in the globally widespreadlichen genus Usnea. Fungal ecology, 35, 51-61
Open this publication in new window or tab >>Morphology drives water storage traits in the globally widespreadlichen genus Usnea
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2018 (English)In: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 35, p. 51-61Article in journal (Refereed) Published
Abstract [en]

Links between lichen morphology, internal/external water storage and distribution patterns are poorly known. We compared mass- (WC, % H2O) and area-based (WHC, mg H2O cm−2) hydration traits in seven pendent or shrubby Usnea species from oceanic to continental climates. All species held more external than internal water. Internal WHC and WC increased with specific thallus mass (STM, mg cm−2), while external WC decreased. Shrubby species had higher STM and total WHC than pendent ones. The continental Usnea hirta (shrubby) had the highest total and external storage; the suboceanic Usnea longissima (pendent) had the lowest internal storage. Morphology drives hydration traits and explains distributions of some Usnea species, but such traits did not distinguish oceanic from widespread species. Shrubby species maximize water storage and thus prolong hydration after rainfall events and/or hydration by dew. The low internal WHC in pendent species is likely an adaptation to frequent hydration in humid air.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Epiphytic lichens, Functional traits, Specific thallus mass, Water-holding capacity, Water content
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-151932 (URN)10.1016/j.funeco.2018.06.007 (DOI)000444930900006 ()2-s2.0-85050654829 (Scopus ID)
Funder
Swedish Research Council Formas, 2016-00553
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2018-10-05Bibliographically approved
Maaroufi, N. I., Palmqvist, K., Bach, L. H., Bokhorst, S., Liess, A., Gundale, M. J., . . . Meunier, C. L. (2018). Nutrient optimization of tree growth alters structure and function of boreal soil food webs. Forest Ecology and Management, 428, 46-56
Open this publication in new window or tab >>Nutrient optimization of tree growth alters structure and function of boreal soil food webs
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2018 (English)In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 428, p. 46-56Article in journal (Refereed) Published
Abstract [en]

Nutrient optimization has been proposed as a way to increase boreal forest production, and involves chronic additions of liquid fertilizer with amounts of micro- and macro-nutrients adjusted annually to match tree nutritional requirements. We used a short-term (maintained since 2007) and a long-term (maintained since 1987) fertilization experiment in northern Sweden, in order to understand nutrient optimization effects on soil microbiota and mesofauna, and to explore the relationships between plant litter and microbial elemental stoichiometry. Soil microbes, soil fauna, and aboveground litter were collected from the control plots, and short- and long-term nutrient optimization plots. Correlation analyses revealed no relationships between microbial biomass and litter nutrient ratios. Litter C:N, C:P and N:P ratios declined in response to both optimization treatments; while only microbial C:P ratios declined in response to long-term nutrient optimization. Further, we found that both short- and long-term optimization treatments decreased total microbial, fungal, and bacterial PLFA biomass and shifted the microbial community structure towards a lower fungi:bacterial ratio. In contrast, abundances of most fungal- and bacterial-feeding soil biota were little affected by the nutrient optimization treatments. However, abundance of hemi-edaphic Collembola declined in response to the long-term nutrient optimization treatment. The relative abundances (%) of fungal-feeding and plant-feeding nematodes, respectively, declined and increased in response to both short-term and long-term treatments; bacterial-feeding nematodes increased relative to fungal feeders. Overall, our results demonstrate that long-term nutrient optimization aiming to increase forest production decreases litter C:N, C:P and N:P ratios, microbial C:P ratios and fungal biomass, whereas higher trophic levels are less affected.

Keywords
Nematode, Mesofauna, Microbes, Boreal forest, Ecological stoichiometry, Leaf litter quality, Nutrient tios
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-150809 (URN)10.1016/j.foreco.2018.06.034 (DOI)000440770600006 ()
Funder
Swedish Research Council Formas, 2010-67
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2018-08-20Bibliographically approved
Maaroufi, N. I., Nordin, A., Palmqvist, K. & Gundale, M. J. (2017). Nitrogen enrichment impacts on boreal litter decomposition are driven by changes in soil microbiota rather than litter quality. Scientific Reports, 7, Article ID 4083.
Open this publication in new window or tab >>Nitrogen enrichment impacts on boreal litter decomposition are driven by changes in soil microbiota rather than litter quality
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 4083Article in journal (Refereed) Published
Abstract [en]

