| 1. |
- Arnebrant, Kristina, et al.
(författare)
-
Changes in microfungal community structure after fertilization of Scots pine forest soil with ammonium-nitrate or urea
- 1990
-
Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 22:3, s. 309-312
-
Tidskriftsartikel (refereegranskat)abstract
- The microfungal population structure of two Scots pine forest soils in Southern Sweden was studied 8–13 yr after nitrogen fertilization. The different fertilizers used. ammonium nitrate and urea. influenced the species composition in different ways. The main effect of the NH4NO3 treatment was an increased isolation frequency of Penicillium spinulosum and 4Oidiodendron echinulatum, while Penicillium cf. brevi-compactum. Mortierella subgenus Mortierella. Chaunopycnis alba and Oidiodendron griseum were isolated less frequently in ammonium nitrate-amended treatments compared to the non-fertilized control. In the urea-fertilized plots the isolation frequency of P. cf. brevi-compactum increased, while that of C. alba. O. echinulatum, O. griseum and P. spinulosum decreased in comparison with control plots. The changes in species composition were most evident at the highest rate of application, 600 kg N ha−1, especially when NH4NO3 was used as a fertilizer.
|
|
| 2. |
- Arnebrant, Kristina, et al.
(författare)
-
Measurements of ATP in forest humus
- 1991
-
Ingår i: Soil Biology & Biochemistry. - 0038-0717. ; 23:6, s. 501-506
-
Tidskriftsartikel (refereegranskat)abstract
- The measurement of ATP as an estimate of microbial biomass C in humus was studied. Three different acid extractants, H2SO4, TCA and H3PO4 were compared, as well as two different buffers, Tris and arsenate. No difference in extraction efficiency was found when the light output was converted to ATP content using internal ATP standards, but the different extraction agents and buffers influenced the light output. Several pretreatments and storage conditions were investigated. Incubation at 25°C for 1–7 days gave ca 50% higher ATP values than incubation at 4°C. Sieving did not affect the result. For long-term storage of humus, 4°C is recommended instead of freezing, since freezing reduced the ATP content to ca 80% of the amount found in humus stored at 4°C after 2 months. Freezing of the humus extract resulted in even larger losses of ATP. Humus from eight coniferous forests in Sweden was investigated with respect to ATP content and microbial biomass, estimated with the substrate induced respiration rate method (SIR). A close linear relationship (r = 0.95) was found between the two types of measurement. Calculated from this relationship the amount of ATP (at 25°C) was 3.2μmg−1 biomass C.
|
|
| 3. |
- Bååth, Erland, et al.
(författare)
-
Growth rate and response of bacterial communities to pH in limed and ash treated forest soils
- 1994
-
Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 26:8, s. 995-1001
-
Tidskriftsartikel (refereegranskat)abstract
- Culturable and total bacterial counts, bacterial growth rate and tolerance to pH, as well as microbial biomass, were studied in two coniferous forest soils. The pH had been changed by addition of lime and wood-ash from 4.3-4.4 to 7.0 in one soil and from 3.9-4.4 to 6.1 in the other. Higher total microbial activities and higher bacterial growth rates, measured as soil respiration rate and thymidine incorporation rate, respectively, were found in the treatments with increased pH. Similar effects of soil pH on the thymidine incorporation rate were found using two different methods, by measuring rates in either a soil slurry with all bacteria present or using a subsample of bacteria extracted from soil after homogenization-centrifugation. The number of culturable bacteria was up to 5.1 times higher in the high pH soils, while the acridine orange direct counts were unaffected by the treatments. Thus, the proportions of culturable bacteria increased in the limed and ash-treated soils compared to the untreated controls. An altered bacterial community composition due to liming was indicated by an altered response to pH, where the pH of the soil was correlated to the optimum pH for growth of the bacterial community. The ATP content of the soil was unaffected or increased in treatments with high pH compared to the control, while microbial biomass estimated by the substrate induced respiration technique (SIR) was always higher in limed and ash-treated plots.
|
|
| 4. |
|
|
| 5. |
- Bååth, Erland, et al.
(författare)
-
Microfungi in coniferous forest soils treated with lime or wood ash
- 1993
-
Ingår i: Biology and Fertility of Soils. - 0178-2762. ; 15:2, s. 91-95
-
Tidskriftsartikel (refereegranskat)abstract
- Microfungal species composition was studied in coniferous forest soils which had been treated with lime or wood ash. The pH increased by about 2.5 units at the highest rate of application. Fungi were isolated 4–5 years after the treatments using a soil washing technique. At one site, Öringe, clear differences in species composition due to liming were found. Penicillium spinulosum, Oidiodendron cf. truncatum, Mortierella spp., and two sterile taxa decreased in abundance in limed areas, while Geomyces pannorum, Penicillium cf. brevicompactum, Trichoderma polysporum, and Trichosporiella sporotrichioides increased in isolation frequency. At another site, Torrmyra, the effect of liming was less pronounced, although the pH changes due to the treatments were larger compared to the Öringe site. However, T. polysporum increased, while a sterile taxon decreased in abundance in lime- and wood ash-treated plots. The changes in microfungal species composition after liming were similar to those found earlier in urea-treated soils, and opposite to those found in artifically acidified or ammonium nitrate-fertilized soils
|
|
| 6. |
- Nilsson, M., et al.
(författare)
-
The microfungal communities of a mixed mire in northern Sweden
- 1992
-
Ingår i: Canadian Journal of Botany. - : Canadian Science Publishing. - 0008-4026. ; 70:2, s. 272-276
-
Tidskriftsartikel (refereegranskat)abstract
- The microfungal communities of a mire in northern Sweden were studied. Three plant communities were sampled at two depths, one dry ombrotrophic, one wet ombrotrophic, and one wet minerotrophic site. The fungi were isolated on malt agar using the dilution-plate technique. The most commonly isolated species were Chaunopychnis alba, Mortierella isabellina, Mortierella pulchella, Mycelium radicis atrovirens, Penicillium spinulosum, and a sterile isolate. Penicillium spinulosum, Penicillium thomii, and Mortierella pulchella were dominant in the hummocks, whereas Mycelium radicis atrovirens, Cladosporium sp., and one unidentified isolate were found more often in the wet plant communities. Chaunopychnis alba was isolated more frequently at the minerotrophic site compared with the other two sites. Cladosporium sp., Verticillium bulbillosum, a sterile isolate, and several yeast taxa were most abundant close to the surface. Species composition was most different between the dry hummocks and the two wet sites. In the hummocks the fungal community was more similar between the two depths than in the lawns where the groundwater surface was close to the vegetation surface.
|
|
