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| 2. |
- Bååth, Erland, et al.
(author)
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Impact of microbial-feeding animals on total soil activity and nitrogen dynamics - a soil microcosm experiment
- 1981
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In: Oikos. - 1600-0706. ; 37:3, s. 257-264
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Journal article (peer-reviewed)abstract
- Abstract in UndeterminedThe long-term impact of microbial-feeding animals on microbial populations was studied in microcosms containing pine seedlings growing in a gamma sterilized humus-sand mixture. Organism communities of diverse complexity were introduced into the microcosms. The two main experimental series contained microorganisms only and microorganisms and microorganism-feeding nematodes, respectively. After 18 months the following analyses were made: soil chemical characteristics, weight and nitrogen content of the seedlings, soil respiration, abundance, biomass, and in some cases, species composition of the different soil organism populations. During the incubation, leaching of nitrogen from the microcosms was measured continuously. The rate of nitrogen leaching from the microcosms increased during the first 6 months. During the remaining 12 months the leaching stabilized at a low rate. Initially, the series with microbial-feeding nematodes had a lower rate of nitrogen loss through leaching compared to the series with only microorganisms added. Towards the end of the experiment the situation was reversed. The pine seedlings showed a very poor growth in all series with no significant differences between the treatments. In the microcosms, bacteria appeared to be the most important microorganism group; fungi, algae and yeasts were present in low amounts. The presence of bacterial feeding nematodes reduced the number of bacteria but did not reduce the soil respiration rate. A significant correlation was obtained between the numbers of nematodes and the respiration rate of the microcosms, which is interpreted as an increased bacterial production rate due to the presence of bacterial-feeding animals.
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| 3. |
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| 4. |
- Bååth, Erland, et al.
(author)
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Fungal populations in podzolic soil experimentally acidified to simulate acid-rain
- 1984
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In: Microbial Ecology. - 1432-184X. ; 10:3, s. 197-203
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Journal article (peer-reviewed)abstract
- Abstract in UndeterminedThe effect of experimental acidification on the soil microfungalcommunity was studied in the humus layer of a coniferous forest in northern Sweden. The study was made 4 years after the last application of sulfuric acid. Fungal species composition was altered by treatments of 100 and 150 kg sulfuric acid ha-1 each year for 6 years, yet no differences were found between the control treatment and an application of 50 kg ha-1. The abundance of Penicillium spinulosum and Oidiodendron cf. echinulatum II increased with increasing rates of acid application, whereas only small changes were found for other isolated fungal taxa. Soil respiration rate and fluorescein diacetate (FDA)-active fungal biomass were significantly different from the control treatment at all 3 levels of acidification.
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| 6. |
- Lund, B, et al.
(author)
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Novel cluster of alpha-interferon gene sequences in a placental cosmid DNA library.
- 1984
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In: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 81:8, s. 2435-9
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Journal article (peer-reviewed)abstract
- A human cosmid library was constructed and probed with a human alpha interferon (IFN-alpha) cDNA clone. One clone giving a strong hybridizing signal was isolated and characterized. The cosmid DNA insert represents a section of the human genome containing three regions of IFN-alpha-like sequences. The DNA was characterized with restriction endonuclease mapping, thereby allowing comparison to similar linkage groups reported recently and determination of homologous regions on the known physical map. The three IFN-alpha-like sequences were analyzed by a partial sequence analysis. Mapping and sequence data establish this section as a not-yet-described cluster of IFN-alpha sequences in the human genome; however, a part of the section matches to some degree to a previously described genomic region. The region described here could represent genetic polymorphism or a duplicated segment.
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| 7. |
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| 8. |
- Lundgren, B., et al.
(author)
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Bacterial numbers in a pine forest soil in relation to environmental-factors
- 1983
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In: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 15:6, s. 625-630
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Journal article (peer-reviewed)abstract
- Abstract in Undetermined Numbers of soil bacteria stained with acridine orange (AO) or fluorescein diacetate (FDA) were studied for 3 and 2 yr respectively. Three pine forest sites were used and both organic and mineral soil layers were included. Different patterns of fluctuation in bacterial numbers were found each year. Significant correlations were demonstrated between AO-stained bacterial numbers and soil moisture content and between FDA-stained bacteria and the accumulated precipitation during a week before the sampling date. In multiple regression analyses 60–80% of the variation in numbers of AO-stained bacteria could be accounted for by soil moisture and numbers of bacterial-feeding nematodes at the sampling dates, and 30–45% of the variation in numbers of FDA-stained bacteria was accounted for by precipitation.
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| 11. |
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| 12. |
- Söderström, Bengt, et al.
(author)
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Decrease in soil microbial activity and biomasses owing to nitrogen amendments
- 1983
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In: Canadian Journal of Microbiology. - 0008-4166. ; 29:11, s. 1500-1506
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Journal article (peer-reviewed)abstract
- Microbial biomass and soil respiration rate decreased after application of 150 kg NH4NO3–N∙ha−1 to different coniferous forest podzols. The decrease was already found 3 months after fertilization and was still evident after 3–5 years. Changes in pH, organic matter, or water content in the soils could not explain the decreases. In laboratory experiments, several unfertilized forest soils were treated with 2 mg of NH4NO3–N or of urea–nitrogen∙g wet soil−1. The ammonium nitrate addition resulted in severe depressions of the respiration rates during and up to 175 days of incubation and the decrease was evident after about 1 week. The urea treatment initially increased the respiration rate of the soils, but this appeared to be a transitory effect.
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