In nitrogen (N) limited boreal forests, N enrichment can impact litter decomposition by affecting litter quality and by changing the soil environment where litter decomposes. We investigated the importance of litter quality and soil factors on litter decomposition using a 2-year reciprocal transplant experiment for Picea abies needle litter, derived from plots subjected to 17 years of N addition, including control, low and high N treatments (ambient, 12.5 and 50 kg N ha(-1) yr(-1), respectively). Our data show that changes in soil factors were the main pathway through which N impacted litter decomposition, with rates reduced by approximate to 15% when placed in high N relative to control plots, regardless of litter origin. Litter decomposition was correlated to soil microbiota, with Picea abies litter decomposition positively correlated with gram negative and fungal functional groups. Our results suggest that previous findings of increase soil C accumulation in response to N deposition is likely to occur as a result of changes in soil microbiota rather than altered litter quality.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-140236 (URN)10.1038/s41598-017-04523-w (DOI)000403874900066 ()28642496 (PubMedID)
Available from: 2017-10-20 Created: 2017-10-20 Last updated: 2018-06-09Bibliographically approved
Palmqvist, K., Franklin, O. & Nasholm, T. (2017). Symbiosis constraints: Strong mycobiont control limits nutrient response in lichens. Ecology and Evolution, 7(18), 7420-7433
Open this publication in new window or tab >>Symbiosis constraints: Strong mycobiont control limits nutrient response in lichens
2017 (English)In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 7, no 18, p. 7420-7433Article in journal (Refereed) Published
Abstract [en]

Symbioses such as lichens are potentially threatened by drastic environmental changes. We used the lichen Peltigera aphthosaa symbiosis between a fungus (mycobiont), a green alga (Coccomyxa sp.), and N-2-fixing cyanobacteria (Nostoc sp.)as a model organism to assess the effects of environmental perturbations in nitrogen (N) or phosphorus (P). Growth, carbon (C) and N stable isotopes, CNP concentrations, and specific markers were analyzed in whole thalli and the partners after 4months of daily nutrient additions in the field. Thallus N was 40% higher in N-fertilized thalli, amino acid concentrations were twice as high, while fungal chitin but not ergosterol was lower. Nitrogen also resulted in a thicker algal layer and density, and a higher C-13 abundance in all three partners. Photosynthesis was not affected by either N or P. Thallus growth increased with light dose independent of fertilization regime. We conclude that faster algal growth compared to fungal lead to increased competition for light and CO2 among the Coccomyxa cells, and for C between alga and fungus, resulting in neither photosynthesis nor thallus growth responded to N fertilization. This suggests that the symbiotic lifestyle of lichens may prevent them from utilizing nutrient abundance to increase C assimilation and growth.

Place, publisher, year, edition, pages
WILEY, 2017
Keywords
CN stable isotopes, lichen, nitrogen, Peltigera aphthosa (L, ) Willd, phosphorus, photosynthesis, source allocation, symbiosis
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-140474 (URN)10.1002/ece3.3257 (DOI)000411341800023 ()28944027 (PubMedID)
Projects
Bio4Energy
Available from: 2017-10-25 Created: 2017-10-25 Last updated: 2019-09-06Bibliographically approved
Esseen, P.-A., Ekström, M., Westerlund, B., Palmqvist, K., Jonsson, B. G., Grafström, A. & Ståhl, G. (2016). Broad-scale distribution of epiphytic hair lichens correlates more with climate and nitrogen deposition than with forest structure. Canadian Journal of Forest Research, 46(11), 1348-1358
Open this publication in new window or tab >>Broad-scale distribution of epiphytic hair lichens correlates more with climate and nitrogen deposition than with forest structure
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2016 (English)In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 46, no 11, p. 1348-1358Article in journal (Refereed) Published
Abstract [en]

Hair lichens are strongly influenced by forest structure at local scales, but their broad-scale distributions are less understood. We compared the occurrence and length of Alectoria sarmentosa (Ach.) Ach., Bryoria spp., and Usnea spp. in the lower canopy of > 5000 Picea abies (L.) Karst. trees within the National Forest Inventory across all productive forest in Sweden. We used logistic regression to analyse how climate, nitrogen deposition, and forest variables influence lichen occurrence. Distributions overlapped, but the distribution of Bryoria was more northern and that of Usnea was more southern, with Alectoria's distribution being intermediate. Lichen length increased towards northern regions, indicating better conditions for biomass accumulation. Logistic regression models had the highest pseudo R-2 value for Bryoria, followed by Alectoria. Temperature and nitrogen deposition had higher explanatory power than precipitation and forest variables. Multiple logistic regressions suggest that lichen genera respond differently to increases in several variables. Warming decreased the odds for Bryoria occurrence at all temperatures. Corresponding odds for Alectoria and Usnea decreased in warmer climates, but in colder climates, they increased. Nitrogen addition decreased the odds for Alectoria and Usnea occurrence under high deposition, but under low deposition, the odds increased. Our analyses suggest major shifts in the broad-scale distribution of hair lichens with changes in climate, nitrogen deposition, and forest management.

