| 1. |
- Iovieno, Paola, et al.
(författare)
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Effect of drying and rewetting on bacterial growth rates in soil.
- 2008
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 65:3, s. 400-407
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Tidskriftsartikel (refereegranskat)abstract
- The effect of soil moisture on bacterial growth was investigated, and the effects of rewetting were compared with glucose addition because both treatments increase substrate availability. Bacterial growth was estimated as thymidine and leucine incorporation, and was compared with respiration. Low growth rates were found in air-dried soil, increasing rapidly to high stable values in moist soils. Respiration and bacterial growth at different soil moisture contents were correlated. Rewetting air-dried soil resulted in a linear increase in bacterial growth with time, reaching the levels in moist soil (10 times higher) after about 7 h. Respiration rates increased within 1 h to a level >10 times higher than that in moist soil. After the initial flush, there was a gradual decrease in respiration rate, while bacterial growth increased to levels twice that of moist soil 24 h after rewetting, and decreased to levels similar to those in moist soil after 2 days. Adding glucose resulted in no positive effect on bacterial growth during the first 9 h, despite resulting in more than five times higher respiration. This indicated that the initial increase in bacterial growth after rewetting was not due to increased substrate availability.
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| 2. |
- Iovieno, Paola, et al.
(författare)
-
Soil microbial community structure and biomass as affected by Pinus pinea plantation in two Mediterranean areas
- 2010
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 45:1, s. 56-63
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Tidskriftsartikel (refereegranskat)abstract
- Stone pine (Pinus pinea L.) has been widely introduced for afforestation in Mediterranean areas. Despite its wide distribution and its presence since ancient time, it is mostly considered as non-native to the Italian peninsula. Plantation of non-native species may have a strong impact on the soil microbial community and, consequently, on nutrient cycling and soil functions. The effect of stone pine on soil microbial community structure and biomass, as revealed by phospholipid fatty acid (PLFA) analysis and fungal biomass indicators, was investigated in two Mediterranean areas in south Italy, where the climax tree species was holm oak (Quercus ilex L.) and some patches were afforested with stone pine. We studied soils from two sites with different parent material, volcanic lava and limestone (calcareous soil). The soil pH range was wider in the calcareous than in the volcanic soils. At both sites, the soils under stone pine had lower pH and higher organic matter content than under holm oak. Microbial biomass was, on average, 1.3-1.4 fold higher in the soils under holm oak than under stone pine. The PLFA composition was different in soils under stone pine compared with holm oak, while the changes in PLEA composition induced by the different tree species were comparable at the two sites. The changes in the PLFA composition were significantly correlated to soil pH and relative concentrations of PLFA indicators (mol%) previously demonstrated to indicate pH effects were also correlated to pH. Thus, both in the volcanic and the calcareous soils, stone pine plantation affected soil microbial community structure and the mechanism for this change appeared to be soil pH changes. (C) Elsevier B.V. All rights reserved.
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