| 1. |
- Rinnan, Riikka, et al.
(författare)
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Fifteen years of climate change manipulations alter soil microbial communities in a subarctic heath ecosystem
- 2007
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 13:1, s. 28-39
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Forskningsöversikt (refereegranskat)abstract
- Soil microbial biomass in arctic heaths has been shown to be largely unaffected by treatments simulating climate change with temperature, nutrient and light manipulations. Here, we demonstrate that more than 10 years is needed for development of significant responses, and that changes in microbial biomass are accompanied with strong alterations in microbial community composition. In contrast to slight or nonsignificant responses after 5, 6 and 10 treatment years, 15 years of inorganic NPK fertilizer addition to a subarctic heath had strong effects on the microbial community and, as observed for the first time, warming and shading also led to significant responses, often in opposite direction to the fertilization responses. The effects were clearer in the top 5 cm soil than at the 5-10 cm depth. Fertilization increased microbial biomass C and more than doubled microbial biomass P compared to the non-fertilized plots. However, it only increased microbial biomass N at the 5-10 cm depth. Fertilization increased fungal biomass and the relative abundance of phospholipid fatty acid (PLFA) markers of gram-positive bacteria. Warming and shading decreased the relative abundance of fungal PLFAs, and shading also altered the composition of the bacterial community. The long time lag in responses may be associated with indirect effects of the gradual changes in the plant biomass and community composition. The contrasting responses to warming and fertilization treatments show that results from fertilizer addition may not be similar to the effects of increased nutrient mineralization and availability following climatic warming.
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| 2. |
- Rinnan, Riikka, et al.
(författare)
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Temperature adaptation of soil bacterial communities along an Antarctic climate gradient: predicting responses to climate warming
- 2009
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 15:11, s. 2615-2625
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Tidskriftsartikel (refereegranskat)abstract
- Soil microorganisms, the central drivers of terrestrial Antarctic ecosystems, are being confronted with increasing temperatures as parts of the continent experience considerable warming. Here we determined short-term temperature dependencies of Antarctic soil bacterial community growth rates, using the leucine incorporation technique, in order to predict future changes in temperature sensitivity of resident soil bacterial communities. Soil samples were collected along a climate gradient consisting of locations on the Antarctic Peninsula ( Anchorage Island, 67 degrees 34'S, 68 degrees 08'W), Signy Island (60 degrees 43'S, 45 degrees 38'W) and the Falkland Islands (51 degrees 76'S 59 degrees 03'W). At each location, experimental plots were subjected to warming by open top chambers (OTCs) and paired with control plots on vegetated and fell-field habitats. The bacterial communities were adapted to the mean annual temperature of their environment, as shown by a significant correlation between the mean annual soil temperature and the minimum temperature for bacterial growth (T-min). Every 1 degrees C rise in soil temperature was estimated to increase T-min by 0.24-0.38 degrees C. The optimum temperature for bacterial growth varied less and did not have as clear a relationship with soil temperature. Temperature sensitivity, indicated by Q(10) values, increased with mean annual soil temperature, suggesting that bacterial communities from colder regions were less temperature sensitive than those from the warmer regions. The OTC warming (generally <1 degrees C temperature increases) over 3 years had no effects on temperature relationship of the soil bacterial community. We estimate that the predicted temperature increase of 2.6 degrees C for the Antarctic Peninsula would increase T-min by 0.6-1 degrees C and Q(10) (0-10 degrees C) by 0.5 units.
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| 3. |
- Rousk, Johannes, et al.
(författare)
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Temperature adaptation of bacterial communities in experimentally warmed forest soils
- 2012
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 18:10, s. 3252-3258
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Tidskriftsartikel (refereegranskat)abstract
- A detailed understanding of the influence of temperature on soil microbial activity is critical to predict future atmospheric CO2 concentrations and feedbacks to anthropogenic warming. We investigated soils exposed to 3-4 years of continuous 5 degrees C-warming in a field experiment in a temperate forest. We found that an index for the temperature adaptation of the microbial community, T-min for bacterial growth, increased by 0.19 degrees C per 1 degrees C rise in temperature, showing a community shift towards one adapted to higher temperature with a higher temperature sensitivity (Q(10(5-15 degrees C)) increased by 0.08 units per 1 degrees C). Using continuously measured temperature data from the field experiment we modelled in situ bacterial growth. Assuming that warming did not affect resource availability, bacterial growth was modelled to become 60% higher in warmed compared to the control plots, with the effect of temperature adaptation of the community only having a small effect on overall bacterial growth (<5%). However, 3 years of warming decreased bacterial growth, most likely due to substrate depletion because of the initially higher growth in warmed plots. When this was factored in, the result was similar rates of modelled in situ bacterial growth in warmed and control plots after 3 years, despite the temperature difference. We conclude that although temperature adaptation for bacterial growth to higher temperatures was detectable, its influence on annual bacterial growth was minor, and overshadowed by the direct temperature effect on growth rates.