Place, publisher, year, edition, pages
NRC Research Press, 2016
Keywords
climate change, epiphytic lichens, forest structure, nitrogen deposition, temperature
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-129029 (URN)10.1139/cjfr-2016-0113 (DOI)000386675600012 ()
Projects
Statistical methods for ecological research on data from national monitoring programs. Funded by the Swedish Research Council. Grant Number 340-2013-5076.
Funder
Swedish Research Council, 340-2013-5076
Available from: 2016-12-20 Created: 2016-12-20 Last updated: 2018-06-09Bibliographically approved
Maaroufi, N. I., Nordin, A., Palmqvist, K. & Gundale, M. J. (2016). Chronic Nitrogen Deposition Has a Minor Effect on the Quantity and Quality of Aboveground Litter in a Boreal Forest. PLoS ONE, 11(8), Article ID e0162086.
Open this publication in new window or tab >>Chronic Nitrogen Deposition Has a Minor Effect on the Quantity and Quality of Aboveground Litter in a Boreal Forest
2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 8, article id e0162086Article in journal (Refereed) Published
Abstract [en]

There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal soils. However, key underlying mechanisms explaining this increase have not been resolved. Two potentially important mechanisms are that aboveground litter production increases, or that litter quality changes in response to N enrichment. As such, our aim was to quantify whether simulated chronic N deposition caused changes in aboveground litter production or quality in a boreal forest. We conducted a long-term (17 years) stand-scale (0.1 ha) forest experiment, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1)) in northern Sweden, where background N deposition rates are very low. We measured the annual quantity of litter produced for 8 different litter categories, as well as their concentrations of C, N, phosphorus (P), lignin, cellulose and hemi-cellulose. Our results indicate that mosses were the only major litter component showing significant quantitative and qualitative alterations in response to the N additions, indicative of their ability to intercept a substantial portion of the N added. These effects were, however, offset by the other litter fractions where we found no changes in the total litter fluxes, or individual chemical constituents when all litter categories were summed. This study indicates that the current annual litter fluxes cannot explain the increase in soil C that has occurred in our study system in response to simulated chronic N application. These results suggest that other mechanisms are likely to explain the increased soil C accumulation rate we have observed, such as changes in soil microbial activity, or potentially transient changes in aboveground litter inputs that were no longer present at the time of our study.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-126512 (URN)10.1371/journal.pone.0162086 (DOI)000382877400057 ()27580120 (PubMedID)
Available from: 2016-10-27 Created: 2016-10-10 Last updated: 2018-06-09Bibliographically approved
Maaroufi, N. I., Nordin, A., Hasselquist, N. J., Bach, L. H., Palmqvist, K. & Gundale, M. J. (2015). Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils. Global Change Biology, 21(8), 3169-3180
Open this publication in new window or tab >>Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils
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2015 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 21, no 8, p. 3169-3180Article in journal (Refereed) Published
Abstract [en]

It is proposed that carbon (C) sequestration in response to reactive nitrogen (N-r) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which N-r deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50kgNha(-1)yr(-1)) in the boreal zone of northern Sweden to understand how atmospheric N-r deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of similar to 15% and a significant increase of similar to 30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10kgCkg(-1)N. We also found a concomitant decrease in total microbial and fungal biomasses and a similar to 11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26kgCkg(-1)N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
boreal forest, boreal soil, carbon sequestration, carbon sink, nitrogen deposition, soil C pool, soil spiration
National Category
Environmental Sciences Geology
Identifiers
urn:nbn:se:umu:diva-107288 (URN)10.1111/gcb.12904 (DOI)000358485200029 ()25711504 (PubMedID)
Available from: 2015-08-31 Created: 2015-08-21 Last updated: 2018-06-07Bibliographically approved
Palmroth, S., Holm Bach, L., Nordin, A. & Palmqvist, K. (2014). Nitrogen-addition effects on leaf traits and photosynthetic carbon gain of boreal forest understory shrubs. Oecologia, 175(2), 457-470
Open this publication in new window or tab >>Nitrogen-addition effects on leaf traits and photosynthetic carbon gain of boreal forest understory shrubs
2014 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 175, no 2, p. 457-470Article in journal (Refereed) Published
Abstract [en]

Boreal coniferous forests are characterized by fairly open canopies where understory vegetation is an important component of ecosystem C and N cycling. We used an ecophysiological approach to study the effects of N additions on uptake and partitioning of C and N in two dominant understory shrubs: deciduous Vaccinium myrtillus in a Picea abies stand and evergreen Vaccinium vitis-idaea in a Pinus sylvestris stand in northern Sweden. N was added to these stands for 16 and 8 years, respectively, at rates of 0, 12.5, and 50 kg N ha(-1) year(-1). N addition at the highest rate increased foliar N and chlorophyll concentrations in both understory species. Canopy cover of P. abies also increased, decreasing light availability and leaf mass per area of V. myrtillus. Among leaves of either shrub, foliar N content did not explain variation in light-saturated CO2 exchange rates. Instead photosynthetic capacity varied with stomatal conductance possibly reflecting plant hydraulic properties and within-site variation in water availability. Moreover, likely due to increased shading under P. abies and due to water limitations in the sandy soil under P. sylvestris, individuals of the two shrubs did not increase their biomass or shift their allocation between above- and belowground parts in response to N additions. Altogether, our results indicate that the understory shrubs in these systems show little response to N additions in terms of photosynthetic physiology or growth and that changes in their performance are mostly associated with responses of the tree canopy.

Keywords
Biomass allocation, Chlorophyll content, Photosynthetic capacity, Stomatal conductance, Vaccinium
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-90845 (URN)10.1007/s00442-014-2923-9 (DOI)000336378800003 ()
Available from: 2014-07-22 Created: 2014-07-01 Last updated: 2018-06-07Bibliographically approved
Johansson, O., Palmqvist, K. & Olofsson, J. (2012). Nitrogen deposition drives lichen community changes through differential species responses. Global Change Biology, 18(8), 2626-2635
Open this publication in new window or tab >>Nitrogen deposition drives lichen community changes through differential species responses
2012 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 18, no 8, p. 2626-2635Article in journal (Refereed) Published
Abstract [en]

Nitrogen (N) deposition has increased globally over the last 150 years and further increases are predicted. Epiphytic lichens decline in abundance and diversity in areas with high N loads, and the abundance of lichens decreases along gradients of increased deposition. Thus, although N is an essential nutrient for lichens, excessive loads may be detrimental for them. However, these gradients include many correlated pollutants and the mechanisms behind the decline are thus poorly known. The aim of this study was to assess effects of N deposition, alone, on the epiphytic lichen community composition in a naturally N-poor boreal forest. For this purpose, whole spruce trees were fertilized daily with N at five levels, equivalent to 0.6, 6, 12.5, 25, and 50 kg N ha-1 yr-1, during four consecutive growing seasons (20062009), and changes in the abundance of lichens were monitored each autumn from the preceding year (2005). The studied lichen communities were highly dynamic and responded strongly to the environmental perturbation. N deposition detectably altered the direction of succession and reduced the species richness of the epiphytic lichen communities, even at the lowest fertilization application (6 kg N ha-1 yr-1). The simulated N deposition caused significant changes in the abundance of Alectoria sarmentosa, Bryoria spp., and Hypogymnia physodes, which all increased at low N loads and decreased at high loads, but with species-specific optima. The rapid decline of A. sarmentosa may have been caused by the added nitrogen reducing the stability of the lichen thalli, possibly due to increases in the photobiont: mycobiont ratio or parasitic fungal attacks. We conclude that increases in nitrogen availability, per se, could be responsible for the reductions in lichen abundance and diversity observed along deposition gradients, and those community responses may be due to physiological responses of the individual species rather than changes in competitive interactions.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2012
Keywords
Alectoria sarmentosa, boreal forest, bryoria, diversity, Hypogymnia physodes, lichens, nitrogen deposition, Platismatia glauca, richness
National Category
Earth and Related Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-57599 (URN)10.1111/j.1365-2486.2012.02723.x (DOI)000306228300023 ()
Available from: 2012-08-08 Created: 2012-08-08 Last updated: 2018-06-08Bibliographically approved
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