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| 4. |
- Li, Jinquan, et al.
(författare)
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Temperature adaptation of soil microbial respiration in alpine, boreal and tropical soils : An application of the square root (Ratkowsky) model
- 2021
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27:6, s. 1281-1292
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Tidskriftsartikel (refereegranskat)abstract
- Warming is expected to stimulate soil microbial respiration triggering a positive soil carbon-climate feedback loop while a consensus remains elusive regarding the magnitude of this feedback. This is partly due to our limited understanding of the temperature-adaptive response of soil microbial respiration, especially over broad climatic scales. We used the square root (Ratkowsky) model to calculate the minimum temperature for soil microbial respiration (Tmin, which describes the temperature adaptation of soil microbial respiration) of 298 soil samples from alpine grasslands on the Tibetan Plateau and forest ecosystems across China with a mean annual temperature (MAT) range from −6°C to +25°C. The instantaneous soil microbial respiration was determined between 4°C and 28°C. The square root model could well fit the temperature effect on soil microbial respiration for each individual soil, with R2 higher than 0.98 for all soils. Tmin ranged from −8.1°C to −0.1°C and increased linearly with increasing MAT (R2 = 0.68). MAT dominantly regulated Tmin variation when accounting simultaneously for multiple other drivers (mean annual precipitation, soil pH and carbon quality); an independent experiment showed that carbon availability had no significant effect on Tmin. Using the relationship between Tmin and MAT, soil microbial respiration after an increased MAT could be estimated, resulting in a relative increase in respiration with decreasing MAT. Thus, soil microbial respiration responses are adapted to long-term temperature differences in MAT. We suggest that Tmin = −5 + 0.2 × MAT, that is, every 1°C rise in MAT is estimated to increase Tmin of respiration by approximately 0.2°C, could be used as a first approximation to incorporate temperature adaptation of soil microbial respiration in model predictions. Our results can be used to predict future changes in the response of soil microbial respiration to temperature over different levels of warming and across broad geographic scales with different MAT.
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| 5. |
- Nottingham, Andrew T., et al.
(författare)
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Adaptation of soil microbial growth to temperature : Using a tropical elevation gradient to predict future changes
- 2019
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25:3, s. 827-838
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial biogeochemical feedbacks to the climate are strongly modulated by the temperature response of soil microorganisms. Tropical forests, in particular, exert a major influence on global climate because they are the most productive terrestrial ecosystem. We used an elevation gradient across tropical forest in the Andes (a gradient of 20°C mean annual temperature, MAT), to test whether soil bacterial and fungal community growth responses are adapted to long-term temperature differences. We evaluated the temperature dependency of soil bacterial and fungal growth using the leucine- and acetate-incorporation methods, respectively, and determined indices for the temperature response of growth: Q10 (temperature sensitivity over a given 10oC range) and Tmin(the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q10and Tmin of growth. Across a MAT range from 6°C to 26°C, the Q10and Tmin varied for bacterial growth (Q10–20 = 2.4 to 3.5; Tmin = −8°C to −1.5°C) and fungal growth (Q10–20 = 2.6 to 3.6; Tmin = −6°C to −1°C). Thus, bacteria and fungi did not differ significantly in their growth temperature responses with changes in MAT. Our findings indicate that across natural temperature gradients, each increase in MAT by 1°C results in increases in Tmin of microbial growth by approximately 0.3°C and Q10–20by 0.05, consistent with long-term temperature adaptation of soil microbial communities. A 2°C warming would increase microbial activity across a MAT gradient of 6°C to 26°C by 28% to 15%, respectively, and temperature adaptation of microbial communities would further increase activity by 1.2% to 0.3%. The impact of warming on microbial activity, and the related impact on soil carbon cycling, is thus greater in regions with lower MAT. These results can be used to predict future changes in the temperature response of microbial activity over different levels of warming and over large temperature ranges, extending to tropical regions.
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| 6. |
- van Gestel, Natasja C., et al.
(författare)
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Comparing temperature sensitivity of bacterial growth in Antarctic marine water and soil
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:4, s. 2280-2291
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Tidskriftsartikel (refereegranskat)abstract
- The western Antarctic Peninsula is an extreme low temperature environment that is warming rapidly due to global change. Little is known, however, on the temperature sensitivity of growth of microbial communities in Antarctic soils and in the surrounding oceanic waters. This is the first study that directly compares temperature adaptation of adjacent marine and terrestrial bacteria in a polar environment. The bacterial communities in the ocean were adapted to lower temperatures than those from nearby soil, with cardinal temperatures for growth in the ocean being the lowest so far reported for microbial communities. This was reflected in lower minimum (Tmin) and optimum temperatures (Topt) for growth in water (−17 and +20°C, respectively) than in soil (−11 and +27°C), with lower sensitivity to changes in temperature (Q10; 0–10°C interval) in Antarctic water (2.7) than in soil (3.9). This is likely due to the more stable low temperature conditions of Antarctic waters than soils, and the fact that maximum in situ temperatures in water are lower than in soils, at least in summer. Importantly, the thermally stable environment of Antarctic marine water makes it feasible to create a single temperature response curve for bacterial communities. This would thus allow for calculations of temperature-corrected growth rates, and thereby quantifying the influence of factors other than temperature on observed growth rates, as well as predicting the effects of future temperature increases on Antarctic marine bacteria.
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| 7. |
- Barcenas-Moreno, Gema, et al.
(författare)
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Adaptation of soil microbial communities to temperature: comparison of fungi and bacteria in a laboratory experiment
- 2009
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 15:12, s. 2950-2957
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Tidskriftsartikel (refereegranskat)abstract
- Temperature not only has direct effects on microbial activity, but can also affect activity indirectly by changing the temperature dependency of the community. This would result in communities performing better over time in response to increased temperatures. We have for the first time studied the effect of soil temperature (5-50 degrees C) on the community adaptation of both bacterial (leucine incorporation) and fungal growth (acetate-in-ergosterol incorporation). Growth at different temperatures was estimated after about a month using a short-term assay to avoid confounding the effects of temperature on substrate availability. Before the experiment started, fungal and bacterial growth was optimal around 30 degrees C. Increasing soil temperature above this resulted in an increase in the optimum for bacterial growth, correlated to soil temperature, with parallel shifts in the total response curve. Below the optimum, soil temperature had only minor effects, although lower temperatures selected for communities growing better at the lowest temperature. Fungi were affected in the same way as bacteria, with large shifts in temperature tolerance at soil temperatures above that of optimum for growth. A simplified technique, only comparing growth at two contrasting temperatures, gave similar results as using a complete temperature curve, allowing for large scale measurements also in field situations with small differences in temperature.
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| 8. |
- Bååth, Erland, et al.
(författare)
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Soil and rhizosphere microorganisms have the same Q(10) for respiration in a model system
- 2003
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 9:12, s. 1788-1791
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Tidskriftsartikel (refereegranskat)abstract
- We compared the Q10 relationship for root-derived respiration (including respiration due to the root, external mycorrhizal mycelium and rhizosphere microorganisms) with that of mainly external ectomycorrhizal mycelium and that of bulk soil microorganisms without any roots present. This was studied in a microcosm consisting of an ectomycorrhizal Pinus muricata seedling growing in a sandy soil, and where roots were allow to colonize one soil compartment, mycorrhizal mycelium another compartment, and the last compartment consisted of root- and mycorrhiza-free soil. The respiration rate in the bulk soil compartment was 30 times lower than in the root compartment, while that in the mycorrhizal compartment was six times lower. There were no differences in Q10 (for 5-15°C) between the different compartments, indicating that there were no differences in the temperature relationship between root-associated and non-root-associated organisms. Thus, there are no indications that different Q10 values should be used for different soil organism, bulk soil or rhizosphere-associated microorganisms when modelling the effects of global climate change.
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| 9. |
- Rinnan, Riikka, et al.
(författare)
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Plant-mediated effects of elevated ultraviolet-B radiation on peat microbial communities of a subarctic mire
- 2008
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 14:4, s. 925-937
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Tidskriftsartikel (refereegranskat)abstract
- Elevated ultraviolet-B (UVB) radiation has been reported to have few effects on plants but to alter the soil microbial community composition. However, the effects on soil microorganisms have to be mediated via plants, because direct radiation effects are only plausible on the uppermost millimeters of soil. Here, we assessed secondary effects of UVB on soil microbes. The responses in the dominant plant Eriophorum russeolum, peat pore water and microbial communities in the peat were recorded at a subarctic mire in the middle of the third growing season under field exposure simulating 20% depletion in the ozone layer. The UVB treatment significantly reduced the sucrose and the total soluble sugar (sucrose+glucose+fructose) concentration of the plant leaves while increasing the sucrose concentration in the belowground storage organ rhizome. The starch concentration of the leaves was also slightly reduced by elevated UVB. In the plant roots, carbohydrate concentrations remained unaffected but the total phenolics concentration increased under elevated UVB. We suggest that the simultaneously observed decrease in bacterial growth rate and the altered bacterial community composition are due to UVB-induced changes in the plant photosynthate allocation and potential changes in root exudation. There were no effects of elevated UVB on microbial biomass, peat pore water or nutrient concentrations in the peat. The observed responses are in line with the previously reported lower ecosystem dark respiration under elevated UVB, and they signify that the changed plant tissue quality and lower bacterial activity are likely to reduce decomposition.
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